The Art of Phacoemulsification

The Ar Artt of Phacoemulsification The Ar t of Phacoemulsification Editors Keiki R Mehta MD MBBS DOMS MS (Ophth) FORC...

Author: Keika R. Mehta | John J. Alpar

312 downloads 1403 Views 13MB Size Report

This content was uploaded by our users and we assume good faith they have the permission to share this book. If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below!
Report copyright / DMCA form

DOWNLOAD PDF

The Ar Artt of Phacoemulsification

The Ar t of Phacoemulsification Editors Keiki R Mehta MD MBBS DOMS MS (Ophth) FORCE (India) DO (Ireland)

DO (London) FRSH (London) FIOS (USA) Medical Director: Mehta International Eye Institute Chief: Ophthalmic Services, Colaba Eye Hospital Chief: Surgical Services, Netra Rukshak, Rural Eye Services Wing, Mumbai, India Head: Eye Department, Breach Candy Hospital and Research Centre, Mumbai Hon Ophthalmic Consultant Surgeon: Armed Forces, India Hon Ophthalmic Consultant to the Governor of Maharashtra Past President: All India Ophthalmological Society, Intraocular Implant Society, India and

John J Alpar MD FACS FICS PA Diplomate: American Board of Ophthalmology Diplomate: Hungarian Board of Ophthalmology Clinical Professor: Texas Tech University School of Medicine Medical Director: Panhandle Ophthalmological Research Foundation, Texas, USA Fellow: American Academy of Ophthalmology, Saint Luke Eye Institute Amarilo, Texas, USA

JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD New Delhi

Published by Jitendar P Vij Jaypee Brothers Medical Publishers (P) Ltd B-3 EMCA House, 23/23B Ansari Road, Daryaganj Post Box 7193, New Delhi 110 002, India Phones: 3272143, 3272703, 3282021 Fax: 011-3276490 E-mail: [email protected] Visit our web site: http://www.jpbros.20m.com

Branches • 202 Batavia Chambers, 8 Kumara Kruppa Road, Kumara Park East, Bangalore 560 001, Phones: 2285971, 2382956 Tele Fax: 2281761 E-mail: [email protected] • 1A Indian Mirror Street, Wellington Square Calcutta 700 013, Phone: 2451926 Fax: 2456075 E-mail: [email protected] • 282 IIIrd Floor, Khaleel Shirazi Estate, Fountain Plaza Pantheon Road, Chennai 600 008, Phone: 8262665 Fax: 8262331 E-mail: [email protected] • 106 Amit Industrial Estate, 61 Dr SS Rao Road, Near MGM Hospital Parel, Mumbai 400 012 , Phones: 4124863, 4104532 Fax: 4160828 E-mail: [email protected]

The Art of Phacoemulsification © 2001, Editors All rights reserved. No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the editors and the publisher. This book has been published on good faith that the material provided by editors is original. Every effort is made to ensure accuracy of material, but the publisher, printer and editors will not be held responsible for any inadvertent error(s). In case of any dispute, all legal matters to be settled under Delhi jurisdiction only.

First Edition: 2001 ISBN 81-7179-790-3

Publishing Director: RK Yadav Typeset at JPBMP typesetting unit Printed at Gopsons Paper Ltd., Noida

Contributors

Alpar John J

MD FACS FICS PA

Garry P Condon

MD

Clinical Professor Texas Tech University School of Medicine Medical Director Panhandle Ophthalmological Research Foundation, Texas, USA Fellow American Academy of Ophthalmology Saint Luke Eye Institute Amarilo, Texas, USA

Director, Division of Glaucoma Allegheny General Hospital MCP Hahnaman University Pittsburgh, Pennsylvania, USA

Fine Howard I

Masket Samuel

MD

Clinical Assistant Professor Oregon Health Sciences University Portland, Oregon Oregon Eye Assocciates, Eugene Oregon, USA

Richard S Hoffman

MD

Oregon Eye Associates, Eugene, Oregon, USA

Fry Luther L

MD

Director and Chief Fry Associates PA/Ophthalmology 310 East Walnut, Garden City, Kansas, USA

Jonathan P Ellant

MD

Chief St Clare’s Hospital and Health Care Center Assistant Professor Mt Sinai School of Medicine New York, USA

Luis W Lu

MD FACS

Instructor University of Pittsburgh School of Medicine ELK County Eye Clinic Center for Advanced Eye Care St. Marys, Pennsylvania, USA

Louis D Nichamin

MD

Medical Director Laurel Eye Clinic Brookville, Pennsylvania, USA MD

Clinical Professor Jules Stein Eye Institute UCLA, Los Angeles, USA

Allen David E

MD FRCOphth

Consultant Ophthalmologist City Hospitals, Sunderland Sunderland Eye Infirmary Queen Alexandra Road, Sunderland, UK

Arnott Eric J

MD DO FRCS FRCOphth

Consultant Ophthalmologist Arnott Eye Centre, Trottsford Farm Headley, Nr Brandon Hamshire, UK

Packard Richard

MD FRCS FRCOphth

Ophthalmic Surgeon Prince Charles Eye Unit Windsor, UK

Durval Carvalho M

MD

Chief Cataract Department Centro Brasileiro de Cirurljia, de Olhros (CBCO); Member Conselho da Sociedade Brasileria de Cataracta, Brazil

vi

THE ART

OF

Durval Carvalho M Jr

P HACOEMULSIFICATION MD

Doctorate, Departamento de Oftalmologia da Universidade Sao Paulo (USP) Member, Departamento de Oftalmologia da Universidade Federal de Goias (UFG), Brazil

Arshinoff Steve A

MD FRCSC

Enrique Chipont

MD PhD

Ophthalmic Surgeon Instituto Oftalmologico de Alicante IOIS General Secretary, AVDA–DE Denia, Alicante, Spain

Agarwal Amar

MS FRCS FRCOphth (Lon)

Ophthalmic Surgeon York Finch Eye Associates 2115 Finch Avenue W, Suite 316, Toronto, Ontario, Canada

Consultant Ophthalmic Surgeon Dr Agarwal’s Eye Institute 13 Cathedral Road, Chennai, India

Davis Peter L


MD, FRCS (C)

Senior Ophthalmologist North Okanagan Health District Vernon BC V1T 2M9, Canada

Aron-Rosa Danielle

MD

Ophthalmic Surgeon 28 Ave, Raphael, Paris, France

Joseph Leon A

MD

Consulting Surgeon Polyclinique Comiti, Dept of Ophthalmology 20000, Ajaccio, France

Claude S Leon

MD

MD

Professor, Dipartimento Di Discipline Chirurgiche, Via Vettoio, Blocco 117A, 6710 Coppito (AQ), Italy

Leopoldo Spadea

MD

University of L’AQuila S Salvatore Hospital, L’AQuila, Italy

Luigi Mosca

MD

University of L’AQuila S Salvatore Hospital, L’AQuila, Italy

Oshika Tetsuro

MD

Ophthalmic Surgeon University of Tokyo School of Medicine 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan

Alio Jorge L

MD (Path) FRSH (Lon) DO

Agarwal Jaiveer

MD

Director and Chief Dr Agarwal’s Eye Institute 13 Cathedral Road, Chennai, India

Agarwal Sunita

MD FSVH (WG) FRSH (Lon) DO

Director and Chief Dr Agarwal’s Eye Institute 15 Eagle Street, Bangalore, India

Agarwal T

MD


France

Emilio Balestrazzi

Agarwal Athiya

MD PhD

Professor and Chairman of Ophthalmology, Medical Director Instituto Oftalmologico de Alicante IOIS General Secretary, AVDA–DE Denia, Alicante, Spain

Col Akhil Bharadwaj

MD

Chief Eye Surgeon, Armed Forces, Asvini, Colaba Mumbai, India

Dada Vijay K

MD DOMS

Chief and Professor Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences New Delhi, India

Namrata Sharma

MD

Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences New Delhi, India

Tanuj Dada


Kapoor Shashi

MD

Consulting Ophthalmic Surgeon Kapoor Eye Clinic, 409 Om Chambers Kemps Corner Mumbai, India

C ONTRIBUTORS Kelkar Shrikant

MD

Murthy KR

MD

Director and Chief National Institute of Ophthalmology 1187/30, Ghole Road, Shivaji Nagar Pune, India

Consultant Ophthalmic Surgeon Prabha Eye Clinic 504, 40th Cross, 8th Block Jayanagar, Bangalore, India

Lahane Tatyarao P

Sachdev Mahipal S

MD

Professor and Head Grant Medical College JJ Group of Hospitals Mumbai, India

Maniar Ranjit H

MD

Head, Shushrusha Hospital, Mumbai Honorary Ophthalmic Consultant Jankikund Hospital, Chitrakoot

Mehta Cyres K

MD

Consultant Ophthalmologist Mehta International Eye Institute Colaba Eye Hospital Mumbai, India

Mehta Keiki R

MD

Medical Director Mehta International Eye Institute Chief, Ophthalmic Services Colaba Eye Hospital Chief, Surgical Services Netra Rukshak: Rural Eye Services Wing Head, Eye Department Breach Candy Hospital and Research Centre Sea Side, 147 Shahid Bhagat Singh Road, Mumbai, India

Mody Kirit K

MD FRCS

Medical Director Salil Eye Clinic & Contact Lens Centre, 506 Om Chambers, 123 August Kranti Marg, Kemps Corner, Mumbai, Hon Professor Grant Medical College Hon Eye Surgeon GT General Hospital Conwest Jain Clinic Hospital Smt. Lilavati Hospital Mumbai, India

Murthy Gowri J

MD

Consultant Ophthalmic Surgeon Prabha Eye Clinic 504, 40th Cross, 8th Block Jayanagar, Bangalore, India

vii

MD

Cornea Fellowship (USA), Phacoemulsification, Excimer Laser, Cornea and Contact Lens Specialist New Delhi Centre for Sight A-23 Green Park, Aurobindo Marg New Delhi, India

Pradeep Venkatesh Pool Officer Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences New Delhi, India

Shroff Noshir M

MD

Medical Director Shroff Eye Centre A-9 Kailash Colony New Delhi, India

Ranjan Dutta

MD

Shroff Eye Centre A-9, Kailash Colony New Delhi, India

Gurpreet Singh

DO

Shroff Eye Centre A-9, Kailash Colony New Delhi, India

Vajpayee Rasik B

MD

Professor Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences New Delhi, India

Vishal Gupta

MD


Inderjit Singh Professor and Head Coffs Harbour Hospital 69 Albany Street, Coffs Harbour New South Wales 2450, Australia

Preface

Advances in the field of Cataract surgery and intraocular implantation over the last 50 years have been astonishing. Phacoemulsification, had a slow beginning, but in the last 5 years has exploded forwards. Improvements in technique are increasing at a rapid pace, as the advantages of small incision cataract surgery, the instant patient rehabilitation physical and visual are obvious. Nevertheless, the ultimate expression of minimal patient inconvenience and minimal delay in resumption of patient’s lifestyle is the legacy of Phacoemulsification It was in the winter of 1989 when one of us (KRM) performed our first cataract operation utilizing Phacoemulsification. From that moment onwards, we had no doubts that this was a winning combination and in future all cataract operations would be performed with this technique and with this technique only. The procedure has changed since then. It has evolved and improved significantly. The technique has been perfected. The technology has progressed. The quality of the surgery is now virtually unsurpassable, and most importantly, surgeons all over the world now trust and rely on the Phacoemulsification technique. Old concepts change, giving way to new ideas, as fresh advances in all fields of science and medicine forge ahead. Phacoemulsification surgery and its complications are no exception. We have tried to be highly selective in modifying old concepts and including not only those changes that have widespread acceptance but also have included newer developments which will make their mark in the new millennium. The visual needs of patients are dictated by their circumstances, which include age, occupation, leisure interests, and their independence. As an adviser to a patient, the ophthalmic surgeon must consider the individual requirements of the patient and balance these against the potential risks of surgical treatment. As a surgeon, his or her attitude is tempered by his or her experience, knowledge of the experiences of others and confidence in his or her own ability to achieve perfection of results that should shine as a beacon of excellence in the community. The primary intent of the book, The Art of Phacoemulsification is to provide an introduction to the subject of Phacoemulsification as well as the framework on which could be constructed the study of that discipline. Presentation of the material begins with the most fundamental aspects and builds up successive levels of knowledge.

x

THE ART

OF

PHACOEMULSIFICATION

The purpose of this volume is to consider, in-depth, all aspects of Phacoemulsification. It is hoped that it will provide the ophthalmic surgeon who intends to commence Phacoemulsification surgery with the information necessary for effective and safe participation. For those who are already in this exciting field, this book should provide a useful source of reference. It is designed to consider both the problem and its solution. The solution has many variations but all should take into account the vulnerable tissues that are required to be protected during surgery. Every step of Phacoemulsification procedure is critical in determining the final surgical outcome. The surgery is a sequence of steps, each fundamentally important to the entire procedure. Thus while this treatise has designed to allow the readers to refine and enhance their surgical technique, it should reveal the latest advances in both the science and art of the modern technique of Phacoemulsification cataract surgery. The Art of Phacoemulsification has been conceptualized by some of the foremost cataract surgeons in the world. These contributing authors share their preferred techniques and ideas presenting the most advanced methods of surgical procedures, the newest equipment available, and their methods of managing the cataract patient. It will undoubtedly be apparent to many readers that some subjects have received a greater emphasis than others. These represent to some extent, our special interests and experiences. The major task of keeping abreast of the dynamic changes in Phacoemulsification surgery is nearly nondescribable. No single surgeon can speak authoritatively about every subject. Nor can every aspect of the subject be covered. This book covers a fair set of surgical methods and complications. Each chapter thus is an insight into the technique suitable for each surgeon and most importantly; the technique, which best suits that particular case. Each surgeon provides a detailed description directly from his or her experience of the more important Phacoemulsification techniques and his or her reaction to each new development. All contributors are aware that the production of a book having such a large volume of information, takes many months. Time and tide wait for none and certainly; the fast changing field of Phacoemulsification has new developments literally every day. The subject is developing rapidly, but it is our hope that the wealth of experience incorporated here will be valuable not only in the present time, but also for the future. This book is a multi-authored text and is, as such, abounds in differing literary styles. The editors have sought to provide a level of organizational conformity and scientific balance without sacrificing the originality and style of the individual authors. A distinctive feature of this book is the diversity of its many outstanding contributors. Probably the outstanding characteristic of this book is the editors’ ability to select critically important contributions to the management of cataract problems. These are analyzed and evaluated based on their vast experiences as ophthalmic surgeons and consultants.

P REFACE

xi

We would like to thank the contributing authors who are by their own right, considered the outstanding leaders in the field of Cataract surgery. This book would be non-existent without the devoted and tireless efforts of these physicians who contributed to this text while maintaining a rigorous daily practice. With promising laser techniques on the horizon, non-invasive Cataract surgery may soon be feasible. Many of these exciting developments are arriving so rapidly that even senior consultants in the field are often hard-pressed to keep up with the latest advances. What the future holds for us is difficult to portend, but one thing is certain, it will be exciting. Finally, the editors wish to take the liberty to express their deep appreciation to Jaypee Brothers Medical Publishers, India’s premier medical publication company, for their unflagging encouragement and tireless assistance in the production of The Art of Phacoemulsification. Mr Jitender P Vij, the Managing Director of Jaypee is truly a gem of a man, not only for his great faith that I would, one day, finally finish this epitome, but also for the general all-round editorial assistance given, the well laidout pages and the crisp photographs which have made it, truly, a world class book.

Keiki R Mehta John J Alpar

Contents

1. Commencing Phacoemulsification: The Basics .................................................. 1 Keiki R Mehta, Ranjit H Maniar

2. The Phacomachine ................................................................................................... 15 Mahipal S Sachdev, Pradeep Venkatesh

3. New Phacomachines Offer More Control ......................................................... 32 David E Allen

4. Cavitating Microbubbles Create Shock Waves that Emulsify Cataract ...................................................................................................... 45 Peter L Davis

5. Local Anesthesia ....................................................................................................... 51 KR Murthy

6. Ocular Anesthesia for Small-Incision Cataract Surgery ........................................................................................................ 58 Samuel Masket

7. The Limbal Incision ................................................................................................ 64 Shashi Kapoor

8. No Anesthesia Cataract Surgery .......................................................................... 76 Amar Agarwal, Athiya Agarwal, Sunita Agarwal

9. Clear Corneal Cataract Surgery ............................................................................ 86 Keiki R Mehta, Cyres K Mehta

10. Capsulorrhexis: A Beginner’s Guide .................................................................. 94 Shashi Kapoor

11. Capsulorrhexis: Principles and Advanced Techniques ................................103 Shrikant Kelkar

12. Hydrodissection and Hydrodelineation ........................................................... 112 Keiki R Mehta, Cyres K Mehta

xiv

T HE ART

OF

PHACOEMULSIFICATION

13. Phacoemulsification: The Quadrantic Cracking, Chopping and Stuffing Technique ................................................................................................. 118 Noshir M Shroff, Ranjan Dutta, Gurpreet Singh

14. Current Phacoemulsification Techniques ......................................................... 130 Richard Packard

15. Phaco Slice and Separate ..................................................................................... 154 Steve A Arshinoff

16. Cataract Extraction and Lens Implantation: The Implosion Technique .................................................................................... 161 Eric J Arnott

17. Phacoemulsification in Special Situations ...................................................... 170 Rasik B Vajpayee, Tanuj Dada

18. Zen in the Art of Phaco ...................................................................................... 177 Jonathan P Ellant

19. My Personal Technique of Vertical “Hubbing” Phacoemulsification ................................................................................................ 187 Keiki R Mehta

20. Innovative Nucleotomy Techniques .................................................................. 204 Vijay K Dada, Namrata Sharma, Tanuj Dada

21. Phacoemulsification in White Cataracts .......................................................... 214 Rasik B Vajpayee, Tanuj Dada, Vishal Gupta

22. Phacoemulsification in Difficult Cases ............................................................ 223 Inderjit Singh

23. Irrigation and Aspiration following Phacoemulsification .......................... 246 Keiki R Mehta, Cyres K Mehta

24. Foldable Intraocular Implants ............................................................................ 253 Vijay K Dada, Namrata Sharma, Tanuj Dada

25. History of Lens Implantation ............................................................................. 263 Eric J Arnott

26. Implantation Techniques of Acrylic Foldable Intraocular Lens and its Clinical Results ........................................................................................ 268 Tetsuro Oshika

27. The Mini-loop Plate and Accommodating Lenses ....................................... 288 J Stuart Cumming

28. Suprahard Cataracts: Their Evaluation and Management ......................... 299 Keiki R Mehta, Kirit K Mody

C ONTENTS

xv

29. Stretch Pupilloplasty for Small Pupil Management in Cataract Surgery ...................................................................................................... 314 Luther L Fry

30. Management of Glaucoma in Cataract Patients ...........................................322 Gowri J Murthy, KR Murthy

31. Phacoemulsification in the Previously Filtered Eye .................................... 329 Garry P Condon, Luis W Lu

32. Phacoemulsification in Patients with Significant Astigmatism ................ 344 Luis W Lu, Louis D Nichamin

33. Cataracts in Patients with Uveitis .....................................................................353 Enrique Chipont, Jorge L Alio

34. Corneal Endothelium and its Protection in Phacoemulsification ................................................................................................ 365 Keiki R Mehta, Cyres K Mehta

35. Phacoemulsification in the Presence of Pseudoexfoliation: Challenges and Options .......................................................................................381 I Howard Fine, Richard S Hoffman

36. Phacoemulsification in Severe Chronic Obstructive Pulmonary Disease ................................................................................................. 388 I Howard Fine, Richard S Hoffman

37. The Prevention of Complications and their Management in Phacoemulsification ................................................................................................ 393 Keiki R Mehta

38. Management of Posterior Chamber IOL Capture ........................................ 415 Durval M Carvalho, Durval M Carvalho Jr

39. IOL Scleral Fixation in Aphakic Eyes .............................................................422 Durval M Carvalho, Durval M Carvalho Jr

40. Phakonit and Laser Phakonit ............................................................................. 446 Amar Agarwal, Athiya Agarwal, Sunita Agarwal

41. Pharmacology of Intraocular Solutions and Drugs used in Phacoemulsification ................................................................................................ 453 Keiki R Mehta, TP Lahane

42. Triple Procedure with Phocoemulsification before Trephination ............ 462 Emilio Balestrazzi, Leopoldo Spadea, Luigi Mosca

43. Multiport Phaco Tip: A Safer and More Effective Training Device for Phacoemulsification ........................................................ 471 Keiki R Mehta

xvi

THE ART

OF

PHACOEMULSIFICATION

44. Intraocular Lenses Dislocated into the Vitreous .......................................... 479 John J Alpar

45. Favit: A New Technique to Manage Dropped Nuclei ................................ 486 Amar Agarwal

46. Laser Phaco Cataract Surgery ............................................................................. 493 Sunita Agarwal, J Agarwal, T Agarwal

47. Endoscopy-Assisted Phacoemulsification ......................................................... 500 Claude S Leon, Joseph A Leon, Danielle Aron-Rosa

48. Phacoemulsification: The Eye Camp Way ...................................................... 507 Keiki R Mehta, Kirit K Mody, Ranjit H Maniar, Cyres K Mehta, Akhil Bharadwaj

Index ............................................................................................................................ 529

The Ar Artt of Phacoemulsification The primary intent of this book is to provide an introduction to the subject of Phacoemulsification. Presentation of the material begins with the most fundamental aspects and builds up successive levels of knowledge. Every step of Phacoemulsification procedure is critical in determining the final surgical outcome. The surgery is a sequence of steps, each fundamentally important to the entire procedure. This book has been prepared by some of the foremost cataract surgeons in the world. These contributing authors share their preferred techniques and ideas presenting the most advanced methods of surgical procedures, the newest equipment available, and their methods of managing the cataract patient. This is a uniquely up-to-date book which covers scientific principles and current clinical and research trends, with practical information on patient assessment, variable surgical techniques, clinical results and the identification, avoidance and the management of complications. Keiki R Mehta, one of India’s foremost cataract surgeons, commenced intraocular implants in India in 1972, and developed in 1975, for the first time in the world, a soft HEMA Intraocular implant. He initiated Phacoemulsification for cataract surgery in 1979 and is known as the “Father of Phacoemulsification in India“. An exceptional surgeon, he has operated live in workshops, teaching phaco all over India. Dr Mehta is a popular teacher in great demand at conferences and symposia and has written many scientific books and published scientific papers, both at national and international level. He has been awarded eight gold medals and innumerable oration awards from national / international bodies. Extremely innovative, he has been on the cutting edge of technology and has devised multiple new techniques and instruments. John J Alpar is an exceptionally skilled surgeon , edited an extremely popular book, which literally became in the 1990’s, a bible for implant surgeons, termed ” Fechner’s Intraocular Lenses”,. With Professor Fechner of Hanover, Germany, Dr Alpar produced a book, impressive by its well-organized structure, its wealth of information, its practicality and the superb technique of presentation. A prodigious speaker and author, Dr Alpar has delivered 178 lectures, published 158 scientific articles , 11 chapters, 4 books and attended over 320 meetings. Widely traveled, he is a life member of the All India, Mexican and Hungarian Ophthalmological Societies, the Indian and Canadian Implant Societies, and is member of the Medical Societies in Peru, Japan, France. Dr John Alpar is respected worldwide for the quality of his work, the scope of his knowledge, his sharp intellect and brilliance and his keen, incisive analysis of facts.

Contributors include • Alpar John J • Fine Howard I • Fry Luther L • Jonathan P Ellant • Luis Lu W • Masket Samuel • Allen David E • Arnott Eric J • Richard Packard • Durval Carvalho M • Durval Carvalho M Jr • Arshinoff Steve A • Davis Peter L • AronRosa Danielle • Joseph Leon A • Emilio Balestrazzi • Oshika Tetsuro • Alio Jorge L • Enrique Chipont • Agarwal Amar • Agarwal Athiya • Agarwal Jaiveer • Agarwal Sunita • Agarwal T • Col Akhil Bharadwaj • Dada Vijay K • Kapoor Shashi • Kelkar Shrikant • Lahane Tatyarao P • Maniar Ranjit H

ISBN 81-7179-790-3

Rs.

JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD B-3 EMCA House, 23/23B Ansari Road, Daryaganj Post Box 7193, New Delhi 110 002, India

Keiki R Mehta Ranjit H Maniar

Commencing Phacoemulsification: The Basics

1

INTRODUCTION Phacoemulsification is a superb technique, but to be able to conduct it comfortably and effectively all the appliances, solutions and even the personnel in the theatre need to be properly located and trained to respond to any situation which may arise. It is imperative that the surgeon understands the basic applications of each of the different requirements. For maximum efficiency and safety, proper location and arrangements, right from the operating table, the microscope, the surgeon’s chair, the instruments on the trolley, the placement of the staff nurse, the assistants, and even that of the wardboys, have to be carefully planned and worked out in advance. Phacoemulsification is an instrument-based surgery. It is also a high-pressure surgery, with periods of calm alternating with high tension. Moreover, as such there must be adequate space in the theatre so that effective and rapid movement when and if required can take place smoothly. Too compact a theatre is a sure prescription for disaster. THE OPERATING ROOM: REQUIREMENTS AND NECESSITIES The operating room—requirements and necessities of primary importance is a properly designed and functioning operating room or theatre (Fig. 1.1). There are many important points, which need to be considered. Some of them will be felt unnecessary, but the strength of any chain is dependent on the weakest link. Thus every link has to be given its importance and considered on its own merits.

2

THE A RT

OF

PHACOEMULSIFICATION

Lighting Lighting often does not get the importance it deserves. It is important that the theatre can be lighted up properly, but equally important can also be darkened adequately. It should be lighted sufficiently with shadowless theatre lamps of adequate power (minimum 50,000 Lux lamps). Though most of the surgery is done under the operating microscope, there are times when good peripherally focused lights are an advantage as for squint or oculoplasty surgery. Additional, movable goose-neck direct or fiberoptic side theatre lamps are a necessity with good illumination and are especially good for capsulorrhexis in hard opaque cataracts. In addition, in case the theatre is darkened, provision should be made for spot lighting of the instrument trolley, the phaco unit, life-support systems, anesthetic equipment, with a lighting device on a rheostat so that the intensity is adequate for the scrub and circulating nurse and the anesthetist to see the equipment clearly, but is not so bright as to blind the surgeon. Many surgeons need a spot of light focusing on the operating table in addition to the operating microscope lights. General illumination of the theater is also an important requirement. Though the powerful focused lights may be shut off, gentle illumination is needed in a theatre to allow for movement. Tube lights, ideally should never be used in the theatre as they are very distracting especially when the flicker increases as the tube gets a little older. In addition the flicker fusion frequency of the operating staff tend to be affected by the tube light especially when they are tired after a long session, increasing surgeon and staff irritability Darkening the theatre enhances the contrast under the operating microscope and is extremely useful when doing a capsulorrhexis especially in a hard cataract. When the main theatre is darkened, provision needs to be made to gently illuminate the floor so that personnel can still move around without tripping on objects. It is important that spot lighting should be kept off places where high reflectance stainless steel appliances and instruments are placed. This is to prevent extraneous glare from reflection from these shiny surfaces. The colors of the clothing worn by the operating room personnel should be soft and muted avoiding harsh colors. Pastel shades of blue, green or yellow are quite acceptable, however; red and ocher should be avoided Air-conditioning and Ventilation The ventilation of the room should be adequate and the air-conditioning sufficient to compensate for the number of personnel who are going to be in the room. The air-conditioning vents should be so arranged that they do not allow the air to be blown over the operating surfaces and at the same time keep the theatre cool. The ideal operating temperature would vary from surgeon to surgeon, however, a good comfortable temperature level in India is 70o C. The ideal air-conditioning would be one-way, taking in air from outside, filtering it, cooling it, and then expelling it out again after circulating through the operation theatre. Most theatres in India and in most of the smaller hospitals and nursing homes would seem to have window- mounted

COMMENCING PHACOEMULSIFICATION : T HE B ASICS

3

air-conditioning. The size and number should be adequate to provide good cooling with the air intake for fresh air always remaining open. It is very important that every evening following surgery the filters of the air-conditioner should be washed and soaked in a dilute solution of Cetavalon for half an hour prior to being re installed in the air-conditioner. The position of the units should be such that they do not blow over the sterile field, or blow directly onto the operating staff. Noise Level in the Theatre An operating theatre should be an oasis of calm. It is therefore important that the operating room should be located in a quiet area of the hospital or facility, and away from distracting sounds. It is essential that the windows be double-glazed (twin sheets of glass with an air-space between them) to keep the noise level down to a minimal level. It should be imperative that the operating staff learn from the beginning that unnecessary talk be kept to a minimum level and communications as far as possible should be by hand signs. This would guarantee that the surgeon, and the staff enjoy adequate peace and quiet to be able to concentrate on doing a good job. Background soft music should always be played in the operating theatre as it defuses tensions. The music should neither have a harsh beat nor irregular cadences. Electrical Power and Outlets The power points in the operating theatre should use high-quality reputable switches of an adequate output so that they are not overloaded and at the same time, good contacts are obtained between the plugs and the sockets. Often, even in so-called, Five Star facilities, it is seen that from a single outlet, using multipoint extensions, a number of lines are drawn. The wires then are left carelessly on the floor. All power points should be far away from the surgical field and preferably from a central hanging pod so that one cannot accidentally trip over the wires. In case it is required to trail a wire on the floor, it must be well protected with a masking tape so it is not accidentally pulled out in the dark. The power outlets should be rated at a sufficient level to comfortably run the medical equipment. Over loading of the points often leads to failure at a critical time during surgery. It is also imperative that fuses be provided for every media outlet in the theatre of the self-adjusting type which could be reset simply by pushing in a button rather than the older wire-looped fuses. Sensitive instruments like a phacoemulsification machine and life-support evaluation systems (cardiac monitor or oxygen saturation monitors should always be run through an on-line UPS (uninterrupted power supply). This permits the surgery to be completed even if the lights go off or the power supply fluctuates or even trips (Fig. 1.2). Power Generators In India, as with many developing countries, power outage is not uncommon. It is important when the theatre is planned that one should compensate for this problem.

4

THE A RT

OF

PHACOEMULSIFICATION

Though it would be nice to have automatic switch-over power systems where the load is taken temporarily on batteries and then automatically shifted to the generated supply, it is a very costly system which is rarely used. Instead small power generators are utilized, adequate to run the theatre lamps, general lighting and power the instruments, including the Phacoemulsifier and support systems. It is important that the wiring be so organized that all that needs to be done, at the time of a power failure, is to turn on the switch and start the generator. The load on the generator should never exceed 75 percent of its rated output to prevent overload and tripping. The generators, which are usually run off petrol, kerosene or diesel, all have a few common features. They are all noisy, smelly and temperamental. Hence they need to be placed in a room with good ventilation, and isolated so that the sound and smell does not reach in the hospital or theatre complex. They should be serviced regularly, and personnel trained to start and run the units. Scrubbing Facilities The scrubbing room should be separate and kept outside the theatre. There is a specific reason for this. When gloves are worn there is always glove powder scattered around which is then be circulated in the room leading to contamination. Not only does this choke up the filters of the air-conditioner, but leave a patina of dust all over the sterile surfaces of the room. Personnel in the Theatre The ideal theatre room composition should be a scrub nurse, who surgically assists the surgeon, and a circulating nurse, who remains unsterile. In my theatre, where I like to have a turnover of around 12 to 15 cases per day, preferably in a threehour period, I find it best to use two separate teams. The scrub nurse who surgically assists me in the surgery will, after the case is finished, wash the instruments, place them into the sterilizing box and then put it herself into the autoclave. The scrub nurse then washes up again, dons a fresh gown and gloves and commences preparing for the next case preparing the table and opening up the disposables which are handed to her by the circulating nurse. The unsterile circulating nurse will open the presterile disposables, remove the instruments from the sterilizer, and hand them across to the scrub nurse. The second scrub nurse, who has been assisting me with the second cases, finishes, moves out, and the totally prepared first scrub nurse is ready to commence the next case. This technique has a big advantage that the scrub nurse knows all about the instruments, where they are placed and their functional status. In addition it makes for far faster and more efficient application. Theatre Autoclave The autoclave should be a rapid action unit with flash sterilizing ability. A number of sterilizing systems are now available. Statim is a common one in usage (I use


5

the Statim Cassette Autoclave, which has an 8-minute cycle, just perfect) and has preset operative timing levels, has adequate safety fail-safe built-in, and even has a small printout which confirms that the autoclaving cycle was complete and effective. The cassette system makes it very simple to insert and remove the instruments. Another good system is the Totawer and the Korean system which work in essentially identical manner. It is important to have a proper place to store the autoclaved instruments and theatre linen. The corridors and wall nooks are not for this purpose. It has to be in a well-ventilated room, far away from any traffic so that sterility is not compromised. The Operating Table The operating table has, as its primary requirement rock-solid stability even under deflecting forces, like inadvertent pressure at the head end, or accidental tail end pressure or lateral pressure. The standard operating table with the rotating axis in the middle is not suitable for ophthalmic surgery as the slightest pressure at either the head end of the table or the tail end of the table causes the entire platform to rock. When an operating microscope is being used, zero movement is permissible with any level of safety and efficiency. A very steady table is mandatory. Some of the operating tables are exceptional, like the Marquette system which is, however extremely costly. Alternately, more economical systems like the EyeTech table seem to work equally well and are sufficiently rigid for ophthalmic use. The table should be motorized permitting free movement both up and down in fine increments so that it could be fine tuned with the surgeon and the microscope in position. There should be the ability to tilt the head end of the patient a little up or down to compensate for those with a larger anterior/posterior diameter of the head, or when little children are being operated. It should wide enough to accommodate the patient, but narrow at the head end so that it does not impede the surgeon especially when temporal; surgery is being undertaken. It is also important that there should be adequate place under the table for the surgeon’s feet, the foot pedal console of the phacoemulsification unit, as well as for the foot pedal console of the operating microscope. Foot-mounted electrical controllers for an operating table should be avoided as the irrigating fluid, be it normal saline, Ringer lactate, or balanced salt solution (BSS) is bound to splash on the floor leading to a short circuit. The operating table should also have the ability to take a right sided arm rest where the arm can be positioned by the anesthesiologist for placing an IV cannula for any intravenous injection or sedation as may be needed the need for inserting a very uncomfortable arm support under the back of the patient (Fig.1.3). The mattress of the operating table should be at least 3 inches thick. The primitive 1 inch hard, unyielding, uncomfortable theatre mattress should be dispensed off with. Unlike general and orthopedic surgery where the patient is deeply sedated or even unconscious, the average ophthalmic patient is wide awake. With the advent of topical anesthesia, with the patient having to lie, totally without moving for

6

THE A RT

OF

PHACOEMULSIFICATION

long minutes at an end, the minimum which could be expected is a comfortable rubber mattress. The discerning and concerned surgeon should try sleeping on his or her own operating table to see its comfort level. There has always been discussion as to whether wrist support is required. Proponents of the wrist support system feel that it helps in stabilizing the wrist, and at the same time permits a little cavity or gully for collection of fluids rather than letting the fluid rundown the face. On the other hand, there are others who feel that it restricts the freedom of movement of the hand around the face and since usually the forehead is already being used to support the fingers the presence of a wrist rest is superfluous. It is basically a surgeon’s choice. I personally feel it interferes more with the surgery than helps, and though I have used it in many operating theatres, have never felt that it was really necessary. Personally I feel it restricts the free movement of the phaco handpiece. However, it is an individual choice. The Surgical Chair Phacoemulsification requires both hands and both feet to be utilized simultaneously. It stands to reason that the surgical chair is an important piece of surgical equipment. It gives the surgeon stability, supports his back, it gives a comfortable seating arrangement. It is important to remember that the feet have to be kept on the pedals for the full time of the surgery, and the surgical chair must be so designed that it prevents any pressure on his thighs. It is imperative that the chair be very comfortable, for the surgeon will need to sit on it for long hours every day if he is to complete his surgical list. Any discomfort, overtime, tends to get magnified, which affects, in the final score, the surgical competence. In the intracapsular days, most surgeons operated without any magnifying aids except for low-powered spectacle magnifiers or head-worn loupes, and operated standing. The advent of extracapsular cataract surgery changed the entire gambit. The necessity of visualizing the red glow meant the use of a coaxial operating microscope became mandatory. With the use of automated irrigation/aspiration units, both feet needed to be utilized. Thus the surgeon had no option except to sit and operate. Ideally the operating chair should have a minimum of five and preferably seven smoothly moving, nylon castors, to give total stability, with a lock on at least two of them, to immobilize the chair. The arm rest should be of adjustable height and properly padded and designed with a slight hollow so that during surgery the resting elbows should not slip off (with, as one may well expect, dire consequences). They should support the elbow, but at the same time, should neither restrict, nor interfere with, the surgeon’s movement. The chair should also fit easily under the operating table, with adequate space for the surgeon’s thighs. The area below the head rest should not be in contact with the chair or its armrests, neither should the base touch against the operating table. The height of the chair could be either electrically or hydraulically adjusted so that the appropriate height for each individual patient and the surgeon can be utilized. Finally, the chair must be grounded.


7

Operating Microscope The microscope is perhaps the most important single piece of equipment in the theatre. Without an exceptional microscope, good phacoemulsification is difficult, if not impossible. The basic requirements are as follows: Excellent optics with clear vision at the edge of the optics There should be no blooming or distortion of the image and the lenses need to be color corrected. The latest microscopes (Zeiss) have apochromatic optics. Adequate depth of focus The entire lens should be visible from the front to the back without refocusing. This is very important since when doing phaco the traverse of the tip from the front to the back of the lens is almost 4 to 5 mm and it is important that excellent focus be available at all times. Perfect coaxial optics Are of prime importance if a good red glow is to be visualized. In modern extracapsular cataract extraction (ECCE) and, even more so, phacoemulsification, the surgeon literally operates against the background of the red glow. A good glow from one edge of the pupil to the other is thus a basic requirement. Good X-Y device The advantage is that the position of the microscope can be adjusted during surgery utilizing the foot controls without having to manually push a heavy microscope around. A good X-Y device also compensates for the little head movement which is to be expected during surgery. Automated zoom magnification It is not absolutely essential but is extremely useful as one can zoom in for a difficult situation ( doing rhexis in a hypermature cataract, or to see the edges of the capsule while doing posterior rhexis) and then zoom out with a reduced magnification for more effective surgery. Easily movable without damaging the unit Should be mounted on movable castors so that it could be positioned easily and locked in place in the operating theatre. Proper and stable optics delivery The arm connecting the microscope head to the supporting pillar should have adequate movement but at the same time should possess rock-solid stability. It should be possible to position the microscope head easily and then lock the arms. Tilt optics Not mandatory but makes a great deal of difference in comfort. The horizontal to vertical tilt arrangement (range of 90 degrees) is in the opinion of the author a really useful device as it makes the difference between operating comfortably and struggling and operating. It is particularly useful when operating on patients who cannot lie flat and who have to be literally operated in a 45-degree position. One can position the microscope to be parallel to the plane of the head and then simply tilt the optics to operate comfortably.

8

THE A RT

OF

PHACOEMULSIFICATION

Fig. 1.1: Layout of operation theatre with phaco on right

Fig. 1.2: Showing set-up with video, VCR, cardiac monitor, oxygen saturation monitor and cautery on right side of surgery

Preoperative Microscope Positioning It is imperative that the microscope be positioned accurately at the time of commencing surgery. Ideally the microscope should be on the right side of the patient, the same side at which the phacoemulsification unit is kept. The left side is reserved for


9

Fig. 1.3: Taken from the foot end of the patient. Anesthetist on the surgeon’s right side and instrument table on the surgeon’s left side

Fig. 1.4: Showing the double tubing Surge Suppression System attached to the author ’s Alcon Legacy

permitting the patient to be shifted from the gurney or trolley to the table and the subsequent removal after surgery. The ideal place for keeping the instrument trolley is at patient’s left. The surgical assistant stands on the same side. The operating microscope camera should have its monitor placed at the surgeons right, set slightly

10

THE ART

OF

P HACOEMULSIFICATION

Fig. 1.5: The balancing balls designed by Dr Tony Fernandez for softening eye

behind the surgeon so that the scrub nurse and the anesthetist can both follow the progress of the surgery, at the same time it will not distract the surgeon. An X-Y attachment is a very useful adjunct as it allows the stabilization of the optical axis to the patient’s eye during surgery without unnecessary coarse movements of the optical head. The X-Y device should be placed at its zero position prior commencing the surgery. Most microscopes have removable autoclavable plastic, metal or silicone caps for the microscope. Alternatively, cloth covers, which can be autoclaved, can be utilized. It is important that all the arrangements and positioning of the microscope be done prior to commencing the surgery. The luminosity of the microscope should be kept at the lowest level consistent with good vision. It is important to remember that the so-called ‘cold” fibreoptic light is not really cold but simply not too hot. A good heat shield must be fitted in the microscope especially if the microscope has a filament bulb. Keep the light intensity low until required. Prior commencing, the surgeon should place the focus at one-third position, i.e. if the traverse can be visually divided into three parts, it should be fitted in the upper third. This allows the surgeon to have more than adequate range during surgery. The surgeon should commence with the microscope focused at the limbus where the initial incision will be made. Placing the setting at the upper one-third position of the head traverse, enables the available traverse ( up-down movement) of the microscope to be utilized effectively. It is also important to adjust the microscope optics to the surgeon’s ametropia and his interpupillary distance if the microscope is used in a multi-user environment.

C OMMENCING P HACOEMULSIFICATION: T HE B ASICS

11

To enable good coaxiality so as to obtain an excellent red glow the corneal plane must be exactly at right angles to the microscope tube. Be certain to position the eye perfectly prior commencing. Many microscopes come with a small round macular occluder which can be brought into position after the critical part of the surgery is over to diminish the quantum of light entering the macula. A simple alternate technique is to change the angle of the optics immediately after the cortical aspiration is over and to dim the light. Modern phaco surgery is now so fast that sometimes one wonders whether it is really required, however it is a good practice and should be followed. Footwear Use in the Theatre The use of footwear is very much dependent upon the surgeon. I personally prefer to use stocking feet rather than using slippers or shoes as I personally feels that it gives far better control. The use of thin-soled tennis shoes would perhaps work just as well. The thick-soled Nike and Adidas shoes though excellent in the sport field are not really useful as the fine control is lost. Using the X-Y control with stocking feet is a snap as the toes can easily encircle the knob. However, thin-soled shoes do seem to work well. The problem comes about in utilizing the X-Y control on the microscope. Stockinged feet are able to comfortably go around the tip of the X-Y knob permitting exquisite control. The important guidelines to observe are comfort. Be careful not to use loose floppy footwear like rubber slippers or cotton slippers, as they tend to slide over the footswitch area and can, in a critical moment, jam the footswitch and precipitate problems. The Patient in the Operating Theatre Positioning the Patient in the Theatre The patient’s head should be positioned in such a manner that the iris plane is parallel to the floor and perpendicular to the coaxial light of the microscope. In case the patient’s eyebrow is pronounced or the nose is pronounced, both of which would interfere with the surgery, one can easily shift to a full temporal approach. I personally prefer to enter at the 10 o’clock position in the right eye and the same in the left eye. The only time I change positions to a full temporal approach is when space is inadequate for a proper exposure. It is always very tempting, after scrubbing, to enter the operating room and wear the gloves from the instrument trolley, next to the patient. It is important to don the rubber gloves prior to entering the theatre, and as far away from the instruments trolley as possible. Whenever gloves are snapped on, talcum/glove powder, which is on the gloves, tends to be liberated and then falls as a fine patina all over the instruments and the eye. Prior to commencing surgery the surgeon should wipe his or her hands with a sterile dry towel, after putting on the gloves so as to remove the excess gloves powder. Washing is also acceptable but must then be in copious distilled water as otherwise it simply cakes the gloves, making matters worse. The dry towel scrub is the best to remove excess glove powder.

12

THE ART

OF


Preparation of the Eye The area around the eye and the eye itself are washed with 10 ml of 50 percent diluted Betadine 5 percent ( povidone-iodine) solution. A cotton bud soaked in full strength Betadine solution is swept along the lashes to make sure that they are well cleaned. Subsequently the eye is flushed out with distilled water or with Ringer lactate to remove all the impurities. There is never any need to cut lashes. Draping the Eye The area around the eye is dried thoroughly with a sterile towel. A sterile self-adhesive plastic drape, either individually, or as a part of a complete drape, must now be placed over the eye. The method of placement is fairly simple. The eyelids are kept widely open either by the surgeon’s left hand or kept open by the surgical assistant using cotton buds. The sterile drape is positioned over the opened eye, the tip of the index finger is allowed to press the drape in between the opened area, gradually letting the drape stick onto the lashes and then onto the area around the eye. Using a blunt-tipped scissors, the plastic drape is tented and then incised down the middle being careful that the cornea is not accidentally touched. A soft wire speculum or a self-retaining speculum is then inserted in such a manner that the incised drape turns over the lashes, and then passes under the lids, held in place by the speculum, isolating them from the sterile field. Another big advantage of draping is that at no time is there any accidental touch at the time of insertion of the phacoemulsification probe or the implant in the eye. Following the application of the drapes, a second cloth drape can be put over the site. It has three functions: (i) it acts as an additional sterile barrier, (ii) cuts down on reflections, and (iii) acts as an absorbent media. Use of Lid Stitches In the days of intracapsular and later extracapsular cataract surgery, the use of lid sutures or superior rectus sutures was almost a routine. In the phaco era, lid stitches are used extremely rarely and are quite unnecessary. The only time any sutures are used is a superior rectus suture placed if the surgeon requires more exposure as when he or she wishes to do a combined glaucoma and cataract procedure. By eliminating the use of a superior rectus stitch, postoperative ptosis incidence is markedly reduced, it is infinitely less traumatic, eliminates the hematomas, which occasionally accompanied the placing of the stitch, and reduces postoperative inflammation. Since more often than not, topical anesthesia is the technique of choice, the eye is kept stable enough by the patient and the use of the superior rectus stitch is thus redundant. Suction Facilities To maintain a dry field during surgery is important. It is very difficult to operate with a pool of liquid reflecting back the microscope light. Rather than repeatedly

C OMMENCING P HACOEMULSIFICATION: T HE B ASICS

13

swabbing the area dry, which leads to conjunctival irritation and interferes with the surgeon, the best is to keep a small suction available. A good option is the use of self-retaining speculum with aspiration ports attached to a small dental suction which gives suction in the range of 5 to 7 mm Hg. An alternate method is to utilize a drainage device like a sterile plastic bag which can be attached on to the side of the eye to hold the excess fluid as it drains out, or to use an absorbent wick drape which permits easy leakage. Which ever device is used, it is important to keep the floor dry. Dripping irrigating solution can be a source of great irritation to the surgeon when it falls on his or her feet, or wets his or her clothes. In addition the dripping liquids tends to cause the phaco foot switch to become slippery and may even jam in time thanks to the dried salt crusts. In addition, the saline is electrically conductive and is thus an electrical hazard. FURTHER READING 1. Mehta KR, Sathe SM, Karyekar SD: Computer Terminal Usage and Eye Fatigue, Xth Congress APAO. Soc Proc 2:946-48, 1985. 2. Mehta KR: Phacoemulsification cataract extraction with foldable IOLS-First 50 cases. All India Ophthl Soc Proc 56-60, 1989. 3. Mehta KR: Progressive corneal endothelial decompensation—extended wear contact lenses with aphakia. All India Ophthl Soc Proc 109-14, 1989. 4. Mehta KR: Endocapsular phacoemulsification and posterior chamber IOL implantation. All India Ophthl Soc Proc 217-20, 1989. 5. Mehta KR: Post-cataract astigmatism: A comparison between phacoemulsification and ECCE procedure: cataract with and without intra-ocular implantation. All India Ophthl Soc Proc 226-29, 1989. 6. Mehta KR: Posterior capsular capsulorrhexis with shallow core vitrectomy following implantation in paediatric cataracts. All India Ophthl Soc Proc 207-10, 1995. 7. Mehta KR: The loop tri suction nonphaco technique of small incision cataract surgery. All India Ophthl Soc Proc 210-12, 1995. 8. Mehta KR: The clear corneal phacoemulsification with injectable silicone lenses. All India Ophthl Soc Proc 218-22, 1995. 9. Mehta KR: An Advanced but simple keratometer for control of postoperative astigmatism. All India Ophthl Soc Proc 122-23, 1990. 10. Mehta KR: Posterior chamber implantation. All India Ophthl Soc Proc 143-44, 1990. 11. Mehta KR: YAG laser damage to intraocular implants—an evaluation. All India Ophthl Soc Proc 14750, 1990. 12. Mehta KR: Phacoemulsification—is it the true III world answer for eye camps. All India Ophthl Soc Proc 301-303. 1990. 13. Mehta KR: An analysis of causative factor leading to eye strain caused by computer monitor screens. All India Ophthl Soc Proc 334-36, 1990. 14. Mehta KR: Single stitch elliptical funnel incision for cataract surgery. All India Ophthl Soc Proc 25354, 1991. 15. Mehta KR: Bifocal intraocular implants—a functional evaluation based on 425 cases. All India Ophthl Soc Proc 271-74, 1991. 16. Mehta KR: Phacoemulsification with flexible PC IOL—is it really a step forward. All India Ophthl Soc Proc 287-88, 1991. 17. Mehta KR: The new phaco cleave technique for hard cataracts. J Intraocular Implant and Refractive Society, India 1(1): 74-75, 1996. 18. Mehta KR, Sathe SN, Karyekar SD: The new soft intraocular lens implant. Am Intraocular Implant Society J4(4):200-05, 1978. 19. Mehta KR, Sathe SN, Karyekar SD: New soft posterior chamber implant, X Congress of the AsiaPacific Academy of Ophthalmology. New Delhi,1985. 20. Mehta KR: Clear corneal phaco with injectable silicone IOL proc. All India Ophthl Soc Proc (Mumbai) 1995.

14

THE ART

OF


21. Mehta KR: Phaco with flexible IOL—is it a step forward. All India Ophthl Soc Proc (Bangalore) 1991. 22. Mehta KR: The tripod posterior chamber flexible acrylic implant —the answer to better stability. APIIA Conference, 1997. 23. Mehta KR: Intralenticular “hubbing” technique for simple eye camp phacoemulsification—a simple technique. APIIA Conference, 1997. 24. Mehta KR: Newer techniques for eye camp safe phaco techniques. APIIA Conference, 1997. 25. Mehta KR: Intralenticular “hubbing” phaco technique for safe phaco. Proc of SAARC Conference, Nepal, 1994. 26. Mehta KR: The New Multiport Phaco Tip for Safer, More Effective Phacoemulsification, with Virtually Zero Capsular Damage. Proc of SAARC Conference, Nepal, 1994.

Mahipal S Sachdev

The Phacoemulsifier

2

INTRODUCTION It is very important than a thorough knowledge of the phacoemulsification machine is available to the operating surgeon. There are many machines available in the market, each with their own characteristics. However once the basics of the machine are understood, it becomes simple to analyze them, and having done so, understand how exactly they work. All machines fall into two basic categories, those utilizing a peristaltic pump and those using a Venturi pump. It is critical that every surgeon learns about the machine parameters and their individual effects, how they interrelate and in total how they affect the environment in which the surgery is performed. The Machine: Basic Features The phacoemulsification machine (Fig. 2.1) is essentially a system which generates ultrasound energy transmitted to the tip of the handpiece. The machine console only generates the electrical energy. The conversion

Fig. 2.1: The Laser Phacoemulsifier Machine (Alcon Legacy)

16

THE A RT

OF

PHACOEMULSIFICATION

of electrical energy into ultrasound is at the handpiece level. The body of the machine thus basically has controls which modulate every key requirements, be it diathermy, irrigation-aspiration control, ultrasound energy stability, or even the height of the irrigation bottle, etc. The fine-tuning is done by the foot switch which gives the surgeon more flexibility. Every phacoemulsifier has five basic functions; diathermy, irrigation, irrigationaspiration, ultrasonic fragmentation and vitrectomy. Each of these functions has a handpiece to match them. Irrigation Handpiece The irrigation handpiece is used when only irrigation is required. It is connected to an irrigating cystitome for anterior capsulotomy, or to an irrigating loop for hydrodissection. Many machines have the ability to preset controls so that when only irrigation is required, the foot switch functions purely as an on-off mechanism. Irrigation-Aspiration (I-A) Handpiece The infusion liquid is sent to the anterior chamber through the connected tubes. The basic function of the I-A handpiece is to aspirate liquid and cortical material through the aspiration port, at the same time infusing chamber-maintaining liquid into the anterior chamber. Essentially the irrigation-aspiration (I-A) handpiece, has a either single piece metal (stainless steel or titanium) irrigation-aspiration sleeve or has an aspiration sleeve with a silicone sleeve that fits snuggly around the aspirating tip. The I-A tip differs from the phaco tip in being smooth and rounded with a single aspiration port on the side of the tip and not at the end. The sleeve may be turned to orient the irrigation port in any direction. The irrigation ports in the silicone sleeve should be kept perpendicular to the metallic aspiration port as this helps direct the infusion fluid along the iris plane. This reduces iris flutter during the surgery. Typically the I-A handpiece has a rounded tip with the aspirating port at one side usually 0.75 mm to 1.5 mm away from the tip. The opening can be in a diameter of 0.2, 0.3, 0.4, or 0.5 mm. The overall diameter of the I-A handpiece usually varies from 2.5 to 3.0 mm depending on whether the aspiration sleeve is metal, or of silicone. The angulations of the I-A handpiece can be straight, 45° bent, or has a 90° bend. Most surgeons prefer to utilize the curved I-A tip. Recently Alcon in its Legacy phaco machine has taken out a tip which can be varied as desired termed a “steerable tip”. The commonly used I-A port is a 0.3 nun port. It has the safety feature that it will aspirate the cortex and not the capsule. It is however wise to keep on one’s table a 0.5 port so that at times when you wish to aspirate larger particles it is available. The larger port is also useful when doing a direct aspiration, as is often done in a congenital cataract. Irrigation/aspiration handpieces corne with metal or silicone sleeves, each having their own advantages.

T HE P HACOEMULSIFIER

17

Metal Sleeves Metal sleeves allow a more regular inflow since they neither are compressed by the incision edges nor are they compressed if the tip is moved in a tunnel obliquely when oar-locking can obstruct the flow. Having smoother edges they are easier to introduce into the phaco tunnel. They also do not snag on the edges of the iris. Naturally being metal, they last much longer (Fig. 2.2).

Fig. 2.2: Irrigation/aspiration metal sleeved handpiece curved, and 90 degrees bent

Silicone Sleeves Silicone sleeves have greater flexibility and by molding themselves to the walls of the tunnel (basically, once a tunnel is opened, it is no longer a slit but elliptical in shape) give a better fit, thus diminishing the leakage from the chamber. This is important especially if the eye pressure is a bit high, chamber is shallow, or in children (Fig. 2.3).

Fig. 2.3: Silicone-sleeved bent for irrigation/aspiration bent

The Diathermy Handpiece In diathermy handpiece is a very essential adjunct and is ideal when a blood-free field is required typically in preparation of squared or smile (chexron) scleral or semiscleral incision.

18

THE A RT

OF

PHACOEMULSIFICATION

Diathermy handpieces can be coaxial (Erasertm) or of the forceps type. The coaxial type is excellent in preparing and having a bloodless scleral area. The forceps on the other hand can also be used for sealing the edges of the conjunctiva together (coaptation) at the end of the surgery. It is essential that the minimum quantum of diathermy be utilized. In most modern machines the control of the quantum of diathermy is linear, i.e. it is controlled by depressing the foot pedal. The maximum and minimum values can be preset on the console. Anterior Vitrectomy Handpiece The unit can be either of the guillotine type or of the rotating type with a triangular tip. In the earlier days most machines had the rotating vitrectomy tip, but it was soon recognized that the moment the unit got a little older it tended to entrap and tug on the vitreous and hence the guillotine vitrector has now become a standard in most machines. For anterior vitrectomy, the tip usually comes with a perfusion sleeve which can be removed if so desired. On the console, the essential values of flow rate, cut rate and vacuum can be set to suit individual requirements. Ultrasonic Handpiece Bimanual It has become customary for many surgeons to use separate handpieces for irrigation and aspiration. This helps immensely in cortical removal (Fig. 2.4).

Fig. 2.4: Bimanual hand pieces, separate for irrigation/aspiration

Phacoemulsification of a lens nucleus depends upon ultrasonic power which is the function of the acoustic vibrator that has been incorporated into the ultrasonic handpiece. Attached to this vibrator is a hollow titanium needle or the phaco tip. The acoustic energy produced along the ultrasonic handpiece is then transmitted onto the phaco tip (Fig. 2.5).


19

Fig. 2.5: Phacoemulsification handpiece with four crystals (Alcon Legacy)

The acoustic vibrator is of two types: magnetostrictive or piezoelectric device. The acoustic vibrator converts electrical energy into mechanical energy under the influence of an electrical signal. The acoustic vibrator oscillates longitudinally at a frequency between 30,000 and 60,000 Hz. This imparts a linear motion to the ultrasonic tip. The stroke amplitude of the linear movement is 3.1000 of an inch and the acceleration 80,000 to 2,40,000 G. Magnetostrictive Handpiece Magnetostrictive handpiece was the first in use, and has now been phased out. It uses an electric current to induce a magnetic field which results in the linear movements of the ultrasonic tip. The electromagnetic field is generated by a coil of wires wrapped around the handpiece. Advantages and Disadvantages of Magnetostrictive Handpiece • • • • • • •

Can be autoclaved repeatedly with no risk to the handpiece Much sturdier. Does not break if dropped Can be repaired easily The handpiece is larger (almost the width of the base of a billiard cue) It is much heavier Needs to be water-cooled The greatest problem is that power delivery is inadequate and often at peak powers tends to be erratic, more so as the handpiece gets older.

Piezoelectric Handpiece Piezoelectric handpiece uses electric energy to reorient the piezoelectric crystal which in turn is translated into linear movement. The piezoelectric transducer requires a direct electrical contact to be made with the crystal.

THE A RT

20

OF

PHACOEMULSIFICATION

Advantages and Disadvantages of Piezoelectric Handpiece • Has a more efficient power delivery. With the use of multiple crystals the full range of delivery can be made very smooth even at very small increments. • It is air-cooled • Is very much lighter, almost featherweight as compared to the magnetostrictive handpieces • It is however very fragile and can break on being dropped • Costly to repair. Some handpieces may need to be calibrated every 1500 phaco procedures for optimal output. Phaco Tip The phaco tip can have various bevel angles ranging from 0° to 60° and comes in various shapes and sizes. The phaco tip is made of titanium and is hollow with the distal opening functioning as the aspiration port. The acoustic energy produced along the ultrasonic handpiece is then transmitted onto the phaco tip. The angle of the tips are for basically two reasons: a flat tip, like the 0° and 15° are excellent for holding but very poor for cutting; on the other hand to make a trench in a hard cataract the 60° tip is ideal, but because of its large surface area of the oblique opening, its holding power is poor. Tips may also be of various types, flared at the end (Cobra tip) or with the tip bent (Mackool tip) or with small ports, termed ABS port (Fig. 2.6). Entering into the anterior chamber is easy with Fig. 2.6: Peristaltic pump of the 60° tip and progressively harder with a 15° Legacy machine or a 0° tip. The commonly used tips are 30° and 45° phaco tips.

Alcon

Analyzing the Tips 0° Tip 15° Tip 30° Tip 45° Tip 60° Tip

Basically a flat, square cut tip with minimum cutting power but excellent holding capacity. Ideal for phaco chop techniques. Less cutting and more holding power. Suitable for improving follow ability. Balanced cutting and holding power. Suitable in most of the phaco procedures. Sharp cutting with good cutting ability and less holding power. Very sharp cutting edge with minimum holding power. Ideal for grooving hard cataracts.


21

Tuning the Phaco Tip The phaco tip is screwed into the handpiece directly using a wrench. The handpiece is then tuned so as to synchronize the mechanical movement of each tip with the handpiece. Autotuning also allows the handpiece to maintain its frequency irrespective of change in the density of the medium. A loose or a heavily used needle will not tune. It is also customary to tune every time a needle is changed. Some of the newer machine (Sovereign Allergan) can retune the needle in few seconds. The irrigation fluid is made to flow through the two side ports on the silicone sleeve. The silicone hub threads the sleeve onto the outer casing of the handpiece. In some instruments (Alcon), an internal rigid sleeve has also been designed to separate the aspiration and the irrigation fluids. This is also supposed to reduce the bubble formation that is often encountered during the phaco procedure. Phaco Power Settings There is no predetermined “correct” power. Initially the manufacturer’s recommended settings are used. With experience, each surgeon “fine-tunes” his settings. Power variables are adjusted intraoperatively depending on • Density of nucleus where phaco tip is engaged • Amount of tip engaged • Linear velocity of the tip during emulsification. When the power is inadequate, the tip will fail to cut the nucleus, and tend the push excessively on the nucleus which lead to zonular stress and can be dangerous. When the power is too much, rather than holding the nucleus it will cause the nucleus to flyaway from the ultrasound tip, termed chatter. Too much power can also accidentally pierce the nucleus, making a hole in the capsule and leading to a dropped lens, a catastrophe, best avoided. Thus setting a safe power setting prior commencing is important. A safe “standard” setting is as under. The ultrasound power is set to 50 to 70 percent. If the lens is soft, it is decreased to about 30 percent and if it is hard, the power is increased to 80 percent or 90 percent. Power is reduced if the nucleus chatters. At this stage, the linear ultrasound mode is changed to pulse mode, which tends to hold the nucleus better against the tip and by giving a break between each pulse enables the fragments to corne to the tip easier. The third-generation machines, having four crystals per handpiece, have far better fragmentation control and rarely need the power to be turned up above 70 percent. It is best to consult each individual manufacturer regarding their safe “recommended” settings and only after experience is derived on that machine gradually change the values to suit ones individual style of phaco. Ultrasound is inaudible. The buzzing audible sound often mistaken for ultrasound, is simply the harmonic overtones of the handpiece and phaco tip.

22

THE A RT

OF

PHACOEMULSIFICATION

Phacoemulsification Terminology Phaco power Phaco power is the ability of the phaco handpiece to cut or emulsify a cataract. Phaco power is directly related to stroke length, frequency and efficiency of handpiece. Stroke length Stroke length is the distance by which the titanium phaco tip moves to and fro. It is the most important factor in deciding the phaco power. The stroke length can be altered by changing the phaco power setting of the machine. Frequency Frequency is the number of times the tip oscillates and is fixed for a particular phaco handpiece. It is measured in kHz. Preset levels Each surgeon sets his level which he does not wish to exceed during the surgery, both for minimum levels as well as maximum levels. This is done so that the safe levels are not exceeded inadvertently during the stress of surgery. Linear v/s panel In linear control, pressing the foot-pedal leads to gradual rise of the parameters from zero to preset maximum with a linear relation to the footpedal control. In panel mode, the parameter reaches the preset panel maximum on pressing the foot switch without any linear foot pedal control. Essentially it panel is simply on or with no variables in between, panel mode is normally utilized for diathermy, flow rate or for vitrectomy settings, never for power settings or aspiration settings on phacoemulsification. Constant v/s pulse phaco power In constant mode, power is delivered continuously and it can be linear or panel controlled. Pulse mode allows phaco power to be delivered at preset intervals which can be varied. The pulse mode gives relative intervals where there is absence of tIP movement. This improves the flow characteristics and helps in evacuating small nucleus particles towards the end of the surgery. The pulse mode is also relatively safer for the epinucleus because a more consistent and predictable cutting power will provide greater stability in the posterior chamber. Maximum phaco power Maximum phaco power is preset by the surgeon. It determines the maximum obtainable ultrasonic energy when the foot pedal is fully depressed. Actual phaco power Actual phaco power in a machine with a linear foot-pedal control is proportional to foot pedal position and denotes the power actually being delivered at a given time. Effective phaco time (EPT) Effective phaco time is the total phaco time at 100 percent phaco power. It can be less than the total foot-pedal time. EPT is very significant as less EPT indicates proportionately less energy delivered to the eye thereby reducing the side effects of phaco power. When one compares the energy used between different types of procedures, or even between different instruments, one has to compare the EPT which is a much more accurate index.


23

How does phacoemulsificatlon work? There are various steps involved in the actual phacoemulsification process. • Mechanical contact of the tip with the lens • Acoustical wave transmitted through fluid in front of the tip • Cavitation At the cessation of the forward stroke, the tip has imparted forward momentum to the fluid and the lens particles in front of it. On the tip being retreated, the fluid cannot follow thereby creating a void in front of the tip. The void is collapsed by the implosion (cavitation) of the tip thereby creating additional shock waves. • There is an impact of fluid and lens particles being pushed forward in front of the tip. Considering the mechanics of phaco it is clear that there is attenuation of energy on phacoemulsifying within nuclear material. This reduces the deleterious effects on the corneal endothelium. Therefore, posterior chamber phaco helps to maintain the safety of the procedure by increasing the working distance from the endothelium. Further, if phaco power is used only when the tip is in the nucleus, the safety margin is significantly enhanced. The ultrasonic handle has three functions, namely, irrigation, aspiration and fragmentation. These can be operated separately or simultaneously. The dynamics of irrigation and aspiration are now considered in detail. Irrigation System In most phacomachines, irrigation during phacoemulsification is provided by gravity feed through the space between the titanium phaco tip and the sleeve. The amount of irrigation is determined by the bottle height relative to the patient’s eye, by the sleeve diameter, and most importantly by the loss of fluid from the eye. Stable anterior chamber dynamics: Irrigation = aspiration + leakage from the wound. Rigid sleeves may be preferred over flexible sleeves because the irrigation does not get compromised while manipulating the handpiece in the incision. The height of the irrigation bottle during phaco is usually placed between 65 cmand 75 cm above the eye level. The eye should be at the same level above the floor as the pump (cassette) of the phacoemulsifier. Aspiration System Aspiration is defined as the evacuation of fluid through a closed system. Two important concepts concerning aspiration are flow rate and vacuum level. Flow rate Flow rate is the quantity of the fluid pulled from the eye per minute through the instrument tip and irrigation tubing. Flow rate therefore helps in bringing the material towards the tip. Flow rate is measured in cc/min and is dependent on the level of vacuum created in the aspiration tubing by the aspiration pump

24

THE A RT

OF

PHACOEMULSIFICATION

and surface area of the port of aspirating tip. Flow rate determines the rate of rise of the aspiration vacuum when the aspiration port is occluded. Vacuum Vacuum level is the difference in pressure between atmospheric pressure and the pressure inside the aspiration tubing. This is a negative suction pressure that is created by the pump. Port vacuum (mm Hg/min) = the vacuum created (mm Hg) port area (mrn)2 The vacuum level created at the port therefore varies inversely with the diameter of the tip. The vacuum or negative suction force created helps in holding the material to the tip and its final aspiration. Aspiration Pumps Depending on the machine, three kinds of pumps are used to control aspiration and produce the negative suction pressure, i.e. the vacuum (Fig. 2.7). They are • Peristaltic pump • Venturi pump • Diaphragmatic pump.

Fig. 2.7: The peristaltic pump of the opticon P4000 machine

The peristaltic pump is also known as a “constant flow” pump while the Venturi and the diaphragmatic pumps are of the “constant vacuum” variety. Peristaltic Pump Peristaltic pump (Figs 2.8 and 9) was popularized by the heart-lung machine. In these pumps, a pressure differential is created by compression of the aspiration tubing in a rotatory motion. When the rotational speed is low, vacuum develops only when the aspiration port is occluded. On occlusion, vacuum builds up to preset


25

Fig. 2.8: Full function display of the Alcon Legacy Machine

value in a stair-stepped pattern. By increasing the rotational speed, as in the newer generation machines, a linear build-up of vacuum occurs even without occlusion of the tip. It can thus be made to simulate a Venturi or a diaphragmatic pump. Advantages of a Peristaltic Pump • • • •

•

Fig. 2.9: Hand-held full function remote control of Alcon which controls the Alcon Legacy Machine

• •

Vacuum build-up occurs only on occlusion of the aspiration port. There is a large safety margin in this pump as it is slower in building up vacuum The peristaltic pump is a dedicated anterior segment system The peristaltic system is a more forgiving system as there is no inadvertent pull on the ocular structure since vacuum builds up only on occlusion The fluidics of the peristaltic pump are more controlled with little or no deflation of the anterior chamber on sudden removal of occlusion Vacuum level and flow rate may be controlled independent of each other Peristaltic pump allows both zero and high vacuum phaco.

Disadvantages of a Petlstaltlc Pump • The vacuum build-up is directly related to the density of occlusion which in turn would depend upon the bevel angle of the titanium tip and the tissue density • The vacuum build-up is in a stair-stepped pattern

26

THE A RT

OF

PHACOEMULSIFICATION

• Because of the stair-stepped pattern of the vacuum build-up, there could be more pulsations in the anterior chamber • True linear aspiration is not seen, however newer pumps do simulate a linear build-up of vacuum • One has to mechanically approach the nuclear or cortical matter to first achieve occlusion for vacuum to build up in order to aspirate the tissue. However, the rapid rotation mode has significantly improved the followability of the tissue, even in the peristaltic pump. Venturi Pump A Venturi pump uses compressed gas to create inverse pressure. Vacuum generated is related to gas flow which in turn is regulated by a valve (vacuum build-up occurs linearly in a consistent manner from zero to a preset value. The build-up is almost instantaneous on pressing the foot-pedal. Due to this there is an increased risk of iris trauma and posterior capsular rents which make these pumps unsafe, particularly so for beginners. Advantages of a Venturi Pump • There is a good follow ability of the tissue • The vacuum build-up is linear • There is a consistent increase in the vacuum from zero to the preset level on depressing the foot switch • Nuclear and cortical material can be attracted towards the probe on depressing the foot pedal. Disadvantages of a Venturi Pump • This pump has the least safety margin and is not forgiving to the surgeon • The rise time is too fast • There is an immediate rise in the vacuum on pressing the foot switch to position 3 without any linear foot pedal control • The incidence of iris chaffing and posterior capsular rents have been reported to be much higher with this pump as compared to’ the peristaltic pump • Venturi pump does not allow either zero to high . vacuum phaco. Diaphragm Pump A diaphragm pump uses a flexible membrane within a cassette to generate vacuum. Build up of vacuum is more linear and reaches the preset level even without occlusion. This makes it unsafe. However, lens material can be aspirated without having to mechanically approach it. Advantages of Diaphragm Pump • There is an improved linearity of vacuum build-up • The flow rate and aspiration are faster • Tissue can be pulled towards the center as vacuum builds up to preset even without occlusion


27

• There is a greater control with the diaphragm pump during posterior segment surgery. DIsadvantages of a DIaphragm Pump • This being a faster pump it offers lesser safety margin • Foot pedal depression does not have a very good graded control over vacuum build-up • Rise of vacuum depends on the fluid in the chamber • Vacuum build-up reaches preset level even without occlusion. This leads to inadvertent pull on ocular tissue resulting in a higher complication rate • A Venturi is not a forgiving pump and has to be handled by newcomers with caution though in the hands of an expert it can give excellent results. Physics of Phaco: Certain Aspects Aspiration pressure It is modified depending on the stage of surgery and is inversely proportional to the diameter of the aspirating port. The ultrasonic tip has a port diameter of 1.00 to 1.20 mm with which the maximum vacuum achievable is 70 to 100 mm of Hg. However, in new machines (Alcon’s Legacy, and the Allergan Sovereign series, etc.) the vacuum can be raised to 500 mm of Hg in the phaco mode. The I-A tip has a diameter of 0.3 mm and the aspiration pressure may be increased to 500 mm of Hg. Rise Time and Pump Flow Rise time Rise time is a measure of how rapidly vacuum builds up once the aspiration port is occluded. Pump flow Pump flow is a measure of the rotational speed of the peristaltic pump head (which in turn determines flow rate and aspiration). This changes from machine to machine. RelationshIp of Illse TIme and Pump Flow As the pump flow increases, vacuum builds rapidly as the tip is occluded and therefore the rise time decreases. Pump flow is usually preset by the surgeon and is measured as a percentage. Normally 100 percent is equal to flow rate of 35 cc/minute. It is an overall measurement of fluid turnover in the eye. Pump flow determines rise time and event time. Vacuum Settings Maximum vacuum Determine the maximum obtainable vacuum when the aspiration port is fully occluded. Maximum vacuum is preset by the surgeon and is measured in mm of Hg. Typical settings are 65 to 75 mm Hg for phaco and 400+ mm Hg

28

THE A RT

OF

PHACOEMULSIFICATION

for irrigation aspiration. The speed at which this vacuum is achieved is determined by the pump flow setting and the bore of the aspirating tube. Actual vacuum It indicates pressure at the aspirating port at a given time. This depends on the maximum preset pump flow, degree of tip occlusion and position of the foot pedal when linear control is used. RelationshIp Between Pump Flow, Irrigation and Aspiration With an increase in the pump head rotational speed, the pump flow increases. Due to this, both aspiration rate and irrigation flow also increase. Relationship between pump flow, rise time and vacuum To reach a preset vacuum, as pump flow increases the rise time decreases, e.g. if pump flow is doubled the rise time gets halved. Fluidic Balance Fluidic balance is the balance between inflow of fluid into the eye and the outflow of fluid out of the eye, which helps in maintenance of the IOP. An adequate fluidic balance provides • Constant lOP • Stable anterior chamber • Protects corneal endothelium and posterior capsule. The amount of irrigation is determined by the bottle height relative to the patient’s eye, by the sleeve diameter, and, most importantly, by the loss of fluid from the eye. The following situations may exist: • Balanced anterior chamber dynamics: Irrigation = Aspiration + Leakage • Tight Wound (Irrigation decreases): 400 microns Size and Planar Configuration • Single-plane incision 2.5 by 1.5 mm rectangular tunnel • Two-plane incision 2.5 by 1.5 mm rectangular tunnel • Three-plane incision 2.5 by 1.5 mm rectangular tunnel plus a perpendicular arcuate component. STRENGTH OF CLEAR CORNEAL INCISIONS VERSUS LIMBAL OR SCLERAL INCISIONS Paul Ernst in 1994, demonstrated that rectangular clear corneal incisions in animal models show higher resistance to external deformation utilizing pinpoint pressure as compared to square limbal incisions. The question of stability of the corneal tunnel has been the challenge of pinpoint pressure. The concept has been that whether cataract wound strength should be evaluated by challenging one’s incision using a pinpoint pressure on the posterior lip of the incision. Howard Fine and many other surgeons have demonstrated that it is not a correct test, as it is very unlikely that the patient would challenge his or her own wound strength by pressing with so fine an instrument as to pinpoint the exact site of pressure, which may leak. It is more appropriate to check the challenge with a blunt hook, which closely resembles the pressure, induced by a fingertip or knuckle, which is the most likely way the patient, would exert pressure. It is very unlikely that even a small percentage of incisions would leak spontaneously with blunt pressure (Fig. 9.1). Questions have been raised regarding the relative safety of clear corneal incision versus a limbal-based corneal incision. Though, in theory, the limbal-based corneal incision would heal faster, and have a stronger ability to prevent leakage, the corneal incision gives excellent stability against leakage, and against accidental pressure.The one big disadvantage of the limbal-based corneal incision is the greater likelihood of ballooning of the conjunctiva, either at the site of the incision or even sometimes

CLEAR C ORNEAL CATARACT S URGERY

Fig. 9.1: Side port being made with 1.2 mm MVR blade

89

Fig. 9.2: Clear corneal tunnel being prepared with corneal substance

the complete conjunctiva, billowing forwards, making visualization of the anterior chamber structures during the surgical procedure more difficult. A point of caution Park in 1997 has demonstrated that violation of the glaucoma bleb could threaten the integrity, not only of pre-existing filtering bleb but could also make the zone very amenable to subsequent infection. In addition, there is always likelihood that even a minor trauma like a hard rub to the eye could lead to a small hemorrhage. TECHNIQUES Fine et al in 1992 described the first self-sealing corneal tunnel incision for small incision cataract surgery utilizing a 3.00 mm diamond knife. The technique utilized was a two-plane incision. The first incision was performed perpendicular to the plane of the cornea (Fig. 9.2). The depth of the incision is kept at roughly 200 microns. Though ideally done with a calibrated diamond knife, it is more often, than not, done using the unguarded edge of the diamond knife, with the incision being made a little deeper than a superficial scratch. In doing the second plane, the knife enters deep into the primary incision and then continues in a plane parallel to the corneal plane, forming the cleavage in the corneal stroma. In practice it is simple to do, if the operating surgeon places the flat of the diamond blade, opposed to the conjunctiva, and then enters via the primary incision made. It gives a virtually perfect placement in the stromal zone (Fig. 9.3). The tip of the diamond knife after a 2 mm tunnel is constructed, is then allowed to “dimple” the edge of the Descemet’s, and is then simply pushed forward in the same plane, to achieve a cut in a straightline configuration (Fig. 9.4). Alternatively, the surgeon can use a round disk knife to dissect open a shallow stromal tunnel of the required length and then enter the chamber with the knife. Caution should be used in not entering the chamber with the rounded disk knife as it does not give a straight line cut and will compromise the valve function of the incision.

90

THE ART

OF


Fig. 9.3: Tip entered into anterior chamber. Tunnel complete

Fig. 9.4: If required the tip can be dimpled down prior insertion into anterior chamber

Paul Ernst has clearly demonstrated that to be astigmatically neutral the incision should be squared. (i.e. the length and the width of the tunnel should be equal). Williamson in 1993 was the first to utilize a 300 to 400 microns primary clear corneal incision. Rationale for the Williamson incision was that a thicker external edge to the roof of the tunnel had a less likelihood of tearing. Langerman in 1994 described the single hinge incision in which the primary incision was made vertically in the cornea for a depth of ¾ of the cornea (400 microns) with the calibrated diamond knife. Subsequently, half way through the depth of the incision a horizontal groove is made in the stroma. The knife is then passed parallel to the corneal plane for a length of 2.00 mm, is dipped down to dimple the Descemet’s membrane and penetrates into the anterior chamber. Langerman felt that this initial “hinge” gave total protection towards accidental leakage of aqueous by pressure on the posterior flange of the incision. This technique led to an improved resistance for leakage from the incisional edges by the application of external pressure leading to deformation. New Blade Technologies The Fine Tri-diamond knife was developed with Mastel so that the entry incision into the cornea and exit from the cornea into the anterior chamber could be made in an extremely sharp thin line without a necessity to depress the tip of the knife down which often results in a tendency for tearing of tissue or scrolling of the Descemet’s membrane. It also makes for a superb self-sealing valve. Rhein Medical developed a 3-D blade of 2.8 mm in width. This blade has differential slopes on the anterior and posterior surfaces, so that the forces of the tissues exerted along the blade will automatically allow the blade to “flow” in the plane of the cornea with no risk of an early entry nor of an inadvertent anterior escape. One simply places the tip of the blade where one desires the external incision. The blade is then pushed in the plane of the cornea with no attempt to applanate the cornea or attempt to enter the eye by dimpling. Perfect incision can be made rapidly, and more importantly, reproducibly produced.


91

CLEAR CORNEAL INCISIONS AND ASTIGMATISM One has to clearly understand the rationale of clear corneal incisions • Excellent access to the anterior chamber for proper rhexis performance and access to the cataract and for IOL placement. • Virtually bloodless incision • Enables the formation of a self-sealing incision, resistant to deformation or leakage. • Variable incision architecture to reduce or eliminate pre-existing astigmatism • Faster physical rehabilitation of the patient. Most surgeons will permit immediate postoperative bending over by the patients or even strenuous physical activity without the risk of wound disruption. • Being an anastigmatic incision, the refractive stability is almost perfect enabling additional reading spectacles to be prescribed in 4 days time. • A much quieter eye, with faster healing, virtually no irritation or redness and no “flag” signs of inflammation. TOPOGRAPHIC CONTROL OF CORNEAL ASTIGMATISM Astigmatism has always been an integral part of cataract surgery. Intracapsular cataract extraction (ICCE) is still popular in many parts of the world especially in Asia, Middle East and Africa. The ICCE technique generally utilized the Graefe knife or scissor based, 180-degree corneal incision. Subsequent wound closure by suturing with 10/0 nylon usually saddled the poor patient with an exorbitant quantum of variable astigmatism. The shift to extracapsular cataract surgery (ECCE) did little to reduce the astigmatism, as invariably a two plane or a three plane, large implant had to be inserted. It was the advent of phacoemulsification that has made the surgeon, and the patient, appreciate the advantages of small incision surgery and apply the concept in an endeavor to reduce astigmatism still further. The greatest advantage of clear corneal < 3.00 mm (also termed sub-three) incision, was that it was literally an astigmatic neutral incision. Evaluating corneal changes utilizing the computerized corneal topographer has significantly improved the understanding of how these incisions work and what has to be done to reduce their astigmatic tendencies. Ideally, corneal topography should be done in all cases in an effort to evaluate the astigmatic component and the resting status of the cornea. In order to understand the effect of clear corneal sutureless incisions, one has to comprehend that the shape of the corneal dome is derived partly from lamellar collagen bundles and the relative elasticity of the corneal tissue. Trauma induced to a cornea, be it an injury or even simply, surgery, affects the regularity of the corneal surface. As the lesions heal, alterations are induced to the corneal shape. It must however be clearly appreciated that while a corneal incision made of 2.8 mm size will induce no topographically demonstratable astigmatic changes whatsoever, one of 4.00 mm or 5.00 mm will induce against-the-rule (ART) astigmatism, more so, if the incisions are not properly constructed.

92

THE ART

OF


It is perfectly feasible to combine phacoemulsification and astigmatic surgery on the table. However this is acceptable only provided, the cornea is quite regular (< 2.00 D astigmatism) and the maximum width of the incision to be utilized is 3.00 mm, or smaller. If the astigmatic component is more or if one is going to be enhancing the incision to 4.00 or more, it makes more sense to do it as a twostep procedure. Do phaco as a primary procedure, allow the cornea to stabilize postoperatively, and only then after doing a computerized corneal topography , plan and complete the astigmatic procedure. CONCLUSION Clinically, clear corneal incisions have now become the most popular option for cataract extraction IOL implantation throughout the world. Spearheaded by phacoemulsification and the now sub-three (< 3.00 mm ) sized incisions, significant improvements in surgical techniques have resulted in a keen appreciation of astigmatism, how it is induced and what can be done to reduce, if not eliminate it entirely. Being naturally anastigmatic, phacoemulsification incisions serve as an ideal background datum to achieve a zero refractive status, and at the same time, in managing residual astigmatism, obviate the necessity for complex calculations. Clear corneal incisions have had an outstanding record of safety with exceptional cosmetic outcome and should increase in popularity with time. FURTHER READING 1. Kirk S, Burde RLM, Waltman SRL: Minimizing corneal endothelium damage due to intraocular lens contact. Invest Ophthalmol Vis Sci 16:1053, 1977. 2. Ernst PH, Kiessling LA, Lavery KT: Relative strength of cataract incision in cadaver eyes. J Cataract Refract Surg 17(suppl):668-71, 1991. 3. Ernst PH, Lavery KT, Kiessling LA: Relative strengths of scleral corneal and clear corneal incisions constructed in cadaver eyes. J Cataract Refract Surg 21:39-42, 1994. 4. Ernst PH, Neuhann T: Posterior limbal incision. J Cataract Refract Surg 22:78-84, 1996. 5. Ernst PH: The corneal lip tunnel incision. J Cataract Refract Surg 20:154-57, 1994. 6. Ernst PH: The self-sealing sutureless wound: Engineering aspects and experimental studies. In Gills JP, Martin RG, Sanders DR (Eds): Sutureless Cataract Surgery. SLACK Inc: Thorofare 23-39, 1992. 7. Edelhauser HF, Gonnering R, Van Horn DL: Intraocular irrigating solutions—a comparative study of BSS plus and lactated Ringer’s solutions. Arch Ophthalmol 96:516-20, 1978. 8. Edelhauser HF, Van Horn DL, Schultz RO et al: Comparative toxicity of intraocular irrigating solutions on the corneal endothelium. Am J Ophthalmol 81:473-81, 1976. 9. Edelhauser HF, Van Horn DL, Hynduiuk RA et al: Intraocular irrigating solutions—their effect on the corneal endothelium. Arch Ophthalmol 93:648-57, 1975. 10. Edelhauser HF, Rosenfeld SI, Waltman SR et al: Discussion of comparison of intraocular irrigating solutions in pars plana vitrectomy. Ophthalmology 93:114-15, 1986. 11. Fine IH, Finchman RA, Grabow HB (Eds): Clear Corneal Cataract Surgery and Topical Anesthesia Slack Inc: Thorofare 1993 12. Fine IH: The Rhein 3-D diamond knife. Eye World 1:2-24, 1996. 13. Fine IH, Fichman RA, Grabow HB: Clear Corneal Cataract Surgery and Topical Anesthesia Slack Inc: Thorofare 1993. 14. Fine IH: Architecture and construction of a self-sealing incision for cataract surgery. J Cataract Refract Surg 17(suppl): 672-76, 1991. 15. Fine IH: Cortical cleaving hydrodissection. J Cataract Refract Surg 18:508-12, 1992.


93

16. Mehta KR: Pitfalls encountered in 1500 consecutive posterior chamber implant. All India Ophthl Soc Proc 165-66,1986. 17. Mehta KR: Phacoemulsification cataract extraction with foldable IOLS—first 50 cases. All India Ophthl Soc Proc 56-60, 1989. 18. Mehta KR: Endocapsular phacoemulsification and posterior chamber IOL implantation. All India Ophthl Soc Proc 217-20, 1989. 19. Keiki R Mehta: Post-cataract astigmatism—a comparison between phacoemulsification and ECCE procedure—cataract with and without intraocular implantation. All India Ophthl Soc Proc 226-29, 1989. 20. Mehta KR: Posterior capsular capsulorrhexis with shallow core vitrectomy following implantation in paediatric cataracts. All India Ophthl Soc Proc 207-10, 1995. 21. Mehta KR: The clear corneal phacoemulsification with injectable silicone lenses. All India Ophthl Soc Proc 218-22, 1995. 22. Mehta KR: The new shelve and shear technique for simplified phacoemulsification. All India Ophthl Soc Proc 222-24, 1995. 23. Mehta KR: Posterior chamber implantation. All India Ophthl Soc Proc 143-44, 1990. 24. Mehta KR: YAG Laser damage to intraocular implants—an evaluation. All India Ophthl Soc Proc 14750, 1990. 25. Mehta KR: Phacoemulsification—is it the true III world answer for eye camps. All India Ophthl Soc Proc 301-03, 1990. 26. Mehta KR: An analysis of causative faction leading to eye strain caused by computer monitor screens. All India Ophthl Soc Proc 334-36, 1990. 27. Mehta KR: Single stitch elliptical funnel incision for cataract surgery. All India Ophthl Soc Proc 25354, 1991. 28. Mehta KR: Bifocal intraocular implants—a functional evaluation based on 425 cases. All India Ophthl Soc Proc 271-74, 1991. 29. Mehta KR: Phacoemulsification with flexible PC IOL—is it really a step forward? All India Ophthl Soc Proc 287-88, 1991. 30. Mehta KR: The New Phaco cleave technique for hard cataracts. J Intraocular Implant and Refractive Society India, 1(1): 74-75, 1996. 31. Mehta KR, Sathe, SN, Karyekar SD: The new soft intraocular lens implant. Am Intra-Ocular Implant Society J 4(4):200-205, 1978. 32. Mehta KR, Sathe SN, Karyekar SD: New soft posterior chamber implant. X Congress of the AsiaPacific Academy of Ophthalmology. New Delhi,1985. 33. Keiki R Mehta: When not to do an anterior chamber implant. All India Ophthl Soc Proc 164 -165,1986. 34. Mehta KR: Mehta Tangential Chop (MTC) technique for phacoemulsification. All India Ophthl Soc Proc (Chandigarh) 1996. 35. Mehta KR: Phaco-levitation—a peaceful way. All India Ophthl Soc Proc (Chandigarh) 1996. 36. Mehta KR: Comparison of centration stability and capsular response to AcrySoft and silicone S130 lenses. All India Ophthl Soc Proc 1998. 37. Mehta KR: Intralenticular “hubbing” technique for simple eye camp phacoemulsification—a simple technique. APIIA Conference 1997. 38. Mehta KR: Management of subincisional cortex in small incision cataract surgery (SICS). Proc of SAARC Conference, Nepal, 1994. 39. Mehta KR: Intralenticular “hubbing” phaco technique for safe phaco. Proc of SAARC Conference, Nepal, 1994. 40. Mehta KR: The new multiport phaco tip for safer, more effective phacoemulsification, with virtually zero capsular damage. Proc of SAARC Conference, Nepal, 1994.

94

THE ART

OF

PHACOEMULSIFICATION

Shashi Kapoor

Capsulorrhexis (CCC): A Beginner’s Guide

10

INTRODUCTION Continuous curvilinear capsulorrhexis (CCC) is one of the revolutionary innovations of modern cataract surgery. It was presented to the ophthalmic, surgical community in 1985 and 1986 by Fercho, Graether, Gimbel, and Neuhann. These ophthalmologists were able to use and appreciate CCC because they had developed methods for performing phacoemulsification totally within the capsular bag, i.e. they were not using an iris plane approach in which the superior pole of the cataract is tipped superiorly out of the bag for tip access. Terminology CCC—continuous, circular, capsulorrhexis. The border does not need to be “circular”, but may be ovoid or elliptic. Hence, the more generic word “curvilinear” has replaced “circular”, leaving the abbreviation the same—CCC. Anatomy of Lens Capsule The posterior zonular fibers are inserted 1.0 to 1.5 mm from the equator, while the anterior zonular fibers are attached approximately 2.0 mm from the equator. Since the diameter of the adult crystalline lens is 9.5 to 10.0 mm, the “zonulefree” area, on the anterior capsule is approximately, 6.0 mm in diameter only. It is therefore ideal to create a tear limited to the zonule-free area, preferably slightly inside the zonular frontier, as zonular fibers have been observed more centrally than has previously been considered.

CAPSULORRHEXIS (CCC): A B EGINNER’ S GUIDE

95

Technique Prerequisites Absence of positive pressure— facilitated by use of viscoelastic agents, air, irrigation, or a “closedchamber” technique, where a bent needle, used to perform the CCC, perforates the preplaced incision, before any other entry is made into the anterior chamber. Instruments Cystotomes, bent needles or forceps, can all be used effectively. Existing ultrasonic or thermal devices, are not believed to offer any advantages. Initiation of Tear Beginning of CCC peripherally, carries a greater liability than beginning centrally. With the initial cuts made centrally, radial stress vectors across the anterior capsule are interrupted, resulting in less tendency for the tear to extend towards the equator. It is always easier to spiral the initial tear out to enlarge a capsulotomy, than it is to pull a peripheral tear back towards the center. Technique Using a bent needle, of 23 G to 25 G, a perforation is made in the Figs 10.1 A to C: Continuous curvilinear capsulorrhexis center of the anterior capsule. By (CCC): (A) central puncture with cystotome and progression extending this with the sharp edge of tear to the 3.0 O’clock position, (B) the curvilinear tear is continued counterclockwise with the capsular flap folded of the needle, a horizontal incision over itself, and (C) the progressing tear is blended at 3.0 is made (Fig. 10.1A). The tip of the O’clock with the cystotome having re-engaged the ventral needle is now used to redirect the surface of the capsule for optimum control (Gimbel) tear in a counterclockwise direction. This creates a flap with a smooth curve as it is beginning. The flap is then pulled along in a circular manner by means of gentle traction with the needle tip. If the tear starts to extend peripherally, it is usually the result of positive vitreous pressure

96

THE ART

OF

PHACOEMULSIFICATION

and can be counteracted by reinflating the anterior chamber with viscoelastic. A light touch is needed, because if one presses too hard on the flap, it creates a responding increase in vitreous pressure, which forces the tear outward. As the flap progresses, large amounts of capsular folds will present and must be pushed out of the way, so that one can visualize the exact point at which to place the tip of the needle (Fig. 10.1C). When completing the CCC, one should overlap the tear such that the last part of the tear joints the first part from the outside towards the center, thus resulting in a continuous edge. If the overlap is created from the center towards the outside, it will result in a small triangular flap, with a tendency to tear towards the equator or beyond. The best control of the progressing tear is achieved by grasping the developing capsular flap, with the desired instrument close to where the capsule is tearing at the time. The direction of the tear can be controlled by the position of the instrument. Placing the tip of the instrument a little peripheral to the advancing tear, will direct it outwards. Placing it a bit central to the tear will direct it towards the center. Tear patterns may vary, and progress clockwise or counterclockwise. There are cases however, when no form of CCC may be achieved. These include capsules that are heavily fibrosed and shrunken, as in certain congenital, secondary, and traumatic cataracts. In these patients, a continuous, curvilinear opening often still may be achieved by using a capsule scissors to cut through the fibrosed part of the anterior capsule. In the nonfibrosed area, the smooth edge border of the CCC is achieved by the usual methods. A Kraff-Utrata forceps can be used to perform CCC. The initial puncture in the anterior capsule is made with a bent needle, (or with the forceps itself, if the tips of the forceps are sharp enough), and the rest of the CCC is continued with the forceps. Using the forceps requires a larger opening into the anterior chamber as compared to a bent needle, and viscoelastic is usually necessary. Two-staged CCC In this procedure, the original capsulotomy is just large enough to admit the smaller endocapsular phaco probe and a second instrument for lens manipulation. After the

Figs 10.2A and B: Two-staged continuous curvilinear capsulorrhexis (CCC)


97

lens material is removed a small initial opening is converted to a larger one, of the desired diameter, while still maintaining the continuous tear edge. The second capsulotomy is started with a tangential snip on one side of the opening with a Vannas scissors (Figs 10.2A and B). This requires a viscoelastic agent in the anterior chamber and lens capsule. It is important to prevent the side of the capsule opening from folding over or under at the scissors tip so as to prevent a V-cut. Also, the snip is not taken to the scissors point, because the point may create an irregularity in the line of the cut. Such a notched cut destroys the integrity of the continuous tear. Once the tangential cut is successfully achieved, the second continuous tear is then extended, using Utrata forceps to complete a larger circle, which is centered in the pupil, and is of the desired diameter. The forceps enlarges the original capsulotomy by removing a strip or ribbon of additional capsule. Two-staged CCC is Particularly Useful • In patients with small pupils, when an originally small CCC requires subsequent conversion to a larger CCC. • When the original CCC is made inadvertently small. • For corneal endothelial protection in intercapsular and endocapsular cataract extraction. A similar technique may be used in blunting or turning back, short inadvertent tears of the anterior capsular border. Posterior CCC (PCCC) Posterior CCC uses the principle of CCC and is used to advantage, when a small linear or triangular tear inadvertently occurs in the posterior capsule, in order to convert it into a smooth CCC that is resistant to radial extension. The PCCC is accomplished just as one does an anterior CCC. The size of the PCCC is kept as small as possible to preserve the maximum support by the posterior capsule. Equatorial capsular tears, posterior capsule tears near the equator or with extensions to the equator are not suitable for PCCC. PCCC may also be used, for making primary posterior capsulectomies, in removing posterior plaques, or to blunt, small extending tears with posterior continuous. Intumescent Cataracts and CCC Intumescent cataracts are a special problem for any form of capsulotomy, especially CCC. The internal lens pressure simply splits any rent towards the equator. A useful technique in such cases, is to decompress the lens by first aspirating some lens cortex. Another difficulty is the poor visualization of the tearing edge, in milky white cataracts, where there is no red reflex. In such instances, Lee has found it extremely useful to perform CCC under air. The distortion of the tearing capsule under an air-lens interface is apparently, exceptionally clear.

98

THE ART

OF

PHACOEMULSIFICATION

Advantages of CCC There are several advantages of CCC: • In-situ phacoemulsification is facilitated, and the ultrasonic turbulence is contained within the lens capsule. • IOL implantation and verification in the bag is greatly facilitated because of the smooth-edge visible rim. • IOL rotation with no chance of decentration caused by loops coming out of the bag is allowed. • No capsular tags or V-shaped tears are left that can extend into the posterior capsule, under even minimal, mechanical stress. • A diaphragm quality of the capsule for sulcus placed lenses is maintained or preserved in the event of a ruptured posterior capsule. • Chances of posterior synechiae are reduced. • In-the-bag IOL implantation in the very elastic capsule of children is facilitated. ECCE and CCC Most surgeons recommend one or two “relaxing incisions” in the CCC, prior to nuclear expression in extracapsular cataract extraction (ECCE). The relaxing incision helps prevent untoward complications as zonular tears, vitreous loss, unintended ICCE, or even prolapse of lens into the vitreous cavity. Hydrodissection, hydrodelineation, and hydroexpression techniques are useful adjuncts, when using CCC along with ECCE. Complications of CCC These include: • Shrinkage of anterior capsular opening • Capsular bag hyperdistention • Epithelial cell hyperproliferation on the posterior capsule. CAPSULAR CONTRACTION SYNDROME Capsular contraction syndrome is seen after ECCE using can-opener capsulotomy or CCC. While rarely with can-opener capsulotomies, with anterior radial capsular tears, it is relatively frequent with CCC. The syndrome consists of an exaggerated reduction in the anterior capsulotomy opening and equatorial capsular bag diameter. This may also

Fig. 10.3: (Davison) Capsular contraction syndrome with capsulorrhexis opening displaced inferiorly and open to only 2.0 mm several months after surger y in eye with pseudoexfoliation


99

lead to a malposition of the IOL. These effects seem more exaggerated in small CCC openings and the older patient (Figs 10.3 to 10.6). It is due to capsular bag contraction from fibrous dysplasia of residual lens epithelial cells, countered by relatively unopposed weak zonular support. This is particularly seen, in pseudoexfoliation, advanced age, and in association with uveitis, pars planitis, and myotonic muscular dystrophy. Fig. 10.4: (Davison) Excessive capsular contraction has shrunk the capsulorrhexis opening to approximately 2.0 mm. The opening is decentered as is the silicone optic and the capsular bag; so the zonular fibers are visible below. Pseudoexfoliative material can be seen on the fibers

Role of IOL Material

Hayashi et al showed the reduction in the area of anterior capsule opening at various postoperative intervals after continuous capsulorrhexis and compared any differences in the area reduction between polymethylmethacrylate (PMMA), silicone, and soft acrylic IOLs. Figure 10.7 shows retroillumination photographs, which illustrate the typical postoperative changes in the anterior lens capsule of the three optic materials. Figure 10.7 top left, shows an eye after undergoing PMMA IOL implantation. A slight degree of Fig. 10.5: (Hansen) Red reflex of an eye with dense contraction and fibrosis of the anterior capsular fibrosis and well-centered, but anterior capsule opening occurred extensively constricted capsular opening (1.3 mm). Note the radial stress lines and the broad fibrous rim of over the PMMA optic. Figure 10.7, top the circular capsulotomy. The three-piece posterior right, shows an eye after undergoing chamber IOL is completely within the capsular sac and silicone IOL implantation. shows a mild inferotemporal decentration The contraction of the anterior capsule progressed markedly up to 3 months after surgery. The degree of fibrosis in the anterior capsule was also extensive. Figure 10.7, bottom shows an eye after soft acrylic IOL implantation. The anterior capsule contraction was very slight. Surprisingly, no fibrosis in the anterior capsule was evident in some cases in the soft acrylic IOL group. The study clarified that the area of the anterior capsule opening gradually decreased for up to 3 months after surgery. However, after 3 months, the area reduction in the anterior capsule opening showed no further progression. The percentage of the area reduction with the silicone IOL

100

THE ART

OF

PHACOEMULSIFICATION

Fig. 10.6: (Hansen) Photograph of a case immediately after Nd: YAG laser anterior capsulotomy in a cross pattern, cutting through the fibrous rim of the constricted opening

was greater than that with the polymethylmethacrylate and soft acrylic intraocular lenses. No significant difference was observed between the PMMA and soft acrylic intraocular lenses. Furthermore, although it could not be quantitated in this study, the degree of fibrosis in the anterior capsule was most extensive in the silicone IOL, followed by the PMMA IOL. On the other hand, the anterior capsule fibrosis over the soft acrylic optic was extremely slight.

Prevention Capsular fibrosis is caused by metaplastic lens epithelium. The more epithelium that is left, the greater the potential for capsule contraction. Since twice as much epithelium is removed with a 5.5-mm capsulectomy as with a 4.00-mm capsulectomy,

Fig. 10.7: Retroillumination photographs showing postoperative changes in the anterior lens capsule. (Top left) after a polymethylmethacrylate (PMMA) IOL implantation. A slight degree of contraction and fibrosis in the anterior capsule was observed over the PMMA optic. (Top right) An eye after a silicone IOL implantation. A marked contraction of the anterior capsule opening occurred for up to 3 months. The degree of fibrosis in the anterior capsule was also prominent, especially along the capsulorrhexis edge. (Bottom) An eye after soft acrylic (AcrySof) IOL implantation. The anterior capsule contraction over the soft acrylic optic was very slight. It was surprising that no fibrosis in the anterior capsule was evident

CAPSULORRHEXIS (CCC): A B EGINNER ’ S GUIDE

101

one should make the larger anterior capsulectomy in vulnerable eyes. The sphincter effect of an intact capsulorrhexis is important in creating significant capsule shrinkage. A can-opener capsulotomy with deliberately created anterior radial capsular defects may be appropriate in lose eyes with zonular weakness. Another influence in maintaining capsular bag size and shape and good functional IOL position is the use of a one-piece, all-PMMA IOL with a relatively firm broad haptic structure. Nishi suggested vacuuming the undersurface of the anterior capsule to significantly reduce the amount and effect of residual lens epithelial cells.

Fig. 10.8: Six anterior YAG capsulotomies are almost not visible, three weeks after creation in a patient with pseudoexfoliation

Fig. 10.9: Same eye as in Figure 10.8 six anterior YAG capsulotomies have been redefined with more YAG separation

Role of Nd:YAG Laser Early anterior radial YAG laser, relaxing capsulotomy helps resolve the ultimate contraction of the anterior capsulectomy opening (Figs 10.8 and 9). These anterior capsulotomies may also reduce the incidence of more rare complications of excessive zonular traction and its sequelae, IOL dislocation and retinal detachment. If capsule contraction is noted, consider YAG laser relaxing anterior capsulotomies at 2 to 3 weeks postoperatively. Active capsular fibrosis and attendant contracture of the anterior capsule and indeed the entire capsular diameter can be influenced with early YAG laser intervention, whereas later intervention may not help really as much. CAPSULAR

BAG

HYPERDISTENTION

“Capsular block” implies fluid hyperdistention of the capsular bag from occlusion of the circular anterior capsule opening by the IOL optic; the resulting anteriorplacement of the optic induces an artificial myopia; the source of the fluid is unclear, although some have suggested that it is retained viscoelastic (Fig. 10.10). Other possibilities include transudation through the lens capsule or exudation from the lens epithelial cells. Capsular block is generally self-limiting and is only associated with capsulorrhexis and IOLs flexible or mobile enough to move forward against the capsule opening; it has not been observed with the traditional can-opener

102

THE ART

OF

PHACOEMULSIFICATION

Fig. 10.10: (Masket) Schematic representation of the capsular block phenomenon. The highly flexible one-piece lens depicted in this model is bowed forward, the optic portion blocks the capsulorrhexis, and the capsular bag is distended

Fig. 10.11: (Masket) String of pearls observed as the hyperproliferation of lens epithelial cells (Elschnig pearls) surrounding a previously formed Nd: YAG laser posterior capsulotomy

capsulotomy or with one-piece PMMA IOLs. A small Nd:YAG laser opening in the anterior or posterior capsule permanently relieves capsular block. HYPERPROLIFERATION

OF

LENS

EPITHELIAL

CELLS

Hyperproliferation of lens epithelial cells in the form of Elschnig pearls on the central posterior capsule, surrounding a previously made laser capsulotomy, has been reported (Fig. 10.11). The “string of pearls” that forms around the capsulotomy reduces the opening, making the capsulotomy potentially too small to be optically adequate. The pearls appear to form on the anterior hyaloid and capsulotomy edge, using either as scaffolding, and then progress centrally. The epithelial cells surrounding the capsulotomy are dense, but became more sparse peripherally. Perhaps a stimulus to epithelial cell growth is present in the anterior vitreous, since the string of pearls does not form until after the posterior capsule has been opened. The “string of pearls” has only been observed in cases in which the IOL diameter was larger than the anterior CCC. In this situation, the anterior capsule overlaps the IOL edge, and the anterior and posterior capsules cannot fuse in a true Soemmering’s ring because the optic is sandwiched between the capsule leaflets. The reduced effective size of the posterior capsulotomy associated with the hyperproliferation of lens epithelial cells, has required Nd: YAG laser “retreatment” in many patients.

Shrikant Kelkar

Capsulorrhexis: Principles and Advanced Techniques

ANTERIOR

11

CAPSULORRHEXIS

History The problems related to the sulcus implantation of posterior chamber intraocular lenses (PC IOLs) during the period of about 1975 to early 1980s lead to the idea in favor of placing the intraocular lens implant into the capsular bag which lead to a better centration of the implant. The new design of Simcoe loops (modified C loop) improved better centration. However decentration was not uncommon. The analysis of this decentration showed that in spite of the fact that the lenses were in correct endocapsular situation tears of the anterior capsule originated, luxating one loop into the sulcus which was considered a precondition for subsequent decentration. Realizing the above difficulty in the centration of lens the idea of continuous curvilinear capsulorrhexis (CCC) was born. The credit goes to Tobias H Neuhann and his brother Thomas in developing the technique of capsulorrhexis. At the same time totally independent development by Howard Gimbel who was working on the same idea called this technique as “continuous tear capsulotomy”. Finally, Neuhann and Gimbel called their development continuous curvilinear capsulorrhexis which soon gained popularity all over the world. Physics of Capsulorrhexis If we consider a strip of paper to be torn into two pieces it can be done in two ways: one is as shown in Fig. 11.1A—what can be considered as shearing technique or Fig. 11.1B—ripping.

104

THE ART

OF

PHACOEMULSIFICATION

Figs 11.1A and B: (A) Shows the shearing technique as compared to the ripping technique in (B). Note shearing is a much more controlled technique

Capsulorrhexis with Shearing Capsulorrhexis starts when the cystitome enters point a and proceeds to point b in a radial manner (Fig. 11.1C). At point b the cystotome is pulled in the direction of the arrow to reach point c to create a capsular crack which gets folded over to lie on the top of intact anterior capsule. At the position d the flap is engaged with cystotome or forceps and is pulled in the direction of curved arrow. Figure 11.1D shows the progress of capsulotomy. This flap is a mirror

Figs 11.1C to E: Rhexis by shearing. Note the position of the dot indicates successive placement site for needle rhexis

CAPSULORRHEXIS: PRINCIPLES

AND

ADVANCED TECHNIQUES

105

Figs 11.1F and G: Capsulorrhexis by ripping technique: Dot indicates point where the tear is held with the forceps

image of the area of capsulorrhexis performed so far and its edges will indicate in which direction the capsulorrhexis will proceed. Figure 11.1E shows one-third of the rhexis completed. Take a note of the point at which the instrument engaged the capsule which has remained 2 to 3 O’clock hours away from the point of (n) shearing. Instead if the instrument was placed to say at point m, an artificial stress line would be created that would compromise the predictability of the direction of shear. In shearing technique the flap must be spread out flat otherwise it would convert the shear to modified rip. Capsulorrhexis with Ripping Figures 11.1F and 11.1G demonstrate the ripping technique. The surgeon must note that the direction of pulling is much more towards the center of the capsule and the flap is engaged by pulling the instrument at a point which is much closer to the tear. The ripping technique has the tendency to extend peripherally. It has been found that ripping techniques are more difficult to control and are more likely to extend peripherally compared to shearing technique. Yet one must know its ability in changing the direction of the tear. Initiation of Capsulorrhexis The capsule can be incised at point a, proceeding to point b. The triangular flap thus created is grasped at point c and drawn in the direction of the arrow in a curvilinear fashion. Shearing forces will be equally acting at point b and d. In Figures 11.1H and I the pulling motion has changed to a curvilinear direction shown by the arrow. Figure 11.1J shows its further progress.

106

THE ART

OF

PHACOEMULSIFICATION

Figs 11.1H to J: Triangle tear technique of capsulorrhexis

Methods • • • •

Needle technique Forceps technique Capsulostripsis Diathermy capsulotomy

Capsulorrhexis can be performed by number of methods. All these methods give practically the same results. It involves a continuous symmetrical linear opening of the anterior capsule. In order to get good postoperative results capsulorrhexis must satisfy: Site For optical and functional results the capsulotomy must be centered on the pupil which reduces the possibility of irido-capsular-synechial formation. Suitability (for IOL implantation) Since there is a huge range of IOLs available. The surgeon must first choose the lens and perform the capsular opening accordingly.


AND

ADVANCED TECHNIQUES

107

Integrity of the zonules In order to avoid damage to zonular fibers the capsulotomy should be performed carefully in the pre-equatorial zones. Aperture The aperture must be wide enough to allow emulsification of the nucleus easily. A large capsular aperture facilitates easy and quick aspiration of the cortical material. At the same time it should not be so wide as to allow the nucleus to prolapse into the anterior chamber during hydrodissection procedure which usually happens in grade I and grade II cataracts and hence between 5 mm and 6 mm is the ideal size of capsulotomy. Shape If we consider the shape of the eyeball as a round clock, the movement while doing the capsulotomy should be like a radiating arm moving in a circular fashion. Similarly the opening should be round. Last but very important aspect is to have continuous margin. The advantages of the continuous margins are: • Correct centration of the lens in the bag. • The edges of the incision are strong and elastic enough and reduce the risk of capsuler rupture extending to the periphery which can happen in a canopener technique. Principles To achieve the above results the surgeon has to keep in mind the following principles: One must keep in mind before proceeding to surgery that any mistake made during this procedure may face subsequent problems. • It is desirable to use high magnification so that surgeon can control every step of the procedure, adjust the sight and width of the incision and avoid traction process as and when possible. • The light beam must be angled to provide good red reflex of the fundus. • The intensity of the microscope light must be sufficient to facilitate clear view of the capsule and the red reflex. • The pupil must be widely dilated which makes it easier for the surgeon to perform capsulotomy; small pupil can bring contact between cystitome and iris. Dilated pupil also facilitates good red reflex. • A deep chamber reduces the risk of endothelial and iris damage hence the depth of the chamber must be maintained during the entire capsulotomy procedure. The high molecular weight viscoelastic substances are the best tools for this. • One should keep in mind the attachment of the zonuler fibers. On the safer side the capsular aperture should not extend more than 3 mm peripherally from the center of the anterior pole of the lens. • The shape and size of the capsulotomy must be planned by the surgeon prior to beginning the capsular aperture. • The entrance of the instrument into the anterior chamber must be well planned. One must keep in mind the anatomical variations of the individual eye like myopia, hypermetropia, etc. Thus it is desirable to have an optimal working

108

THE ART

OF

PHACOEMULSIFICATION

position with respect to the planes of the anterior capsule and the iris. Correct use of the instrument and the released hands of the surgeon makes the job easier. The forceps or the cystitome must be handled gently and carefully. They must be used on the surface of the capsule with practically no pressure applied on the cataractous lens. The surgeon must avoid touching the iris because every such touch can reduce the size of the pupil. The surgeon must keep in mind that in younger patients the capsule is thin and elastic and the capsulotomy tends to extend easily towards the equator. Any time surgeon anticipates the difficulty he should stop what is being done and inject the viscoelastic substance to deepen the chamber which allows him a greater margin for maneuvers and errors. Advantages of CC Capsulorrhexis Intraoperative Advantages • CCC limits the risk of tears extending to the periphery and to the posterior capsule during surgery especially in young patients. • Hydrodissection becomes safe and easy. • It restricts the intraocular turbulence inside the capsule. • Reduces the stress on the zonules during surgery. • Most important is that it allows easy aspiration of the cortex and does not let any anterior capsular tags get caught into the aspiration port. • It permits the correct positioning of the IOL in the bag because the surgeon has excellent view of capsular rim. Last but the most important is that since the rim is can be stretched even a slightly large lens can also be manipulated with a comparatively small capsular opening. Postoperative Advantages • Due to extensive contact area between the loop of the IOL the anterior capsule the possibility of decentering is reduced. • Not being in contact with the ciliary body pigment dispersion, hyphema and inflammation are reduced. • In the presence of ruptured posterior capsule after doing anterior vitrectomy a large optic diameter lens can be inserted over the anterior capsule. • Since the lens is put in the bag there is no need to use miotics or the need for iridectomy. It also avoids pupillary capture. Difficulties during Rhexis Rhexis Escape In some cases while the procedure of capsulorrhexis is proceeding on the aperture goes on increasing towards the periphery. The moment this happens the surgeon must ensure that the chamber is adequately deep by injecting more viscoelastic


AND

ADVANCED TECHNIQUES

109

substance. It is advisable to use a cystotome attached to a viscoelastic syringe so that in case the chamber becomes shallow more viscoelastic can be injected into the chamber immediately. The chamber will deepen and the tendency for the rhexis to extend will be minimized. At this moment the flap should be caught close to the point in the capsule, the surgeon should then extend controlled pressure directed towards the center of the pupil. Alternative to this technique, instead of forceps or needle one can take deeply curved scissors, deepen the anterior chamber with the viscoelastic and cut the capsule with scissors at the escape point and redirect the opening back to the initial route. One can also choose a new point to start rrhexis in another position operating in a counterclockwise direction and try to join to the first rrhexis escape point. In spite of these maneuvers if the rrhexis extends, abandon the idea of continuous capsulorrhexis and continue with can-opener capsulotomy. Capsulorrhexis in Special Cases Pseudoexfoliation The surgeon must be aware that in this condition the capsule is fragile so the opening must be small so that it does not reach the zonules or create traction forces. Such a small opening can subsequently be extended after the insertion of IOL or subsequently by YAG laser. Young Patients In very young patients proper pupillary dilatation is a big problem. In addition reduced scleral rigidity increases the tendency to positive vitreous pressure. This leads to loss of control in the direction of capsulotomy with an increased risk of peripheral escape. In children therefore the initial incision must be small which can be better controlled by forceps than needle. Viscoelastic substances must be kept in hand. Hypermature or Intumescent cataract Capsulotomy can be done easily when the red reflex is seen. In such situations like hypermature cataract there is no red reflex so capsulotomy becomes extremely difficult as there is no perception of the capsular flap. In addition when the cataract is swollen there are more chances of peripheral escape because of the greater tension on the anterior capsule. When the cataract is intumescent, the contents are usually very liquid like milk, it is advisable to let the semiliquid cortex escape through a central incision, this should be removed with I/A and chamber should be filled with viscoelastic substance, the flap must be taken under a high magnification with very high illumination. This is a good indication to use forceps instead of needle. Instead of red reflex illumination it is advisable to use high intensity oblique illumination. Some surgeons prefer air in the anterior chamber instead of viscoelastic substance. It is advisable to use cystitome instead of forceps when the air is injected into the anterior chamber. Black cataracts also pose the same problem. In small pupils it is advisable to use viscoelastic to deepen the anterior chamber. Use of iris hooks or bimanual stretching is also recommended.

110 POSTERIOR

THE ART

OF

PHACOEMULSIFICATION

CAPSULORRHEXIS

Posterior capsulorrhexis is a linear continuous circular capsulotomy with all the advantages of elasticity, stability and long-term resistance. This procedure is done in children which avoids second surgery or YAG laser. The surgeon proceeds in the same way as in the anterior CCC. The phacoemulsification is carried out, the anterior segment is filled with viscoelastic substance, the bag is also filled with viscoelastic substance. The first step is to perforate the posterior capsule. Viscoelastic is again introduced behind the posterior capsule which can prevent vitreous prolapse. The second step is to carry out posterior CCC with needle or forceps. In some cases when the vitreous prolapses anteriorly, vitrectomy is done. The remaining tyre like capsular residue provides the stable and secure site for IOL fixation. This posterior capsulorrhexis done in pediatric cataract surgery can avoid secondary membrane formation. Disadvantages of CCC The introduction of capsulorrhexis has led to a new problem called capsular shrinkage syndrome or capsular phimosis. This problem is observed more frequently in patients suffering from pseudoexfoliation syndrome, uveitis, retinitis pigmentosa, in combination with polymethylmethacrylate (PMMA) or silicone IOL implantation. All the above mentioned diseases have reduced number of zonular fibers as common observation. Special Techniques • • • •

Fluorescein blue light assisted capsulorrhexis for mature cataract. Staining the capsule with indocyanine green for white cataracts. Trypan blue capsule staining for better visualization in capsulorrhexis. Diathermy capsulotomy.

Trypan Blue Staining When retroillumination is absent, e.g. dense cataract, it is difficult to discriminate the anterior capsule from the underlying lens tissue and capsulorrhexis carries a high risk of radial capsule tears. To overcome this difficulty and better visualization of capsulorrhexis during surgery, one can utilize: (i) use of side illumination, (ii) hemocoloration of the capsule with autologous blood, and (iii) staining the capsule with gentian violet 0.1 percent or methylene blue 1 percent. All these procedures are relatively time consuming and require an adjustment of the surgical technique and may have endothelial toxicity. On the other hand trypan blue stain enables the surgeon to visualize the capsulorrhexis in the absence of red reflex and does not affect the endothelium. Before injecting the dye anterior chamber is injected with air, removing the aqueous through the cannula. Trypan blue, 0.1 ml in a conccentration of 0.1 percent in


AND

ADVANCED TECHNIQUES

111

phosphate buffered sodium chloride is applied to the anterior capsule. After few seconds anterior chamber (AC) is thoroughly irrigated, viscoelastic substance is injected into the AC (Fig. 11.1K). Because of the blue stain the outline of the capsulorrhexis is easily visible. There is an additional benefit that the peripheral anterior capsule ring remains stained and clearly visible during phacoemulsification. Diathermy Capsulotomy In order to overcome the difficulty in doing capsulorrhexis under circumstances such as mature 11.1K: The edges of the rhexis cataract and absence of red reflex, many surgeons Fig. can be stained with trypan blue for better use diathermy capsulotomy. One must keep in visibility mind that some fundamental research from Denmark showed that the extensibility of the capsule edge after diathermy capsulotomy was reduced to half than that of the CCC technique as done by needle or forceps. It was also noticed that the breaking force required to break the diathermy capsulotomy was one-fifth of that required to break the CCC edge. So, the surgeon must keep in mind the risk of inadvertent capsule opening subsequently by tearing during phacoemulsification or on implantation of IOL. CONCLUSION Every surgeon dreams to provide greatest degree of stability of vision to his or her patients. In other words, the surgeon tries to restore the patient’s vision very close to the normal healthy eye without glasses. The new technique of CCC has introduced a biggest breakthrough in performing small incision or phaco surgery. The most important advantage of continuous capsulorrhexis is that it holds the nucleus down in the bag during phacoemulsification surgery. It makes the surgeon keep the instrument tip in the bag and work on the nucleus. The second advantage is, it helps to maintain intact capsular bag. The circular opening into the anterior capsule opens the window over the nucleus. The structural rigidity and integrity of the capsular bag are almost identical to a completely intact bag. In the can-opener technique, the purpose was to permit the nucleus to get out of the bag while CCC holds the nucleus inside. The principle of capsulorrhexis is well established now and its technical performance is being refined and advanced everyday. Capsulorrhexis is a fundamental surgical principle. These days the ophthalmic instrument manufacturing companies are bringing out many tools for the maximum comfort of the individual surgeon. Stability of the capsular bag and centration of IOL by this technique make emmetropia possible.

112

THE ART

OF

PHACOEMULSIFICATION

Keiki R Mehta Cyres K Mehta

Hydrodissection and Hydrodelineation

12

HYDRODISSECTION Hydrodissection is the creation of a cleavage plane between the nucleus and the cortex. It can also be defined as the separation, by a fluid dissecting wave, of the nucleus from the external cortex adhering to the capsule. It is important to appreciate that the cleavage plane is not between the capsule and the cortex. If that were so, then there would never be any need to do cortical aspiration. Hydrodissection is a very important step for endocapsular phacoemulsification. Its biggest advantage is that it permits free maneuvers on the nucleus in the bag without, in any way transgressing on the safety of the capsule. It must be clearly noted that effective and safe hydrodissection can only be done after a good rhexis. It is unsafe to do hydrodissection in a can-opener capsulotomy, or if the rhexis has, inadvertently, run away into the periphery. Injecting fluid at this time will cause the tear to spread backwards. Hydrodissection Technique The technique involves injecting a small amount of fluid (Ringer lactate or BSS) under the anterior capsule with a fine blunt cannula connected to a 3.00 ml syringe. Because of the fluid pressure and the dissecting ability of the fluid to take the path of least resistance, the fluid separates the cortex and the epinucleus and only partly between the capsule and the cortex. During the hydrodissection, the fluid wave can be seen clearly (unless it is a very hard cataract or an opaque one) to separate the cortex from the nucleus and is indicative of a successful hydrodissection. More hydrodissection is usually carried out in three sites commencing with the 4.00 O’clock position (Fig. 12.1) followed by the 2.00 O’clock position (Fig.12.2) and finally followed

HYDRODISSECTION

Fig. 12.1: Hydrodissection at 8 O’clock position

AND

HYDRODELINEATION

113

Fig. 12.2: Hydrodissection at 2 O’ clock position

by hydrodissection at 8.00 O’clock position. It is important that small aliquots of fluid be utilized, as excess fluid especially in a hard brown cataract is liable to balloon the capsule posterior, rather than spreading as a wave, and may, if more fluidic pressure is applied, rupture the capsule. It is important to visualize while injecting the fluid diffusion wave. The ideal syringe is a 3.00 ml Luer-Lok, plastic, disposable, Teflon-coated or siliconized. This type of a syringe permits a better control, prevents too much pressure from being applied, the plunger moves very smoothly, and does not stick. Too thin a cannula, (ideal is 24-26 G, flat cannula), even if it is blunt is liable to puncture the capsule if accidentally inserted too far into the periphery. Also a thin cannula permits the fluid to emerge in a sharp jet, at high velocity, which is not required. The one way to be sure the hydrodissection is complete is to check whether the nucleus rotates freely in the bag. The ideal technique of cannula placement for effective hydrodissection is to place the cannula just within the capsulorrhexis edge, slightly tenting it or lifting it upwards. This technique termed as cortical cleaning hydrodissection was originally conceived by Dr Howard Fine. Injecting the fluid along the rhexis edge permits the fluid wave, literally to shear close to the capsule thus, significantly diminishing the quantum of cortical remnants which will need to be aspirated after the primary nucleus is removed by phacoemulsification. In all cases hydrodissection should be followed by mechanical rotation (Fig. 12.3) of the nucleus to be sure that the nucleus rotates freely. Rotation confirms that all the adhesions between the epinucleus and the cortex have been broken. It is important to appreciate that if the lens does not rotate freely one must do hydrodissection again, till smooth rotation is achieved. It is important that after every injection of fluid the lens should be gently pressed backwards. This technique is termed as compression hydrodissection, and works by causing the fluid to disperse and spread out as a flat lamellar zone at the back of the nucleus and thereby enhance the hydrodissection. This technique should be conducted gently following each injection of fluid under the capsular flap. Compression hydrodissection thus, decompresses a filled capsular bag, and at the same time hydrodissects or shears off any adhesions.

114

THE ART

OF

PHACOEMULSIFICATION

Fig. 12.3: Rotation following hydrodissection

Fig. 12.4: Viscodissection to permit the lens to rotate vertically prior phacoemulsificaiton

Viscohydrodissection The parameters change radically when a viscous material (Healon, Provisc, Viscoat or hydroxypropylmethylcellulose–HPMC) is used. Since it takes much more force to inject, one has to be totally sure of the quantity injected; otherwise rupture of the posterior capsule becomes inevitable. In addition, the viscous fluid will force the iris-lens diaphragm forwards, shallowing the anterior chamber, to almost a mere chink. The fluid stays back as it is too viscous to escape from the sides of the 22 G opening normally used for the hydrodissection cannula (Fig. 12.4). Though it is easier to commence, fluid wave is rarely seen unless it is a very immature cataract. In a hydrodissected nucleus with an adequate sized capsulorrhexis, it tends to push the nucleus forwards and prolapse it out of the rhexis opening. The authors utilize viscodissection only after hydrodissection is complete to rotate the edge of the lens forwards in their technique of vertical phacoemulsification. For safety purposes, viscodissection should only be done after hydrodissection with BSS is complete and it is certain that the lens is freely mobile. Caution would dictate that viscodissection, unless used for a specific purpose, may best be left in abeyance. HYDRODELINEATION OR HYDRODELAMINATION Hydrodelineation is the term coined by Anis Aziz to describe the cleavage of lens structures through the injection of fluid. It is also termed hydrodelamination or hydrodemarcation. The technique is fairly simple. A small bore cannula (26–28 G), blunt-tipped, attached to a Luer-lok 1.00 ml plastic syringe, filled with BSS or Ringer lactate, is placed in the middle of the nucleus, and pushed forward into the nucleus till it reaches the middle of the nucleus (in soft cataracts), or meets resistance (medium to hard cataracts). The point of resistance is where the soft outer nucleus meets the harder central nucleus. At the point of resistance, the cannula is pulled back a fraction of a millimeter, and the fluid is injected. The fluid passes into the body of the cataract, and the dissected plane is usually identified by the appearance of a golden ring around the nucleus. This golden ring may not always be visible nor always clear depending on the density of the cataract. Sometimes only a dark separation plane may be noticed. As with hydrodissection, hydrodelamination must produce a cleavage and

HYDRODISSECTION

AND

HYDRODELINEATION

115

Figs 12.5 and 6: Hydrodelineation showing golden rings

a good separation of the nucleus from the epinuclear zone. If only a portion of the ring appears (Fig. 12.5 and 12.6), it may be necessary to reintroduce the cannula in a different place and try to inject the fluid again. It is important to appreciate the differences between hydrodissection and hydrodelamination. Hydrodissection is done to permit phacoemulsification in the bag. If the nucleus did not rotate, it would not be possible to chop a lens, rotate the nucleus for further chopping, and it would also not be possible to allow each sequential piece of the nucleus to be rotated into its best place for removal. None of these techniques could be possible if the nucleus remained adherent to the capsule. On the other hand, hydrodelamination is performed for safety. Hydrodelamination was a necessary preliminary step in the phacoemulsification technique of four-quarter grooving. It tells the surgeon how far he could groove with ultrasound into the periphery without taking any risks. In addition, hydrodelamination involves separation of the peripheral softer epinucleus from the deeper harder nucleus. Thus, in essence, the harder nucleus sits on a softer epinucleus bed. One can phaco the harder part with impunity knowing that the peripheral softer nucleus acts as a buffer safe zone. To recapitulate, the firm nucleus can be worked on within the softer nucleus of almost rubber-like consistency. This particular technique is especially useful with endocapsular phacoemulsification with nuclear cleavage and with the chip and flip technique. Decompression of the Capsule Bag Decompression of the capsule bag means reducing the pressure by allowing the excess fluid to leak out of the sides of the capsular bag and out of the anterior chamber. If the nucleus is hard, hydrodelamination becomes an impossibility, and there even hydrodissection becomes technically difficult. In a dense nucleus the fluid wave is no longer visible and the fluid injection seems to have no effect. The surgeon is tempted to inject more and more at a higher pressure hoping to get a separation, but what does happen however is that the posterior capsule tents backward and as the pressures increases, the thin capsule gives way, rupturing. It is thus a disaster waiting to happen.

116

THE ART

OF

PHACOEMULSIFICATION

How does one recognize that this complication is impending? In a soft cataract even a single injection at a single site under the capsule while doing hydrodissection is adequate. However in the case of a hard or a suprahard cataract, it is important to inject at multiple points. This disperses the fluid and gives more sites for the fluid under pressure, to escape. The second important step is to compress on the nucleus, with the heel of the cannula after every injection, which disperses the fluid. In case the fluid does not come out, two important signs have to be recognized: the chamber shallows very much, and the eye pressure rises sharply. The tendency of the surgeon is to reform the chamber by either injecting a viscoelastic, or still worse, by pressing on the nucleus with a repositor or cannula. Both techniques will lead to a posterior rupture. The correct way of handling this situation is to insert a thin blade iris repository under the edge of the capsule, at 5 O’clock and simply sweep it in both directions. Almost immediately the surgeon will be rewarded with a gush of fluid (which had been entrapped) and the eye immediately softens. Hydrofracture It is a technique, which involves possible separation of the lamella of the internal nucleus by a combination of ultrasonic needle penetration and a pressure injection of BSS. This method is known as a hydrosonic technique and was commenced by Dr Anis of USA. It has the advantage that it fragments the nucleus into little fine bits permitting easier phacoemulsification. However, with the advent of chopping technique it is now rarely utilized and is purely of academic interest. CONCLUSION Both the techniques of hydrodissection and hydrodelamination have the advantage that they also help the surgeon assess the degree of hardness of the lens and therefore, indirectly assess the quantum of ultrasound time, which would be required. Both techniques are essential and though in standard chopping methods hydrodelamination is not utilized, it still is a useful method especially if one expects difficulties to occur during the surgery. It also has the advantage that if a rhexis has been done a little too small, hydrodemarcation reduces the nucleus into its component parts diminishing the size thus, permitting the hard nucleus to be chopped and removed within the soft epinucleus buffer zone. FURTHER READING 1. Fine IH: Cortical cleaving hydrodissection. J Cataract Refract Surg 18(5:) 508-12, 1992. 2. Mehta KR, SM Sathe, SD Karyekar: Computer Terminal Usage and Eye Fatigue, Xth Congress APAO. Soc Proc 2:946-48,1985. 3. Mehta KR: Pitfalls encountered in 1500 consecutive posterior chamber implant. All India Ophthl Soc Proc 165-6,1986. 4. Mehta KR: Phacoemulsification cataract extraction with foldable IOLS—first 50 cases. All India Ophthl Soc Proc 56-60,1989. 5. Mehta KR: Clear corneal phaco with injectable silicone IOL proc. All India Ophthl Soc Proc (Mumbai) 1995.

HYDRODISSECTION

AND

HYDRODELINEATION

117

6. Mehta KR: Mehta tangential chop (MTC) technique for phacoemulsification. All India Ophthl Soc Proc (Chandigarh) 1996. 7. Mehta KR: Combined astigmatic annular keratotomy and phaco—a corneal topographic analytical technique. All India Ophthl Soc Proc (Chandigarh) 1996. 8. Mehta KR: Phaco-levitation—a peaceful way. All India Ophthl Soc Proc (Chandigarh) 1996. 9. Mehta KR: Lollipop phaco cleavage—a new technique for hard cataracts. All India Ophthl Soc Proc (Bangalore) 1991. 10. Mehta KR: SICS mon-phaco—hydroexpression with an irrigating vectis. Proc of SAARC Conference, Nepal, 1994. 11. Mehta KR: Management of subincisional cortex in small incision cataract surgery (SICS). Proc of SAARC Conference, Nepal, 1994. 12. Mehta KR: The new multiport phaco tip for safer, more effective phacoemulsification, with virtually zero capsular damage. Proc of SAARC Conference, Nepal, 1994.

118

THE ART

OF

PHACOEMULSIFICATION

Noshir M Shroff Ranjan Dutta Gurpreet Singh

Phacoemulsification: The Quadrantic Cracking, Chopping and Stuffing Technique

13

INTRODUCTION Phacoemulsification if it proceeds smoothly is an excellent procedure with early and extremely gratifying visual recovery. However, should a complication arise, the result can be disastrous with the patient’s sight under threat. A surgeon’s skills may range from excellent to average. An excellent surgeon will not have much difficulty in adapting to any new procedure including phacoemulsification. Unfortunately not many surgeons belong to this category, where there is little or no difficulty in adapting to the new technique of phacoemulsification. The vast majority of us belong to the second group of “average surgeons”. Not uncommonly an average surgeon begins phacoemulsification, has a few complications in the first few cases, loses confidence and gives up. Therefore, a nucleofractis technique which is useful for the vast majority of average surgeons, would be one which has a high order of safety with least chances of a posterior capsular rent and damage to the corneal endothelium, is easily reproducible and is easy to perform. Modern nucleofractis techniques can broadly be divided into two types: (i) four quadrant cracking, and (ii) stop and chop technique. Four-Quadrant Cracking (Shepherd’s Modification of Gimbel’s Divide and Conquer Technique) It is easier to handle four small quadrants rather than two large halves. Hence, this technique is easier for the beginner. Moreover, central sculpting debulks the hard central nuclear core. However, the disadvantage is that this technique uses more phaco power and phaco time.

QUADRANTIC CRACKING , CHOPPING

AND

STUFFING TECHNIQUE

119

Stop and Chop (Koch’s Modification of Nagahara’s Phaco Chop Technique) This technique has the advantage of using less phaco power and time as compared to quadrantic cracking. It is a very effective technique for hard nuclei. However it is an inherently difficult procedure for the beginner. A nuclear half is simply too big a piece to tackle and most complications of this technique arise due to this fact. The large nuclear cumbersome fragment, if not impaled exactly midway, tends to rock sideways on the phaco tip, particularly if the occlusion is not adequate. The lack of firm grip on the piece makes subsequent chopping frustratingly ineffective. Moreover, the absence of a second trench in the Stop and Chop technique makes it difficult to convert each “half” into “quarters”. As the chopper moves toward the center from the periphery, the final portion (i.e. the central bulk of the nucleus) is difficult to chop. Interconnecting fibrils may at times pose difficulty in separating the fragments, necessitating the use of excessive force with the chopper (Fig. 13.1). Significant lateral forces are thus required for separating the fragments. This puts stress on the capsular bag and makes it an unsafe procedure. In contrast to this, the pre-existent second trench perpendicular to the first, in the quadrantic-cracking technique, makes fragment separation possible with minimal lateral force.

Fig. 13.1: In the Stop and Chop technique (above), the final portion i.e. the central bulk of the nucleus is difficult to chop. Interconnecting fibrils make separation of the fragments difficult. Significant lateral forces are thus created which put stress on the capsular bag. On the other hand in the Quadrantic cracking technique (below), pregrooving leaves a thin posterior nuclear plate and minimum force is required to crack each nuclear half into quarters

120

THE ART

OF

PHACOEMULSIFICATION

The danger of damage to the lens capsule in the Stop and Chop technique is very real. A forceful phaco chop can easily cause a posterior capsule rent. A large fragment will require a longer centripetal chop, which may inadvertently tear the edge of the rhexis and extend it. One may avoid the rhexis edge with a shorter centripetal chop (i.e. by starting at the midperiphery rather than the equator), but this will eventually require wider lateral separation of the nuclear fragments and put stress on the capsular bag. Also, multiple phaco chops give rise to multiple fragments. These can act as splinters, and in conjunction with anterior chamber turbulence, cause endothelial damage. Keeping in mind that most of the above complications occur only due to the large nuclear “halves”, we have devised a technique that combines the best features of both techniques. QUADRANTIC CRACKING, CHOPPING AND STUFFING TECHNIQUE Our technique of quadrantic cracking, chopping and stuffing starts with four-quadrant fracture followed by tackling each quadrant using low power and high vacuum settings. Thus it combines the safety of quadrantic cracking with the efficacy of Stop and Chop and is suitable for most grades of nuclei. Preliminary Steps Following suitable ocular anesthesia, a small conjunctival flap is made and a bloodfree zone is created with a bipolar cautery. The authors prefer prefer making a posterior limbal incision to a clear corneal incision, as it results in lesser induced astigmatism and provides a longer tunnel, which is self-sealing and watertight (due to its valve-like action). A limbal incision also has the advantage that it can be covered with the conjunctival flap at the conclusion of surgery, which acts as an additional barrier against intraocular microbial invasion. The anterior chamber is filled with a high molecular weight cohesive viscoelastic substance and a side port incision is prepared. Capsulorrhexis is performed using a bent 26-gauge needle followed by hydrodissection (and sometimes hydrodelineation). These two steps are absolutely necessary and provide the key to successful phacoemulsification. Bimanual rotation using two lens hooks ensures that the nucleus has adequately been separated from the cortex. Central Debulking and Pregrooving The first step is to create a groove from the center of the nucleus towards 6 O’ clock, stopping just short of the edge of the rhexis. The parameters the authors use during sculpting are 50% U/S power (linear mode) and 30 mm Hg vacuum (Fig. 13.2). The bulk of phaco power is used in this step. The phaco tip is deep inside the central core of the nucleus. So, most of the phaco energy is dissipated within the nucleus far away from the endothelium and the posterior capsule. The groove is created by shaving in layers and is as wide as the sleeve of the phaco


AND

STUFFING TECHNIQUE

121

Fig. 13.2: Sculpting is done by shaving layers towards 6 O’clock. Ultrasonic power is at 50% (linear mode) with vacuum at 30 mm Hg. The starting point of the first groove is slightly nearer the superior pole and not at the exact center

tip and as deep as possible. Using a spatula (second instrument) through the side port incision the nucleus is rotated by 90° and a second groove is created in a similar manner (Figs 13.3 and 13.4). This is followed by the third and the fourth grooves. One should ensure during sculpting that the starting point of each groove is slightly nearer the superior pole of the nucleus and not at the center itself (Fig. 13.5). Otherwise at the end of sculpting a thick central mound may be left on the center of the posterior nuclear plate and will make subsequent cracking difficult. In this regard a Kelman tip is very useful. Its tip has a bend close to its distal end and permits very effective and efficient downslope sculpting in the superior part of the nucleus, allowing prompt access to the posterior plate for fracturing. Thus there is no residual central mound and one is left with a thin and evenly shaved posterior plate. Additionally this shape allows working on either the left or right side of the central trench by simply turning the tip in either direction along its long axis. The authors have found this tip extremely useful in moderate to hard nuclei. Another point that needs to be kept in mind while sculpting is that one should ensure adequate depth of the grooves so as to easily facilitate cracking. An indicator of adequate sculpting is the presence of red glow seen through the thin posterior nuclear plate (Fig. 13.6). Finally, once the center has been debulked and all four grooves have been made, one is left with the nucleus resembling a Maltese cross.

122

THE ART

OF

PHACOEMULSIFICATION

Fig. 13.3: The second instrument is used to rotate the nucleus by 90 degrees in preparation for the second groove

Fig. 13.4: The second groove is made perpendicular to the first


AND

STUFFING TECHNIQUE

123

Fig. 13.5: If sculpting is started at the exact center, it is difficult to gain access to the deeper portions of the nucleus leaving behind a central mound especially if a straight tip is used. The Kelman tip permits effective and efficient downslope leaving a thin and evenly shaved posterior nuclear plate

Fig. 13.6: After all four grooves have been created, they are further deepened till a satisfactory red glow is obtained

124

THE ART

OF

PHACOEMULSIFICATION

Fig. 13.7: Cracking is achieved with minimal horizontal force

Cracking Since the central hard core of the nucleus has already been debulked and all four grooves have been created with adequate depth, cracking is easily performed using the phaco tip and the second instrument with minimal horizontal force (Fig. 13.7). Thus undue stress on the capsular bag has been avoided. For this step the foot pedal is kept in position 1. The fracture is attained by the two instruments pushing away from each other (phaco tip to 9 O’clock and second instrument to 3 O’clock). Alternatively, beginners may find cracking easier by simply using two hooks. The first fracture divides the nucleus into two halves. Following this, the nucleus is rotated by 90° and the distal “half” is fractured into “quarters” using the pre-existent groove. The other nuclear half is rotated distally and similarly cracked till we achieve four separate quadrants (Fig. 13.8). Sometimes the first fracture does not completely divide the nucleus into two halves. In this case, the fracture is completed by rotating the nucleus by 180° and performing cracking on the undivided portion. Segment Removal The parameters are now changed. Ultrasonic power is reduced to 30% (pulse mode) and vacuum is increased to 120 mm Hg and the authors now proceed as one would in the Stop and Chop technique, i.e. engaging and holding each nuclear fragment and chopping it into smaller pieces.


AND

STUFFING TECHNIQUE

125

Fig. 13.8: The nucleus is rotated every 90 degree till four separate nuclear quadrants are obtained

One can engage each quadrant from the apex, the sides or the undersurface. However, the apex offers too small an area to ensure a good hold and the sides of the fragment have very irregular surfaces. Engaging a quadrant from an irregular surface can cause it to tumble and rent the posterior capsule (Fig. 13.9). Therefore, the authors prefer to engage the quadrant from its undersurface; its area is large and smooth and the phaco tip can be effectively occluded thus providing a good hold on the fragment. There are two ways of achieving this. One way is to depress the base of the fragment with a hook thus tilting up the apex and exposing the undersurface of the quadrant to the phaco tip (Fig. 13.10). The other way is to lift up the apex directly with the hook and guide the phaco tip to the undersurface (Fig. 13.11). Once the quadrant has been effectively impaled onto the phaco tip, it is pulled to the center of the capsular bag away from the posterior capsule, and the endothelium and a chopper is introduced through the side port. With the phaco tip holding the quadrant steady, the chopper is sunk into the nuclear substance and retracted towards the phaco tip (Fig. 13.12). Just before it reaches the tip, the chopper is moved sideways and away from the tip (towards 3 O’clock). Simultaneously the

126

THE ART

OF

PHACOEMULSIFICATION

Fig. 13.9: Engaging a quadrant from an irregular surface can cause it to tumble and cause a rent in the posterior capsule. Engaging by the undersurface prevents this besides providing a good hold on the piece

Fig. 13.10: The second instrument presses down on the base of the quadrant thus raising the apex. The undersurface is now exposed to the phaco tip which can effectively engage it


AND

STUFFING TECHNIQUE

127

Fig. 13.11: Alternatively, one can directly lift the apex with the second instrument and guide the phaco tip below the quadrant. One should ensure that the bent part of the Sinskey hook is kept horizontal and not pointing down towards the posterior capsule. This step should be attempted in pedal position 1 (irrigation) which will ensure that the hook as well as the phaco tip is well away from the capsule

Fig. 13.12: With the phaco tip effectively holding the quadrant, the chopper is sunk into the nuclear substance and retracted towards the phaco tip

128

THE ART

OF

PHACOEMULSIFICATION

Fig. 13.13: As the chopper approaches the phaco probe it is moved sideways and away from the tip. Simultaneously the tip holding the nucleus is moved in the opposite direction

phaco tip is moved sideways in the opposite direction (towards 9 O’clock) dividing the quadrant into two fragments (Fig. 13.13). The chopper guides the engaged piece and then stuffs it into the phaco tip, all the time keeping the other fragments away (Fig. 13.14). The fragment is emulsified using a combination of this stuffing action, high vacuum and intermittent bursts of low phaco power. Likewise each quadrant is tackled in this manner by this method of chopping, stuffing and emulsification. One must all the time ensure that epinuclear and cortical matter is not aspirated during segment removal as this material acts as a protective buffer and prevents accidental posterior capsule rupture. Epinucleus Removal With ultrasonic power set at 10% (linear mode) and vacuum at 80 mm Hg the distal rim of the epinuclear shell is engaged by the phaco probe in pedal position 2 and pulled towards the center of the capsular bag. The epinucleus is pulled by the phaco tip towards the incision, while the second instrument simultaneously provides countertraction in the 6 O’clock direction. The epinucleus easily flips around the second instrument and is emulsified in the center of the capsular bag. Sometimes,


AND

STUFFING TECHNIQUE

129

Fig. 13.14: The smaller pieces are now stuffed into the phaco tip with the chopper and emulsified using bursts of low phaco power and high vacuum

the portion of the epinucleus engaged to the phaco tip breaks off from the rest of the epinuclear shell. In this case, after emulsifying the broken-off piece, the remainder of the shell is rotated to the 6 O’clock position, engaged by the phaco tip, brought to the center of the bag, and then finally emulsified. One should proceed very carefully in this delicate phase as the absence of the main bulk of the nucleus makes the posterior capsule relaxed and there is a danger of the floppy capsule coming into contact with the phaco tip. Thereafter cortex is removed with the irrigation-aspiration tip. The authors prefer to remove 12 O’clock cortex by the bimanual method after creating a second side port incision. The anterior chamber is then filled with viscoelastic substance and a foldable IOL is implanted. Viscoelastic removal followed by testing the wound for its self-sealing nature concludes the operation. CONCLUSION The authors have been using this technique on most of their patients with gratifying results. It combines the safety of quadrantic cracking with the efficacy of Stop and Chop and is appropriate for most types of cataracts. This technique is reproducible and is ideal for the beginner as well as the experienced.

THE ART

130

OF

PHACOEMULSIFICATION

Richard Packard

Current Phacoemulsification Techniques

14

INTRODUCTION Small incision cataract surgery was 30 years old in 1997. Since its inception the techniques involved have been constantly improving and this has been matched by innovations in phaco machinery and intraocular lens materials and design. At almost every meeting or edition of the throw-away papers somebody puts forward some new variation. It can be very confusing. The following shows my current techniques developed over 20 years experience in small incision cataract surgery. PATIENT

PREPARATION

AND

ANESTHESIA

Preparation Patients are not routinely given any premedication. They will have had a simple drop regime prior to reaching the operating theater as follows: G. Phenylephrine 2.5% G. Homatropine 2% Two drops of each 30 minutes preoperation G. Benoxinate 0.4% Two drops every 10 minutes for 30 minutes preoperation In the operating theater prior to administering any anesthetic, povidones iodine is instilled into the eye. This will then be in contact with the tissues for about 10 minutes before being washed out at the start of the operation.

CURRENT PHACOEMULSIFICATION TECHNIQUES

131

Topical Anesthesia The drop regime above is sufficient for topical anesthesia. This technique was not used often in our department until recently because the anesthetists prefer not to give any intravenous sedation, if required, without control of the airway. The advent of intraocular unpreserved lignocaine 1% at the start of the procedure and for hydrodissection has increased the number of patients operated upon without peribulbar injection. This is because the need for additional intravenous sedation is almost eliminated. Peribulbar Anesthesia Medication Mixture Plain lignocaine 2% 8 ml mixed with hyalase. Needle

Long shank 23 gauge needle attached to 10 ml syringe.

Technique 3 ml are injected inferiorly back from the infraorbital notch and 3 ml superiorly over the supraorbital notch. Both injections point nasally. A mercury bag is then placed on the eye for about 5 minutes not to soften the eye but to help spread the local anesthetic. PHACOMACHINES

IN

USE

1. Alcon Legacy 2. Allergan AMO Prestige 3. Allergan AMO Sovereign The Legacy has the high vacuum cassettes in use and has been modified for bimodal and burst phaco. The microtip and ABS technology have improved the anterior chamber stability considerably compared with earlier configurations of this machine. The Prestige has a unique pump monitoring arrangement. This helps to minimize postocclusion break surge in the anterior chamber by slowing the rate at which the pump regains full speed. This makes it very safe as the chamber does not collapse and intracameral contents are not sucked into the phaco tip. This machine is now available with a 21 gauge phaco needle. The Sovereign is new and not yet available commercially though it is being launched shortly. It has developed on the microchip control of machine parameters seen in the Prestige and Diplomax machines. It has the ability to set different values for phaco with and without bursts of variable length, vacuum and pump speed which differs depending on whether the phaco tip is occluded or unoccluded. It is also possible to vary the pump speed in any setting depending on vacuum thresholds.

132

THE ART

OF

PHACOEMULSIFICATION

All these machines allow a slow rise time to maximum vacuum settings which is safer when teaching residents in training. The Sovereign will allow very rapid vacuum rise time on occlusion if so desired. Tips and Sleeves Current tips are 30 degree. This provides the best compromise for sculpting and nuclear fragment removal. These are used with both machines and are covered by silicone sleeves. The Legacy has the Kelman tip also which has very much greater cavitation than conventional straight tips and is particularly useful for very hard nuclei. INCISIONS Side Port Incisions Instruments

Alcon 15 degree knife, toothed St. Martins forceps.

Technique The limbal conjunctiva is grasped with the forceps at about 11 O‘clock to steady the eye. The 15 degree knife is held in the right hand with blade parallel to the iris. The point of the knife is applied to the limbus at the capillary arcade approximately 60 degrees to the right of the tunnel incision (Fig. 14.1). The knife is advanced fully to produce an incision 1 ½ mm wide. This just the right size for the bimanual handpieces used for irrigation and aspiration. The second incision is made with the knife in the left hand at about 60 degrees to the left of the phaco incision (Fig. 14.2). They will easily self seal at the end of the procedure.

Figs 14.1 and 14.2: Side port

Note The incision is made at the edge of the capillary arcade so that the small amount of bleeding will mark its site for insertion of the nucleus manipulator later. Temporal Incision Instruments Colibri toothed microsurgical forceps, Alcon phaco slit blade 2.75 mm angled.


133

Technique The Colibri forceps grasp the limbus at the left end of the incision site to steady the eye. A Fine Thornton ring will also do this very well. The tip of the slit knife is held against the limbus at an angle of 60 degrees. The knife is pushed gently (Fig. 14.3) forward until the bevel is just covered. The knife is then angulated backwards so that the blade is pointing up the slope towards the center of the cornea. The blade is now advanced (Fig. 14.4) very slowly. The progress Fig. 14.3: Starting the phaco incision of the passage of the knife can be seen clearly. When the tip of the knife is 2 mm into clear cornea the handle is lifted and the knife advanced again (Fig. 14.5) but this time pointing to the scleral spur opposite. When this last is done slowly a straight entry into the anterior chamber is produced which acts efficiently as an internal valve. ANTERIOR

CHAMBER

MAINTENANCE

The chamber is now filled with viscoelastic through the side port. Provisc (sodium hyaluronate 1%) is what I use at present. I do not think there is much too choose between the various sodium hyaluronates, however HPMC does not perform as well in the eye but it is cheaper. Viscoat is reserved for problems during the phaco to tamponade a posterior capsule rupture. Capsulorrhexis Instruments Straight disposable cystitome, Duckworth and Kent titanium capsulorrhexis forceps. Technique • The eye is overfilled with viscoelastic elastic as above to flatten the anterior capsule.

Fig. 14.4: Advancing the slit knife

Fig. 14.5: Making the internal incision

134

THE ART

OF

PHACOEMULSIFICATION

Fig. 14.6: Cystitome cutting capsule

Fig. 14.8: Folding the flap onto the untorn capsule

Fig. 14.7: Starting to tear with forceps

Fig. 14.9: Finishing the rhexis

• Refocus the microscope on the anterior capsule and make sure there is good magnification, particularly if there is a less than helpful red reflex. Note There is much less tendency for the capsular tear to move peripherally during the rhexis if the surface is flattened out. If the surgeon is worried about the rhexis getting out of control at any stage of the capsulotomy , more viscoelastic injected into the eye will usually arrest the problem. • The cystitome is attached to the irrigation handpiece or the viscoelastic syringe and inserted through the tunnel. The instrument held in the right hand is steadied by the index finger of the left hand. The capsule in the center of the lens is engaged with the tip of the cystitome and the sharp edge is used to cut the capsule for about 1 mm (Fig. 14.6). The capsule is then torn in a C-shape. The flap of capsule thus created is laid on top of the adjacent untorn capsule so that it can easily be grasped by the capsulorrhexis forceps. • The capsulorrhexis forceps having been inserted into the eye are used to grasp the capsular edge. This is then torn in a circular manner constantly changing the angle of the vector forces by regripping the capsular edge as the tear progresses (Figs 14.7 to 14.9).


135

Note The ideal angle of pull to produce the tear depends on both a horizontal and a vertical component. This is particularly important in young eyes with elastic capsules. Do not expect the capsule to tear in the direction you are pulling Capsules vary considerably in consistency and elasticity. As a general rule the younger the patient the more elastic and these capsules are much more difficult to control. The angle of pull is often at an obtuse angle to the direction of tear to prevent drift to the periphery. Aim to make these capsulotomies small (4mm) and they will probably end up about 6 mm. Capsulorrhexis

Size

The ideal size for a capsulorrhexis is between 5 and 6 mm. In any event the capsulorrhexis should lie on the edge of the implant. Making it any larger can lead to difficulties with control and is unnecessary. With some implant materials (such as silicone) it is particularly important that at the end of the procedure the rhexis is not too small. A rrhexis of 4.5 mm or less may lead to contraction and capsulophimosis. The implant may then decenter and the patient experience glare from the opaque edge of the capsule. Note

If the rhexis looks too small after the I/A enlarge it.

Technique Inject viscoelastic into the anterior chamber; do not overfill it as this will put the capsule under tension. Use Vannas scissors to make an oblique cut at the rhexis edge, grasp this new tear with the capsulorrhexis forceps and tear carefully round. Reasons for Problems with Capsulorrhexis • The most common problem is loss of control of the tear so that it moves peripherally (Fig. 14.10). This may be due: i. Elasticity of the capsule combined with lack of rigidity of the sclera as in younger patients (Figs 14.11 and 14.12). ii. Excessive pressure from behind the lens. iii. Any other cause for loss of the anterior chamber and escape of viscoelastic.

Fig. 14.10: Rhexis moving peripherally

Fig. 14.11: Elastic juvenile capsule

136

THE ART

OF

PHACOEMULSIFICATION

Fig. 14.12: Preventing capsule going to periphery by pulling away from tear

Fig. 14.13: Leakage of liquid lens material as the capsule is punctured

The cure for all of these is to inject more viscoelastic, if the problem persists change to a high viscosity viscoelastic such as Healon GV. • If the tear appears to stop this is due to anterior zonular fibers abnormally far forward. Do not persist with the rhexis in this direction or it will rapidly tear towards the equator. Start the rhexis the other way round by making a small cut with Vannas scissors and then joining it up again at the point where it had previously stopped. • When there is a poor or no red reflex as in white cataracts or very advanced nuclear cataracts with extreme sclerosis capsulorrhexis can be very taxing. There are a few simple maneuvers which will improve visibility somewhat: i. If you do not do so already, sit temporally, visibility is enhanced. ii. Tilt the microscope so that the light is oblique to the capsule and will reflect from the torn edge. Or use the oblique (non-coaxial light) if available on the microscope. iii. Increase the magnification so that the iris fills your field, focus accurately. What you lose in depth of field is gained by ease of vision of the capsular edge. iv. In white cataracts (Figs 14.13 and 14.14) when liquid lens material fills the eye as the capsule is punctured, use the I/A to clear the chamber and suck out anterior cortex. Refill the eye with viscoelastic, your view of the capsule will then be much better. • Small pupils, although they can be enlarged by various means, still make the rhexis more difficult. Viscoelastic may be used to push the pupil open and thus expose more capsule. Also the nucleus manipulator can push the iris aside (Fig. 14.15), in the area where the capsulorrhexis forceps are tearing the capsule HYDRODISSECTION Instruments Visitec hydrodissection cannula (with rectangular cross-section), 2 ml disposable syringe filled with BSS.


Fig. 14.14: Using the I/A for removing excess soft lens matter

137

Fig. 14.15: Using the nucleus manipulator to hold aside the iris

Technique As the hydrodissection cannula is moved towards the rhexis start to inject BSS to lift its edge. The hydrodissection cannula is placed under the edge of the capsule at about the 3 O‘clock position. The capsule is tented up to peel it off the cortex and advanced 1 mm peripherally. BSS is injected rapidly but smoothly to produce cortical cleavage. This is seen as a fluid wave (Fig. 14.16) advancing rapidly under the nucleus and epinucleus. The tip of the cannula is then placed on the center of the nucleus and then pushed backwards towards the posterior capsule (Fig. 14.17). This maneuver has the effect of helping to spread the fluid around the capsule and complete the cleavage. If it is felt that the hydrodissection is incomplete, a second injection of BSS can be made at the 6 or 12 O‘clock position. In hard or medium cataracts it may be difficult to separate nucleus from epinucleus as in hydrodelineation and is often not necessary. If it is felt desirable to get the hard part of a nuclear fragment away from its attached epinucleus during phaco this can be done with the nucleus manipulator. However in soft cataracts, it is advantageous to see clearly the extent of the nucleus, so that the phaco tip does not inadvertently pass through soft nucleus, epinucleus and capsule.

Fig. 14.16: Fluid wave traveling behind nucleus

Fig. 14.17: Pressing back on the nucleus to spread the fluid

THE ART

138

OF

PHACOEMULSIFICATION

Sometimes with very soft cataracts, part of the nucleus is pushed through the rhexis during the hydrodissection, this does not matter. It will facilitate the aspiration of the soft nucleus. LENS

REMOVAL

General Points • Check that the machine is working satisfactorily before placing the phaco tip in the eye. This includes making sure the machine parameters are those desired. • Check that the phaco tip is undamaged and that its bevel is at 90 degrees to the irrigation sleeve openings. The exposed tip should be about 1.5 mm beyond the end of the sleeve. • Check that the foot pedal is comfortably placed. Instruments Colibri toothed microsurgical forceps, phaco handpiece, Duckworth and Kent nucleus manipulator (actually called a Mackool iris repositor). Technique for Soft Nuclei Machine Settings

Alcon Legacy

AMO Prestige

AMO Sovereign

Phaco tip bevel Bottle height Sculpting Vacuum Aspiration rate Nuclear removal Vacuum Phaco power

30° 21 gauge 70 cm

30° 19 gauge 70 cm

30° 19 gauge 70cm

40 mmHg 15 cc/min

35 mmHg 18 cc/min

10 mmHg 20 cc/min

200 mmHg 30% linear

150 mmHg 30% linear

200 mmHg 20% linear

Emulsification The Colibri forceps are used to lift gently the edge of the wound and the phaco tip enters the eye bevel down. The machine should be in foot position 0 as the anterior chamber is still deepened by the viscoelastic. Note If the eye has a shallow chamber, or the pupil is not well dilated and the iris is at risk of damage as the phaco tip enters the eye, redeepen the chamber with viscoelastic. If Viscoat is available and it is being used to protect the endothelium during phaco anyway then this problem will not arise. Once the irrigation ports are safely in the eye, the foot pedal is depressed to position 1 allowing the irrigation fluid to deepen the anterior chamber. • Sculpting: With soft cataracts it is very easy to pass straight through the lens if too much power is used when sculpting. It should be done with smooth movements and the edge of the delineated nucleus should not be passed. Make a deep central groove because even though it may not crack, it will facilitate the pulling of the edge of the lens centrally after it has been sliced.


Fig. 14.18: Slicing the nucleus

139

Fig. 14.19: Separating the sliced nucleus

• Nucleus removal: i. With the phaco tip in the eye in irrigation mode insert the nucleus manipulator through the side port incision. ii. Pass the tip of the manipulator (turned on its side) under the rhexis and out to the equator of the nucleus in the 3 O‘clock position. iii. Engage the nucleus with the manipulator and pull towards the central groove (Figs. 14.18 and 14.19), as the manipulator reaches the groove, use the phaco tip to separate the Fig. 14.20: two sides of the cut you have made. It does not matter if there is full separation or not. iv. Turn the nucleus with the manipulator and the phaco tip and repeat the chopping at intervals of two clock hours. This technique known as the “soft slice” will mean that the segments of nucleus even though they are not separated will fold in towards the center of the eye when they are engaged by the phaco tip. v. Bury the phaco tip in one of the segments. No U/S power is needed for this because of the softness of the nucleus. Allow vacuum to build and when it has, pull the segment (Fig. 14.20) centrally for removal. The nucleus will peel apart along the preprepared cuts. Do this for each part of the nucleus. vi. The epinuclear shell will still be in the eye, but because of the cortical cleavage hydrodissection, will be free to be aspirated. Pass the phaco tip under the rhexis edge into the epinucleus at 6 O‘clock and as vacuum builds pull it centrally for removal. Do not use U/S as this will break occlusion and also punch holes in the epinucleus. Sometimes the manipulator is needed to help the phaco tip to engage the epinucleus by moving it from the equator towards the center.

140

THE ART

OF

PHACOEMULSIFICATION

Technique for Medium Hard Nuclei Machine Settings

Alcon Legacy

AMO Prestige

AMO Sovereign

Phaco tip bevel Bottle height Sculpting Vacuum Aspiration rate Nuclear removal Vacuum Aspiration rate Phaco power

30° 21 gauge ABS 70 cm

30° 19 gauge 70 cm

30° 19 gauge 70cm

40 mmHg 15 cc/min

35 mmHg 18 cc/min

10 mmHg 14 cc/min

350 mmHg 25 cc/min 70% linear



This type of cataract is by far the easiest to remove. The nucleus offers some but not too much resistance to emulsification but also has enough substance to allow easy hydrodissection, manipulation and cracking. It is the ideal type of nucleus for beginners to learn on. Emulsification The eye is entered as already mentioned for the soft cataract. • Sculpting: In medium hard cataracts the nucleus offers some resistance to sculpting. Accordingly, the amount of power needed to emulsify it is that which does not push the nucleus across the eye. It is better to press down with the foot and increase the phaco power than put the superior zonules at risk by pushing at the nucleus. The anatomy of the nucleus should be borne in mind during sculpting. Initially the anterior cortex is removed widely to expose the hard core. This core is then grooved to a depth of 90% of the nuclear thickness. Note As nucleus hardness increases the passes of sculpting should attempt to remove thinner and thinner slivers of nucleus. Note As the phaco tip advances it should be slightly elevated to avoid passing straight through the nucleus. It is important to remember that the center of the nucleus is 2.5-3.0 mm but that because of its elliptical cross-section this reduces rapidly as the phaco tip moves peripherally. The grooves in the nucleus need not go beyond the edge of the 5.0 mm rhexis, provided that sufficient depth has been achieved cracking will occur easily with grooves of this length. It is also important that they are not significantly wider than the phaco needle or else cracking will be much less efficient. Tips for Judging the Depth in the Nucleus when Sculpting • Remember the diameter of the phaco needle (0.9-1.1 mm) • Remember the anatomy of the lens with hard central nucleus surrounded by epinucleus and cortex that are softer • Watch the change in the red reflex, it gets brighter • Refocus the microscope frequently so that the focus is at the plane of emulsification


Fig. 14.21: Cruciate grooves

141

Fig. 14.22: Cracking I

When the first groove has been made, the nuclear manipulator is passed into the eye through the side port and placed in the groove. The nucleus is then rotated anticlockwise to present the next area of nucleus to be sculpted. These medium hard nuclei are generally easy to rotate. Following the fashioning of all four grooves (Fig. 14.21) to create a cruciate shape of appropriate depth, the nucleus can be cracked. Note Although I have used the chopping technique and still do to facilitate the removal of large nuclear fragments. I find that my technique for nucleofractis is the most predictable and consistent, also it is the easiest to teach our residents in training. • Cracking i. Using the manipulator to move the nucleus so that a groove is placed at the apex of the triangle formed by the phaco tip and the manipulator. ii. These two instruments (Figs 14.22 and 14.23) are then put at the bottom of the groove. iii. The phaco tip stabilizes the nucleus while the manipulator moves to the left. In a medium hard nucleus little effort should be needed to crack it. The crack should take place centrally but the effect should cause the equator to separate also. This is important for quadrant removal later. • Quadrant removal i. Each quadrant is split in turn and then the manipulator is used to lift the apex of the first quadrant to present it to the phaco tip (Fig. 14.24). Note If the first quadrant that is approached for removal does not readily detach itself from its position, move to the smallest and try to engage it. Once one quadrant has been removed the others come easily. ii. Initially the foot pedal is used in position 3 (phaco mode) to impale the nuclear quadrant on the phaco tip and thus cause occlusion. The foot pedal is now moved into position 2 (I/A) and vacuum is allowed to build. When it is felt that a good grip has been achieved on the nuclear quadrant it can be moved to the center of the capsulorrhexis. In this position using mostly vacuum assisted by low levels of linearly controlled U/S power, the quadrant is emulsified.

142

THE ART

OF

PHACOEMULSIFICATION

Fig. 14.23: Cracking II

Fig. 14.24: Lifting the first quadrant

iii. The next quadrant is moved into position by the manipulator, tilted up and emulsified as already described. The remaining two quadrants are dealt with similarly. Note With the higher levels of vacuum currently being used, care must be exercised to avoid anterior chamber collapse when occlusion breaks. A number of methods are available on modern machines to mitigate against this eventuality. Firstly continuous irrigation, here even in position 0 the chamber will always be filled so that the postocclusion break surge is neutralized. The use of non-compliant tubing as used in all the machines the author currently uses will help to minimize the effect of any residual line vacuum. On the AMO Prestige phaco machine a mechanical model of events in the anterior chamber exists in relation to the pump mechanism. This allows the pump speed to slow to 0 after occlusion and maximum vacuum has been achieved. As the piece of nucleus being removed clears the tip and occlusion breaks, instead of the pump accelerating to its predetermined speed it reaches it after a pause. The anterior chamber can thus equilibrate without any risk of collapse. This is particularly important with harder cataracts. The Aspiration Bypass System tips on the Legacy approach chamber fluidics in a different way. Here there is a small hole drilled in the phaco tip near to its base. This means that there is a constant flow of fluid through the needle even when in full occlusion. Thus occlusion break response is thus considerably lessened and much higher vacuum levels can then be used efficiently and safely. The Sovereign has even more monitoring of the anterior chamber than the Prestige, with the sampling of the pressures in the anterior chamber many times per second. The machine can be programmed to respond to a whole range of predetermined thresholds during phaco, which may vary between occluded and unoccluded modes. However where these mechanical aids are not present, surgeon anticipation of the likelihood of this event has to suffice. The foot pedal has to be lifted immediately prior to the clearing of the port in the phaco tip.


143

Technique for Hard Nuclei Machine Settings

Alcon Legacy

AMO Prestige

AMO Sovereign

30° ABS Kelman 80 cm

30° 80 cm

30° 80 cm

Sculpting Vacuum Aspiration rate

40 mmHg 20 ml/min

35 mmHg 18 ml/min

10 mmHg 20 cc/min

Nuclear removal Vacuum Aspiration rate

400 mmHg 25 mmHg

260 mmHg 16 mmHg

400 mmHg 18 mmHg

100% panel if required 90% linear 60% linear

100% panel if required 90% linear 60% linear

80% panel 60% linear 60% short bursts unoccluded 60% continuous occluded

Phaco tip bevel Bottle height

Phaco power Sculpting Nuclear removal

The hard nucleus presents the phaco surgeon with one of his greatest challenges. The ability of the tip to penetrate the nucleus, often in the face of weak zonules and combined with controlling sharp nuclear fragments so as to avoid damaging capsule or endothelium need special skills to avoid problems. • Sculpting: In order to minimize the movement of the nucleus away from the phaco tip which might put the zonules on the stretch, high ultrasonic power settings are necessary. The use of maximum power on panel control means the greatest possible acceleration of the tip into the hard nucleus, thus it is more efficient and ultimately less power is used. Since adopting this approach phaco times in hard nuclei have been reduced and nuclear movement largely eliminated. The Kelman tip with its high cavitation also helps considerably. Note In hard cataracts the cut edge of the nucleus produces (Fig. 14.25) a characteristic white tramline. This will alert the surgeon when a good red reflex suggested only a moderately hard nucleus. • Cracking: In hard cataracts cracking may be relatively easy as the nuclei are some times quite brittle. However the plates of the nucleus (Fig. 14.26) often do not part cleanly, therefore it is essential to make sure that the grooves in the nucleus are of adequate depth. The most common cause of cracking difficulties with hard nuclei is due to insufficient depth of the grooves. If problems arise return to each groove and gently redeepen it. This may be facilitated by lengthening the amount of the phaco trip protruding from the sleeve (Fig. 14.27). Make sure that all quadrants are well separated before starting to remove them. • Quadrant removal: Hard nuclei are also large nuclei, it is often sensible once the quadrant has been well engaged by the phaco tip to take a chopper and reduce the size. This is done by pulling the chopper from the periphery of the quadrant towards the phaco tip. Maintaining occlusion of the tip is vital

144

THE ART

OF

PHACOEMULSIFICATION

Fig. 14.25: White tramlines of a hard cataract

Fig. 14.26

to avoid hard fragments of the nucleus careering around the anterior chamber. It is important to balance vacuum and power and so avoid lens chatter. Once the fragment of nucleus has occluded the port on the phaco tip, even with hard cataracts, surprisingly little ultrasonic power is required to massage it through (Fig. 14.28). Lens chatter causes the nuclear fragments to bounce away from the tip, this has two effects. Firstly the hard pieces of nucleus will abrade the endothelium and second the machine is working inefficiently and far more power than necessary will be used, it will also take longer. As discussed already those phaco machines such as those used by the author which allow high vacuum and have advanced fluidics to minimize postocclusion break surge improve safety and efficiency in these difficult eyes. Note There is often little in the way of protective epinucleus in hard cataracts. Injecting Viscoat above and below the nuclear fragments not only protects the endothelium and posterior capsule it also holds the fragments stable in the anterior chamber as they are emulsified.

Fig. 14.27:

Fig. 14.28: Full occlusion for nuclear removal with high vacuum and low phaco power with the Sovereign


145

Emulsification in Special Situations Small Pupil Modern nuclear disassembly techniques allow much safer phaco than previously in small pupil cases. There are two situations that are commonly found, firstly eyes with small but mobile pupils, and second pupils stuck down by synechiae. • If the pupil is not smaller then 3.5 mm and is mobile, overdeepening the anterior chamber will usually allow enough capsule to be exposed to permit capsulorrhexis. If not, judicious use of the nucleus manipulator following the forceps around the rhexis will mean it can be completed without pupil modification. The manipulator is used also to move the iris away from the phaco tip (Fig. 14.15) in the immediate area where it is working during emulsification. This will allow the grooves for nucleofractis to be cut safely. Note It is essential to ensure good hydrodissection in these cases, as visibility is so limited. • Pupils which are stuck by synechiae are often very small (1 mm). There is no way that the case can be completed without enlargement of the pupil. Enlargement of the Pupil Instruments Viscoelastic syringe with Rycroft cannula, two nuclear manipulators. Technique i. Synechiae are broken down initially with viscodissection (Fig. 14.29). The viscoelastic cannula is introduced through the side port incision and the tip placed through the pupil. Viscoelastic is injected gently to free the iris from the anterior lens capsule. This should produce a round but very small opening when the anterior chamber is further deepened with viscoelastic. ii. The two manipulators are then introduced one through the side port and one through the tunnel incision. They are used to stretch the iris gently from 3-9 O‘clock and from 6-12 O‘clock (Fig. 14.30). This will breakdown

Fig. 14.29: Breaking down synechiae with viscoelastic

Fig. 14.30: Stretching the pupil

146

THE ART

OF

PHACOEMULSIFICATION

existing fibrous tissue but should not damage the sphincter so that the pupil often is functional postoperatively. When viscoelastic is then introduced the pupil will be found to be satisfactorily large. Combined Glaucoma and Cataract Surgery Small incision cataract surgery lends itself very well to combination with glaucoma filtering surgery to produce a safe effective operation, which has little effect on astigmatism. It works particularly well with foldable intraocular lenses, as the wound requires minimal modification. Instruments for the trabeculectomy Vannas scissors, St Martins toothed forceps, bipolar cautery wand, Colibri toothed microsurgical forceps, Alcon angled 3.2 mm phaco slit blade, Crozafon sclerotomy punch, 8/0 Vicryl stitch, micro needle holder. Technique i. A conjunctival flap based on the fornix is formed with St Martins forceps and the Vannas scissors. The conjunctiva is dissected off Tenon’s capsule. This is then dissected from the sclera and removed from the area of the trabeculectomy wound. ii. The scleral vessels are gently cauterised using the bipolar wand. iii. A 4 mm vertical groove is prepared using the slit knife as already described 2 mm behind the anterior limbus. The knife is then turned back to its usual position and a tunnel formed as already described. Phacoemulsification now proceeds normally. iv. After the lens has been inserted and before the viscoelastic has been removed from the eye the Crozafon punch is inserted through the wound. The distal end of the cutter hooks over the edge of the internal part of the tunnel and the punch is closed (Fig. 14.31). The punch is then removed and the tissue in it removed. The sclerotomy is Fig. 14.31: Using the Crozafon punch inspected to see how many bites will be required to produce an adequate opening, this is usually two. The sclerotomy should be about 1mm from the proximal lip of the wound and should leak aqueous gently when it touched with a dry sponge. vi. A small iridectomy is then made and the viscoelastic removed with the I/A. vii. For closure of the wound use 8/0 Vicryl stitches at each end of the conjunctival wound. viii. Inject BSS through the side port and observe the bleb forming.


147

White Cataracts These cases are, as already stated in the discussion of capsulorrhexis, very challenging. However even if the rhexis has been satisfactorily accomplished there are still a few points worth noting. When Removing the Nucleus • The nuclei in these cases are often not only hard but very mobile. In order to maximize control during emulsification introduce the manipulator early on to stabilize the nucleus. This is particularly important when sculpting. Note Use of a chopping technique is not recommended in these cases because the capsule can be difficult to see when the chopper is passed to the equator and it is thus easily damaged. • There is little if any epinucleus or cortex to protect the posterior capsule in the presence of sharp nuclear fragments. Use the same precautions as mentioned in relation to hard cataracts. EPINUCLEUS

REMOVAL

The main points in relation to persistent epinucleus have already been discussed under the section on soft cataracts. However if there is a bowl of epinucleus as sometimes occurs with no break in the edge it can present the surgeon with some difficulty. Here are some suggestions: • Use the nucleus manipulator to go out to the equator of the capsular bag to pull the epinucleus centrally • If this does not work the manipulator can be used to divide the edge and allow the phaco tip to occlude on one side • Finally if all else fails and the epinucleus refuses to cooperate use viscoelastic to get under the edge and lift it centrally for aspiration. IRRIGATION/ASPIRATION I/A Handpieces The bimanual irrigation/aspiration handpieces considerably facilitate cortical removal, particularly that found subincisionally. The advantage of cortical cleaving hydrodissection is that there is relatively little cortex left to aspirate. Machine settings Both Alcon Legacy and AMO Prestige—Maximum vacuum 400+ mmHg, linear aspiration flow 24 ml/min. Technique Occlusion of the aspiration port is all important to achieve efficient cortical removal. Once this has happened the cortex can be dragged centrally for aspiration. i. Begin the cortical removal with the irrigation in the left hand and the aspiration in the right. The deep chamber produced by the closed wounds will help considerably the removal from the fornices of the capsular bag. Aspirate

148

THE ART

OF

PHACOEMULSIFICATION

Fig. 14.32: Bimanual irrigation/aspiration facilitates cortical removal

CAPSULAR

CLEANING

all that is easily accessible with one hand and then simply change hands to reach the rest. Sub-incisional cortex used to present particular problems and was a common reason for capsular breaks during I/A. Note If any cortex does not come easily for whatever reason, leave it in situ until later. When the viscoelastic is injected prior to lens implantation it is used to viscodissect the remaining cortex. The lens is then implanted and with the protection of the posterior capsule by the IOL, the already loosened cortex is easily removed with the I/A (Fig. 14.32).

There are sometimes remnants of cortical material which need to be removed from the posterior capsule prior to lens implantation. They can either be polished off using a Kratz scratcher or similar to abrade the capsule gently or be aspirated off with the I/A in low vacuum mode. If these remnants are not removed they can lead to early capsular wrinkling. Capsule Polishing Instruments

Kratz scratcher on irrigation handpiece with free flow irrigation.

Technique A circular movement is used on the capsule and a halo reflex from the posterior capsule indicates the correct plane. There is no feeling of contact with the capsule, this is a visual technique. Vacuuming the Capsule Instruments I/A handpiece with phaco machine set with vacuum at 35 mmHg and aspiration rate at 16 cc/min. Technique With settings on the machine at this low level the posterior capsule can be safely picked up in the I/A port with little or no risk of its breaking. Residual cortex and plaque can often be aspirated off by this means. If there is persistent plaque, which does not polish off or cannot be aspirated from the posterior capsule either it can be left (for 3 months) for later YAG laser capsulotomy or posterior capsulorrhexis should be considered. This technique allows more rapid visual rehabilitation than delayed YAG but there are a few surgical points to be considered before undertaking it. Posterior

Capsulorrhexis

Instruments Straight cystitome as used for anterior capsulorrhexis mounted on viscoelastic syringe, capsulorrhexis forceps.


149

Technique i. The cystitome is introduced and the anterior chamber gently filled with viscoelastic. Do not overfill the eye as it will put too much tension on the capsule. ii. The tip of the cystitome engages the capsule (Fig. 14.33) centrally and produces a small tear. In young patients with elastic capsules this can prove surprisingly difficult. Viscoelastic is injected slowly under the posterior capsule to push back the vitreous face. Fig. 14.33: Starting the posterior iii. The capsulorrhexis forceps grasps the torn capsulorrhexis edge of the capsule and the tear is started. The posterior capsule is much more diaphanous than the anterior and also more elastic (Fig. 14.34). Producing the posterior rhexis seems to require more pull than the anterior. Aim to produce a posterior rhexis 2/3 of the size of the anterior. Note It is important to make sure that the rhexis is truly completed, if it has a radial break at the edge this can spread when the IOL is placed in the bag. When it is anticipated that there may be anterior capsular epithelial cell growth across the anterior hyaloid, an anterior vitrectomy followed by pushing the IOL through the posterior rhexis should be considered (Fig. 14.35). INTRAOCULAR

LENS

IMPLANTATION

General Consideration Viscoelastic The eye will need to be refilled with viscoelastic prior to implantation, currently I use Provisc. It is important, particularly with a folding lens, to make sure that the capsular bag is well distended and the anterior chamber is also deep. This

Fig. 14.34: Tearing the diaphanous posterior capsule

Fig. 14.35: Posterior chamber lens through posterior capsulorrhexis

150

THE ART

OF

PHACOEMULSIFICATION

will allow easy placement of the IOL and its unfolding with minimum trauma to the ocular contents. Wound Sizing In small incision cataract surgery there is now a bewildering array of lenses available in a variety of materials. Some folding lenses can be implanted through unenlarged wounds, often however some adjustment of the wound will be necessary. The folding lens, which I currently use, is the Alcon MA60 or MA30 Acrysof. The former will pass easily through a 3.5 mm opening, the latter through 3.2 mm. The phaco slit knife can be used to ease the edge of the wound and thus enlarge it sufficiently. Lens Implant At present I use only Alcon AcrySof for all cataracts except high myopes where the dioptric range is not available. I have stopped using PMMA because it does not fold and therefore denies my taking an advantage of small incision. Silicone I will no longer use because although on the whole my results were good, the capsular effects and occasional foreign body reaction in the eye are not satisfactory. PolyHEMA I like as a material and have been involved in trials of a new design of lens made of this material. However it is as good as Acrysof in terms of capsular opacity and YAG laser rates. My own experience of acrylic is now 8 years, the results in visual terms as well as the very low capsulotomy rate are impressive. This material also works very well in compromised eyes with uveitis, glaucoma, diabetes, etc. The size of the MA60 and three-piece design mean that it can be used also as a backup lens and the gentle unfolding of acrylic allows insertion folded even with a capsular break. The lack of capsular contraction that this IOL produces permits me to insert it safely into the bag in the presence of a capsulorrhexis break with little risk of decentration. Implantation Instruments Angled McPherson forceps, Seibel folding paddles, Duckworth and Kent (Buratto) insertion forceps, Colibri microsurgical forceps, lens dialing hook. Technique

i. Open the wagon wheel container for the lens and ask the nurse to squirt BSS on to the lens. Note This material is affected by temperature in that if the lens is too cold it is harder to fold. It is best if available to place it in a warming cabinet. ii. Move the microscope away from the eye and reduce the magnification. With the McPherson forceps place the lens on the back of the wagon wheel case. iii. Take the Seibel paddles and open them press down on the edge of the lens to make sure their is no meniscus of BSS underneath it and fold the lens. This done by closing the paddle forceps having placed the lens in the


Fig. 14.36: Folding the lens with paddle forceps

iv. v. vi.

vii.

151

Fig. 14.37: Gripping the lens with the Buratto forceps

grooves on the inside of the paddles (Fig. 14.36). The lens can be folded either from 6 to 12 or 3 to 9. The author prefers the 6 to 12 fold. Down the microscope check that the lens has folded in half rather than asymmetrically which would impair implantation. With the Buratto forceps grasp the lens along the top of the paddles (Fig. 14.37). Turn the lens so that the straight edge of the folded optic faces the left. This will mean that the haptic which turns on unfolding is outside of the eye not in the capsular bag. Introduce the distal haptic to the wound which is gripped by the Colibri forceps and allow it to form a D-shape (Fig. 14.38). Push the optic gently into the eye. As the haptic releases on entering the eye dip the forceps down to place the distal haptic in the bag. With the optic now in the eye the hand is rotated so the folded spine of the IOL is superior (Fig. 14.39). The lens is squeezed gently and then released (Fig. 14.40). Normally it drops down into the bag and slowly unfolds. The Buratto forceps can then be removed from the eye.

Fig. 14.38: Introducing the distal haptic

Fig. 14.39: Rotate the lens

THE ART

152

OF

PHACOEMULSIFICATION

Fig. 14.40: Release the lens

Fig. 14.41: Rotating the lens into the bag

Note If the lens does not release cleanly rapidly squeeze it again and release again, because of the slow unfolding the forceps can be released faster than the lens regains its unfolded shape. viii. The lens dialing hook now enters the eye and is used to push the optic into the bag if it is not there already and then with a gentle rotary movement the lens and its trailing haptic are dialed into the capsular bag (Fig. 14.41). The AcrySof MA30 is introduced similarly but it an also be implanted with two injecting systems one is disposable (Alcon Monarch) (Fig. 14.42) the other reusable (Duckworth and Kent)(Fig. 14.43). VISCOELASTIC Instruments removal.

REMOVAL

I/A handpieces with machine set at same settings as for cortical

Technique The I/A handpieces are introduced into the eye and aspiration is commenced over the center of the optic. The irrigation port can be pushed onto the optic to encourage viscoelastic to come around the IOL and into the anterior chamber for aspiration It is possible to observe down the microscope the viscoelastic disappearing down the I/A port.

Fig. 14.42: Alcon Monarch injecting system

Fig. 14.43: Duckworth and Kent breech loading injector

CURRENT PHACOEMULSIFICATION TECHNIQUES INCISION

153

CLOSURE

Closing the Self-Sealing Wound Technique The hydrodissection cannula attached to a syringe filled with BSS is placed in the side port incision and the eye reinflated so that it feels quite firm when the center of the cornea is pressed. If the wound is still leaking stromal hydration can be useful. The endothelial pump starts to work within a few minutes of the end of the procedure. The watertightness of the wound is tested by placing a dry sponge posterior to the wound and pressing. It should remain dry. In the vast majority of cases a suture is not required because the tunnel wound and its internal valve close satisfactorily. If the surgery has been complicated and the IOL has been inserted unfolded or when tested with a sponge the wound has not sealed properly a suture will be placed. Suturing the Wound Instruments Colibri toothed microsurgical forceps, micro needle holder, Alcon 10/0 nylon suture CU1 needle. Technique With viscoelastic in the eye to retain its firmness, the lip of the wound is lifted with the Colibri forceps. A horizontal pass is made with the needle along the bed of the wound from right to left. The needle is now passed through the upper part of the tunnel from inside out. It is reinserted through the outside of the tunnel again and into the wound to create a horizontal mattress stitch. This is tied into the wound (Fig. 14.43) and the ends trimmed. No great tension is needed on the stitch as it generally is acting only to buttress the tunnel. FINAL

CONSIDERATIONS

The conjunctiva is picked up and cefuroxime is injected subconjunctivally. The drape is then removed and a shield placed over the eye. Postoperatively the patient receives one bottle of G Maxitrol to be instilled 4 times daily for 2 weeks and then twice daily until it is finished.

154

THE ART

OF

PHACOEMULSIFICATION

Steve A Arshinoff

Phaco Slice and Separate*

15

INTRODUCTION Techniques of dividing the cataractous lens into smaller pieces for easier phacoemulsification have been evolving since Kelman first introduced Christmas tree capsulotomy in association with sculpting and cracking, in 1967.1 Gimbel was the first to propose a formalized “technique” with “divide and conquer nucleofractis”, 2 which many others later modified according to their own preferences.3-7 Nagahara’s 1993 technique of phaco chop,8 was popular, but difficult, due to its need for a very large capsulorrhexis and for the surgeon to reach out to the periphery of the lens, under the capsulorrhexis with the phaco chopper. Paul Koch overcame this problem with “stop and chop” one year later.9 More recently, in 1995, H. Fukasaku introduced “snap and split phaco”, which has the advantages of eliminating both sculpting and the need to go out to the periphery with any instruments.10 Fukasaku’s technique has not gained wide acceptance due to its need for the surgeon to exert considerable stress on the nucleus to achieve a snap, a step that many surgeons are not prepared to adopt, and also because the technique works best on lenses more dense, and therefore more brittle, than those usually encountered in many practices. The author devised the technique of “phaco slice and separate” after studying and trying those of Fukasaku and the others mentioned above. Slice and Separate was first presented at the annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS) on April 26, 1997, in Boston, Massachusets, and published in the Journal of Cataract and Refractive Surgery in April, 1999.11 The * Reprinted with changes, with permission from J Cataract Refract Surgery 25:474-78,1999.

PHACO SLICE

AND

SEPARATE

155

author’s technique was changed from those of his predecessors, above, to achieve 5 goals which the author felt were not adequately achieved with previous techniques: • Permit all of the work to be done in the central 3 to 5 mm of the lens, thus making the technique safer, and directly applicable to small pupil phaco surgery. • Divide the lens in a manner to minimize zonular stress, thus increasing safety, especially for cases of pseudoexfoliation, or postvitrectomy cataracts. • Completely eliminate sculpting, which is inefficient and may cause excessive zonular stress, particularly in very dense nuclear cataracts. • Reduce phaco time to a minimum, thus making the procedure more endothelial cell friendly. • Make the procedure relatively independent of nuclear density, so that the surgeon does not have to significantly vary the approach to the lens from case to case, thus reducing complication rates. Method The technique is illustrated in Figures 15.1A to H, and a detailed description of issues pertinent to nuclear disassembly is given below. Preoperative patient preparation, anesthesia, incision, and other surgical steps are only mentioned where materially different in this procedure compared to other common cataract techniques. Hydrodissection Cortical cleaving hydrodissection is achieved, as taught by Fine,12 using balanced salt solution in a 6 cc syringe with a 27-gauge hockey stick cannula. Meticulous hydrodissection is essential to this technique, as frequent nuclear rotation is required. Consequently, the author usually does it twice: once injecting the balanced salt solution (BSS) under the nasal lip of the capsulorrhexis, and again under the temporal lip. He then checks for nuclear freedom by slight gentle nuclear rotation with the hockey stick cannula. GETTING

READY

TO

SLICE

In all chopping techniques, the anterior lens cortex can obstruct visibility and is gently phacoemulsified off by encircling the inside edge of the capsulorrhexis with the phaco before proceeding to slice and separate. This step also helps cortical removal because it creates an even frilly cortical edge at the capsulorrhexis margin which assists in the aspiration of any residual cortex. No phacoemulsification is done inside the eye until both the phaco tip and the Nagahara chopper (Asico #AE2515) are secure inside the anterior chamber (to stabilize the eye), and the phaco is run on I/A for a few seconds to clear some central viscoelastic, permitting free fluid flow. The

First

Slice

The first slice is the most difficult and most critical. The Nagahara chopper tip is gently placed against the nucleus just inside the capsulorrhexis lip proximal to the incision, and the nucleus is nudged distally. The phaco tip, which is already

156

THE ART

OF

PHACOEMULSIFICATION

Fig. 15.1A: The procedure does not require access to the periphery of the lens, and consequently is illustrated here with a mid-dilated pupil. The first step is meticulous cortical cleaving hydrodissection, followed by removal of the cortex covering the nucleus, in the area of the capsulorrhexis, so that nuclear manipulation does not become visually obstructed by floating cortex

Fig. 15.1B: Phaco “Slice and Separate” is illustrated for a right handed surgeon. It is begun by impaling the nucleus with the phaco tip to stabilize it, followed by inserting the Nagahara chopper into the nucleus, to its full depth, just inside the distal margin of the capsulorrhexis

Fig. 15.1C: The Nagahara chopper is drawn, just to the left side, and past the phaco tip, in a slicing motion, to divide the lens in half. Brittle harder lenses will develop propagation of the slice, sometimes even before the chopper gets to the phaco tip, but softer, less brittle lenses may require the slice to be carried through to the proximal margin of the capsulorrhexis

Fig. 15.1D: The chopper is then reinserted into the slice, beside the phaco tip, and the 2 halves of the lens are separated to effectively achieve peripheral cortical as well as nuclear separation

PHACO SLICE

AND

SEPARATE

157

Fig. 15.1E: The nucleus is rotated clockwise about 30 degrees, and a second slice is made in the distal nuclear half. In order to attain satisfactory depth with the phaco tip, it is often necessary to traverse part of the proximal nuclear half with the phaco, for the first two or three slices

Fig. 15.1F: The sliced piece is then separated from the remaining part of the distal heminucleus to achieve good cortical separation. The posterior capsule usually becomes visable with this maneuver, beginning with the second slice

Fig. 15.1G: The lens is again rotated and slicing and separating repeated. Removal of the nuclear pieces can be begun at any time. Sometimes it is easier to remove one of the first pieces to create working space, but sometimes, if the separations are more difficult to achieve, it is easier to slice up the entire nucleus before removing any piece

Fig. 15.1H: Usually the second, or later, piece of pie is removed first, because separations of the pie pieces becomes cleaner as the procedure progresses. Once a space is opened up, when a piece has been removed, the subsequent slices become easier, and are merely continued all around

158

THE ART

OF

PHACOEMULSIFICATION

in the eye, is now buried into the nucleus, aiming just to the right of and beyond (if the phaco is being held in the right hand) the geographic center of the nucleus (central in depth as well), making sure that the anterior surface of the phaco needle stops below the nuclear surface. In the author’s experience, this is optimally achieved with the phaco machine set on linear pulse, about 5 per second, with a 50% duty cycle. The vacuum is set at about 150 mm Hg using a peristaltic pump and standard sized needle (however the Alcon ABS smaller needles require vacuum of about 275 mm Hg). If the vacuum is set too high, the phaco will tend to erode through the nucleus, rather than stabilizing it. It is easier to achieve nuclear stabilization if the silicone sleeve of the phaco needle is recessed from the tip 3 to 4 mm, rather than the more customary 2 to 3 mm, because it is not desirable for the irrigation port to enter the nuclear tunnel created by the phaco needle. Thirty, fifteen, or zero degree phaco needles may be used, with the author’s own preference being the 30 degree tip, because it is able to be easily occluded to achieve slicing, but the emulsification of the segment is not slowed as it is significantly with the steeper angled tips. Furthermore the 30 degree angulation of the needle aperture roughly equals the entry angle of the phaco needle into the nucleus, resulting in the needle opening pointing directly inferiorly in the lens during surgery. The Nagahara chopper is now inserted into the nucleus just inside the distal edge of the capsulorrhexis. In more dense nuclei, this is not always that easy. It may be facilitated by tilting the chopper upwards, so that it enters the nucleus with the sharp edge leading, in a rotatory downward movement, not straight down. The chopper enters the lens and is moved progressively deeper as it is pulled just to the left side of the phaco tip. If the phaco needle has not been advanced far enough, the lens will tend to rotate when the chopper is inserted and drawn toward the phaco tip. If this occurs, just phaco in a bit further. In softer, less brittle nuclei, the slice will not spontaneously propagate proximally as slicing progresses, and as a consequence the chopper must be drawn past the side of the phaco tip, often as far as the proximal capsulorrhexis edge. In that case, the chopper must then be replaced adjacent to the end of the phaco tip, in the slice, before separation is attempted,. The separation is better if rotation in opposite directions, rather than simply pulling, is used, because rotation causes the distal nucleus and cortex to separate into two first, and continuing the rotation causes the separation to propagate proximally. In harder, more brittle nuclei, the same is done, but in this case, the slice tends to spontaneously propagate as the chopper approaches the phaco tip, thus obviating the need to go past the phaco tip with the chopper, and making medium density nuclei the easiest cases. In very dense nuclei, it is sometimes difficult to get the chopper deep enough into the nucleus to achieve through and through slicing. If this occurs, after passing the chopper through the nucleus, do not attempt to separate, just return and slice again in the same trough in order to achieve adequate depth of penetration of the chopper. Occasionally, especially when the technique is new to a surgeon, the first slice is incomplete, or not in the originally planned direction. This is usually due to the surgeon’s fear of going too deep, something that is actually very difficult to do. If incomplete separation occurs, do not worry, just go on to the successive

PHACO SLICE

AND

SEPARATE

159

slices. Each successive slice is easier than the last, and it does not really matter how the nucleus is sliced, as long as the pieces are small enough to be easily emulsified. The Second and Subsequent Slices The second slice is easier than the first, because a central depression has already been made in the nucleus, and so it is easier to get deeper with the second entry of the phaco, and easier to judge how deep you are. After completion of the first slice the Nagahara chopper is inserted distally into the trough and the nucleus is rotated about one and one half clock hours clockwise (right-handed surgeon). The phaco is then inserted into the distal half of the nucleus, at its right side, about one half or less clock hour from the edge, sometimes traversing the distal aspect of the proximal nuclear half in order to attain sufficient depth. The distal half is stabilized on the phaco tip, exactly as above, and the Nagahara chopper is used to create a second slice, just at the left edge of the phaco tip, in the same manner as above. Good separation is achieved, again by rotation in opposite directions. Because the first slice is the most difficult, it is wise not to aspirate this first liberated pie piece first, as it may still be attached to the right heminucleus. It is rather preferable to repeat the steps of rotation and slicing again once, a few times, or until the whole nucleus has been sliced up, before removing any pieces. The pieces are easily aspirated and emulsified by using the chopper to separate the pieces not being removed toward the left, while rotating the phaco which is holding the piece to be aspirated, to the right, thus creating ample space to aspirate out the first and subsequent pieces. Rotation of the lens pieces is easily achieved with the phaco chopper, which has a blunt rounded tip. The surgeon should, however be sure that the phaco machine is irrigating, so that the posterior capsule is taut, and not curled around the phaco chopper, when nuclear rotation is performed. Sometimes a shelf is created with the first slice. This occurs if the phaco chopper was not inserted to full depth, and slicing therefore did not go down to the center of the lens, and the deep half of the lens was just pulled apart without any guiding slice. If this occurs, it becomes difficult to extract the nuclear pieces on one side because they are partially wrapped around a shelf of nucleus. This is resolved by just completing all of the slices around the nucleus until you get to one that is easy to remove. The rest just follow in succession. Further facilitation is achieved by going through the accidentally created nuclear shelf with the phaco, as successive pie pieces are grasped for slicing. Completing the Procedure Once the nucleus has been sliced, emulsified and aspirated, irrigation/aspiration of residual cortex is done in a standard fashion. The posterior capsule is then vacuumed. An additional posterior capsule cleaning trick that the author likes is to use a 6 cc syringe of BSS and a hockey stick cannula. If the cannula is allowed to be placed tangential to the plane of the posterior capsule, and the BSS is ejected in puffs, allowing the capsule to come up around the hockey stick tip between puffs, the low viscosity of BSS (1.0 mPs) causes excellent dissection of the cortical material remaining, off the posterior capsule.

160

THE ART

OF

PHACOEMULSIFICATION

The capsular bag and anterior chamber are then inflated with viscoelastic, the incision enlarged if needed to accommodate the intended IOL, and the IOL inserted. Viscoelastic is then removed using the authors rock and roll technique. 13 ,14 Finally, vancomycin 1 mg/0.1 cc is injected through the side port. The incision and side port are checked for leakage. SUMMARY Phaco slice and separate is the most gentle technique of phacoemulsification that the author has ever tried. It never requires any instrument to be placed out beyond the boundary of the capsulorrhexis, and consequently is very safe, and a good technique for small pupil cases. Because the nucleus is stabilized on the phaco tip before any stressful action is performed, it is also excellent for cases of pseudoexfoliation or lenticular instability or subluxation. It does, however, require a bit different mind set from older techniques of phacoemulsification, because of the lack of a sculpting step, and having to deal with multiple slices simultaneously. This change may require surgeons to take a bit of time to get used to seeing and understanding what is happening during the case. The effort, however, soon is rewarded by smoother surgery, with less concern for nuclear density and pupil size, and fewer complications. With experience, the simplification of surgery, due to the fact that the technique is relatively independent of nuclear density, pupil size and lenticular stability, makes the surgeon’s day in the operating room run much more smoothly and significantly reduces the risk of complications. REFERENCES 1. Kelman CD: Phacoemulsification and aspiration—a new technique of cataract removal (a preliminary report). Am J Ophthalmol 64: 23-35, 1967. 2. Gimbel HV: Divide and conquer nucleofractis phacoemulsification—development and variations. J Cataract Refract Surg 17:281-89, 1991. 3. Davison JA: Minimal lift-multiple rotation technique for capsular bag phacoemulsification and intraocular lens fixation. J Cataract Refract Surg 14:25-34, 1988. 4. Shepherd John R: In situ fracture. J Cataract Refract Surg 16:436-40, 1990. 5. Fine IH: The chip and flip phacoemulsification technique. J Cataract Refract Surg 17:366-71, 1991. 6. Pacifico Ronald L: Divide and conquer phacoemulsification—one handed variant. J Cataract Refract Surg 18:513-17, 1992. 7. Fine IH, Maloney WF, Dillman DM: Crack and flip phacoemulsification technique. J Cataract Refract Surg 19:797-802, 1993. 8. Nagahara K: Phaco-chop technique eliminates central sculpting and allows faster, safer phaco. Ocular Surgery News October 12-13, 1993. 9. Koch PS, Katzen LE: Stop and chop phacoemulsification. J Cataract Refract Surg 20:566-70, 1994. 10. Fukasaku H: Phaco snap phacoemulsification. Alcon Video Film Festival. American Society of Cataract and Refractive Surgery Annual Meeting San Diego, California, 1-5, 1995. 11. Arshinoff Steve A: Phaco slice and separate. J Cataract Refract Surg 25(4): 474-78, 1999. 12. Fine IH: Cortical cleaving hydrodissection. J Cataract Refract Surg 18:508-12, 1992. 13. Arshinoff Steve A: Rock ‘n’ Roll Removal of Healon GV. Alcon video film festival. American Society of Cataract and Refractive Surgery Annual Meeting, Seattle, Washington. June 1-5, 1996. 14. Arshinoff Steve A: Rock ‘n’ Roll Removal of Healon GV. In Arshinoff Steve A (Ed): Proceedings of the 7th Annual National Ophthalmic Speakers Program (Ottawa, Canada, June 1996). Medicopea 1997.

Eric J Arnott

Cataract Extraction and Lens Implantation: The Implosion Technique

16

INTRODUCTION There have been more changes in cataract surgery over the last five decades than occurred over the previous three millennia. In the West the intracapsular was changed to the extracapsular cataract extraction (ECCE) in the mid 1970s, and over the last two decades this has been superseded by the phacoemulsification of the cataractous lens. In the world as a whole, these progressive changes have swept over the continents like a tidal wave. While in the USA some 97% of cataracts are performed using the ultrasonic technique, in the UK the figure is 50% and in the Asian countries some 10%. In both of these latter areas, the percentage of operations performed using ultrasound or laser, for cataract surgery, will increase over the years until “the small incision removal of the cataractous lens with insertion of an intracapsular lens implant” becomes the standard procedure. Various factors have militated against the more rapid adoption of phacoemulsification as the standard cataract operation. Not least are the expensive surgical machinery required for its performance and the surgeons learning curve in adopting this procedure. Another important consideration is the general state of the eye and adnexa, with its cataractous lens, in the Third World, as compared to the eye with a cataract in the Western world. In Asian countries poverty, malnutrition, disease and adverse climatic conditions will often present the surgeon with a cataractous eye that cannot easily be treated with small incision cataract surgery. The Asian eye with its adnexa may have scarring of the lids, conjunctiva and cornea; resulting in an eye, which has contracted lids, misplaced lashes and a sunken immobile globe. Moreover the cornea may be semiopaque and the pupil small and non-dilatable.

162

THE ART

OF

PHACOEMULSIFICATION

In the event of an eye with a cataract that requires surgery, the presence of poor exposure and a fixed small pupil, may influence the surgeon to consider doing an extracapsular procedure rather than phacoemulsification. The majority of Asian cataracts are mature with a brunescent nucleus, whereas most Western cataracts are relatively immature. Current technology and newer techniques of surgery are enabling surgeons to do phacoemulsification on lenses with very dense nuclei, which would have been considered impossible some years ago. While the lens with a dense nucleus may be more difficult to phaco than a softer cataract it does have the advantage of being more brittle which makes its splitting and chopping easier. Just as in cataract surgery there has been a shift from intracapsular to extracapsular and finally phacoemulsification, so in “phaco” itself there has been a progressive change in the procedure. In the original operation as described by Charles Kelman in 1968 the anterior capsule was opened with a”Christmas tree” configuration and the nucleus was dislocated into the anterior chamber of the eye, prior to phacoemulsification. The opening into the anterior capsule was modified into a “can-opener” by Robert Sinskey et al in 1972. With this larger opening in the anterior capsule, the nucleus could be phacoemulsified in the posterior chamber. In 1987 Howard Gimble and Thomas Neuhnann introduced the concept of capsulorrhexis of the anterior capsule, with a circular tear opening being made. While considerably improving the surgical procedure, since it allowed a lens implant to be inserted totally within the confines of the capsular bag, it did cause some problems with the phacoemulsification of the nucleus. In the older techniques, the larger opening in the anterior capsule gave greater access for the removal of the nucleus. In the presence of a capsulorrhexis the surgeon had a much more limited access to the nucleus. This led to the introduction of advanced “phaco” procedures such as “divide and conquer”. For its removal the lens was divided and emulsified. The implosion procedure is a variant means of phacoemulsifying the nucleus in the presence of a capsulorrhexis. The Surgical Approach The eye for surgery is prepared with mydriatic drops to dilute the pupil and antibiotic guttae to kill any bacteria lying in the conjunctiva and fornices. A steridrape covers the lashes and a lid speculum exposes the globe (Fig. 16.1). The Incision

Fig. 16.1

The incision into the eye may be made using, either the clear corneal or scleral tunnel approach (Fig. 16.2). The clear corneal incision described by Eric Arnott in 1975 and remodified by Howard Fine in 1992 may be either one or two step in style. It is made either in the corneal meridian with the steepest slope or

CATARACT EXTRACTION

AND

LENS IMPLANTATION: THE IMPLOSION TECHNIQUE

Fig. 16.2

163

Fig. 16.3

in the lateral meridian at 3 O’clock in the left eye and 9 O’clock in the right eye. A diamond keratome of some 3.2 mm width is used (Fig. 16.3) If the scleral tunnel approach is to be used the incision is usually made in the 12 O’clock meridian. The opening into the anterior chamber is microscopic some 3.2 mm in cord width and three step in configuration, giving a water type seal at the end of the operation. The initial incisions some 300 microns in depth [the tissue at the corneoscleral junction being some 700 microns in thickness] are made either at the corneoscleral junction or just posterior to it, in the sclera. From the depth of this incision a lamella split is made extending anteriorly into clear cornea for some 2 mm; the plane of this incision being parallel to the iris-lens diaphragm. From the anterior limit of this second portion of the section the anterior chamber is entered using a 3.2 mm keratome; this penetration being at right angles to the second part of the incision. When the tip of the keratome has just perforated into the anterior chamber it is pointed towards the apical anterior surface of the lens. In this way a self-sealing incision is obtained. Reconstitution of AC with Viscoelastic Solution A Wycroft cannula on a syringe filled with viscoelastic solution is inserted into the anterior chamber and passed over the anterior surface of the lens to lie just within the pupillary margin in the 6 O’clock meridian. In filling the anterior chamber with this viscoelastic solution the aqueous humor is replaced, further pupillary dilation may be achieved, the anterior surface of the lens is flattened, and a protective layer is coated over the corneal endothelium. Capsulorrhexis A capsulorrhexis is performed, creating a round hole some 5.5 mm in the elastic cuticular anterior capsule (Fig. 16.4). This

Fig. 16.4

164

THE ART

OF

PHACOEMULSIFICATION

Fig. 16.5

Fig. 16.6

is one of the most important and precise part of the operation. The anterior capsule of the lens is perforated with a bent needle tip placed at the midpoint of the anterior capsule. A linear tear is made (Fig. 16.5), the upper edge of which is converted into a flap. This is held with forceps (Fig. 16.6), and with a continuing circular movement and repeated gripping of the torn flap near to the tearing edge, a capsulorrhexis is fashioned. Hydrodissection Before removing the lens contents it is necessary to free the nucleus from the surrounding capsule. The tip of a Wycroft cannula fitted to a 2 ml syringe filled with balanced salt solution (BSS) is placed under the lip of the anterior capsule and a little fluid is injected to flow around Fig. 16.7 the inside of the lens capsule (Fig. 16.7). The tip is moved to different meridians of the edge of the lens capsule each time injecting a little fluid. This has the effect of not only freeing the cortex from the lens capsule but also of washing away some of the equatorial cells; the removal of these germinal cells reduces the incidence of postoperative Elschnig pearl formation. Phacoemulsification of Lens Contents The next stage of the operation is to remove the hard central nucleus with the phaco handpiece tip. The phaco tip is some 1 mm in diameter, with a beveled edge. It is enclosed in a silicone sleeve, which has two side-port holes near its tip. One and a half mm of phaco tip is left exposed beyond the silicone sleeve. While ultrasonic agitation of the tip breaks up the nucleus, bit by bit, fluid enters the eye between the silicone sleeve and the phaco tip.The emulsified debris is aspirated up the phaco titanium tip. Phacoemulsification has been markedly facilitated over the years by progressive improvements in the handpiece. The ultrasonic power, fluid inflow and outflow

CATARACT EXTRACTION

Fig. 16.8

AND


165

Fig. 16.9

can be modified according to the surgeon’s needs. The ultrasonic power can be varied from zero to 100 percent. The fluid inflow is normally 25 cu ml per minute but may be increased or reduced by raising or lowering the level of the inflow bottle. The fluid outflow has two parameters—“the vacuum pressure and the aspiration flow rate”. Variants between these two can be used at all stages of the operation. With the “pulsating pump” form of aspirating unit, the vacuum level will not rise within the system until the nucleus or other material occludes the phaco tip. The greater the level at which the aspirating flow rate has been preset, the more rapidly will the vacuum pressure build up once the tip has become occluded. With high aspiration levels there is more followability of the nucleus. There are essentially three different techniques to phacoemulsify the nucleus of the lens. • The divide and conquer • The implosion method • Chop and stop. In most operations with phaco of the nucleus, a deep groove is made from 12 towards 6 over the anterior surface of the nucleus (Fig. 16.8). When making this groove the tip goes deeper towards the center of the nucleus and shallows towards the 6 O’clock meridian (Fig. 16.9), allowing for the convexity of the posterior capsule. While varying power, vacuum and aspirating levels may be chosen depending on the surgeon’s particular needs, average levels for this part of the procedure would be “phaco” power 70%, the vacuum level 60 mm Hg and an aspiration rate of 25 cu ml per minute. The phaco tip shaves the surface of the nucleus, with an action similar to the planing effect of a chisel. The softer the nucleus the deeper the tip may safely penetrate into its substance without disturbing the position of the nucleus, which could put tension on the zonule or capsule of the lens. With a hard nucleus the tip should shave superficially, with only a third or less of its diameter being embedded in its substance. Divide and Conquer In the divide and conquer technique once the initial deep groove has been made a spatula is inserted into the anterior chamber to join the phaco tip. The tips

166

THE ART

OF

PHACOEMULSIFICATION

Fig. 16.10

Fig. 16.11

of both instruments are placed deep into the groove and with counterpressure against the sides of the groove the nucleus is split into two. These two instruments are next used to rotate the nucleus some 90°. This process is repeated with another groove being made and the nucleus split yet again, so that it has now been divided into 4 quadrants, each of which can be individually emulsified. The vacuum level can be increased at this stage of the procedure to a much higher level. This enables the fragments to be drawn towards the center of the capsular bag where they can be emulsified using low phaco power. The Implosion Method In the implosion technique as with the divide and conquer the initial procedure is to make a deep groove across the anterior surface of the lens .The procedure differs in that the nucleus is not divided prior to its removal but is removed bit by bit in one piece. This has the safety factor in that if the capsule should inadvertently rupture, in an emergency situation, it is easier to deal with one lens fragment rather than multiple pieces of nucleus. The initial deep furrow is debulked on either side leaving intact a rim of nuclear bowl (Figs 16.10 and 11).The phaco tip should at all times be kept in view within the pupil margin in the “safe” triangular area between 4,6, and 8 O’clock. Keeping within this area, only the inferior half of the nucleus can be debulked. Access is gained to the superior half by rotating the nucleus some 90° at which time the debulking process is continued. Further rotation of the nucleus may be required to totally debulk its central contents. When totally debulked the nucleus should resemble a salad bowl with intact rim and inferior nuclear plate (Fig. 16.12). The final part of the “phaco” process is to implode or break off fragments of the nuclear bowl into the cavity of the debulked nucleus, where they can be easily emulsified (Fig. 16.13). Since at this stage of the procedure the more peripheral softer portion of the nucleus is being dealt with, lower power levels may be used, averaging 40%. The vacuum and aspirating levels are left unchanged. This relatively high aspiration rate allows for the phaco tip to manipulate and mobilize the nuclear bowl rim. The tip of the phaco impales the nuclear rim at 3 O’clock causing it to break, implode and rotate into the tip (Fig. 16.14). Due to the “followability” of the

CATARACT EXTRACTION

Fig. 16.12

AND


167

Fig. 16.13

lens, the tip placed at 3 O’clock can move along the rim of the nuclear bowl at the same time that the rim is being brought towards the tip. With this combined process the tip can remain within the safe area. The tip can be moved to other areas within the triangle and break up and fragment the remaining portions of the imploding bowl (Figs 16.15 and 16). With the total removal of the nuclear rim only the thin nuclear plate will remain (Fig. 16.17). Removal of this should present no difficulty as it will normally float off the posterior capsule and be simply emulsified (Fig. 16.18).

Fig. 16.14

Fig. 16.15

Fig. 16.16

Fig. 16.17

168

THE ART

OF

PHACOEMULSIFICATION

Fig. 16.18

Fig. 16.19

The Chop The chop technique may be combined with the “divide and conquer” and “implosion“ procedures or used as a primary procedure. It is best employed in cases with a very hard nucleus, which will be very brittle. High-vacuum pressure up to 200-400 mm Hg may be used. Using this high vacuum and with ultrasonic power the nucleus is impaled near the center of its anterior surface. Once impaled, the vacuum is maintained and the ultrasonic power turned off. A chopping hook is inserted into the anterior chamber and engages the nucleus 1 mm beyond the impaling phaco tip, and drawn towards it. The counterpressure of embedded hook against impaled phaco tip cracks the nucleus. The process can be repeated a number of times breaking the nucleus up into fragments which can be emulsified and aspirated from the capsular bag. It is important to ensure that the hook is at all times within, not over, capsular bag to prevent tension and partial disinsertion of the suspensory ligament of the lens. In the “implosion” technique if the nuclear bowl is particularly hard, the “chop” may be employed to help fracture the rim. Aspiration of Residual Cortex This is performed using the standard irrigating aspirating handpiece with 0.3 mm side port (Fig. 16.19). Lens Implantation With the lens contents removed the capsular bag is now ready to receive the implant. The lens implant may be made of several materials; foldable lenses that go through the phaco incision may be silicone, poly-HEMA (hydroxyethylmethacrylate), or acrylic. Polymethylmethacrylate (PMMA) lenses are more rigid and require the phaco incision to be a little enlarged for their insertion. Most implants have loops, which are attached to the optical portion and contract down when inserted into the capsular bag. Prior to the lens insertion the anterior chamber and capsular bag are filled with a viscoelastic solution. With soft lenses a lens forceps is used to fold over the implant prior to insertion. With the implant folded in the forceps the inferior loop is guided through the

CATARACT EXTRACTION

Fig. 16.20

AND


169

Fig. 16.21

section and across the anterior chamber and into the inferior recess of the capsular bag. The forceps now release the lens allowing the optical portion to unfold half in the anterior chamber and half in the capsular bag. The upper loop may be either looped or dialled into the capsular bag. Prior to inserting the PMMA lens the section is enlarged a further 1.75 mm.The insertion is similar to that of a foldable lens except that the lens is inserted in the unfolded state. The lens, held in forceps, is inserted through the section, across the anterior chamber. As with the soft implant the inferior loop is placed in the inferior recess of the capsular bag. A dialling hook is inserted into the upper crutch of the lens, at the junction of optics and loop. With a clockwise dialling motion the upper loop will be corkscrewed into the capsular bag. As an alternative the upper loop lying just within the section may be held with forceps and looped into the capsular bag. The PMMA lens with totally encircling loops has the advantage of giving great stability to the capsular bag (Figs 16.20 and 21). CONCLUSION With this procedure the incidence of postoperative retinal detachments have been reduced from 2.5% with the old intracapsular operation to 0.15% with the small incisional and intercapsular technique. All other complications including late edema of the macula have also been reduced. The small incisional phaco and implant procedure confers other benefits for the patient. The postoperative convalescence is minimal, the patient being able to return to normal activities immediately. A high percentage of visual acuity recovery is regained within the first 24 hrs. The rapid visual rehabilitation, limited postoperative convalescence and reduced postoperative morbidity have markedly changed the indications for cataract surgery.

170

THE ART

OF

PHACOEMULSIFICATION

Rasik B Vajpayee Tanuj Dada

Phacoemulsification in Special Situations

17

INTRODUCTION Phacoemulsification has become the surgery of choice for a cataract extraction all over the world. Although the technique of phacoemulsification is more or less a standard one, there are certain special situations which warrant either a modification of the standard technique or the use of an additional device to facilitate the surgery. Some of these special situations include a small pupil, a subluxated lens, an intumescent lens, anterior uveitis, vitrectomized eyes and the pseudoexfoliation syndrome. Each of these conditions poses a unique intraoperative problem to the surgeon and demands a detailed preoperative planning on how to tackle them. In this chapter we describe the various innovative techniques developed to handle each of these special situations. SMALL PUPIL This is a frequently encountered problem during phacoemulsification. Although endolenticular phacoemulsification can be performed in the presence of a small pupil, it increases the degree of difficulty for the surgeon and is often a cause for complications. There are various intraoperative techniques that can be used to manipulate the size of the pupil, to facilitate phacoemulsification in a miosed pupil. Intracameral Adrenaline The use of 0.1 cc of 1:10,000 adrenaline, injected directly into the anterior chamber through the side port incision, is useful in dilating the pupil. Only preservative

PHACOEMULSIFICATION

IN

SPECIAL SITUATIONS

171

free drug is to be used. Since the drug is toxic to the endothelium, sodium hyaluronate should be used to coat the corneal endothelium before adrenaline is injected. This is helpful in eyes with an intact dilator pupillae muscle, with no synechiae, fibrosis or hyalinization of the iris musculature. Adrenaline is not to be used in hypertensive or cardiac patients. Iris Hooks Self-retaining iris hooks have been designed by Mackool (titanium) and De Juan (nylon). Three to four hooks are placed through paracentesis sites and the pupil can be widely dilated to a triangular (Fig. 17.1) or square shape. With the use of these hooks, the pupil can be dilated to any size, regardless of the pre-existing pupillary diameter. Although this is an effective technique for pupillary dilatation, it is time consuming, leads to considerable iris manipulation and Fig. 17.1: Three flexible nylon iris retractors being used to dilate the pupil results in a large amount of leakage of fluid from the paracentesis sites. The nylon hooks (Grieshaber and Co) are preferable since these incorporate an adjustable stop which allows the traction on the iris to be manipulated during surgery. Iris Protector Ring Siepser had designed a hydroview iris protector ring (Grieshaber and Co) which can be placed inside the pupil through a 3-mm incision. The ring expands with hydration and gradually ditates the pupil. It is removed at the end of phacoemulsification. Stretch Pupilloplasty This is our personal technique for dilating the pupil. After injecting a high viscosity sodium hyaluronate in the anterior chamber, two Sinskey hooks are employed from two paracentesis sites to engage the inner edge of the pupil. The hooks are placed diagonally opposite each other and then a bimanual stretching of the pupil is done. This stretch is done in the horizontal (3-9 O’clock) and vertical axis (6-12 O’clock) and creates micro tears in the sphincter pupillae, thereby dilating the pupil. A pupil size of up to 6 mm can usually be achieved with this technique. Partial Thickness Sphincterotomies Eight small sphincterotomies are performed using a Rappazzo scissors (used for vitreoretinal surgery) through two side port incisions. The cut is made up to half width of the sphincter pupillae muscle and then a hook is used to stretch the root of the iris in the different meridians in which the sphincterotomies have been made.

172

THE ART

OF

PHACOEMULSIFICATION

A pupillary size of 6 to 7 mm can be achieved with this method. Postoperative miotic therapy is required to decrease the pupil size and prevent iridocapsular synechiae between the sphincterotomy sites and the anterior edge to the capsulorrhexis. Manipulation with the Chopper The second instrument or the chopper can be employed to stretch the pupil in the area of interest while performing phacoemulsification. The chopper can be placed at the edge of the pupil and the iris manipulated to expose the nucleus that is being currently engaged by the phaco probe. The process is then repeated in the other quadrants till the nucleus is completely emulsified. UVEITIS Anterior uveitis is often associated with a small, bound down pupil with a pupillary membrane and dense posterior synechiae. A fibrinoid reaction with pigment deposition over the surface of the IOL is also a common postoperative problem, specific to cases with uveitis. Phacoemulsification should be attempted only if there has been no sign of activity in the past three months. Preoperative topical and systemic steroids can be started 48 hours prior to the surgery. Since the surgeon often encounters a pupillary membrane in such cases, membrane dissection (a technique first described by Osher) is a prerequisite for pupillary dilatation. In this technique, a bent 26/27 g needle or a capsulorrhexis forceps is used to perform a blunt dissection and stripping of the membrane from the edge of the pupil. After the membrane has been removed the pupil usually dilates to an adequate size for phacoemulsification to be performed. All manipulations in the anterior chamber should be performed under a cohesive viscoelastic like sodium hyaluronate, which also binds to the corneal endothelium and gives protection to the endothelial cells, already compromised due to the intraocular inflammation. Intracameral low molecular weight heparin (Fragmin) can be added in the irrigating fluid (10 IU per ml) to decrease the postoperative reaction. A heparin coated/Smart IOL should be used in such cases, to minimize deposits on the surface of the IOL. SUBLUXATED LENS The stabilization of the capsular bag and implantation of the IOL is an important challenge for the phaco surgeon. If the zonular loss is limited to less than one quadrant a standard phacoemulsification may be attempted safely. If the zonular loss is more extensive, lens manipulation may cause further loss of zonular support and lens dislocation into the vitreous. Although an intracapsular extraction was traditionally performed in such eyes, it is now possible to perform phacoemulsification surgery in a subluxated cataractous lens using the PMMA endocapsular ring (ECR). The ring was introduced by Witschel and Legler in 1993 to provide an intraoperative and postoperative stabilization of the capsular bag. The ring currently in use is

PHACOEMULSIFICATION

IN

SPECIAL SITUATIONS

173

the one modified by Morcher (Fig. 17.2) and consists of an open, flexible PMMA filament with eyelets present at the open ends. It is dialled with a Sinskey hook (using the eyelets to insert the hook) under the edge of the anterior capsulorrhexis. The ring expands and occupies the equator of the lens, circumferentially distributing the tension inside the capsular bag and thus acting as an artificial zonule. One can then proceed with phacoemulsification using a setting of low flow and low vacuum, to minimize Fig. 17.2: The Morcher turbulence in the anterior chamber and subsequent zonular endocapsular ring stress. Cionni has recently introduced another modification in the ring with the introduction of a separate fixation element or a hook that extends centrally from the ring (Fig. 17.3). At the free end of the hook is an eyelet for manipulation and suture placement, which can be used to allow scleral fixation without disturbing the integrity of the capsular bag. This is helpful in eyes with an extreme loss of zonular support where the endocapsular ring itself may require a scleral support. Since implantation of the IOL may be associated with an excess pressure on the zonules due to the large inflexible PMMA haptics, these haptics can be tied to the surface of the optic using a 10-0 nylon suture prior to insertion into the anterior chamber. The suture can be cut once the Fig. 17.3: The Cionni endocapsular ring IOL is inside the capsular bag for a gentle unrolling of the two haptics. Another method described by Merriam and Sheng makes use of the flexible nylon iris retractors to hook the edge of the anterior capsulorrhexis to support the lens during the surgery. Two to four retractors can be used for this purpose depending upon the degree of subluxation. The retractors are removed at the end of the surgery and while it may be possible to insert one of the haptics in the ciliary sulcus, the second haptic can be sutured to the sclera with a 10-0 prolene suture for better stabilization. POSTVITRECTOMY Cataract development in phakic eyes after a pars plana vitrectomy is a common occurrence, with reported rates as high as 80 to 100% especially if silicone oil has been used. Phacoemulsification in vitrectomized eyes is a difficult task. Poor pupillary dilatation, posterior synechiae, deep anterior chamber requiring a steep angulation of the surgical instruments, zonular damage, posterior capsular plaques, excessively mobile posterior capsule and capsular tears are some of the problems faced by the surgeon. In addition due to absence of the anterior hyaloid, there is loss of posterior lenticular support and alteration in intraocular fluid dynamics. This leads

174

THE ART

OF

PHACOEMULSIFICATION

a collapse and sagging of the capsular bag during phacoemulsification due to a low vitreous pressure. The use of a superpinky is to be avoided in such eyes and the height of the infusion bottle should be decreased. An infusion port made in the region of the pars plana prior to proceeding with the cataract surgery may prove useful, although this is more relevant to extracapsular cataract extraction (ECCE). The constant inflow of fluid through the infusion cannula maintains a positive vitreous pressure, prevents scleral collapse and allows a comfortable surgery. The infusion port is taken out as the last step during surgery and the sclerotomy port is closed with the preplaced 8-0 Vicryl suture. The integrity of the posterior capsule and the zonules may be disturbed by vitreous surgery. This can lead to a dehiscence of the posterior capsule and zonular dialysis at any time during the phacoemulsification. In such eyes, the endocapsular ring may be required to facilitate a successful IOL implantation. In operated eyes with silicone oil left in the vitreous cavity, a silicone foldable IOL should not be used. INTUMESCENT CATARACT Phacoemulsification in intumescent cataracts is a challenge for the phaco surgery primary because of the difficulty in performing a capsulorrhexis. There is a lack of the red reflex, making the perception of the capsular flap difficult. In addition, since the lens is swollen, there is an increased tension on the anterior capsule and a greater tendency for the margin of the capsulorrhexis to escape towards the periphery of the lens. In such cataracts it is advisable to perform an initial cut in the central capsule to permit escape of the liquid cortex, to decompress the swollen lens. The cortical matter is aspirated out and the anterior chamber filled with a high viscosity viscoelastic substance (Healon GV). Then one proceeds with the capsulorrhexis under condition of high magnification and illumination, using a capsulorrhexis forceps. The surgeon may find it helpful to turn off the light of the operation theater and the microscope, and use an endoilluminator for oblique illumination of the capsule. Another alternative in such cases is to perform the capsulorrhexis under air. This helps to tamponade the egress of liquefied cortical material after an incision in the anterior capsule. A bent 26 g needle is used in performing the capsulorrhexis, if air is to be used. The rhexis forceps requires a large opening and air escapes rapidly if this instrument is used. After completion of the capsulorrhexis, the rest of the procedure is similar to a routine phacoemulsification surgery. PSEUDOEXFOLIATION The pseudoexfoliation syndrome is associated with a weak zonular apparatus with an increased risk of zonular dehiscence during phacoemulsification. Poor pupillary dilatation, a fragile capsule prone to rupture, a degenerated iris, pathological iris vasculature and an increased inflammatory response after surgery are some of the problems encountered in eyes with pseudoexfoliation. The basic tenant of surgery

PHACOEMULSIFICATION

IN

SPECIAL SITUATIONS

175

in such cases is to minimize stress on the zonules. A number of modifications are suggested to facilitate a smooth phacoemulsification in eyes with pseudoexfoliation. The capsulorrhexis should be done with a Rhein or Utrata forceps, that can pinch the capsule and initiate the tear in the capsule. The needle or cystitome, traditionally used to perform the initial tear on the capsule, exerts much more mechanical pressure on the zonules and there may be a possibility of rupture of the zonules. The endocapsular tension ring and an anterior chamber IOL should be kept in reserve since there is a high incidence of zonular and capsular tears. Hydrodissection should be performed with minimal injection of fluid in several different quadrants to decrease intracapsular pressure. The technique of depressing the nucleus down, to complete the hydrodissection should be avoided. The use of the endocapsular ring offers the safest method of phacoemulsification. The insertion of this ring creates a circumferential distribution of forces around the entire zonular apparatus, thereby reducing the localized pull on the zonules, during any intraocular manipulation. The nucleus should be elevated away from the capsular bag with the second instrument to decrease the zonular traction while manipulating the nucleus in the capsular bag. The implantation of the IOL prior to cortical aspiration is also useful because the PMMA haptics stabilize the capsular bag. In such cases the cortical clean up takes a much longer time and this technique is to be used only if the endocapsular ring is not available. Intense postoperative steroid therapy and adequate cycloplegia may be required to control the postoperative reaction. FURTHER READING 1. Bartholomew RS: Lens displacement associated with pseudocapsular exfoliation—a report on 19 cases in southern Bantu. Br J Ophthalmol 54:744-50, 1970. 2. Carpel EF: Pupillary dilation in eyes with pseudoexfoliation syndrome. Am J Ophthalmol 105:692-94, 1988. 3. Cionni RJ, Osher RH: Endocapsular ring approach to the subluxated cataractous lens. J Cataract Refract Surg 21:245-49, 1995. 4. Cionni RJ, Osher RH: Management of profound zonular dialysis or weakness with a new endocapsular ring designed for scleral fixation. J Cataract Refract Surg 24:1299-1306, 1998. 5. De Juan E Jr, Hickingbotham D: Flexible iris retractor (letter). Am J Ophthalmol 111:776-77, 1991. 6. Eckardt C: Pupillary stretching—a new procedure in vitreous surgery. Retina 5:235-38, 1985. 7. Fischel JD, Wishart MS: Spontaneous complete dislocation of the lens in pseudoexfoliation syndrome. Eur J Implant Refract Surg 7: 31-33, 1995. 8. Fuller DG, Wilson DL: Translimbal iris hook for pupillary dilation during vitreous surgery (letter). Am J Ophthalmol 110:577, 1990. 9. Goder GJ: Our experiences in planned extracapsular cataract extraction in the exfoliation syndrome. Acta Ophthalmol 184(suppl): 126-28, 1988. 10. Grusha YO, Masket S, Miller KM: Phacoemulsification and lens implantation after pars plana vitrectomy. Ophthalmology 1998; 105: 287-94. 11. Hutton WL, Pesacka GA, Fuller DG: Cataract extraction in the diabetic eye after vitrectomy. Am J Ophthalmol 1987; 104: 1-4. 12. Lacalle VD, Garate FJO, Alday NM et al: Phacoemulsification cataract surgery in vitrectomized eyes. J Cataract Refract Surg 24: 806-09, 1998.

176

THE ART

OF

PHACOEMULSIFICATION

13. Lumme P, Laatikainen L: Exfoliation syndrome and cataract extraction. Am J Ophthalmol 116: 51-55, 1993. 14. McCuen BW II, Hickingbotham D, Tsai M et al: Temporary iris fixation with a micro-iris retractor. Arch Ophthalmol 107:925-27, 1989. 15. McDermott ML, Puklin JE, Abrams GW et al: Phacoemulsification for cataract following pars plana vitrectomy. Ophthalmic Surg Lasers 28: 558-64, 1997. 16. Meldrum ML, Aaderg TM, Patel A, Davis J: Cataract extraction after silicone oil repair of retinal detachments due to necrotizing retinitis. Arch Ophthalmol 114:885-92, 1996. 17. Merriam JC, Zheng L: Iris hooks for phacoemulsification of the subluxated lens. J Cataract Refract Surg 23:1295-97, 1997. 18. Meyers SM, Klein R, Chandra S et al: Unplanned extracapsular cataract extraction in postvitrectomy eyes. Am J Ophthalmol 86:624-26, 1978. 19. Miller KM, Keener GT Jr: Stretch pupilloplsty for small pupil phacoemulsification (letter). Am J Ophthalmol 117:107-08, 1994. 20. Naumann GOH: Exfoliation syndrome as a risk factor for vitreous loss in extracapsular cataract surgery (preliminary report). Acta Ophthalmol 184(suppl): 129-31, 1994. 21. Nichamin LD: Enlarging the pupil for cataract extraction using flexible nylon iris retractors. J Cataract Refract Surg 19:793-96, 1993. 22. Saunders DC, Brown A, Jones NP: Extracapsular cataract extraction after vitrectomy. J Cataract Refract Surg 22: 218-21, 1996. 23. Shepherd DM: The pupil stretch technique for miotic pupils in cataract in cataract surgery. Ophthalmic Surg 24:851-52, 1993. 24. Skuta GL, Parrish RK II, Hodapp E et al: Zonular dialysis during extracapsular cataract extraction in pseudoexfoliation syndrome. Arch Ophthalmol 105:632-34, 1987. 25. Smiddy WE, Stark WJ, Michels RG et al: Cataract extraction after vitrectomy. Ophthalmology 94: 48387, 1987. 26. Sneed S, Parrish RK II, Mandelbaum S, et al: Technical problems of extracapsular cataract extraction after vitreous surgery (letter). Arch Ophthalmol 104: 1126-27, 1986. 27. Whitsett JC, Stewart RH: A new technique for combined cataract/glaucoma procedures in patients on chronic miotics. Ophthalmic Surg 24: 481-85, 1993. 28. Wilbrandt HR, Wilbrandt TH: Pathogenesis and management of the lens-iris diaphragm retropulsion syndrome during phacoemulsification. J Cataract Refract Surg 20: 48-53, 1994.

Jonathan P Ellant

Zen in the Art of Phaco*

18

“Like water filling a pond, which is always ready to flow off again, it can work its inexhaustible power because it is free, and be open to everything because it is empty.” —Zen in the Art of Archery, by Eugen Herrigel Throughout my training it became apparent to me that most of the phaco surgeons that I assisted were comfortable with only one or two different techniques to remove the nucleus of a cataract. And as I watched dozens of surgeons, they all seemed to use the same one or two techniques. It quickly became clear to me that situations arise in which one’s standard technique is either more risky or less efficient when compared with other alternative approaches to nucleus removal. I wanted to learn as many phaco techniques as possible, so as a resident I tried to watch as many different surgical videotapes as I could get my hands on. Like most surgeons, I also have one or two techniques with which I am most comfortable, and that I use most often. But, I try to remain as flexible as possible during the case and alter my technique as the individual case may dictate. In this chapter I will progress step by step through a phacoemulsification case and try to elucidate some of the situations that these alternative techniques may be useful. I perform my routine case with a temporal hinged clear corneal incision, with continuous curvilinear capsulorrhexis (CCC), and hydrodissection and hydrodelineation though the original incision. I then utilize in the bag divide and conquer nucleofractis techniques as described by Howard Gimbel.1 This is then followed by automated I/A and foldable three-piece IOL placement in the bag. However, *

I would like to thank Howard Gimbel and Richard Mackool for the generous use of their slides

178

THE ART

OF

PHACOEMULSIFICATION

when situations arise that are not routine, I do not hesitate to alter my technique and use one which is safer or more efficient. Incision As I stated, I routinely use a temporal hinged clear corneal incision. When properly created this incision is refractively neutral, stable and easy to perform. Furthermore, it preserves the conjunctiva in case glaucoma filtering procedures need to be performed in the future and is bloodless which is particularly important for patients taking anticoagulants or aspirin. When a patient has greater than 1.25 diopters of with-the-rule (WTR) or oblique astigmatism, I move my incision toward the steep axis and depending on the axis and degree of astigmatism I decide where to place the incision. When the astigmatism is greater than 45 degrees away from the horizontal meridian, I use a corneoscleral tunnel; usually, this results in a more or less superior corneoscleral incision. Viscoelastic Much has been written about the advantage of one viscoelastic over another. Recently a great deal of research has begun to quantify the precise differences in cohesiveness between the different agents.2 Routinely I will use one of the agents that is in the middle of the cohesive/dispersive spectrum. However, in a patient with significant endothelial dysfunction I am careful to select an agent that is more dispersive. I want this viscoelastic to coat the endothelium as well as possible and to remain in the eye to protect the endothelium throughout the case. Cohesive agents tend to be removed in a bolus during phacoemulsification and do not adequately protect the compromised endothelial cells. In those cases where I use a more dispersive agent, I take a few extra seconds at the end of the case to try to remove any residual viscoelastic that may remain in the eye. Capsulorrhexis Continuous curvilinear capsulorrhexis has elegantly transformed the way in which cataract extraction is performed.3 It is arguably the critical step which will determine the ultimate success of the phacoemulsification and IOL placement. Before beginning the CCC, I inject additional viscoelastic into the anterior chamber to try to enlarge the pupil and to flatten the anterior capsule. At this point it is wise to evaluate the adequacy of pupillary dilation. Good dilation of the pupil is very important for safe and efficient phacoemulsification. I have observed extremely talented individuals perform CCC in eyes with small pupils with the leading edge of the rhexis under the pupil, essentially unseen. While this is a most impressive maneuver, I do not recommend it for mere mortals such as myself. I believe that for most of us this is just asking for trouble, and there is not much more trouble than a radial extension of the CCC at this point in the case. I have found that pupil stretching techniques to be extremely useful when the pupil is small.4 I use a bimanual technique with an iris hook through the

ZEN

IN THE

ART

OF

PHACO

179

original incision and a Kuglein manipulator through the side port incision. Occasionally I create an additional paracentesis incision approximately 120 degrees away from the main incision on the side opposite the original paracentesis incision for cases where extensive posterior synechiae are present. In these extreme cases I also use the viscoelastic with its cannula to viscodissect the synechiae. It is very unusual to not obtain adequate pupillary dilation after carefully engaging segments of the pupillary margin 180 degrees from each other with these two (or two similar) instruments and moving the two opposite one another, toward the direction of the trabecular meshwork. The two instruments are then moved to different areas of the pupillary margin and the action is repeated, three or four times is usually adequate. Occasionally, small hemorrhages may occur at the pupillary margin, they are self-limited however, and resolve without any further treatment. Additional viscoelastic is then instilled into the eye to evaluate the adequacy of the pupil dilation. Stretching can be repeated if necessary, but care must be taken to avoid damaging the anterior capsule during any iris manipulation. Several devices have been developed to facilitate dilation including the Beehler pupil dilator and disposable iris retractors. I used the latter during my residency and found them to be quite useful, now however, I rarely use anything other than the technique described above. Minisphincterotomies may also be performed, however these significantly disrupt the blood-aqueous barrier and seem overly traumatic in my view. However, cases may exist where they are necessary and one should keep this option in mind. I usually begin the CCC with a cystitome, and continue it with capsulorrhexis forceps, aiming for a 5 mm opening, or slightly smaller than the optic. If one is seeking additional efficiency, the capsulorrhexis forceps may be used to initiate and complete the CCC.5 During the rhexis I observe the lens for any phacodenesis or zonular dialysis, if any is observed I change my mindset. This is a situation where having flexibility and the knowledge of alternate techniques enables one to perform safer surgery and avoid potentially significant complications. When loss of zonular integrity is recognized, I create a larger CCC, and alter my technique, planning to prolapse the nucleus during hydrodelineation, and perform supracapsular phacoemulsification of the nucleus.6 In this way, one may reduce stress on an already compromised zonular apparatus and complete the case without disinserting more of the zonules. White nuclei and hypermature nuclei present special challenges because no red reflex is present and visualization of the leading edge of the capsular tear is extremely difficult. Many different techniques have been described, including the injection of intracapsular fluorescein, capsule staining with trypan blue, side illumination (with a flashlight or similar illumination device), reducing the overhead lighting, and endoscopic illumination.7-9 In these cases I usually turn off the room lights and increase the magnification of the microscope. I then attempt a smaller than normal CCC (approximately 3-4 mm). By reducing the diameter I am able to increase my margin of error, should the CCC begin to extend radially. The CCC can then be enlarged secondarily after removal of the cataract and implantation of the IOL.10 At times

180

THE ART

OF

PHACOEMULSIFICATION

it is not possible to successfully perform an intact CCC in these cases. When the rhexis begins to extend radially, one may have to convert to a can-opener type capsulotomy for the remainder of the circle. If this occurs, additional care must be taken during hydrodissection and phacoemulsification to prevent a radial tear from being created. One should again consider supracapsular phaco in this instance. After IOL implantation it is occasionally possible to convert the can-opener portion of the capsulotomy to a continuous tear for additional IOL stability and centration.10 CCC in hypermature or Morgagnian lenses can sometimes be performed with relative ease with the use of a little trick. Occasionally after the initial puncture of the anterior capsule in these cases, liquefied cortical material may leak into the anterior chamber and obstruct one’s view. If this occurs after the anterior capsule is pierced with a cystitome, one can place a 27-gauge cannula on an empty syringe, place the tip of the cannula through the opening created in the capsule, into the anterior cortex and aspirate some of the liquefied cortex. Usually the anterior chamber must be re-expanded with additional viscoelastic. After sufficient amounts of cortex have been aspirated, a red reflex is often seen and a careful CCC may be performed in the usual manner.11 Hydrodissection and Hydrodelineation These two steps are extremely important, both to preserve the zonules and to facilitate removal of the nucleus and cortex. I begin using a J-shaped cannula for subincisional hydrodissection. This has proved to be of invaluable assistance to me in removal of subincisional cortex. I then proceed with standard hydrodissection and hydrodelineation using a straight cannula (Fig. 18.1). Before attempting any phacoemulsification, I will use the cannula Fig. 18.1: Hydrodissection tip or a cyclodialysis spatula to rotate the nucleus to ensure that adequate hydrodissection has been performed. Nucleus Removal Numerous techniques have been described, but as I mentioned in the introduction, most surgeons utilize few of them. The more techniques that one is aware of, the more flexible and efficient one can be when intraoperative challenges present themselves. No matter how many techniques one knows, there will always be one or two that are most familiar and with which one has the most experience. I believe that as one obtains more experience, it is possible to use subtle maneuvers to encourage the cataract to behave as one wants it to, but until that time, knowledge of alternative techniques, and the flexibility to use them, will enable the beginning or intermediate phaco surgeon to handle challenging cases with greater safety

ZEN

IN THE

ART

OF

PHACO

181

and efficiency. I will try not to describe all of the different techniques in detail, as they are covered in other chapters in this book and elsewhere.12 Routinely, I use the divide and conquer nucleofractis technique. I learned this technique during my fellowship with Howard Gimbel and while it is more difficult to learn and master than the widely used four-quadrant technique described by John Shepherd, I believe that it offers greater opportunity for flexibility and efficiency, especially when intraoperative challenges arise. In addition, it lends itself especially well to eyes with small pupils and to converting to phaco chop and stop and chop in cases with denser nuclei.13-14 Soft Nuclei Standard divide and conquer techniques may be used, but in younger patients with posterior subcapsular cataracts or in diabetic patients it is often difficult to perform complete fractures in these softer nuclei. As a result it is often necessary to sculpt out a large central bowl of nuclear material, with a very thin posterior plate, and then to fold the nuclear rim in on itself. These cases can sometimes be some of the most difficult to complete without compromising the posterior capsule. Extreme care must be used when sculpting deeply. I advocate generous use of viscoelastic to reposition nuclear elements centrally so that they may be emulsified within the safer central zone in the space created by the capsulorrhexis opening. Occasionally, when attempting to engage the nuclear rim, one has not thinned the posterior plate adequately and is unable to affect a fold. If too much of the nuclear rim is removed the standard “bowl” technique will not work because there is insufficient nuclear rim to grasp with the phaco probe. Placing viscoelastic beneath the posterior plate may displace the remaining posterior nuclear fragment into the safe central zone for emulsification. Alternatively, if the inferior rim has been removed, and enough of the superior rim and adjacent areas still remain, the second instrument (cyclodialysis spatula) can be used to gently nudge the posterior plate inferiorly to allow the phaco probe to engage the superior rim just inside the proximal edge of the capsulorrhexis and enable the surgeon to remove the remaining cataract (Fig. 18.2).15

Fig. 18.2: Eccentric capsulorrhexis and bidirectional phaco

Fig. 18.3: The initial trench

182

THE ART

OF

PHACOEMULSIFICATION

Moderately Dense Nuclei This group of lenses represents the bulk of the cataracts that the average phaco surgeon will encounter. As stated previously, I routinely use divide and conquer nucleofractis.1 In this technique, one begins with the sculpting of a deep central trench just slightly off center, toward the side of one’s dominant hand (Fig. 18.3). I have found down-slope sculpting to be extremely useful in cases without zonular compromise (Fig. 18.4).16 After sufficient depth is obtained the second instrument (i.e. cyclodialysis spatula) is placed deep within the trench adjacent to the phaco probe and the two instruments are positioned on opposite walls of the groove and moved away from each other to crack the nucleus into hemisections (Fig. 18.5). It has been my observation that most surgeons sculpt further into the periphery than is necessary. This is both dangerous and inefficient. When the initial sculpting of the trench is sufficiently deep, it is rarely necessary to sculpt beyond the rim of the capsulorrhexis opening to facilitate complete and consistent cracking.

Fig. 18.4: Down-slope sculpting

Fig. 18.5: The initial fracture

After a small rotation of the nucleus, the phaco probe is used to burrow into the inferior section of the nucleus with a short burst of ultrasonic power. Next, using foot position two on the phaco machine, aspiration is used to engage and stabilize the nucleus. The second instrument is held adjacent to the phaco probe and using a small down and away movement with the second instrument, the phaco probe breaks off a pie-shaped fragment (Fig. 18.6). One may think of this maneuver as similar to phaco chop in attempting to visualize the required hand movements. However, the two instruments are moved away from one another rather than toward each other as with phaco chop. The lens is then rotated and the fracturing maneuver is performed again. This is repeated several times until the cataract is broken into multiple wedge-shaped fragments (Fig. 18.7). These are then engaged with the phaco handpiece and emulsified in the safe central area of the capsular bag, approximately at the level of the capsulorrhexis opening.12

ZEN

Fig. 18.6: Nucleofractis

IN THE

ART

OF

PHACO

183

Fig. 18.7: Pie-shaped segments

Dense Nuclei In these lenses a variation on the trench technique is used. Deep central sculpting is used to create a central crater with the phaco probe, deep enough to thin the posterior plate sufficiently to facilitate cracking (Fig. 18.8). The inferior portion of the nuclear rim is engaged with a burst of phaco energy and the second instrument is used to create a fracture, as described above (Fig. 18.9). The lens is then rotated and the nucleofractis technique is repeated until the lens is completely divided into wedge-shaped pieces. Each wedge is then drawn centrally and emulsified.17

Fig. 18.8: Crater divide and conquer

Fig. 18.9: Removal of a nuclear segment

Recently, I have been increasing my use of the phaco chop technique in these cases (Fig. 18.10). Chopping is a very efficient technique for nuclear division, particularly in dense lenses.13-14 Care must be taken, however, to preserve the anterior capsular rim. Because phaco chop puts the capsule at some additional risk so, I reserve the technique for denser nuclei or for cases with compromised zonules.

184

THE ART

OF

PHACOEMULSIFICATION Posterior Capsule Rupture

Early identification of this event is critical to a good outcome. Initially, when one recognizes a small tear in the posterior capsule, a dispersive viscoelastic should be injected through the tear, in an attempt to keep the vitreous face from prolapsing through the defect in the posterior capsule. When the tear is small, it is sometimes possible to engage the tear with a capsulorrhexis forceps and create a posterior capsulorrhexis. This will stabilize the defect and prevent it from Fig. 18.10: Phaco chop enlarging.18-19 If a large portion of the nucleus is still present in the eye and the rupture is small, one may occasionally rotate the remaining nucleus over the rent (using the nuclear segment to block the defect), and emulsification may continue more or less as before. In this situation, phaco chop may allow more efficient disassembly of the nucleus, minimizing total phaco energy and turbulence. An alternative method involves the use of a sheets glide placed over the capsular opening to create a “pseudo-posterior capsule.”In either of these situations extreme care should be exercised to prevent prolapse of the vitreous into the capsular space. Lowering both the bottle height and the aspiration flow rate will reduce turbulence in the eye and reduce the chance of vitreous prolapse. If large fragments exist one may attempt to engage the lens with the phaco probe and prolapse the nucleus into the anterior chamber where phaco chop may be used to divide the remaining nucleus and remove it from the eye. However, one should use extra care to avoid “post-occlusion surges” as these may increase the incidence of prolapse of vitreous. Once vitreous prolapse is recognized, phacoemulsification should be stopped and one should attempt to manually remove the remaining fragments through the main incision followed by careful and complete anterior vitrectomy. One should consider conversion to an extracapsular extraction at this point if the remaining nuclear segments cannot be safely removed through the original incision. IOL Insertion I routinely use foldable IOLs through a slightly enlarged clear corneal incision. However, I alter the lens that I use depending on the individual needs of the patient. For example, larger optics for diabetics and younger patients or those with large pupils, or acrylic lenses for patients with an increased probability of needing silicone oil and vitrectomy in the future (diabetics and patients with HIV/AIDS). After IOL insertion, if I notice that a tear in the anterior capsule has occurred, I place a small matching incision 180 degrees away in the anterior capsule in the hope of balancing capsular contraction forces and maintaining IOL centration.11

ZEN

IN THE

ART

OF

PHACO

185

If zonular dehiscence has occurred, the IOL can be rotated so that the orientation of one of the haptics is toward the area of the dehiscence using the haptic to push the area of the capsule with the dehiscence back toward its original anatomic location. A PMMA capsular tension ring has been developed by Morcher and has been used with much success for this same purpose.20 Unfortunately, till now of this writing the ring has still not obtained FDA approval for use in the United States. In the case of severe zonular dialysis or loss of large amount of posterior capsule alternative approaches become necessary. These include the placement of an anterior chamber lens, a sulcus-fixated lens (with or without optic capture to facilitate IOL centration), and the suturing of a posterior chamber IOL.21-24 CONCLUSION The ability to recognize and to manage complications during surgery and to have good outcomes is what separates excellent from average surgeons. The willingness to teach oneself a variety of techniques and to understand the most appropriate occasions to use them is very important if one hopes to become a competent phaco specialist. Just as important however, is to be flexible enough to depart from one’s most comfortable techniques and to utilize new approaches to reduce complications and to properly manage them, so as to maximize the visual potential of the patient. When a surgeon has knowledge of many different techniques of nuclear removal and the flexibility to use them, it becomes possible to use phacoemulsification and small incision surgery for even the most dense and complicated cataract cases that one may encounter. REFERENCES 1. Gimbel HV: Divide and conquer nucleofractis phacoemulsification, development and variations. J Cataract Refract Surg 17:281-91, 1991. 2. Arshinoff SA: Dispersive-cohesive viscoelastic soft shell technique. J Cataract Refract Surg 25:16773, 1999. 3. Gimbel HV, Neuhann T: Developments, advantages, and methods of the continuous curvilinear capsulorrhexis technique. J Cataract Refract Surg 16:31-37, 1990. 4. Koch P, Davidson JA: Advanced Phacoemulsification Slack: Thorofare, 1991. 5. Gimbel HV, Kaye GB: Forceps-puncture continuous curvilinear capsulorrhexis. J Cataract Refract Surg 23:473-75, 1997. 6. Maloney WF, Dillman DM, Nichamin LD: Supracapsular phacoemulsification—a capsule-free posterior chamber approach. J Cataract Refract Surg 23:323-28, 1997. 7. Hoffer KJ, McFarland JE: Intracameral subcapsular fluorscein staining for improved visualization during capsulorrhexis in mature cataracts (letter). J Cataract Refract Surg 19:566, 1993. 8. Nahra D, Castilla M: Fluorescein-stained capsulorrhexis (letter). J Cataract Refract Surg 24:1169, 1998. 9. Melles GRJ, De Waard PW, Pameyer JH et al: Trypan blue capsule staining to visualize the capsulorrhexis in cataract surgery. J Cataract Refract Surg 25:7-9, 1999. 10. Gimbel HV, Willersheidt AB: What to do with the limited view. J Cataract Refract Surg 19:65761, 1993. 11. Gimbel HV, Chin PK, Ellant JP: Capsulorrhexis. Ophthalmol Clin North Am 4:441-55, 1995. 12. Gimbel HV, Ellant JP, Chin PK: Divide and conquer nucleofractis. Ophthalmol Clin North Am 4:45769, 1995.

186

.

THE ART

OF

PHACOEMULSIFICATION

13. Koch PS, Katzen LE: Stop and chop phacoemulsification. J Cataract Refract Surg 20:566-70, 1994. 14. Koch PS: The stop and chop phacoemulsification technique. Ophthalmol Clin North Am 4: 497507. 15. Mackool RJ: Eccentric capsulorrhexis and bidirectional endocapsular phacoemulsification. J Cataract Refract Surg 17:221-32, 1991. 16. Gimbel HV: Downslope sculpting. J Cataract Refract Surg 18:614-18, 1992. 17. Gimbel HV: Trough and crater divide and conquer nucleofractis techniques. Eur J Implant Refract Surg 3:123-26, 1991. 18. Castaneda VE, Legler UFC, Tsai JC et al: Posterior continuous curvilinear capsulorrhexis—an experimental study with clinical applications. Ophthalmology 99:45-50, 1992. 19. Gimbel HV: Posterior capsule tears using phacoemulsification—causes, prevention, and management. Eur J Implant Refract Surg 2:63-69, 1990. 20. Cionni RJ, Osher RH:Management of profound zonular dialysis or weakness with a new endocapsular ring designed for scleral fixation. J Cataract Refract Surg 24:1299-1306, 1998. 21. Uthoff D, Teichmann KD: Secondary implantation of scleral-fixated intraocular lenses. J Cataract Refract Surg 24:945-50, 1998. 22. Oshima Y, Oida H, Emi K: Transscleral fixation of acrylic intraocular lenses in the absence of capsular support through 3.5 mm self-sealing incisions. J Cataract Refract Surg 24: 1223-29, 1998. 23. Neuhann T, Neuhann TH: The rhexis-fixation lens. Film ASCRS, 1991. 24. Lyle WA, Jin JC: Secondary intraocular lens implantation—anterior chamber vs posterior chamber lenses. Ophthalmic Surg 24:375-81, 1993.

Keiki R Mehta

My Personal Technique of Vertical “Hubbing” Phacoemulsification

19

PREOPERATIVE PREPARATION The pati ent is dilated with 5% Neo-Synephrine eyedrops with 1 percent homatropine eyedrops. Both the drops are commenced 40 minutes prior surgery. In case the pupil is tardy in dilatation, place a drop of methylcellulose on the cornea, instill a drop of Neo-Synephrine and homatropine on it, lift the lid and shut it over the methylcellulose, tape the eye shut for 5 minutes. Usually after that period, the pupil is well dilated. Another alternate technique to dilate a tardy pupil is to instill a drop of Xylocaine 4%, and then to instill the dilating drops. It functions as the epithelial cells’ closed junctions become tenuous, permitting easier diffusion into the anterior chamber of the dilating drops. I also favor preoperatively treating the patient with a topical antibiotic-NSAID (nonsteroidal antiinflammatory drug) combination for a day prior surgery. The rationale for it is that surgical insult is much less likely to demonstrate any postoperative inflammation. In addition the use of preoperative antibiotics to reduce the risk of postoperative endophthalmitis. ANESTHESIA TECHNIQUE Topical anesthesia is my choice for 98 percent of all cataract surgeries. I use topically, Xylocaine 4% eyedrops (Lidocaine). The Xylocaine is drawn in two syringes through a Millipore (20 micron) filter. One syringe is left outside the operating field to be used prior draping and washing the patient, and kept with the circulating nurse. The second sterile syringe is left on the operating trolley after clearly labeling it. A drop is instilled three minutes prior surgery so that the eye may be washed out with Betadine solution (5% Betadine mixed with distilled water in a 50% dilution).

188

THE ART

OF

PHACOEMULSIFICATION

After washing the eye out, a final drop of Xylocaine is instilled on the cornea prior commencing the case. Normally topical anesthesia is all that I use in virtually all cases. However, if intraoperatively the patient has a problem and the case is likely to take longer (inadvertent vitreous loss, a complaining patient, one who keeps rotating his or her eye like a metronome, etc) I also keep a 5 ml syringe with 2% Xylocard (intravenous Xylocaine, preservative free, normally used by the cardiologists) with a blunt parabulbar cannula. All syringes are plastic, disposable and Luer-Lok type. At that stage it is a simple procedure to give 1.00 ml as a parabulbar injection. It is virtually painless, no pressure needs to be applied to the eye to diffuse the anesthetic agent, and takes effect almost immediately. Though the movement of the eye will take about a minute or so to decrease and stabilize down, the anesthetic agent takes effect almost immediately. I normally like to instill a final drop of 4% Xylocaine after the lid retractor has been placed, just prior starting. I lift the retractors just a little to enable the drop to go all the way up to the fornix. Wait for about 30 seconds, wash off the eye with BSS and commence surgery. I normally do not use the Xylocaine 4% drops again at all. In the younger anxious patients or in those in whom I am not sure of achieving their full cooperation, a little sedation is given intravenously. The amount of sedation being such that the patient does not drop of to sleep but just becomes a little more amenable to control. I like my patients to be able to respond to commands during the surgery. In those cases which need further supplementation, I/V Propofol administered in 10 mg increments induces a transient hypnosis with amnesia which clears rapidly in minutes. In cases where the papillary dilatation is inadequate, despite best efforts at dilatation of the pupil, and where intracameral surgical manipulations will involve iris touch, or in cases where I would intend to use iris retractors (Grieshaber), I like to inject little Xylocard 2% (preservative free Xylocaine) diluted 50% with BSS, to convert it to Xylocard 1%, 0.5 ml injected immediately after the side port opening is made, prior injection of viscoelastic. Wait for a minute, wash out the chamber, and proceed with the surgery. It reduces the iris sensitivity and reduces ciliary proprioception (Grabow). I also like to use intracameral Xylocard in cases where the cataract is very hard and where the surgery is likely to last much longer with more ultrasound energy in the anterior chamber and much more lens manipulation. I am a little hesitant to use topical anesthesia with patients who I cannot converse with during the surgery, like mentally retarded patients, or even patient speaking a language which I am not familiar with. In these patients, I prefer to give a peribulbar injection of 2% Xylocaine with 150 units of hyaluronidase admixed, a single injection administered through a 24 G, 1 inch disposable needle, the injection given through the upper lid. I feel it is important when giving the peribulbar block to insert the tip of the index finger between the orbital ridge of the frontal bone and the eye, which deflects the eyeball away. The patient is requested to look straight upwards at the operating microscope light (visible through the closed lid), and the injection

MY PERSONAL TECHNIQUE

OF

VERTICAL “HUBBING” P HACOEMULSIFICATION

189

of 3.00 ml is given at the point 1/3 towards the nasal point of a line drawn between the two canthi. No massage is given. The eye is taped shut (to prevent accidental corneal abrasion) and the balancing weights (Tony Fernandez, 1992) are placed on the eye. I personally do not prefer to use either Honan Oculopressor, the Super Pinky ball as I feel that in cases of an inadvertent venous leak by a slow hemorrhage in the socket, the pressure induced is likely to compromise the ocular circulation. The balancing weights balls are safer since they are not a constrictive device. The pressure from the balancing balls, is kept on the eye for 5 minutes, the IOP is checked with the Schiotz tonometer. The ideal pressure should be a minimum of 10 deflection using no weight (5.5 gm). The patient should be made comfortable on the operating table. It is preferable that the hands be loosely restrained so that accidentally during the procedure in case the patient falls asleep and suddenly awakes, he should not move his hands up and make an unexpected moment. PREFERRED PHACOEMULSIFIER My present personal choice is the Legacy 20,000 (Alcon). The Alcon Legacy has exceptional fluidics, maintains the chamber well, has excellent ultrasound power, with a sensitive, balanced, stable, 4 crystal handpiece, rarely induces bubble formation and works very well. I usually use the Max-Vac setup with a, 30 degree, 0.9 mm diameter, straight tips which work very well on the hard cataracts common in India. The Kelman 30 degree bent, 0.9 mm tip also works well but sometimes a bit unpredictable. Perhaps the biggest advantage of the Kelman is that, since the tip is curved down, the surgeon does not need to hold the handpiece at a steep angle. The Legacy has superior followability making the procedure much simpler. In addition the dynamic range of fluidics allow the surgeon to really individualize settings at every single phase of cataract removal depending upon the grade of the nucleus. DRAPING AND PREOPERATIVE PREPARATION OF THE EYE The patient’s eye is washed out with 10 ml of Betadine 5% solution diluted with distilled, sterile water (not tap), half and half (50% dilution), taken in a 10 ml plastic syringe. The assistant keeps the lids open widely to permit a proper wash. Subsequently cotton swabs soaked in full strength Betadine, are swept along the lash line to be sure that the lashes are clean and properly prepared. Next the entire area of the eye is again flushed out with distilled water, dried with a sterile towel. Two drops of an antibiotic solution are instilled in the eye (at present I use tobramycin eyedrops). A highly adherent plastic drape, termed as Opsite (Johnson and Johnson) Tegaderm (3M) which is commonly used to isolate the skin for surgical procedures, is placed over the fully opened eye such that it drapes the lashes, deflected outwards and away from the field, and drapes all crevices around the eye and the surrounding area. It is important that there should be adequate oxygenation under the drapes. An ideal device to maintain it are silicone nasal prongs. The tubes are looped around

190

THE ART

OF

PHACOEMULSIFICATION

the ear to stabilize them and the prongs placed in the nostrils. Oxygen (of if not available, even normal air) at a flow rate of 8 volumes/minute. It is very reassuring to the patient to feel air under the drapes which otherwise may make a patient very apprehensive and asphyxiated. In addition it assures adequate oxygenation which is very useful to a patient who has limited respiratory ability (asthmatics or those with chronic pulmonary conditions.) Over the draped eye, a second self-adhesive drape can be utilized, and over that a sterile, absorbent, thick cotton drape with a small hole is fitted over. The head is draped in a double layer of cloth to isolate the forehead and the face away from the site to be operated. It is important to tape a piece of rolled absorbent gauze just in front of the ear on the operating side so accidentally water does not trickle in the ear during surgery, leading to discomfort and sudden head movement. The normal eye (the one not to be operated) is taped shut, gauze placed on it and a protective plastic shield taped over it. The tape directly on the eye is to prevent the gauge from irritating it, and the shield is to protect the eye in case, accidentally the surgeon does apply inadvertent pressure, which may cause the patient discomfort and again may be the cause for the patient fidgeting under the drapes. MONITORING PATIENTS IN THE THEATER I strongly feel that all patients, even if they are under topical anesthesia must be suitably monitored in the theatre. All my patients have a finger-probe oxygen saturation monitor with simultaneous cardiac monitoring. A safety intravenous line is commenced with a 23G Vent-Flo (silicone indwelling venous catheter) which is much more stable and safer than a butterfly venous needle, which tends to be displaced at the slightest movement. I use an anesthesiologist as a standby in all cases. He normally only gives the I/V antibiotics on the table and monitors the patient, but gives supplementary sedation and analgesics if required. In the balance salt solution (BSS plus, considering its high cost, is not really required for short procedures unless the endothelial cell count is significantly low) is added ½ ml of a cardiac, preservative free, epinephrine 1/1000 (without sodium bisulfate) instilled in a 500 ml bottle to maintain the dilatation of the pupil, and to keep a good clean, bloodless field. In addition to the 500 ml bottle of BSS add 10 mg of vancomycin or 40 mg of garamycin. The use of these antibiotics, in my opinion, significantly reduces the risk of endophthalmitis. Other authorities too concur (Linda Strong, 1999, Kraff, Gills 1999). A final drop of Xylocaine is added and the procedure is now commenced. I do not like to utilize more drops as Xylocaine 4% used excessively will lead to punctate epithelial keratitis, corneal erosion and a delayed postoperative rehabilitation, and is said to lead to endothelial cell damage (Marr WG, Wood R 1957). I prefer also to connect dual BSS bottles, connected to each other and to the phacomachine by a thick walled ¾ cm bored, plastic tubing (normally used by Urologists, it is known as a TUR set). The advantage of using this tubing is that


OF


191

it gives a good flow and cuts down on surge developing which is critical in the high flow techniques used (Bangkok system). In addition in the BSS bottles the airways are special long needles which reach right up to the clear air space on top rather than being put in below. It is important for the suction generated in a glass bottle to suck in the air very often leads to fluidic imbalance and suction variables especially if one is operating at low suction near the capsule or in removing the final little bit of cortical or cortex material. OPERATIVE PROCEDURE The patient is requested to look into the operating light and advised that he keeps his eye stable and fixed at the light. It is clearly explained to him that at the time phaco is done he must not move at all. The operating light intensity is kept low until such time that Phacoemulsification is commenced. The plastic drape is incised, and a reversible spring speculum is utilized to give the eyes open. An ideal speculum is the Kratz modified, Barraquer speculum. The spring speculum is preferable to fixed screw speculums, because it has a certain amount of ‘give’ which enhances patient comfort. Another advantage is that with a flexible spring retractor the patient does not fight it. He blinks a few times, tiring the orbicularis, and then keeps the eye wide open. THE INCISIONS A side port incision is made with a Alcon V-lance blade (1.2 mm spear) (Fig. 19.1), made with the blade as parallel to the cornea as possible to get a good self-sealing shelf. The chamber is refilled with BSS from a 3 ml syringe to reform the chamber and repressure the eye in preparation for the main phaco incision. Almost all my implants utilized are Fig. 19.1: Side port being made flexible and in most of the cases a SI40 Allergan silicone foldable lens inserted via an injector (Unfolder in Allerganese), which goes through a 2.8 mm incision. Hence, virtually all my cases have a pure corneal tunnel. In case I will put in a PMMA 5.25 mm IOL, I prefer to do a semiscleral incision in a curved ‘V or chevron ’ incision after reflecting back the conjunctival flap. CORNEAL ENTRY The correct point of entry is posterior to the clear cornea, utilizing the perilimbal capillary plexus as a landmark and slightly anterior to the insertion of the conjunctiva (Fig. 19.2). I always prefer to see a faint capillary bleed where I make my entry. Since the incision is into a slightly vascular area, better long-term wound healing

192

THE ART

OF

PHACOEMULSIFICATION

can be expected rather than a incision into clear cornea. The clear corneal entry can be done in a two-plane incision or in a single-plane incision. However, the single plane incision is best done with the special diamond knife which has a bevel on the blade which is more pronounced anterior than posterior (Fine). Here the diamond knife is placed on the cornea, and following the corneal plane inserted straight in without any Fig. 19.2: Clear corneal tunnel incision attempt at dimpling the cornea. Due to the variance in the front and back bevel of the knife, it enters in smoothly, at the proper plane, and gives an excellent corneal valve. I normally utilize this 2.8 mm diamond, angled keratome (3-D Rhein). In the two-plane entry system, the first incision is placed perpendicular to the corneal plane. I prefer to place the first plane of entry at 10.00 O’clock position. Rather than directly entering into the cornea I prefer to make a shallow groove with the sharp edge of the knife and equal in length to the blade’s width. Care is taken not to incise the conjunctiva, as this will result in conjunctival ballooning during phacoemulsification and during irrigation-aspiration, markedly reducing visibility. The second plane, which essentially creates the cleavage in the corneal stroma and creates the corneal flap valve, is created by placing the shaft (the flat surface) of the blade in apposition with the conjunctiva and advancing in the plane of the cornea. When one had advanced by 2.0 to 2.5 mm, the tip of the diamond knife is turned forwards till it dimples the deeper layer of the cornea. The knife is then allowed to go its full depth creating a perfect rectangular and almost square incision. Dimpling is not required with the Rhein 3D knife with the anterior differential bevel as it automatically enters. Removal of the knife from the eye is equally important. Many a good valve has been ruined by incising the edge during removal of the knife. It is important not to lift the knife during removal but to gradually slide it out in the same plane that it was inserted. It is important to try and attain a perfect square inner entry zone. The characteristics of the flap valve stability depend more on the construction of the inner corneal valve and less on the total width or length of the incision as is commonly thought. If premature tip entry takes place, do not let it continue. Remove the knife and change the position of the entry. Alternatively even the same site can be used but make the knife enter a corneal plane more superficial than the last one. The new incision will tamponade the old one. The incision when finally made, should be 2.8 mm in width and 2.00 mm in length which gives exceptionally good stability. If a 5.25 mm width narrow profile phaco PMMA IOL lenses is to be used, ideally the incision should be a square, but a 5.25 by 4.00 mm length incision usually suffices.


OF


193

The position of the placement of the main phaco incisions is identical in both eyes, namely at the 10.00 O’clock position. If for any reason this site is not appropriate due to a very deep set eye or a prominent forehead or nose, I like to shift to a temporal approach. The big advantage of a fixed sitting position at the head of the patient is that the position of my surgical assistant, the microscope, anesthesiologist, and instruments lie in their fixed places and do not need to be shifted which often leads to confusion and slows down the pace of surgery. I have found the use of an aspirating speculum (Liebermans) to be a great help. The aspirating speculum is connected to a small dental vacuum pump which gives a low vacuum of 5 to 7 mm of Hg which is more than adequate. THE CAPSULORRHEXIS My personal preference is to utilize a sharp tipped forceps to do the rhexis in preference to a needle.(26 G, ¾” length) with its tip bent at a 45° angle (Figs 19.3 to 5). The sharp tipped needle, though it has the advantage that one can enter through a closed chamber, lacks control in hypermature cataracts, marbled cataracts (where the anterior capsule has a differentially thickened capsule, as typically occurs in old, neglected cataracts), or in eyes where the pupil is not fully dilated. On the other hand, where the capsule is thick and leathery, especially in young children, or is lax where there is doubt about zonular integrity, it would make more sense to do a needle rhexis.

Fig. 19.3: Circumcorneal capsulorrhexis

Fig. 19.4: Circumcorneal capsulorrhexis

Via the phaco corneal tunnel entry zone, the anterior chamber is re-formed with viscoelastic. I normally like to use methylcellulose which is frozen. Methylcellulose kept in the compartment just below the freezer increases its density by a factor of three. The frozen methylcellulose compresses the capsule making rhexis extremely easy. In addition frozen hydroxypropylmethylcellulose (HPMC) does not leak or ooze out easily, and is fantastic for use in children where even Healon does not stay in long. Methylcellulose is available as OccuCoat (Storz) in USA and other countries, and in India as Visilon, Hyprosol, Moisol and a host of others. AmVisc Plus (Alcon) is also a good viscoelastic which can be utilized, however it is quite

194

THE ART

OF

PHACOEMULSIFICATION

costly for the Indian situation. Healon, by itself has no place in phacoemulsification surgery as it promptly jumps out the moment the phaco tip goes in. However Healon 5, functions well, and is very useful, though prohibitively priced. In doing a forceps capsulorrhexis, I prefer to make the incision in the capsule using the sharp pointed tips itself. The initial opening is made at 5.00 O’clock, about 2.5 mm inferior, measuring from the Fig. 19.5: Circumcorneal capsulorrhexis center of the lens simply opening a mm in size. Closing the rhexis sharp pointed forceps makes a beautiful little nick in the capsule. Once the nick is made, the capsule is caught in the tips of rhexis forceps, which are then moved to the left in a counterclockwise direction, towards the 11.00 O’clock position. The forceps leaves the previous hold and takes a fresh hold at the tip of the rhexis tear, and the forceps is then swung to towards the 6.00 O’clock position, until it reaches the 8. 00 O’clock position when it is re-held and then gradually swung in such a way that it meets the previous rhexis opening from out, On an average three holds and re-holds are adequate for a good, well controlled rhexis peripherally. Doing a rhexis is like taking a dog for a walk. One needs to pull its direction at right angle to the prompt direction to change it to the new line. If a needle rhexis is desired, I prefer to make the initial capsular opening with a 26 G, ¾ inch needle, performing the initial capsular opening at the 6. 00 O’clock position about 3.00 mm peripherally to the center. The initial opening is made by impaling the needle tip and pulling down, to the 12.00 O’clock position for about a mm and then swinging it to the right to the 3.00 O’clock position, in one smooth maneuver. This simple arc-shaped movement will give rise to a well-positioned flap. The next step is to lay the flap onto the capsule. The point of the needle must be used to move the detached flap in a plane with the residual capsule. Try not to dig it in the capsule. The whole secret is to nudge the capsule along. Since the flap lies in apposition there is no chances of a sudden breakout and often control is better. Be sure to turn the flap, around till it reaches more peripheral to the place where it began and turn it in the meet the origin of the rhexis. The correct shape after completion would, thus resembles an apple. Ideally rhexis is best done under a viscoelastic though it can also be done under BSS and even under air. Viscoelastic has the advantage that it keeps the chamber well formed and tamponades the capsule. If HPMC is used as a viscoelastic substance, it works even better as frozen methylcellulose (kept in the last shelf, below the freezer compartment) as it does not flow out easily, and tamponades the capsule perfectly, maintaining the chamber deep, even in a tight eye.


OF


195

Both air- and BSS-based rhexis can only done with the needle. Using a forceps and opening up the chamber lead to a disastrous collapse of the chamber and even inadvertent contact of the delicate endothelium and the rhexis instrument. In both BSS and an air-based rhexis, the rhexis has to be done before the phaco corneal tunnel is made, so that it is complicated in a totally sealed chamber. If the phaco entry incision has been made prior rhexis, it is safer and better, to use a third incision site for doing the rhexis. Using BSS-filled chamber during rhexis is easy, provided a third port is made with a continuous infusion of BSS (Bluementhal cannula), while the procedure is being done. The only problem is that often the flaps floats around and makes it difficult to carry out the procedure. Though, in theory, air is better in an overmature cataract, and the use of BSS based rhexis avoids the use of the viscoelastic, it is always a bit dicey. I always use frozen methylcellulose-assisted forceps-based rhexis. HYDRODISSECTION AND HYDRODELAMINATION Hydrodissection is done utilising a fine, 2426 G flattened cannula with rounded edges (Fig. 19.6), mounted on a Luer Lock 3.00 ml plastic disposable syringe. I always specify Luer Lock since the time I shot a blocked needle in the eye. Fortunately only the capsule broke with no other problems and the patient retained full vision, but it was an experience, difficult to forget. Hydrodissection should be commenced at a point just below the edge of the capFig. 19.6: Hydrodissection at 2’O clock position sulorrhexis. The tip of the hydrodissection cannula should go just under the edge of the rhexis, slightly lift it up, and then inject. This technique is termed as cortical cleaving hydrodissection (Fine 1992). Hydrodissection should be commenced first at 4.00 O’clock position and subsequently at the 7.00 O’clock and finally at 2. 00 O’clock position. Usually by this time the lens seems to move slightly upwards, indicating that the nuclear zone has been hydrodissected off. It is important after every injection to gently compress the center of the nucleus to enable better hydrodissection and prevent central pooling of the liquid and allow the excess liquid to flow out again. It is important to appreciate that hydrodissection in a hard cataract can sometimes give trouble. The surgeon injects, and the moment the fluid is injected, the chamber shallows and, the intraocular pressure (IOP) rises sharply. What has happened is that the fluid has pooled at the back of the lens, as it has no way to exit, and is now pushing the nucleus forward. Any pressure on the lens in an effort to push it back and deepen the chamber will lead to a posterior capsule rupture. At this stage the correct management is to utilize a thin blade iris repositor and insert

196

THE ART

OF

PHACOEMULSIFICATION

it under the capsular edge at 4.00 O’clock (the site of the primary injection) and sweep it sideways to 8.00 O’clock on the right and to 2.00 O’clock on the left side.. Immediately the fluid will gush out and the eye becomes soft and the chamber automatically deepens. Hydrodelamination as a procedure is now rarely utilized. It was originally conceived as the technique of delineating the hard nucleus and the peripheral epinuclear material. It was in vogue during the four-quadrant grooving technique and was utilized as a method to know how far one could groove in the periphery without accidentally touching the capsule. Since the advent of Nagahara’s chopping techniques, and its multiple variants, hydrodelamination is no longer required. It is, however, still utilized as a means of inducing a soft nucleus to break it into its component parts and permit it to be aspirated easily, especially in young adults. Once the hydrodissection has been done, the nucleus is rotated utilizing a lens rotator. It should rotate freely with no hesitation. If it does not rotate, it is important that you hydrodissect once again. The next step depends on whether the surgeon wishes to either flip the lens out of the bag on its front side (supracapsular tumble) or enable the lens to stand vertically (vertical phacoemulsification), or float the entire lens out (anterior chamber phacoemulsification) (Visco-levitation) (Fig. 19.7) Mehta (1995) Kelman (1997). All three techniques are done by injecting viscoelastic under the lens capsule, at 9.00 O’clock, irrespective of whether it is the Fig. 19.7: Viscodissection to permit nucleus to right or left eye. Injecting at this site leads stand vertically the 3.00 O’clock position of the lens (temporal in the left eye, nasal in the right eye) to tip forwards. Using the same cannula which is being used to inject the viscoelastic, gently nudge the inferior pole of the lens,. A small nudge will make it stand up vertically (Lens salute, Mehta 1997.), if more is injected, the lens will flip over and can be rotated out of the bag supracapsularly (Maloney 1997). If one injects without tipping the inferior pole, it will, if the rhexis is 7.00 mm or more in size, float vertically upwards or viscolevitate (Mehta/Kelman). PHACOEMULSIFICATION TECHNIQUE (Figs 19.8 to 31) There are two methods which I use: the first is the tangential phaco chopping technique—a method which was popularized in 1996 (Mehta), and the second which I prefer is the vertical nuclear ‘hubbing’ phacoemulsification. In 1996 I developed the tangential chopping technique whereby the chop rather than going vertically through the substance of the lens, would go obliquely. One had merely to tip an edge of the nucleus out, impact the nucleus in the middle with a phaco tip and using a sharp-edged but blunt-tipped chopper obliquely the


OF


Fig. 19.8: Impaction of phaco tip into nucleus

197

Fig. 19.9: Chopping proceeds

Fig. 19.10: Lens chopped vertically

Fig. 19.11: Fragment turned and repositioned for chopping

Fig. 19.12: Fragment chopped

Fig. 19.13: Fragment impacted and chopped

lens is plot from the periphery to the center. The advantage was that rather than trying to split the lens vertically literally “shards” of the lens were removed. The lens was rotated and then chopped again, once again obliquely. Ultimately only the thin central shard was remaining which could be flipped out and phacoed. It proved very effective especially in hard cataracts. The big advantage was that the capsule was never at risk.

198

THE ART

OF

PHACOEMULSIFICATION

Fig. 19.14: Pulse phaco to remove final fragment

Fig. 19.15: Irrigation aspiration to remove cortical remnants

Fig. 19.16: Insertion of foldable lens in eye

Fig. 19.17: Tripod (IOLTECH) lens in its own cataset case

Fig. 19.18: Tripod (IOLTEC) being gripped over the ridge in case

Fig. 19.19: Lens being gripped with one tripod followed and two flexed

In 1998, I conceived of the concept of vertical phacoemulsification whereby the nucleus was tilted vertically. Considering that the maximum density of the nucleus is on the middle, common sense dictated that if one could remove the hard central core, one would literally convert the entire nucleus into a simple doughnut. The


OF


Fig. 19.20: Lens being inserted with leading tripod under capsular edge

Fig. 19.22: Tripod lens well positioned in bag

Fig. 19.24: Soft plastic tip being removed from case

199

Fig. 19.21: Lens released allowing both proximal loops to slip in bag automatically

Fig. 19.23: Insertion of SI 40 Allergan lens with Allergan un-folder injector

Fig. 19.25: SI40 silicone lens being positioned in folder

peripheral ring composed off much softer nucleus and epinucleus would come out easily. I, therefore, designed the system of “hubbing” phacoemulsification, where the nucleus could be ‘hubbed’ or removed by coring out the middle of the lens.

200

THE ART

OF

PHACOEMULSIFICATION

Fig. 19.26: Folder being closed

Fig. 19.28: Lens being injected into the eye

Fig. 19.30: Inferior loop trailing being inserted into bag

Fig. 19.27: Folder placed in Allergan “unfolder ” injector

Fig. 19.29: Lens completely unfolded— superior loop swinging in bag

Fig. 19.31: Lens in good position

Technique of Vertical “Hubbing” Phacoemulsification It is a very simple technique. So simple in fact that when I demonstrate it to visitors in my theater, the first comment usually is…”looks easy… why has no one thought of it?“.


OF


201

The technique involves a 6.00 mm rhexis, following a full hydrodissection placing the nucleus vertical viscodissection at the 9.00 O’clock position with the nucleus at 3.00 O’clock position standing out of the capsule bag (Lens salute). The steps of the surgery are as under: Nuclear stabilization Viscoelastic is injected from the side port incision. This manages to stabilize the nucleus and prevent it flopping back. From the side port, enter with the blunt-tipped, but sharp-sided chopper and support the nucleus. Coring the nucleus The next step is to core out the center of the lens. In this technique termed “hubbing”, I like to use the Kelman bent 0.9 dia phaco tip as it penetrate easily in the nuclear matter. The phaco settings are now altered to 70% phaco power, vacuum is reduced to the minimum. Thus, when energized, the phaco tip can penetrate, and move out of the nucleus without displacing it since no suction is involved. Supporting the nucleus from the left with the phaco chopper held flat against the nuclear surface to stabilize it, the phaco tip is placed squarely in the middle of the lens and literally allowed to penetrate virtually all the way through. The first core, made in the middle of the nucleus is called the primary core. Subsequently make three, one secondary core just above, and two, one at each side of the primary core. The next step is to rotate the nucleus by 90° and make the final core. In any lens up to grade 4 in density, a total of five cores (one central primary and four secondary cores) will literally, eliminate the hard central nuclear matter. If it is harder cataract, another set of four cores (termed tertiary cores)are placed a little peripherally and in between the previous four secondary cores. Snapping the periphery The lens is now converted into a doughnut. To aspirate the final rim, it needs to be snapped. The chopper, which till the present was only supporting the nucleus for the coring is now allowed to slip in-between the cored nucleus. Using a phaco in the right hand, the ring is split open using the sharp inner curve of the chopper. After snapping the ring, it is slightly widened. Pulse aspiration of the ring The open end of the doughnut ring is allowed to impact onto the phaco tip. The settings now change, ultrasound power is kept at 20 to 30% depending in the density of the lens, set pulse at 8 pulses per second. Vacuum is set at 400 mm Hg, Flow rate at 18 ml/min, energizing the tip will lead the entire rim of the lens to rotate (carrousel) till it is fully removed. An average phacoemulsification, from beginning to end, done with no haste, in a medium dense grade 4 cataract, with this technique can be completed easily in 6 minutes. Indications Though it is an exceptional technique and can be used in virtually any type of density of nucleus, it, however, does require a little care. It is difficult to tumble the lens through a rhexis smaller than 6.00 mm in size. It is possible to enlarge

202

THE ART

OF

PHACOEMULSIFICATION

the rhexis using the split rotation technique described elsewhere. Since the quantum of ultrasound energy liberated in the anterior chamber is very low, it can be used safely in Fuch’s dystrophy, patients with a low endothelial cell count, or prior keratoplasty, where the regular options do not apply. The important question, often asked is whether doing a regular phacoemulsification as compared to a vertical phacoemulsification shows any disparity in endothelial cell loss. It is often thought that since, in coring U/S energy is used more, the endothelial cells may be affected. But in fact the extra energy is masked off the cells by the fact that a phaco needle buried in the substance of a lens does not radiate any energy out. A Topcon endothelial specular non-contact microscope coupled with its own special “ImageNet” software, showed no cell loss of any significance in a series of 125 consecutive cases. Though, in theory, endothelial cell changes must occur in any surgery, in practice there is hardly a +/- 3.00% variation change in the endothelial cell count. Perhaps the greatest application of this technique is that it is an exceptional transition technique for teaching residents, fellows and young pledging surgeons the art of phacoemulsification without inducing any complications. It is easy to do, minimizes the risks of capsular damage, removes the chances of inadvertent iris contact, and enables even a hard cataract be done with safety in a short period of time. It is thus the technique of choice in eye camps where, I am sure, it will supplant the regular technique in time. FURTHER READING 1. Mehta KR: Pitfalls encountered in 1500 consecutive posterior chamber implant. All India Ophthl Soc Proc 165-166,1986. 2. Mehta KR: Posterior capsular capsulorrhexis with shallow core vitrectomy following implantation in paediatric cataracts. All India Ophthl Soc Proc 207-210,1995. 3. Mehta KR: An advanced but simple keratometer for control of postoperative astigmatism. All India Ophthl Soc Proc 122-123,1990. 4. Mehta KR: The new clover leaf stabiliser (CLS) for the safe and effective insertion of posterior chamber IOL over a broken capsular face. All India Ophthl Soc Proc 251-253,1995. 5. Mehta KR: Shelve and shear phacoemulsification: All India Ophthl Soc Proc (Mumbai) 1995. 6. Mehta KR: Mehta tangential chop (MTC) technique for phacoemulsification. All India Ophthl Soc Proc (Chandigarh) 1996. 7. Mehta KR: HEMA intracameral hood—corneal turbulence control in phaco. All India Ophthl Soc Proc (Chandigarh) 1996. 8. Mehta KR: Phaco-levitation—a peaceful way. All India Ophthl Soc Proc (Chandigarh) 1996. 9. Mehta KR: Lollipop phaco cleavage—a new technique for hard cataracts. All India Ophthl Soc Proc (Bangalore) 1991. 10. Mehta KR: Phaco with flexible IOL—is it a step forward. All India Ophthl Soc Proc (Bangalore) 1991. 11. Mehta KR: The prephaco split technique using the contrasplit forceps–a new technique. All India Ophthl Soc Proc 1998. 12. Mehta KR: Intralenticular “hubbing” technique for simple eye camp phacoemulsification–a simple technique. APIIA Conference, 1997. 13. Mehta KR: Astigmatic control using the new curved—laminating keratotomy technique. APIIA Conference 1997. 14. Mehta KR: The tripod posterior chamber foldable acrylic lens. Proc of SAARC Conference, Nepal, 1994. 15. Mehta KR: Phacoemulsification, the “roller-flip” way for suprahard cataracts—it works great. Proc of SAARC Conference, Nepal, 1994.


OF


203

16. Mehta KR: Intralenticular phacoemulsification—a new technique. Proc of SAARC Conference, Nepal, 1994. 17. Mehta KR: Management of subincisional cortex in small incision cataract surgery (SICS). Proc of SAARC Conference, Nepal, 1994. 18. Mehta KR: Intralenticular “hubbing” phaco technique for safe phaco. Proc of SAARC Conference, Nepal, 1994. 19. Mehta KR: Effective endothelial cell protection during phacoemulsification with HEMA intracameral contact lens (HICL). Proc of SAARC Conference, Nepal, 1994. 20. Mehta KR: The new multiport phaco tip for safer, more effective phacoemulsification, with virtually zero capsular damage. Proc of SAARC Conference, Nepal, 1994.

204

THE ART

OF

PHACOEMULSIFICATION

Vijay K Dada Namrata Sharma Tanuj Dada

Innovative Nucleotomy Techniques

20

INTRODUCTION Phacoemulsification is now the most preferred modality for cataract extraction according to the latest ASCRS survey.1 The various nucleotomy techniques are generated to avoid complications and to ensure safe phacoemulsification procedure. We herein, describe the following nucleotomy techniques. • Modified phacoemulsification in situ, for weak zonular apparatus. • Petalloid phacoemulsification, for hard cataracts • Sinus fracture and intranuclear nucleotomy, for semihard cataracts, and • Slit nucleotomy technique for soft cataracts. MODIFIED

PHACOEMULSIFICATION

IN

SITU

A modified methodology of in situ phacoemulsification is described which imparts minimal stress on the zonular apparatus. This is especially relevant in cases of zonular weakness where undue stretch may cause partial or total zonular dialysis during rotation. The phaco procedure is begun by inserting the phaco tip into the chamber prior to emulsification. Central sculpting a groove approximately 2½ to 3 phaco tips wide with specific attention to down sculpting, approximately 90% of nucleus depth, is done in order to consume part of the posterior plate or the backbone of the nucleus (Fig. 20.1A), thus, the central hard nucleus, epinucleus and cortex within the confines of the capsular bag. For this debulking procedure, the phaco power is initially kept at 50% and increased further as per the hardness of the nucleus. The aspiration flow of fluid is 20 cc/min and vacuum is 11 mm Hg.

INNOVATIVE N UCLEOTOMY TECHNIQUES

205

Fig. 20.1A: Central debulking, sculpting to 90% depth

Fig. 20.1B: Horizontal fracture along 3 and 9’O clock meridian

A deep groove facilitates instruments to be in place for a subsequent fracture and increases the working space. During this part of phaco it is imperative not to rock or move the nucleus so as to keep the zonules and anterior capsule intact. Following an adequate debulking, the second instrument (chopper) is inserted through the side port and a horizontal fracture is created by karate fracture at 6 O’ clock to divide the lower half of the nucleus into 2 quadrants. Right

206

THE ART

OF

PHACOEMULSIFICATION

Fig. 20.1C: Vertical fracture of the inferior hemisection

Fig. 20.1D: Pie-shaped nucleus is phacoemulsified after stabilization with the second instrument

hand fixes the nucleus on the right side of the center, left hand does vertical fracture at the center by downwards movement of the blunt chopper along 3 and 9 O’clock meridian (Fig. 20.1B). Fracture into distal and proximal half is done after complete removal of the foot from foot pedal, i.e. no function. The phaco tip is then used to engage the inferior hemisection and 2 pie-shaped “pizza


207

pieces” are fractured using the second instrument to stabilize the nucleus (Fig. 20.1C). The tip of the quadrant or “pie” is engaged into the phaco tip and pulled forwards into the center pupillary zone for safe emulsification (Figs 20.1D and E). The second instrument/chopper/manipulator may be used to tilt the central apical portion up in order to facilitate grasping by the phaco tip just as in other nuclear cracking techniques. If necessary (i.e. in cases of large and dense endonuclei) individual fragments may be cleaved further, resulting in small manageable

Fig. 20.1E: Superior hemisection left for phacoemulsification

Fig. 20.1F: Deep groove facilitated at superior hemisection

208

THE ART

OF

PHACOEMULSIFICATION

Fig. 20.1G: Vertical fracture facilitated at superior hemisection (no nucleus rotation)

Fig. 20.1H: The level of the phaco tip is turned down to emulsify the pie-shaped nuclear fragment

fragments, small enough to be aspirated. A crater is then created in the proximal half within the confines of the capsulorrhexis in situ, without rotation of the nucleus (Fig. 20.1F). The phaco tip is directed slightly downwards just as one does during sculpting. The groove is used to fracture the upper hemisected nucleus


209

into 2 quadrants (Fig. 20.1G). The bevel of the phaco tip is turned down to pick up each quadrant separately which is emulsified in situ (Fig. 20.1H). This modified methodology of central debulking and in situ phacoemulsifcation is particularly suitable in cases where degree of stress imparted to the zonular apparatus has to be minimized. It is especially relevant in cases of anticipated weak zonular apparatus, like pseudoexfoliation, uveitis, hypermature or traumatic cataracts and glaucoma. This technique further ensures minimal lens rotation and eliminates the need to sculpt in the periphery. A remarkable index of safety is entailed as each fragment is emulsified in the central safety zone in a stable environment with the phaco tip. Moreover, as no sharp instruments approach the posterior capsule, this technique is safer than the conventional chopping technique. PETALLOID

PHACOEMULSIFICATION

Transitional phaco surgeons may hesitate to deeply chop the central core of hard cataracts which resists complete division even in expert hands due to elasticity and tenacity of the posterior nuclear plate. If the instruments are placed too anteriorly in the trench, the bottom of the bridge is not split, because the inappropriate placement of instruments creates a torque in the area rather than a splitting force.2 On the other hand, an inappropriate deeper fracture may inadvertently rupture the posterior capsule. We herein, describe a useful technique for phaco surgeons who are still in the learning curve for performing phacofracture of hard nuclei. Technique Debulking of the central hard nucleus is facilitated by sculpting a crater (75% depth) with the phaco tip (Figs 20.2A and B). The phaco parametres are: power— 70% and vacuum—10 to 12 mm Hg. This removes the hardest core tissue from within the middle of the hard cataract and provides enough room for the working of the instruments and subsequent manipulation of the nuclear fragments. The 2nd instrument (chopper) is introduced via the side port and Nagahara chopping3 is facilitated within the confines of the capsulorrhexis to separate out a petal shaped nuclear fragment still attached to the unchopped intact central disc (Fig. 20.2C). The nucleus is then rotated by 2 to 3 clock hours and another petalshaped fragment is chopped. Each ‘petal’ constitutes predominantly the nuclear rim, the base of which is formed by the central disc, giving it a petalloid configuration. The same technique of rotation, chopping and rotation is performed to form 6 to 12 such “petals” depending on the hardness of the nucleus (Fig. 20.2D). The vacuum is raised 100 to 110 mm Hg during nuclear emulsification. Each petal may be emulsified in the central capsular bag separately or all may be left in place until all “petals” have been formed. The advantage of waiting until all “petals” have been formed is the maintenance of maximal capsular distention which keeps the capsular bag stretched and helps to avoid inadvertent posterior capsular tear. However, the advantage of removing each fragment separately is

210

THE ART

OF

PHACOEMULSIFICATION

to allow more space for easy chopping of the other segments of the remaining rim. Nevertheless, caution is mandatory while doing the latter since, as more segments are removed, less lens material is available to expand the capsule and the lax capsule has a greater tendency to be aspirated into the phaco tip especially if high aspiration rates are used. Following consumption of the nuclear rim (Fig. 20.2E), the central mobile disc of the nucleus (Fig. 20.2F) is emulsified. Twenty eyes underwent petalloid phacoemulsification with foldable silicone intraocular lens implantation (SI30NB:Allergan ) with no untoward intraoperative complications. The mean phaco time was 1.02 ± 0.06 minutes and the mean percentage endothelial cell loss was 4.2 ± 0.8% at the end of 3 months follow-up. Postoperatively, all eyes achieved a visual acuity of 20/20 at the end of first week.

Figs 20.2A to F: (a and b) Central debulking upto 75% depth, (c) Karate chop at the paracenter to create the edge of a petal, (d) Chopping, rotation and chopping create the petalloid configuration, (e) The central disk and the base of the petal remains following emulsification of the petals, and (f) central disk and the base of the petal are emulsified in the end

This technique is based on the anatomic relationship between the lens fibers and the lenticular sutures. During embryologic development lens fibers elongate and join forming 2 sutures, one anteriorly and one posteriorly.4,5 With time, as more fibers are added these sutures branch off into increasingly complex patterns. The radially oriented fibers create potential cleavage planes that are amenable to separation.5 The lens epithelial cells lay down concentric layers of nuclear tissue which become dense centrally and less dense peripherally. These concentric layers resemble the lamellar organisation of a tree trunk. Thus the peripheral area of a hard cataract offers less resistance and a more predictable shearing stress as compared to the center which is much more dense.


211

This modified method of “petalloid” phacoemulsification is particularly suitable and comfortable for transitional phaco surgeons who are as yet hesitant to completely chop the dense central core of hard nuclei. An experienced surgeon may be able to determine and gauge the depth of the central crater and the density of tenacious and elastic fibers of the posterior plate. However, this may not be true for the beginners. For learning phaco surgeons chopping in the center of a hard nucleus is difficult, as the hardness of the nucleus precludes the depth at which the fracture has to be facilitated. On the other hand, chopping the relatively softer “paracenter” may allow a better perception of depth. The fracture which is radial is more physiological with the arrangement of the lens fibers as compared to the one which is horizontal. In an untoward situation, the traditional horizontal fracture may cause an unexpected and unequal break in the nucleus so that the phaco probe directly impinges on the posterior capsule. The process of partial central debulking, peripheral chopping and emulsification and then central disc emulsification offers a more graduated effect and is thus more predictable. A greater predictability is attributed to impaling from less hard periphery towards a more hard central core. Thus this procedure works on progressive harder gradient by going from periphery towards the paracenter. The small residual nucleus core is phacoemulsified separately with ease due to its small size and larger room for manipulation and movement. We recommend this procedure as an alternative to technique of performing phacofracture of a hard nucleus during phacoemulsification. SINUS

FRACTURE

AND

INTRANUCLEAR

NUCLEOTOMY

The technique of sinus fracture and intranuclear nucleotomy facilitates and accomplishes a successful phacoemulsification in dense or hard nuclei. Technique Using a 30o phaco tip a central crater is sculpted approximately 2.5 to 3 phaco tips wide and upto 90% of the nuclear depth. The central hard nucleus is debulked, leaving a peripheral rim of nucleus, epinucleus and cortex within the confines of the capsular bag. A deep groove allows instruments to be in place for a subsequent horizontal fracture of the nucleus into two halves. The phaco probe with bevel upwards is then inserted into the center of the inferior hemisection to create a sinus (Fig. 20.3A). The lateral wall of the sinus is widened to accommodate the phaco tip and the chopper (Fig. 20.3B). A mechanical force is then applied along the lateral wall of the sinus with these two instruments (Fig. 20.3C). Thus the inferior hemisection is divided into two quadrants (Fig. 20.3D). The individual fragments may then be cleaved further in a similar manner and aspirated out. The superior nuclear hemisection is dealt with, in a similar way. In intranuclear nucleotomy, 4 such sinuses are made (Figs 20.3E and F) each at 90° to each other. This is followed by the breaking of the 4 sinuses so that 4 quadrants are generated which are then subsequently emulsified.

212

THE ART

OF

PHACOEMULSIFICATION

Figs 20.3A to D: (a) Phacoprobe is inserted in the hemisection, (b) Chopper is inserted in the hemisection from the site port, (c and d) lateral force is applied to split the hemisection into two quadrants

Figs 20.3E and F: (e) Four sinuses are created for intranuclear nucleotomy, and (f) four sinuses are broken to create four quadrants

Sinus fracture was performed in 50 cases with grade IV nuclear density by a single surgeon (VKD). No intraoperative or postoperative complications were encountered. Successful phacoemulsification was achieved in all eyes. Visual acuity of > 20/40 was obtained in all cases at the end of 1 week. The mean phaco time was 1.09 + 0.6 minutes and mean endothelial cell loss at the end of 3 months was 4.6% + 0.7%. This technique is especially advantageous as the phaco tip is buried deep into the inferior hemisection and thus it reduces the amount of ultrasound energy


213

directed towards the corneal endothelium and the posterior capsule. The turbulence within the eye is decreased which cuts down the production of free radicals generated by the ultrasonic energy hitting the endothelium. The procedure is especially effective on grade IV hard nuclei which might be considered difficult to perform using other phaco techniques. Since no sharp objects approach the posterior capsule, this technique is safer than conventional chopping procedures. The chopper is not inserted underneath the capsule or the iris and therefore the chopping is accomplished far away from the edge of the capsulorrhexis and the endothelium, within the pupil. The large nuclear fragments do not shift into the anterior chamber, thereby decreasing the possibility of endothelium damage. This technique offers higher safety against damaging the capsule and should be adopted as a routine in phacoemulsification of hard and brunescent nuclei. SLIT

NUCLEOTOMY

Phacoemulsification in soft cataracts is as challenging as phacoemulsification in hard cataracts as the capsular bag is relatively loose and phaco probe may cut through the nuclear material without being emulsified. In soft cataracts, a vertical narrow and a deep slit facilitates fracture more easily as there is no cheese wiring (Figs 20.4A and B). Further enough support occurs to ensure adequate purchase on the walls which ensures a cleaner fractures. We do not recommend a wide crater in soft cataracts as enough nuclear material is not present to ensure an adequate fracture.

Figs 20.4A and B: (A) Slit is created with the phacoprobe, and (B) slit is split to create two hemisections

REFERENCES 1. Leaming DV: Practice styles and preferences of ASCRS members—1996 survey. J Cataract Refract Surg 23: 527-35, 1997. 2. Seibel BS: Phacodynamics: Mastering the Tools and Techniques of Phacoemulsification. Slack Inc: Thorofare, 1993. 3. Gimbel HV: Nuclear phacoemulsification. In Steinert (Ed): Cataract Surgery : Technique, Complications and Management. WB Saunders: Philadelphia; 148-161, 1995. 4. Bron A, Smith R et al : Changes in light scatter and width measurement from the human lens cortex with age. Eye 6:55-59, 1992. 5. Duke Elder S: Anatomy of the visual system. In System of Ophthalmology. Vol.II, CV Mosby: St. Louis, 320-23, 1961.

214

THE ART

OF

PHACOEMULSIFICATION

Rasik B Vajpayee Tanuj Dada Vishal Gupta

21

Phacoemulsification in White Cataracts

INTRODUCTION The white cataract, for most surgeons, is perceived as a major challenge to their skill. In ophthalmic practice in the developed world the incidence of these cataracts is low, whereas in the developing countries they represent a significant number of patients seen and operated upon. These eyes are often looked upon with foreboding because of the potential pitfalls envisaged in their surgery. In this chapter, alogical framework is provided to allow many of the problems to be overcome. REASONS

FOR

CATARACTS

TURNING

WHITE

Cataracts are caused in many cases by separation of lamellae within the lens and imbibition of water into these spaces. As this process continues the lens starts to swell and once this occurs it is described as intumescent, these cataracts may be immature or mature. However, the common feature is that the cortex has swollen so that it no longer transmits light and has a shiny hyaline appearance. The nucleus is frequently chalky and small but may also, particularly in older patients, contain a large brunescent nucleus. A later stage of development is the hypermature lens where fluid has begun to leak from the lens and the capsule is wrinkled. MORPHOLOGICAL

CLASSIFICATION

Let us first consider the main types of lenses that are found with white cataracts. Type A (Fig. 21.1)

PHACOEMULSIFICATION

Fig. 21.1: Type A white cataract

IN

WHITE CATARACTS

215

Fig. 21.2: Type B white cataract

Posterior subcapsular cataracts that have been allowed to proceed to maturity These are generally found in younger patients and in the author’s practice in patients of Asian origin. These cataracts have small nuclei and considerable amounts of liquefied lens material. Type B (Fig. 21.2) Hypermature cataracts in older patients often uniocular in non-dominant eyes They tend to have large highly sclerotic nuclei and a thin overlying layer—white cortical matter. The nucleus may have become mobile within the capsular bag as in morgagnian cataracts. Type C (Fig. 21.3) Shrunken fibrotic lenses as seen in complicated uveitic cataracts and eyes that have had a penetrating injury In the latter, there is often little by way of nucleus or cortex between the leaves of the capsule, it may have liquefied and leaked out through a small capsular perforation. The uveitic lenses are often calcified and may need to be removed manually (Fig. 21.4) in a piecemeal manner or

Fig. 21.3: Type C white cataract

Fig.21.4: Manual removal of lens

216

THE ART

OF

PHACOEMULSIFICATION with a vitreous cutter. Often the implant if used will require scleral fixation as no adequate capsular remnants will exist (Fig. 21.5). Type D

Fig. 21.5: Close-up view of uveitic cataract

MANAGEMENT

OF

WHITE

Infantile cataracts such as those caused by maternal rubella very often present as white cataracts. These are normally dealt with by aspiration or lensectomy and so really fall outside the scope of this chapter. CATARACTS

Preoperative Considerations Ophthalmic History Take a careful history to ascertain the following • If there have been any obvious predisposing factors such as trauma or infla– mmatory disease. • The length of the time that vision has been poor and is the problem uniocular. This is important because a long-standing uniocular cataract may well hide significant posterior segment disease of which the patient is unaware. • Precataract vision should be ascertained if possible, there is no point removing a white cataract from an amblyopic eye except for cosmetic reasons. Examination • When checking visual acuity in patients with dense cataracts of this type it is important to carry out a test of light projection. This should be done in an otherwise darkened room using a strong point source of light in each quadrant of vision. Failure to point accurately to the light in any quadrant may indicate significant posterior segment disease. • The anterior segment examination may show evidence of previous penetrating injury. There may be synechiae or pigment on the anterior lens surface indicating inflammatory disease or anterior chamber activity. • Always check the intraocular pressure (IOP), if it is raised there may be unsuspected uniocular glaucoma or because the cataract is swollen and surgery is going to be necessary urgently. If it is low the eye may be becoming phthisical posterior segment problems such as unrepaired retinal detachment may cause this. • Check the cataract itself. Is it swollen and has it shallowed the anterior chamber. Is the nucleus visible at all through the cortex and is it brunescent or morgagnian. Has the capsule become wrinkled indicating leakage of fluid from the lens. • Check the fellow eye. It is most unusual that the other eye, even if it does contain a cataract, will be so bad that no fundal view is precluded. A knowledge that there is age-related maculopathy present is useful in advising the patient about the possible prognosis for vision.

PHACOEMULSIFICATION Further

IN

WHITE CATARACTS

217

Tests

It is essential to carry out an ultrasonic B-scan in patients where the posterior pole is obscured by cataract. This is done to exclude such things as ocular tumors like malignant melanoma of the choroid or retinal detachments. Problems of this type are usually seen where the history has been long-standing and the cataract is uniocular. Surgical Considerations The reasons why these cataracts represent so much of a challenge to the surgeon are three-fold: (i) the lack of any red reflex, (ii) the effect on the ocular tissues of the advanced nature of the disease process, and (iii) the nuclei in these eyes are often small and mobile, whilst some are brittle others can be very hard. Although the capsulorrhexis is certainly the most likely part of the operation to cause difficulty, even if that is successfully achieved, the rest of the ocular tissues in the anterior chamber are more friable than usual and the nucleus may be more difficult to control. Capsulotomy Owing to the difficulties of visualizing the capsule, capsulorrhexis, if the chosen method, presents the most taxing part of the operation in most of these eyes. However as capsulorrhexis confers distinct advantages for the rest of the operation it should ideally be the method used. General Tips to Help Improve Visibility during Capsulorrhexis • Operate from the temporal aspect, the visibility and overall surgical access is surprisingly improved. • Tilt the microscope eyepieces towards you to create oblique illumination, like the sun in winter this creates shadows and throws the capsule into relief. The torn edge of the capsule also has an edge reflection to enhance its location against the white cortex. Some microscopes have an oblique non-coaxial light which is even better for this. A fiberoptic light pipe introduced into the anterior chamber can enhance the view of the tearing capsule very considerably (Fig. 21.6). The room and microscope lights need to be extinguished to get the best effect from this maneuver. • Use very high magnification during the capsulotomy and focus accurately at the plane of the anterior cap. • Overfill the anterior chamber with viscoelastic, a cohesive material like Viscoat (Alcon) or high concentration sodium hyaluronate such as Healon GV (Pharmacia Upjohn) are best for this as they are less likely to escape from the eye at awkward moments. This will flatten the anterior capsule and thus lessen the tendency for the capsule to tear to the periphery. Also the full anterior chamber (AC) will contain the liquid lens matter escaping and minimizes loss of visibility.

THE ART

218

OF

PHACOEMULSIFICATION

Fig. 21.6: Using the light pipe for the capsulotomy

Fig. 21.7: Starting the rhexis

• Attempts have been made in the past to stain the anterior capsule but until recently unsuccessfully. Indocyanin green has now been used to achieve this and aid capsular visibility for capsulorrhexis. • Take your time. Reassess frequently where the tear is and be prepared to top up viscoelastic or refocus or move the light as required to get the best view. Specific Tips • Begin the capsulorrhexis in the center of the capsule with a small tear to allow lens milk to escape (Fig. 21.7). If there is extensive milky fluid obscuring the view of the capsule, remove the cystitome and use the I/A handpieces to aspirate this (Fig. 21.8), also go under the capsule for anterior soft lens material. This lessens the highly reflective nature of the anterior cortex and improves the visibility of the capsule. Using high magnification will allow the surgeon to observe the subtle difference between cortex covered by capsule and that, which is not (Fig. 21.9). • Grasp the torn edge of the capsule firmly, attempt only a small 4.5 mm rhexis. These capsules are often friable and easily extend. A small capsulotomy can always be enlarged later if required. • If the edge of the capsule is lost STOP. Reinflate the AC with viscoelastic, very often this will demonstrate where the capsulotomy has reached and control can be regained. If the edge is still not seen try changing the angle of the microscope to allow the light to play differently on the capsule, increase the magnification further and refocus on where you think it is. • If the rhexis edge is still illusive, consider beginning it again in the opposite direction. This can usually be achieved using the cystitome; begin on the capsule and cut towards the center (Fig. 21.10). This produces a flap which when lifted by viscoelastic can be grasped in the forceps and the two halves of the rhexis may thus be joined.

PHACOEMULSIFICATION

Fig. 21.8: Using the bimanual I/A to clear lens fluid

IN

WHITE CATARACTS

219

Fig. 21.9: Slight color difference apparent with oblique illumination

By using these few simple maneuvers in an unhurried manner, a satisfactory rhexis can generally be achieved. If the rhexis is known to be compromised and cannot be retrieved either revert to a canopener capsulotomy and then perform iris plane phaco as described by Maloney and others or use cautious nucleofractis. In both instances remember that these capsules, both anterior and posterior, are easily damaged. Fig. 21.10: Restarting the rhexis

Radiofrequency Endodiathermy for Capsulotomy An alternative method for achieving a capsular opening which does not require such accurate visualization of the capsule is to use an endodiathermy. The tip of the device is moved slowly around the anterior capsule to create a circular opening. This is achieved due to thermal effect and anneals the capsular edge. Although as a number of studies have shown this edge is not as strong as a capsulorrhexis, it is at least better than a torn or incomplete rhexis when IOL stability within the capsular bag is considered. Also if the device is available it removes much of the anxiety associated with this type of eye. The major disadvantage is the cost if white Fig. 21.11: High frequency radiodiathermy for cataracts are not a common part of a the capsulotomy surgeons clinical practice.

220

THE ART

OF

PHACOEMULSIFICATION

Hydrodissection Both in the softer more liquid white cataracts and those with hard nuclei, hydrodissection is usually easily achieved as the cortex is rarely very adherent. Do not use great pressure on the syringe or soft lens matter under the nucleus will be washed out of the eye and thus will not be able to provide any protection for the posterior capsule during nucleus removal. The loose cortex in these eyes means these nuclei tend to be mobilized with minimal manipulation. Tips for Nuclear Removal Type A Cataracts In type A cataracts the nuclei are small and chalky though not usually very hard. Their mobility may make removal difficult because of the tendency to move away from the phaco tip. • Use the manipulator to stabilize the nucleus (Fig. 21.12). • Use higher phaco power, i.e. 70 to 80 percent to accelerate the tip into the nucleus in conjunction with higher vacuum to hold the tip and thus control it. • Whether cracking or chopping (Fig. 21.13) be aware that the fragments of these nuclei can damage either capsule or endothelium because of their mobility. A layer of Viscoat above and below the nucleus prior to nuclear removal can be helpful in this regard. If successful rhexis has been achieved these nuclei do not normally tax the surgeon’s skill. Type B Cataracts Type B cataracts have nuclei that are often brunescent. Remember the posterior capsule is not protected by a good layer of epinucleus and what is present is often washed out by the irrigating fluid. As above remember that the capsule and endothelium are particularly at risk. Also the zonules are often less strong than normal. Consider: • The use of viscoelastic as above. The capsule protector suggested by Dr Michael

Fig. 21.12: The manipulator is used to stabilize the nucleus

Fig. 21.13: Cracking the nucleus

PHACOEMULSIFICATION

IN

WHITE CATARACTS

221

Colvard if available would be useful to slip under the nucleus to protect the posterior capsule. • Whatever technique is used to break up the nucleus that must be employed with great caution. Chopping may be particularly difficult and hazardous if the rhexis edge is not clearly seen. The chopper can be passed over the top of the rhexis and when chopping is attempted the zonule disinserted. If after Fig. 21.14: High vacuum low phaco power nucleofractis the quadrants are too big for easy removal, they can be chopped individually in the center of the rhexis. • Use a modern phaco machine with high vacuum capability and advanced fluidics to control the nuclear fragments (Fig. 21.14). With these very hard nuclei, it is particularly important to avoid anterior chamber collapse as both endothelium and posterior capsule are at risk. However using high vacuum to minimize ultrasound energy used with a machine that does not have some sort of surge control mechanism of the fluidics is much more likely to lead to anterior chamber instability. Type C Cataracts This last group of cataracts is rather more varied in etiology, i.e. from uveitis to trauma but they generally present a similar picture. The capsule is shrunken, often very leathery and frequently with calcified plaques on either surface. The lens matter may have leaked out to a large extent so that anterior and posterior capsules are fused. If this last is not recognized attempting to do any capsulotomy may result in rupturing the anterior hyaloid. Lensectomy, using a guillotine suction cutter is a good method, phacoemulsification is generally impossible. Sometimes the lenses are so tough that they cannot be cut up and need to be removed intracapsularly as a whole (Fig. 21.5). Tips for Cortical Aspiration • As already stated the cortex in these eyes tends to be very liquid, most of it will therefore wash out. • Occasionally, however, a tough shell of epinucleus may be left behind after the nucleus has been removed. These can prove rather tiresome because the edge is not easy to aspirate. Viscoelastic injected under this plate to lift it and using the phaco tip rather than the I/A tip with its wider bore often helps. • Even with a complete rhexis prior to nuclear removal it is not unusual to find that whatever method has been used to get rid of the nucleus a rhexis break has resulted. It is important to recognize this and to make sure any edges to the capsular tear are not aspirated by mistake during I/A. Using bimanual I/A allows for a deeper chamber and better control of the capsular edge.

222

THE ART

OF

PHACOEMULSIFICATION

• It is not unusual to find quite dense plaques on the posterior capsule in some of these eyes. Some will polish sufficiently with a Kratz scratcher or similar device to avoid the need for further action until postoperative vision has been assessed. Others are so dense that the solution of choice is to perform a posterior capsulorrhexis. Sometimes these plaques actually are part of the posterior capsule and when they abraded will come away leaving the hyaloid face exposed. Tips for Lens Implantation If the eye is healthy and all is as it should be after cortical aspiration any lens of the surgeon’s choice can be implanted. However if there is a history of preoperative trauma and damaged zonules, implant an endocapsular ring prior to IOL insertion to stabilize the capsular bag. If the cataract is uveitic in origin the use of AcrySof (Alcon) is recommended if a folding lens is desired. In the authors’ experience this lens performs at least as well heparin surface, modified Fig. 21.15: Well-centered AcrySof with haptics at 90 degrees from rhexis break PMMA lenses (Pharmacia Upjohn) in such cases. If as is suggested above a rhexis break has occurred, great care must be exercised in choice of IOL and site of implantation. • Plate haptic lenses are not recommended as they may during unfolding extend the break. Even a 3-piece silicone IOL as it unfolds may do the same, due to the explosive nature of the release from the implanting device. However the new unfolder (Allergan) appears to overcome many of these difficulties though the authors would still recommend that the SI40 IOL with PMMA haptics is used. • A lens which unfolds slowly and which is made from a material that causes minimal capsular contraction such as the AcrySof MA60 (Alcon) is ideal (Fig. 21.15). The lens is positioned with haptics at right angles to the break in the rhexis. • If there are doubts about the status of any rhexis rim break, implant the IOL into the ciliary sulcus any IOL of sufficient length (greater than 12.5 mm) will suffice. The lens optic can then be pushed into the bag to give best stability. Postoperatively The majority of these patients have a normal postoperative course, they are placed on whatever the surgeon usually prescribes as medication. These eyes are probably more likely to exhibit corneal disturbance on the first postoperative day as greater intraocular manipulation than usual has been necessary.

Inderjit Singh

Phacoemulsification in Difficult Cases

22

INTRODUCTION Phacoemulsification cataract extraction has come a long way since the late 60s. There has been a considerable improvement in technique and in the equipment we use. Advances in software programs that allow the equipment to respond more intelligently and more precisely have also made the procedure safer. Phacoemulsification cataract extraction in routine cases can be difficult enough because conditions can change very rapidly which the surgeon has to consciously try to control. The technique becomes even more difficult to do in some situations which would be considered as difficult cases or challenges that the surgeon will meet at times. It is very important to have mastered a very structured and precise technique to be able to successfully operate on these challenging cases with minimal complications. The routine phacoemulsification technique a surgeon uses must be adaptable enough to use in these challenging cases without any major change. General Considerations The incisions used in these challenging situations can either be a clear corneal self-sealing wound or a scleral tunnel self-sealing wound. A two-ended technique is advocated for the phacoemulsification. In spite of a number of new techniques for the phacoemulsification itself, the technique that is most predictable, precise and repeatable is some form of nuclear divide and conquer. It is important to minimize the excursion of the phaco tip in these cases and of all the various techniques, the split and lift technique is probably the most useful (Fig. 22.1). This technique allows the phaco tip to work within a small

224

THE ART

OF

PHACOEMULSIFICATION

Fig. 22.1: A phacoemulsification technique suitable for “difficult” cases

Fig. 22.2: Safe zone phacoemulsification. Note position of safe zone

safe zone area (Fig. 22.2) and is particularly useful in small pupil phacoemulsification. In summary, the split and lift technique has several distinct advantages. • It is a bimanual method which gives more control of the nuclear pieces. • The phacoemulsification is done in the safe zone. • Phacoemulsification is done within the capsular bag. • It is very useful for a hard nucleus. • It is very useful in situations where the pupil is extremely small. The essence of the technique Fig. 22.3: Split and lift phaco technique. Note quadrant here is to move the nucleus into control and safe zone phaco the safe zone and split the nucleus into four quadrants. Each quadrant is then lifted from its apex into the phacoemulsification tip. The second instrument is used for quadrant control and if need be for a phaco chop to further divide the quadrant (Fig. 22.3).

PHACOEMULSIFICATION

IN

DIFFICULT CASES

225

In all the situations the smaller the phaco tip the more control there is within the eye and it also affords much better visualization within the eye of all the tissues. It is strongly recommended in these situations to use a microtip whether it is straight or curved. The microtip has a diameter of 0.9 mm compared to the larger tips of 1.1 mm. The port size is decreased by 48% and presents a larger metal surface. This improves efficiency in cutting by increased cavitation. The smaller port also decreases surge and minimizes collapses of the anterior chamber (Fig. 22.4).

Fig. 22.4: Curved micro tip for phacoemulsification. Tip is 0.9 mm diameter. Bent tip more efficient

Hydrodissection of the nuclear cortex from the capsular bag is the most underrated step in the whole procedure. Note that hydrodissection is at multiple points (Fig. 22.5A). Both the cortical layer and nucleus is separated from the capsular bag, so that both the perinuclear cortex and nucleus are easily rotated within the bag. Easy rotation causes the least amount of zonular stress and allows the nuclear material to be brought into the phaco tip (Fig. 22.5B). Irrigation and aspiration of the cortical matter is done as per routine cases, however in most of these situations in challenging cases, the subincisional cortex is Fig. 22.5A: Multiple point hydrodissection the most difficult to remove and in these situations it is highly recommended to use some form of a curved tip, preferably a 90o tip which has been found to be most helpful (see Section on Small Pupils).

226

THE ART

OF

PHACOEMULSIFICATION Difficult Cases Difficult cases would include the following commonly met challenging situations: small pupil, hard nucleus, white cataracts, pseudoexfoliation, traumatic cataract, and miscellaneous other conditions, e.g. high myopia, deep set eye, postvitrectomy eye, and patient with spinal deformities. SMALL

Fig. 22.5B: Two instrument nucleus and perinuclear cortex rotation

• • • • • •

PUPILS

Small pupils in repeated studies have been shown to be the number one cause of complications in cataract surgery. Conditions that are commonly associated with small pupils include.

Patients on chronic miotics Pseudoexfoliation with or without glaucoma therapy Small pupils associated with posterior synechiae Chronic uveitis Iris trauma Horner’s syndrome. Small pupils are usually defined as a pupil of less than 4 mm. A very small pupil would be anything between 2 mm and 3 mm (Fig. 22.6). The problems that we face with a small pupil are the esthetics of the pupil postoperatively and an attempt to maintain some pupillary function as this can be a problem with glare postoperatively. The difficulty that the phacoemulsification surgeon meets with the small pupil include. • Poor visualization which results in poor stereopsis especially posterior to the pupillary margin. • Difficult anterior capsulorrhexis. • Possible damage to the iris and iris pigment epithelium • Inadvertent zonulolysis especially in patients with pseudoexfoliation. • Tears in the anterior and posterior capsule not easily visualized during surgery. These tears can lead to the nucleus being dislodged into the vitreous. Pupils that are damaged during surgery end up being distorted and eccentric (Fig. 22.7). The main problems with distorted pupil include glare disability and problems with esthetics of the pupil.

PHACOEMULSIFICATION

IN

DIFFICULT CASES

227

Fig. 22.6: Small pupil with posterior synechiae. On long-term miotics

Fig. 22.7: Iatrogenic distorted pupil. Note the exposed edge of IOL

Pupil Enlarging Surgery There have been many methods through the decades to overcome small pupils. • Keyhole iridectomy was the only method used particularly or extracapsular cataract extraction (ECCE). • Iris sphincterotomies. • Iris sutures • Modified iris tucking maneuvers. • Modified radial iridotomies.

228

THE ART

OF

PHACOEMULSIFICATION

All the above methods have distinct disadvantages which included distorted pupil and increased bleeding from the pupillary edge during surgery and postoperatively. Theoretically there is an increased breakdown of blood-aqueous barrier causing increased inflammation and increased instances of cystoid macular edema (CME). Some of these methods also required suturing of the cut pupils and this would involve extramanipulation with added risk of retraction syndromes. These methods also do not work very well on very small pupils (Fig. 22.8).

Fig. 22.8: Sutured keyhole iridectomy. Note trauma to iris tissue

Pupilloplasty Surgery These methods involve using specially designed sutures that require multiple passes through the eye. Some of these methods also require sclerotomy. Again this method involves considerable manipulation of the iris tissue. Iris Retractors A number of iris retractors have recently come onto the market to keep the pupil enlarged. These include the following: De Juan flexible iris retractors (Grieshaber, Switzerland) Mackool iris retractors (Storz Instruments, St. Louis, Missouri) (Figs 22.9 and 10). There are a number of problems that can occur with the use of the iris retractors. The proper placement of the paracentesis for these iris retractors is very important and the pupil has to be enlarged in a gradual and controlled fashion to prevent complications. The complications can occur with the use of iris retractors and include: (i) movement of the iris too anteriorly which can result with the

PHACOEMULSIFICATION

IN

DIFFICULT CASES

229

Fig. 22.9: Iris retractors for small pupil phaco

Fig. 22.10: Iris retractors. Note the number of retractors that may be required

phacoemulsification tip and instruments, (ii) the tendency to create a scaffold of iris tissue can occur if the corneal entry site hooks are too long, (iii) thermal or mechanical injuries can occur to the iris if the iris is moved too anteriorly by the retractors, (iv) tenting of the iris can occur intraoperatively if the position again is incorrect, and (v) too rapid a dilatation of the pupil may cause tearing of the pupillary sphincter.

230

THE ART

OF

PHACOEMULSIFICATION

Fig. 22.11

Fig. 22.12

Fig. 22.13

PHACOEMULSIFICATION

IN

DIFFICULT CASES

231

Figs 22.11 to 22.14: Graether pupil expander (Eagle vision, Memphis Tennessee). Note: the strap engages the pupillar y margin and keeps the pupil enlarged. The phaco tip is passed over the strap bridging the gap in the ring

Pupil Stretching Devices These are appliances that can be temporarily placed inside the eye to stretch the pupil, such as: • Hydroview Iris Protector Ring (Escalon-Trek Medical, Skillman, New Jersey). • Graether Pupil Expander (Eagle Vision, Memphis, Tennessee) (Figs 22.11 to 14). These external appliances, however, are not without their problems and possible complications. They take time to apply and because of the increased instrumentation within the eye, may cause endothelial damage. There is also significant increase in the manipulation of the iris to apply these devices successfully. Pupil Stretching Techniques Several methods have been described to stretch a pupil in order to enlarge it. Currently pupil stretching techniques are possibly the safest and most easily applied techniques for enlarging the pupil. The advantage of this technique is very small pupils with dense posterior synechiae that can easily be enlarged with this technique. This technique can also be combined with small partial sphincterotomies at the pupillary margin, especially in those small pupils that have got dense fibrotic rings. The instrumentation that is required for this technique is now fairly simple and they include push/pull iris manipulation hooks, e.g. Kuglein hooks, the Graether Iris Collar buttons (Storz Instruments, St. Louis, Missouri). In a very small fibrotic pupils where sphincterotomies are required, intraocular scissors that have blades that can be rotated around 360 degree axis can be used, e.g. Sutherland scissors (Grieshaber, Switzerland) (Figs 22.15 to 17). It is also very important to use a very retentive type of viscoelastic material which by itself can act as a tamponade to keep the pupil enlarged, e.g. Viscoat (Alcon, Fortworth, Texas). It is not necessary to stretch the pupil in several directions. In most instances stretching from 6 to 12 O’clock is more than sufficient, however where there are numerous posterior synechiae a horizontal stretching in the 3 to 9 O’clock

232

THE ART

OF

PHACOEMULSIFICATION

Fig. 22.15: (Fine) Application of the scissors to the pupillary margin

Fig. 22.16: (Fine) Pupil after eight partial sphincterotomies

Fig. 22.17: Sutherland scissors

direction may also be required. In this situation a second paracentesis port on the opposite side is very useful (Fig. 22.18). Finally, these pupil stretching techniques can be done under topical anesthesia. It is important not to stretch the pupil all the way to the iris roots but only about two-third of the iris tissue. Anterior Capsulotomy The advantages of CCC have been described. CCC can be achieved even in small pupils. A smooth capsulorrhexis border can be made slightly larger than the small pupil by guiding the tear under the iris, at the same time observing the fold at the edge of the capsule flap. It is important that the width of the base of the triangle formed between the folded capsular flap, the pupillary margin and the apex tear can be observed carefully in order to judge how far the edge of the tear is behind the pupil. The larger the base of the triangle formed by the edge of the pupil, the farther to the periphery is the edge of the tear (Fig. 22.19).

PHACOEMULSIFICATION

IN

DIFFICULT CASES

233

Fig. 22.18: Use of Kuglein hooks to enlarge small pupil

Another method of judging where the tear is occurring behind the pupil is to use a collar-stud button or a Kuglein hook to stretch the pupil in the quadrant of the advancing tear. It is important that the tear is not made excessively large and, in fact, it is prudent to make the initial capsulorrhexis smaller than one would ideally want to in a large pupil phacoemulsification. A secondary capsulorrhexis can be done if the original size of the capsulotomy was too small. This can be achieved by making a snip on the edge of one side of the capsulorrhexis and using a capsulorrhexis forceps to tear off a ribbon of the capsule, enlarging the opening of Fig. 22.19: Small pupil capsulorrhexis. the capsulorrhexis. Note circular tear is behind pupil If too small a capsulorrhexis is made it can end up postoperatively with a small fibrosed capsular opening. This can lead to subluxation of the IOL. This problem is most evident in cases of pseudoexfoliation (Fig. 22.20).

234

THE ART

OF

PHACOEMULSIFICATION

Fig. 22.20: Excessively small CCC causing capsular phimosis and contraction

Hydrodissection Hydrodissection is possibly one of the most important steps in the entire procedure as unless the nucleus is easily rotatable the rest of the phacoemulsification becomes virtually impossible. This is particularly true in small pupil phacoemulsification where the quadrants have to be manipulated to a zone which is not only safe but easily visible. Hydrodissection would be noted to be complete once there is anterior movement of the lens-iris-diaphragm with egress of viscoelastic. There is enlargement of the pupil with this maneuver. If necessary, it is important that the rotation of the lens is checked using two hooks prior to the insertion of the phacoemulsification tip. Phacoemulsification As discussed earlier, it is important that safe, repeatable maneuver for phacoemulsification is used. It is recommended that a form of split and lift technique be used where the nucleus is divided into four quadrants and each apex of the quadrant is then lifted in the central safe zone of the pupil for phacoemulsification. Cortical Clean-up Cortical clean-up using an irrigation/aspiration cannula is undertaken. It is important that the port of the cannula be always visible to the surgeon. The cannula must be placed deep in the capsular bag to prevent any incarceration of the iris. To deepen the capsular bag it may be necessary to raise the height of the irrigating solution bottle.

PHACOEMULSIFICATION

IN

DIFFICULT CASES

235

The individual quadrants of the pupils can be retracted using a second instrument and the cortex grasped with the cannula and aspirated once the cannula is brought into view within the pupillary area. The port of the cannula must be rotated superiorly before full aspiration is undertaken. The most difficult area to remove cortex, especially in small pupils, is the subincisional cortex. The problems include overhanging of the pupillary margin and the anterior capsulotomy edge. A two-instrument technique is used here whereby a 90 degree curved I/A cannula (Alcon, Fortworth, Texas) is used with retraction of the iris superiorly using a second instrument (e.g. Kuglein hook). It is important that the anterior chamber, especially the capsular bag, is kept well inflated in order the 90 degree I/A tip clears both the pupil and the anterior capsular edge before any aspiration is actually done of the subincisional cortex (Fig. 22.21).

Fig. 22.21: Varieties of I/A tips. Angled 90o tip is useful for subincisional cortical removal

A second method is to use an aspiration cannula through the side port incision and irrigating cannula placed in the cataract incision. Postoperatively the stretched pupil appears round and is cosmetically very acceptable. It is only with magnification can notches on the pupillary margin be seen. The added advantage of this technique is that most of these pupils are still functioning pupils (Fig. 22.22). Discussion There is no doubt that a small pupil presents a significant challenge to the cataract surgeon. Phacoemulsification is probably the method of choice in dealing with patients with small pupils. It is imperative that any pupil measuring less than 3 mm would require some pupil enlarging surgery. However, this can be minimized by using the pupil stretch technique or some modification of that method. This enables the phacoemulsification to be done in the bag and the IOL inserted well within the bag and minimal postoperative complications with glare and with an acceptable cosmetic result and a round pupil.

236

THE ART

OF

PHACOEMULSIFICATION

Fig. 22.22: Post implant small pupil phaco. Note notches on pupil margin from the use of Kuglein hooks to enlarge the pupil. Pupil is still round in appearance

MATURE

HARD

NUCLEUS

In the hard nucleus the surgeon is faced with several difficulties • Poor red reflex • A thin atrophic capsule • Physical hardness of the nucleus • A large nucleus which is enclosed within the anterior and posterior capsule with little or no perinuclear cortex • Fusion of the nucleus and cortical matter and an elastic cortical plate (Fig. 22.23).

Fig. 22.23: Mature hard nucleus cataract. Note very minimal cortex

PHACOEMULSIFICATION

IN

DIFFICULT CASES

237

Technique The first problem the surgeon is going to meet is a poor red reflex, particularly if the eye is darkly pigmented. The anterior capsule is very thin and atrophic and is likely to be on a stretch which can lead to the capsular tear running out to the periphery of the capsular bag. It is imperative that the anterior chamber is kept deep all the time and a retentive viscoelastic that is going to allow a smooth capsulorrhexis but at the same time being retentive has to be used. A combination viscoelastic is probably the best in this sort of situation, e.g. Duovisc (Alcon, Fortworth, Texas). In most instances it is possible with minor movements of the eye to view the edge of the capsulorrhexis tear as it is reflected by the microscope light. In some situations staining techniques of the capsule may be required and this will be discussed in further detail when white cataract phacoemulsification is discussed. It is important that a sufficiently large capsulorrhexis is made in order that the phacoemulsification tip does not inadvertently hit the capsular edge. The best phacoemulsification technique is still some form of divide and conquer, preferably dividing the lens into four quadrants and then engaging the apex of each quadrant and phacoemulsifying the quadrants deep in the capsular bag furthest away from the corneal endothelium. A phaco-chop maneuver of each quadrant can also be combined with this technique. Once the nucleus is cracked it allows easier access to each quadrant to carry out the phaco-chop. A 45-degree tip is used as it gives much better cutting power. It is important not to move the dense hard nucleus excessively and thus to minimize the movement, a shaving maneuver is used with the phacoemulsification tip. It is not advisable to engage the nucleus in any large chunk but to gradually trench the nucleus by shaving the surface and going deeper in that manner. It is important to be very patient in this technique as it will take time to achieve a deep enough trench. The depth of the trench can be judged by a white leathery reflex from the thick cortical plate. Once this reflex is obtained, cracking of the nucleus can then be undertaken. It is important also that when the cracking is done that all fibrotic bridges between the pieces are also broken. Any fibrotic bridge left will make it extremely difficult to manipulate the quadrants into the phacoemulsification tip. For further protection of the capsule it is possible to use viscoelastic as a pseudocortex and by injecting viscoelastic between the nucleus and the posterior capsule (Fig. 22.24). There should be free usage of the second instrument to stabilize the nucleus and the nuclear fragments in quadrants to prevent tumbling which might not only rupture the posterior capsule but also cause traumatic injury to the corneal endothelium. MATUR E

WHITE

CATARACT

The problem the surgeon faces in this sort of situation is that the white fluffy cortex obscures a clear view of the capsule. The capsule itself is thin and stretched and it is usually difficult to tell what type of nucleus lies within the capsular bag. The nucleus could be very dense or small and partially absorbed or large

238

THE ART

OF

PHACOEMULSIFICATION

Fig. 22.24: Splitting of hard nucleus. All bridges between pieces must be broken by wide separation of the pieces

and flaky (Figs 22.25A and B). Once must also note that there is no epinuclear cortex to cushion the capsular bag. In general terms if the capsulorrhexis can be done then the phacoemulsification can be done. Capsulorrhexis Capsulorrhexis is the main problem as there is hardly any red reflex. Some steps that can be taken to minimize the chances of a poor capsulorrhexis is to use high magnification, have a very darkroom, start the capsulorrhexis in definite steps in the central portion of the capsule first. If the cortical “milk” starts to obscure the view of the tear then this can be flushed out or pushed to one side with the viscoelastic. Keep looking for the edge of the fold which is more easily seen as a linear reflex in the microscope light. Again, in this situation do not attempt to do too large a capsulorrhexis, in fact, err on the side of a small capsulorrhexis which can be extended if need be once the IOL has been inserted in the bag. Other Techniques of Visualization of the Anterior Capsule Other techniques that can be used are by • Using a retinal endoilluminator held outside the eye to enhance sclerotic scatter and therefore give a clearer view of the capsule. • To use various dyes and stains. Currently ICG has been described as being very successful in this technique. A few drops of dilute ICG are massaged onto the anterior capsule under air initially. The air is then exchanged and replaced with viscoelastic. Initially the capsule does not appear to be very easily seen but once a tear is made the dye enhances the edge of the torn capsule and it can be seen very easily.

PHACOEMULSIFICATION

IN

DIFFICULT CASES

239

Figs 22.25A and B: Mature white cataract. Liquid cortex. Flaky, friable nucleus

Other dyes that have been described as being useful are gentian violet and methylene blue, trypan blue (Melles et al: JCRS 25:7-9, 1999). Hydrodissection Do not forget that there is no epinucleus to cushion the wave of fluid so hydrodissection has to be done very carefully. Also the nucleus can be small, hard and partially absorbed and this can float around the anterior chamber. Phacoemulsification The phacoemulsification in the vast majority of these white cortical cataracts is quite easy as the nucleus is usually very chalky and friable. However in some

240

THE ART

OF

PHACOEMULSIFICATION

instances in the hard, partially absorbed nucleus this may have to be prolapsed into the anterior chamber to successfully phacoemulsify. Under these circumstances it is important that the corneal endothelium has been assessed in detail before any phacoemulsification in the anterior chamber is attempted. PSEUDOEXFOLIATION

SYNDROME

(PES)

The increased risk of cataract surgery in patients with pseudoexfoliation is well known. Potential causes of this increased risk include inadequate pupillary dilatation and a tendency for weak zonular attachment. There has also been recent articles which point to a significantly higher incidence of complications in patients with PES. Complications include zonular dialysis, posterior capsule rupture, an increased fibrinous reaction with posterior synechiae and IOL cell deposits. There is also a finding of increased postoperative inflammatory response in patients with PES. These studies have also found an impaired blood-aqueous barrier in these patients. Considering all the above it is important that the cataract surgery itself goes as smoothly as possible with minimum amount of trauma to tissue. The most pressing problem intraoperatively is one of loose zonular attachments. The important features pointing to weak zonular attachments intraoperatively include the following: a very fine powder-like deposits instead of flaky-like deposits on the anterior capsule; excessive folding of the anterior capsule as the capsulorrhexis is being done; excessive give in the capsular equator as irrigation aspiration is being done. If there is any concern that the zonules are loose then the options to the surgeon include the following • Place the IOL implant in the sulcus on top of the capsular bag (Fig. 22.26A). • Use a capsular tension ring, e.g. Morcher ring. These rings help to stabilize the lens in the capsule. The ring will spread out the capsule and distribute zonular force at the equator. In fact these rings act as pseudozonules. The ring itself can be put in the capsular bag at any time during the surgery and currently there are several injectors, e.g. Geuder Shooter which is used fairly successfully in placing the rings in the bag without difficulty. Capsulorrhexis It is always wise to start the capsulorrhexis away from the weak zonular zone. The initial zonular tear has been found to be the most stressful on the zonules and if a quadrant of capsule can be identified as having weak zonules. If an area of capsule can be identified as having weak zonules the capsular tear should be started 180° away from this area. Phacoemulsification In these situations where the zonules are weak it is important that not too much flow of fluid be going to the eye as this might cause further rupture of zonules and vitreous prolapse. It is imperative that the power of the phacoemulsification

PHACOEMULSIFICATION

IN

DIFFICULT CASES

241

Fig. 22.26A: Pseudoexfoliation syndrome (PES). Weak zonules, IOL placed in sulcus

Fig. 22.26B: Late dislocation of IOL and capsular bag in PES

machine is increased but the flow within the eye is decreased. It is also important that the bimanual technique of phacoemulsification be used to help stabilize the cataractous lens. In summary, the key features in this type of case are • Proper placement of incision • Low flow phaco • High phaco energy • Use capsular tension ring.

242

THE ART

OF

PHACOEMULSIFICATION

Intraocular Lens Type As pseudoexfoliation syndrome tends to have a much more pronounced inflammatory response, currently the lens of choice would be an acrylic implant, e.g. AcrySof (Alcon, Fortworth, Texas). This has been shown to cause the least amount of postoperative fibrotic metaplasia of the lens capsule which therefore minimizes the possibility of capsular contraction. Capsular contraction can occur many years down the track and cause dislocation of the IOL implant within the bag itself (Fig. 22.26B). The alternative of course is to use an anterior chamber lens or a sutured posterior IOL implant. TRAUMATIC

CATARACT

The most significant problem the surgeon will face with a traumatic cataract is one of loose zonules or partially subluxated cataracts. Associated with this there could also be other tissue abnormalities including dialysis of the iris root (Fig. 22.27). It is important that the surgeon attempts to minimize any further loss of zonules and therefore minimize the chance of vitreous prolapse into the anterior chamber. The clinical situation within the eye itself might be a contraindication of phacoemulsification which the surgeon has to make a very careful judgement on. If a wrong decision is made and there is substantial loss of zonular fibers then there is the possibility of the loss of the nucleus into the vitreous cavity or the lack of any support for foldable IOL implant.

Fig. 22.27: IOL Implantation in traumatic cataract. Note iris root dialysis and weak zonules

PHACOEMULSIFICATION

IN

DIFFICULT CASES

243

Technique The placing of the incision is important in this situation and the placement should be avoided over the weak zonular area as the constant flow of fluid over this is usually maximal and also the constant placement of instruments into the eye can lead to further stretching and damage the zonules and cause vitreous prolapse. A low flow technique should be used coupled with a high phaco energy to minimize the amount of fluid within the eye and also minimize the amount of movement of the lens capsule complex in doing the phacoemulsification. A large capsulorhexis should be attempted again to minimize the amount of capsular movement during phacoemulsification. In all the situations it is advisable to use a Morcher ring to stabilize the capsule. A two-handed phaco technique is advisable. Capsulorrhexis The capsulorhexis itself should be started toward the weak zonular zone. The initial capsular tear is usually the most stressful to the zonules. The circular portion of the capsulorrhexis causes the least amount of tension on the zonules Phacoemulsification Before phacoemulsification proper, hydrodissection of the nucleus and capsulorrhexis must be done and free rotation of the lens must be obtained. Phacoemulsification is best done using a bimanual method in order that the cataract can be stabilized with a second instrument. The cataract itself is usually fairly soft and easy to phacoemulsify and requires very minimal amount of energy. However, if it is a hard cataract a large capsulorrhexis must be done in order that the phacoemulsification can possibly be done at the iris plane rather than in the capsular bag. In all these circumstances a very retentive type of viscoelastic, e.g. Viscoat (Alcon, Fortworth, Texas) should be used (Fig. 22.28A). Successful outcomes using this technique can be achieved even when there is more than 4 to 6 O’clock hours of zonular loss (Fig. 22.28B). Miscellaneous Cases High Myopia Patients undergoing cataract surgery who are also highly myopic and have a large axial length present with a special problem of a very deep anterior chamber as soon as the phacoemulsification tip is put into the eye. It is important that a short incisional tunnel to minimize the amount of striae. This should be done even if at the end of the procedure one has to use a suture to keep the incision water-tight. Low flow, high energy phaco is ideal in this situation. Of course in these patients there is also the possibility that there are weak zonules and again the use of a capsular tension ring, e.g. Morcher ring, should be considered. If the anterior chamber deepens excessively then it might be necessary to prolapse the nucleus into the anterior chamber and to phacoemulsify

244

THE ART

OF

PHACOEMULSIFICATION

Fig. 22.28A: Dense mature cataract with weak zonular region

Fig. 22.28B: Successful IOL implantation. Note large area of absent zonules

in the anterior chamber. This should be done under good retentive viscoelastic, e.g. Viscoat, and also prior assessment of the corneal endothelium is important. POSTVITRECTOMY

PATIENTS

These patients present with very similar problems to the high myope patients and present with a deep anterior chamber, usually a very brunescent cataract and a small pupil. They also, not uncommonly have some damage to the zonules.

PHACOEMULSIFICATION

IN

DIFFICULT CASES

245

Those that already have silicone oil or have the possible potential of having silicone oil used in the future, the type of IOL is important and currently acrylic implant is probably the best to be used in these patients. Other miscellaneous cases include patients with spinal deformities. These are handled by making the patient comfortable first and the surgeon then adapts his or her position to the patient’s position. It is not always necessary to have the patient lying flat to do a phaco cataract extraction (Fig. 22.29). SUMMARY As the surgeon’s expertise increases, these challenging cases can become more and more routine. It is very important that the surgeon is patient in handling these cases. A sound confident phaco technique is mandatory before attempting these more difficult cases. It is also important that the routine phaco technique the surgeon uses is also used for these difficult cases—thus the advantage of a two-handed phaco technique.

Fig. 22.29: Marked kyphoscoliosis patient unable to lie flat

246

THE ART

OF

PHACOEMULSIFICATION

Keiki R Mehta Cyres K Mehta

Irrigation and Aspiration Following Phacoemulsification

23

INTRODUCTION The procedure of irrigation/aspiration refers to removal of the remaining soft cortical residue from the anterior chamber following nuclear removal. It is completed within the capsular bag at all times and is a closed chamber system. If the hydrodissection procedure has been carried out properly, the quantum of cortical residual material will be very minimal. The cortical material lines the bag and care needs to be exercised that during the removal phase the capsule is not inadvertently sucked into the aspirating port. Complete removal of the cortex leaves a perfectly clean chamber and minimizes the chances of postoperative inflammation on the day following the surgery. The functional recovery is much assisted and posterior capsulotomy is delayed. Irrigation/aspiration is thought of as very simple procedure. The surgeon finishes the nuclear removal part of the phacoemulsification and then relaxes, thinking, that with the removal of the nucleus, his main work is complete. He then goes on to irrigation/aspiration to clean out the cortical residue and breaks the capsule. It is an unfortunately, widely known, but least acknowledged, fact, that more capsules are broken by the surgeon at this, so-called innocuous stage, than all the capsules broken at the nuclear removal ultrasound stage. The guidelines for safe and efficient removal of the cortical material is to progress in small steps, at a virtually constant rate. Start with aspirating the cortex in one quadrant and gradually go around till you reach the starting point. Evaluating the flow characteristics of the cortex controls the quantum of aspiration vacuum. As the aspiration vacuum is increased it reaches a level where the cortex seems to “flow” into the port. At this point, it becomes simple to remove the cortex, as one needs to only move the aspiration port gradually in a circular manner.

IRRIGATION

AND

ASPIRATION FOLLOWING PHACOEMULSIFICATION

247

Sometimes the cortex is adherent to the posterior capsule especially when the hydrodissection has not been done properly. In these circumstances it becomes important to literally strip out the capsule piece by piece from the periphery to the center, using just adequate vacuum to hold the fragment. After a number of pieces have accumulated in the center, the vacuum is increased to aspirate them out together, all at one time. It is important that the maneuvers in the anterior chamber are kept to a minimum. Irrigation/aspiration is always done at the end of the surgery and the pupil will have started to contract by this time, hence inordinate delay will lead to further problems. Thus the irrigation/aspiration should be rapid while at the same time safety should not be compromised. BASIC PARAMETERS FOR COMMENCING IRRIGATION/ASPIRATION For aspiration to be performed correctly certain parameters need to be appropriately instituted • Appropriate tip size • Appropriate vacuum should be applied • Equilibrium between inflow and outflow should be perfect • Ability to alter suction to match the material and safety • Variable progression of quantum of suction. The vacuum to be generated at the aspirating tip is dependent upon the port size of the aspiration handpiece. The larger the port size, the lower should be the total vacuum limit and vice versa. The most common and widely used size is 0.3 mm. The standard operating parameters for an aspiration port of this size would be to keep the irrigation bottles at a height of 60 cm above the patient’s eye, and the vacuum set at 350 mm Hg in the “surgeon” mode (i.e. increasing with increased foot pedal depression) with a flow rate of 15 ml/min. Irrigation/aspiration handpieces come in two types: one which is complete metal in which the tip of the irrigation/aspiration is a single piece of shining metal (usually titanium), or the second type in which the aspirating tube is metal while the irrigation fluid is conducted via a silicone sleeve. Though it is usually a surgeon’s personal preference, however silicone does have its advantages. The silicone sleeve occludes the phaco port better thus maintaining a better anterior chamber; being flexible it matches the contours of the opening and thus reduces leakage. In addition it reflects less light. It has always been a point of debate on which is the ideal port size for the irrigation/aspiration technique. The diameter of the tips available is usually 0.2, 0.3, 0.5, or 0.7 mm. The former two tips are designed to be used with maximum vacuum limits (300 to 400 mm Hg), while the latter two tips need to be used with a minimum vacuum (100 to 200 mm Hg). With the larger size ports there is always a risk of anterior chamber collapse unless the irrigation/aspiration fluidics are perfectly balanced. The 0.3 mm orifice is usually an ideal port size as there is a good balance between the inflow and outflow thus maintaining the chamber well. In addition a 0.3 mm

248

THE ART

OF

PHACOEMULSIFICATION

port would seem to be adequate for virtually all types of cortical debris. If the debris chokes the tip, a thin blade iris repositor inserted from the site port can either clean it or mash it into the port. THE IDEAL CIRCUMSTANCES FOR IRRIGATION/ASPIRATION The inflow and outflow must be balanced utilizing a flexible silicone test chamber prior to commencing surgery. The anterior chamber must remain formed and be kept deep. The pupil must be well dilated so that the I/A probe can have easy access to cortical material. There should be no source of pressure on the eye like an inappropriate lid clamp. The side and main ports should be of the appropriate size to minimize leakage. Adequate surge control facility must exist to prevent barometric changes in the chamber. The use of preservative free, intracardiac adrenaline (0.5 ml of 1/1000 adrenaline) injected into 500 ml of BSS has the ability to retain sufficient dilatation, and prevents the pupil from shutting down. THE BASIC SURGICAL PRINCIPLES OF CONDUCTING PROPER IRRIGATION/ASPIRATION Irrigation/aspiration can be conducted in many ways. However all the methods can be condensed into a simple basic technique, which is used at all times. Enter the anterior chamber using only irrigation, so that the chamber deepens, the capsular bag opens up, and the cortical remnants are easily available, and accessible, for removal. The aspirating port is then taken close to the material to be aspirated, only at this stage the suction is activated by the foot switch, which raises the vacuum so that the orifice becomes obstructed by the cortical material. The tip is moved towards the center of the chamber gently separating the cortex fragments. In the center of the anterior chamber, vacuum is enhanced so as to quickly aspirate the larger cortical clumps, which are free floating in the chamber. Each time aspiration is turned on and off with irrigation running, there are fluidic chamber changes. There is an alteration in the fluid balance of the anterior chamber in this process. When the cortical piece is attracted to the tip, the piece adheres to it, and then as the suction builds up, it is suddenly sucked in, producing surge. Unless the inflow is adequate the chamber is likely to collapse with dire consequences. Many phacoemulsification instruments have computerized surge controls (Alcon Legacy, Storz Millennium. Allergan Sovereign), automatically alter the speed of suction (by altering the speed of the peristaltic pump, in the Alcon and Allergan unit and the speed of the rotor in the Storz unit) to diminish or even eliminate this surge. In some instruments (Like the Opticon and the Mentor units) the use of the flexible diaphragm compensates effectively for the variation. As one analyzes the depth variants of the anterior chamber it becomes obvious that a great deal depends on two inputs, namely, the quantum of inflow and the quantum of fluid outflow. Inflow is dependent upon the diameter of the tube leading into the anterior chamber, the diameter of the connections and the size of the inflow

IRRIGATION

AND


249

ports. It is equally dependent upon the pressure, which is generated by the height of the bottle. The outflow is naturally dependent upon the size of the outflow port in the irrigation/aspiration handpiece, the quantum of vacuum or suction applied to the tip, the diameter of the vacuum tubing, and the firmness or stability of the walls of the tubing. There is also a certain amount of fluid loss, which occurs from leakage from the sides of the main and side port incisions. One always has to remember that the basic rule of aspiration namely that cortical material should be captured from the periphery and then subsequently drawn to the middle of the anterior chamber and then, and only then, by a burst of vacuum power, aspirated. The novice often tries to maintain a constant vacuum level which may at times lead to accidental aspiration of the capsule in the aspirating port leading to a capsular tear. There is another important rule that the aspirating orifice of the instrument must always be visible to the surgeon. This prevents accidental snagging and tearing of posterior capsule. In the event of an accidental miosis, though it is in order to go under the iris in a blind maneuver to hold the cortical fragments. However the fragments should be gently pulled outwards to the center of the pupil, at the same time visualizing the posterior capsule to be sure that no striae appear which would indicate that the capsule has been snagged. RECOGNITION OF POSTERIOR CAPSULE CAPTURE It is imperative during irrigation/aspiration that the surgeon recognizes immediately when the capsule inadvertently, has been captured in the aspirating port. It is important that when irrigation/aspiration is commenced, the focus of the microscope is changed so as to produce a sharp focus onto the posterior capsule, and the position of the eye with relation to the coaxial tube of the microscope be so adjusted so as to achieve the best possible red glow. If the focus is fixed on the posterior capsule the surgeon will realize immediately that the capsule is sucked into the port (captured) when thin and fine lines of folds, termed striae start from the point of capture with radial extensions. The appearance is very suggestive of a sunray appearance. If the capsule is caught in the middle it is easy to note that it has taken place, however if it is caught in the periphery, identification may prove difficult. The accidental capture of the posterior capsule is much easier and more frequent with the larger size ports like the 0.5 or the 0.7 mm size but comparatively less frequent with the smaller 0.2 or 0.3 mm ports. It is important that the moment capture is recognized the surgeon should immediately reverse fluid outflow to release the capture without moving the aspirating tip. Capturing the posterior capsule does not break the capsule (provided the port is smooth and well polished). It is the movement of the aspirating tip once the capture has occurred which breaks the capsule. Thus care should be taken that once the capture is detected, to freeze movement, stop aspiration and break the suction. Some of the better phacoemulsification machines are fitted with active venting capability, which permits an immediate break of vacuum with a positive outflow,

250

THE ART

OF

PHACOEMULSIFICATION

which literally sweeps the posterior capsule away from the aspirating port. It is important that the surgeon is familiar with the controls and adapts himself to it so that at the critical time he does not fumble with the foot controls. Another quick technique to release the adhesion is to simply squeeze on the aspirating plastic/ silicone tube with the thumb and the forefinger, which also acts as an active venting technique. Care should however be taken to note that this technique will not work with the high vacuum tubing is available in such machines like the Alcon Legacy and the AMO Diplomax as the thickness of the tube is such that it simply does not get squeezed. It may be pertinent at this point to explain the principle of the flow rate setting on the phacoemulsification machine. Despite the volumes that have been written on the subject, a simple way of remembering is that flow rate settings controls the speed at which you work in the chamber. A slow flow rate (10 to 20 ml/min) means that it takes a much longer time to develop the level of vacuum you desire, while a fast flow rate (20-40 ml/min) indicates a very rapid onset of the suction. A good medium flow rate is 15 ml/minute. Whenever in doubt, slow down the flow rate and you will rarely get into trouble. ASPIRATION VARIABILITY FOR SUBINCISIONAL CORTEX REMOVAL One of the problems faced by both the novice and the experienced surgeon is the problem of removal of subincisional cortex. Customarily it tends to occur as the surgeon has, as one would say, “painted himself into the corner”, by removing the larger, easier to reach pieces first, leaving the removal of the subincisional cortex to the end. Usually the small clump left strenuously resists any efforts for its removal. Techniques for Subincisional Cortex Removal As a primary requirement the irrigation bottle should be raised a little higher so as to deepen the anterior chamber. The Ice-cream Scoop Maneuver The irrigation/aspiration handpiece should be inserted with only the irrigation on. The handpiece is then lifted 30 degrees vertically in an arc. The aspiration is energized, keeping a sharp lookout on the posterior capsule; the aspiration is gradually increased till the subincisional cortex pieces simply float out. The Bimanual Technique Go from the side port incision in a bimanual (two-handed) technique. Here we use two handpieces each with an individual, single function, either irrigation or aspiration. Hold the irrigation handpiece in the right hand, and the aspiration handpiece in the left hand. Enter via the side port and then gradually insinuate the aspirating needle under the capsule and simply draw out the offending cortical material. Alternate techniques such as the bent cannula (Binkhorst) are not as

IRRIGATION

AND


251

convenient. Various shaped cannulas have been developed with bends at strategic locations but the bimanual technique is the simplest and works exceptionally well. Many reputed surgeons do bimanual irrigation/aspiration as a routine technique with all their cases. The IOL Sweep Technique Place the intraocular implant in the eye and insert it in the bag. Fill the bag with viscoelastic and using a lens rotator, spin the IOL in the bag a few times. Very often the IOL loops will either clean the subincisional cortex out or make it so loose that it aspirates out fairly easily. IOL Compression Aspiration Technique Here after placing the IOL in the bag, simply rotate the loops away from the site of the subincisional cortex, fill the bag with viscoelastic, press on the surface of the implant with the irrigation/aspiration handpiece to deepen the chamber and push the posterior capsule backwards, energize the aspiration and the subincisional cortex will easily come out. The posterior capsule is not at risk as the IOL comes between the capsule and the I/A probe. Sometimes, in a difficult situation, the subincisional cortex simply refuses to come out, then the surgeon is left with the option that he can leave the piece behind and risk it reappearing later (usually between the 3rd and 7th postoperative days), in the visual axis, lying under or over the implant, appearing as soft, white, flocculent material appropriately termed as “cortical rain”. In this circumstance, the surgeon should re-enter the chamber through the previous phaco incision and using low suction aspirate the cortical “rain” out. It is always a fallacy to tell the patient that it will absorb by itself. It may, but by that time the patient is quite apprehensive and unhappy at the outcome of the surgery, in addition its presence leads to an irritable eye, and its absorption will invariably lead to early capsular thickening. With the present day litigious atmosphere in India, it makes more sense to simply aspirate it out. It leaves behind a happy patient and a relieved surgeon. MANAGING THE VITREOUS IN THE ANTERIOR CHAMBER Despite the best efforts of the surgeon an occasional capsular break will take place. It is important to learn how to handle this break, as its appropriate management will govern the quality of vision one will achieve. It is important that at the first sign of the break, the irrigation/aspiration handpiece be removed from the eye. If most of the cortical material has been removed it is important that first the intraocular implant be placed in the bag prior to removing the cortical residue. The logic behind this procedure is that while the bag has been unharmed the implant can easily be put in (bag fixation). In case the bag tears excessively, the implant can be put in the sulcus, i.e. on the anterior capsule (sulcus fixation).

252

THE ART

OF

PHACOEMULSIFICATION

Subsequent aspiration is best done with the use of viscoelastic (dry aspiration). Fill the chamber with viscoelastic and with the left-hand; enter via a side port, using the bimanual aspirator (no irrigation). Gradually aspirate out the fragments, refilling the bag every time the chamber shallows. The big advantage of using viscoelastic is that it compresses the capsular tear opening preventing vitreous from coming out, and at the same time opening up the bag permitting easy access to the cortical remnants. In case the capsular tear has extended, as the surgeon, inattentively, did not recognize the tear in time, it is important to do a shallow anterior vitrectomy by placing the vitrector behind the posterior level (or to put it another way, deeper than the posterior capsule) and then do a little more vitrectomy to remove the vitreous at this location. Try not swirling with vitrector to the sides, as that would then damage whatever capsule is left behind. Subsequently either under air or with the use of Healon which acts as a tamponade onto the vitreous, holding it back, the implant loops can be moved into the bag to achieve a good fixation or alternatively, achieve a sulcus fixation by placing the IOL in front of the anterior capsule. CONCLUSION Irrigation/aspiration is an important step of cataract surgery and needs to be given the full, undivided attention of the surgeon. Caution and careful evaluation of the posterior capsule will go a long way in preventing complications from developing. Most phacoemulsifiers possess positive venting abilities and good chamber maintenance with excellent fluidic ability so as to permit this procedure to be done in a rapid, controlled fashion that is efficacious, yet completely safe. FURTHER READING 1. Mehta KR: Pitfalls encountered in 1500 consecutive posterior chamber implant. All India Ophthl Soc Proc 165-66, 1986. 2. Mehta KR: Phacoemulsification cataract extraction with foldable IOLS—first 50 cases. All India Ophthl Soc Proc 56-60,1989. 3. Mehta KR: Clear corneal phaco with injectable silicone IOL proc. All India Ophthl Soc Proc (Mumbai) 1995. 4. Mehta KR: Phaco-levitation—a peaceful way. All India Ophthl Soc Proc (Chandigarh) 1996. 5. Mehta KR: Lollipop phaco cleavage—a new technique for hard cataracts. All India Ophthl Soc Proc (Bangalore) 1991. 6. Mehta KR: Phaco with flexible IOL—is it a step forward? All India Ophthl Soc Proc (Bangalore) 1991. 7. Mehta KR: SICS nonphaco—hydroexpression with an irrigating vectis. Proc of SAARC Conference, Nepal, 1994. 8. Mehta KR: Management of subincisional cortex in small incision cataract surgery (SICS). Proc of SAARC Conference, Nepal, 1994. 9. Mehta KR: Methylcellulose induced sterile endophthalmitis following phacoemulsification. Proc of SAARC Conference, Nepal, 1994. 10. Mehta KR: The new multiport phaco tip for safer, more effective phacoemulsification, with virtually zero capsular damage. Proc of SAARC Conference, Nepal, 1994.

Vijay K Dada Namrata Sharma Tanuj Dada

Foldable Intraocular Implants

24

In a few months we will celebrate the 50th anniversary of the first intraocular lens (IOL) implantation performed by Harold Ridley on November 29, 1949, at St. Thomas Hospital in London.1 In 1984 Thomas Mazzocco implanted the first foldable IOL made of a silicone elastomer.2 Foldable IOLs are the most preferred introcular lenses. According to the 1997 ASCRS survey, 79% of the respondents said they were interested in putting foldable intraocular implants.3 The growing number of foldable IOLs can be confusing. If the main chemical components are analyzed, IOL materials can be divided into two groups; acrylate/ methacrylate polymers (Table 24.1) and silicone elastomers (Table 24.2). The first group contains rigid PMMA IOLs and the so-called soft acrylic and hydrogel lenses. The second group of IOLs are made of foldable polysiloxanes.The obvious use of small incisions for cataract surgery—low induced astigmatism, fewer postoperative complications, possible less inflammation, and faster rehabilitation of the patient—have encouraged the surgeons to use foldable IOLs. Silicone as an optic material came into vogue for small incision surgery because it can be folded, has good memory, is biocompatible and suffers little surface trauma.4,5 Silicone can be folded at 3 to 9 O’ clock meridian which is a twostep implantation or 6 to 12 O’clock meridian which allows the lens to be placed in a single maneuver. Posterior capsular opacification (PCO) occurs much later with silicone as compared to PMMA IOLs since the silicone optic is much thicker than the PMMA optic and therefore allows posterior capsule to be in close contact with the posterior side of the optic.7 Optic thickness is also responsible for an increased amount of pittings on the IOLs during Nd:YAG capsulotomy. However,

Three piece Three piece Three piece Three piece One piece, plate haptic Three piece One piece One piece, plate haptic

Acrylens ACR360 (Ioptex)

AcrySof MA60BM (Alcon)

Memory Lens U940A (Mentor)

92S (Morcher)

92C (Morcher) HOHEM

Hydroview H60M (Storz)

HydroSof SH30BC (Alcon)

ISH66 (Corneal)

HEMA

HEMA

HEMA/ HOHEXMA

MMA/HEMA

MMA/HEMA

HEMA

HEMA

PMMA

MMA/HEMA

Polypropylene

Polypropylene

PMMA

Polypropylene

Haptic Material

6.0

5.5

6.0

6.0

6.0

6.0

6.0

6.0

Optic Diameter (mm)

11.00

12.00

12.50

10.50

13.00

13.00

13.00

13.65

Total Diameter (mm)

119.0

118.4

118.3

118.1

118.1

119.0

118.9

118.5

1.44

1.44

1.47

1.46

1.46

1.47

1.55

1.47

38

38

18

28

28

20

The Art of Phacoemulsification

Phacoemulsification

The Art of Fiction

Art of the Lie

The Art of Loving

The Art Of Advertising

the art of drowning

The Art of Ethan

The Art of War

Art of the Lie

The Art of Mending

The Art of Seduction

The End of Art

The Art of Rails

The Boundaries of Art

The Art of Seduction

The Art of Theater

The Art of Submission

The Art of Sport

The Art Of War

The Art of Drawing

The Art of War

The Art of War

The War Of Art

The Art of Choosing

The Art of War

The Art of Drawing

The Art of Caricaturing

The Art of Combination

The Art of Plain

The Art of Phacoemulsification

Phacoemulsification

The Art of Fiction

Art of the Lie

The Art of Loving

The Art Of Advertising

the art of drowning

The Art of Ethan

The Art of War

Art of the Lie

The Art of Mending

The Art of Seduction

The End of Art

The Art of Rails

The Boundaries of Art

The Art of Seduction

The Art of Theater

The Art of Submission

The Art of Sport

The Art Of War

The Art of Drawing

The Art of War

The Art of War

The War Of Art

The Art of Choosing

The Art of War

The Art of Drawing

The Art of Caricaturing

The Art of Combination

The Art of Plain

Recommend Documents