The Art and the Science of Cataract Surgery

I

This book was created and written by Professor Boyd at Miramar Plaza Towers, overlooking the Panama Canal, the Pacific Ocean and the city of Panama. Project Director: Andres Caballero, Ph.D Production Manager: Kayra Mejia Page Design and Typesetting: Kayra Mejia Laura Duran Art Design: Eduardo Chandeck Spanish Translation: Cristela F. Aleman, M.D. Medical Illustrations: Stephen F. Gordon, B.A. Trina Fennell, M.S. Samuel Boyd, M.D. Sales Manager: Tomas Martinez Marketing Manager: Eric Pinzon Customer Service Manager: Miroslava Bonilla International Communications: Joyce Ortega

ISBN Nº 9962-613-03-5 ©Copyright, English Edition, 2001. Highlights of Ophthalmology Int'l P.O. Box 6-3299, El Dorado City of Knowledge Clayton, Bldg. 207 Panama, Rep. of Panama Tel: (507)-317-0160 FAX: (507)-317-0155 E-mail: [email protected] All rights reserved and protected by Copyright. No part of this publication may be reproduced, stored in retrieval system or transmitted in any form by any means, photocopying, mechanical, recording or otherwise, nor the illustrations copied, modified or utilized for projection without the prior, written permission of the copyright owner. Printed:

Bogota, Colombia South America

OUTLINE OF MAJOR SUBJECTS

Chapter 1:

Surgical Anatomy of the Human Lens

Chapter 2:

Indications and Preoperative Evaluation

Chapter 3:

IOL Power Calculation In Standard and Complex Cases - Preparing for Surgery

Chapter 4:

Preventing Infection and Inflammation

Chapter 5:

Proceeding with the Operation

Chapter 6:

Phacoemulsification - Why So Important?

Chapter 7:

Preparing for the Transition

Chapter 8:

Instrumentation and Emulsification Systems

Chapter 9:

Mastering Phacoemulsification The Advanced, Late Breaking Techniques

Chapter 10: Focusing Phaco Techniques on the Hardness of the Nucleus Chapter 11:

Complications of Phacoemulsification Intraoperative - Postoperative

Chapter 12: Cataract Surgery in Complex Cases Chapter 13: Manual Extracapsular Techniques of Choice Planned ECCE - Small Incision ECCE Chapter 14: The New Cataract Surgery Developments

II

ACKNOWLEDGMENTS

All the text in this Volume has been written by the author. I am very much indebted to the Master Consultants and to all Guest Experts who are listed in this Front Section of the ATLAS. They are all highly recognized, prestigious authorities in their fields and provided me with most valuable information, perspectives and insights. The production of this ATLAS is a major enterprise. In addition to our dedicated staff at HIGHLIGHTS, three of my most valuable collaborators have been vital to its success: Robert C. Drews, M. D., as Co-Editor of the English Edition; Cristela Ferrari de Aleman, M.D., an expert in phacoemulsification who advised me in all the technical stages of the step-by-step small incision surgical procedures and Samuel Boyd, M.D., for his strong support, valuable advice derived from his expertise in all the vitreoretinal techniques related to cataract surgery. Among my closest collaborators in HIGHLIGHTS, Andres Caballero, Ph.D., the Project Director and Kayra Mejia, my editorial right hand Production Manager of many years have gone the extra mile to accomplish a very difficult task in production of this work. To each person mentioned in this page, on behalf of the thousands of readers of HIGHLIGHTS, I express my profound recognition and gratitude.

III

D EDICATION This 25th Volume of the Atlas and Textbooks of HIGHLIGHTS is dedicated to my colleagues in 106 nations worldwide who faithfully read the HIGHLIGHTS in seven major languages. May "THE ART AND THE SCIENCE OF CATARACT SURGERY" contribute to your further understanding of what is best for your patients. May it also help you to master the "state of the art" techniques in your continuous quest for the right answers. May it provide you with insights in your efforts to rehabilitate vision to millions of people who are still blind from cataract, a curable disease. "The Art and the Science of Cataract Surgery" is also dedicated to the countless ophthalmic surgeons who, through combined efforts with leaders and scientists in industry, have made of modern cataract surgery the safest and most effective major operation in the field of medicine. And, by all means, to the great innovators each of whom developed a new era for cataract surgery in their time. Symbolically, IGNACIO BARRAQUER, M.D., whose innovation of intracapsular extraction by mechanized suction in 1917 resulted in the first practical and efficient method to remove a cataract without vitreous loss. To JOAQUIN BARRAQUER, M.D., for his pioneering work in rendering ophthalmic surgery under the microscope a feasible and practical new method leading to the era of microsurgery. To CHARLES KELMAN, M.D., who, by providing us with phacoemulsification, started the new era of small incision surgery. And to HAROLD RIDLEY, M.D., the symbol of intraocular lens implantation. The recognition to the great innovators is for their ingenuity and for their courage. All innovators stimulate opposition. They all encountered strong opposition but they overcame it through their courage and results.

BENJAMIN F. BOYD, M.D., F.A.C.S.

IV

AUTHOR AND EDITOR-IN-CHIEF

BENJAMIN F. BOYD, M.D., D.Sc. (Hon), F.A.C.S. Doctor Honoris Causa Immediate Past President, Academia Ophthalmologica Internationalis Honorary Life Member, International Council of Ophthalmology Recipient of the Duke-Elder International Gold Medal Award (International Council of Ophthalmology), the Barraquer Gold Medal (Barcelona), the First Benjamin F. Boyd Humanitarian Award and Gold Medal for the Americas (Pan American), the Leslie Dana Gold Medal and the National Society for Prevention of Blindness Gold Medal (United States), Moacyr Alvaro Gold Medal (Brazil), the Jorge Malbran Gold Medal (Argentina), the Favaloro Gold Medal (Italy). Recipient of The Great Cross Vasco Nuñez de Balboa Panama's Highest National Award. Founder and Chief Consultant, Ophthalmology Center of Clinica Boyd, Panama, R.P.; Editor-in-Chief, Highlights of Ophthalmology's ten Editions (Brazilian, Chinese, English, German, Indian, Italian, Japanese, Middle East and Spanish); Author, Highlights of Ophthalmology's Atlas and Textbooks (25 Volumes); Diplomate, American Board of Ophthalmology; Past-President (1985-1987) and Executive Director ((1960-1985) Pan American Association of Ophthalmology; Fellow, American Academy of Ophthalmology; Fellow, American College of Surgeons; Guest of Honor, American Medical Association, 1965; Guest of Honor, American Academy of Ophthalmology, 1978 and Barraquer Institute in Barcelona, 1982 and 1988; Doctor Honoris Causa of Five Universities; Recipient of the Great Cross of Christopher Columbus, Dominican Republic's highest award, for "Contributions to Humanity"; Founding Professor of Ophthalmology, University of Panama School of Medicine (1953-1974); Former Dean and Chief, Department of Surgery, University of Panama School of Medicine (1969-1970); O'Brien Visiting Professor of Ophthalmology, Tulane University School of Medicine, New Orleans, 1983; Honorary Professor of Ophthalmology at Four Universities; Past-President, Academy of Medicine and Surgery of Panama; Honor Member, Ophthalmological Societies of Argentina, Bolivia, Brazil, Canada, Colombia, Costa Rica, Chile, Dominican Republic, Guatemala, Mexico, Paraguay, Peru; Recipient of the Andres Bello Silver Medal from the University of Chile for "Extraordinary Contributions to World Medical Literature."

V

MASTER CONSULTANTS JOAQUIN BARRAQUER, M.D., F.A.C.S., Director and Chief Surgeon, Barraquer Ophthalmology Center; Barcelona, Spain. Professor of Ophthalmology, Autonomous University of Barcelona, Spain. Chair, Academia Ophthalmologica Internationalis. MICHAEL BLUMENTHAL, M.D., Director, Ein Tal Eye Center, Israel. Professor of Ophthalmology, Sidney A. Fox Chair in Ophthalmology, Tel Aviv University. Past President, European Society of Cataract and Refractive Surgery. EDGARDO CARREÑO, M.D., Assistant Professor of Ophthalmology, University of Chile; Director, Carreño Eye Center, Santiago, Chile. VIRGILIO CENTURION, M.D., Chief of the Institute for Eye Diseases, Sao Paulo, Brazil. JACK DODICK, M.D., Chief, Department of Ophthalmology, Manhattan Eye and Ear Hospital, New York. Clinical Professor of Ophthalmology, Columbia University College of Physicians and Surgeons, New York. CRISTELA FERRARI ALEMAN, M.D., Associate Director, Cornea and Anterior Segment, Boyd Ophthalmology Center. Clinical Professor, University of Panama School of Medicine, Panama, Rep. of Panama. I. HOWARD FINE, M.D., Clinical Associate Professor of Ophthalmology, Oregon Health Sciences University. Founding Partner, Oregon Eye Surgery Center. HOWARD V. GIMBEL, M.D., MPH, FRCSC, Professor and Chairman, Department of Ophthalmology, Loma Linda University, California; Clinical Assistant Professor, Department of Surgery, University of Calgary, Alberta, Canada; Clinical Professor, Department of Ophthalmology, University of California, San Francisco, California; Founder and Director, Gimbel Eye Centre in Calgary, Albert, Canada. RICHARD LINDSTROM, M.D., Medical Director, Phillips Eye Center for Teaching and Research. Clinical Professor,, University of Minnesota, Minneapolis. MAURICE LUNTZ, M.D., Chief of Glaucoma Service, Manhattan Eye and Ear Hospital, New York. Clinical Professor of Ophthalmology, Mt. Sinai School of Medicine, New York. OKIHIRO NISHI, M.D., Director of Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. MIGUEL A. PADILHA, M.D., Professor and Chairman, Department of Ophthalmology, School of Medical Sciences of Volta Redonda, Rio de Janeiro. Professor, Graduate Course of the Brazilian Society of Ophthalmology and Director, Central Department of Ophthalmology, Brazilian College of Surgeons. Former President, Brazilian Society of Cataract and Intraocular Implants.

VI

CO-EDITOR ENGLISH EDITION

Robert C. Drews, M.D., F.A.C.S., F.R.C.Ophth. Professor Emeritus of Clinical Ophthalmology, Washington University School of Medicine, St. Louis, Missouri. President Elect of the American Ophthalmological Society Gold Medal of Pan-American Association of Ophthalmology; Rayner Medal, United Kingdom Intraocular Implant Society; Binkhorst Medal, American Intraocular Implant Society; Gold Medallion of the National Academy of Science of Argentina; The Montgomery Medal, Irish Ophthalmological Society; Gold Medal of the University of Rome; Gold Medal of the Missouri Ophthalmological Society. Former Chief of Surgery, Bethesda General Hospital, St. Louis, Missouri, and Former Chief of the Section of Ophthalmology, Bethesda General Hospital, St. Louis and St. Luke's Hospital, St. Louis, Missouri. Past Chairman of the Council of the American Ophthalmological Society, Former member of the American Board of Ophthalmology, and of the Board of Trustees, Washington University in St. Louis. Past President of the Pan American Association of Ophthalmology, International Ophthalmic Microsurgery Study Group, International Intraocular Implant Club, American Intra-Ocular Implant Society, Southern Medical Association, Section on Ophthalmology, Missouri Ophthalmological Society, Missouri Association of Ophthalmology, St. Louis Ophthalmological Society, St. Louis Society for the Blind, Past Vice President, American Academy of Ophthalmology. Named Lectures: the Luedde Memorial Lecturer, St. Louis University School of Medicine; Rayner Lecture, United Kingdom Intraocular Implant Society; Binkhorst Lecture, American Intraocular Implant Society; C. Dwight Townes Memorial Lecture, Louisville Kentucky; The Montgomery Lecture, Dublin, Irish Ophthalmological Society; Boberg-Ans Lecture, Copenhagen, Denmark, ESCRS; G. Victor Simpson Lecture, Washington DC; Gradle Lecture, PAAO; Joseph P. Bryan Glaucoma Lecture, Durham, North Carolina.

VII

GUEST EXPERTS

EVERARDO BAROJAS, M.D., Dean, Prevention of Blindness and Rehabilitation of Sight Society, Mexico, D.F. PROF. RUBENS BELFORT JR., M.D., Professor and Chairman, Department of Ophthalmology, Federal University of São Paulo (Escola Paulista de MedicinaHospital São Paulo), Brazil; Chair, Academia Ophthalmologica Internationalis. RAFAEL CORTEZ, M.D., Director, Ophthalmic Surgery Center (CECOF), Caracas, Venezuela. FRANCISCO GUTIERREZ C., M.D., Ph.D, Anterior Segment Surgery and Pediatric Ophthalmologist Specialist, Department of Ophthalmology, Hospital General de Segovia, Spain. Former Fellow of Ramon Castroviejo, M.D. FRANCISCO MARTINEZ CASTRO, M.D., Associate Professor of Ophthalmology, Autonomous University of Mexico. Consultant in Uveitis, Institute of Ophthalmology "Conde de Valenciana" and Seguro Social Medical Center, Mexico, D.F. JUAN MURUBE, M.D., Professor of Ophthalmology, University of Alcala and Chairman, Department of Ophthalmology, Hospital Ramon y Cajal, Madrid, Spain. DAVID McINTYRE, M.D., Head, McIntyre Clinic and Surgical Center, Bellevue, Washington. CARLOS NICOLI, M.D., Associate Professor of Ophthalmology, University of Buenos Aires, Argentina. Director, "Oftalmos" Institute. FELIX SABATES, M.D., Professor and Chairman, Department of Ophthalmology, University of Missouri, Kansas City School of Medicine, Missouri. JUAN VERDAGUER, M.D., Academic Director, Los Andes Ophthalmological Foundation, Santiago, Chile; Professor of Ophthalmology, University of Chile; Professor of Ophthalmology, University of Los Andes; Past President, Pan American Association of Ophthalmology. LIHTEH WU, M.D., Associate Surgeon in Vitreoretinal Diseases, Instituto de Cirugia Ocular, San Jose, Costa Rica. Consultant in Vitreoretinal Diseases, Department of Ophthalmology, Hospital Nacional de Niños, San Jose, Costa Rica.

VIII

CONTENTS FOCUSING AND OVERVIEW OF WHAT IS BEST Tackling the Challenges Role of Small Incision Manual Extracapsulars IOL's of Choice The Best Phaco Techniques

CHAPTER 1 SURGICAL ANATOMY OF THE HUMAN LENS CLINICAL APPLICATIONS Behaviour of Different Cataracts Anatomical Characteristics of Different Types of Cataract How Cataracts Respond Differently Incidence and Pathogenesis

5 7 7 8

CHAPTER 2 INDICATIONS FOR SURGERY PREOPERATIVE EVALUATION INDICATIONS Role of Quality of Life The Role of Visual Acuity Contrast Sensitivity and Glare Disability Contrast Sensitivity Characteristics Relation of Glare to Type of Cataract Evaluation of Macular Function PREOPERATIVE GUIDELINES IN COMPLEX CASES How to Proceed in Patients with Retinal Disease The Importance of Pre-Op Fundus Exam Cataract Surgery in Diabetic Patients Evaluating Diabetics Prior to Cataract Surgery Importance of Maintaining the Integrity of the Lens Capsule Significant Increase in Complications Following Cataract Surgery Appropriate Laser Treatment Main Options in Management of Co-existing Diabetic Retinopathy and Cataract Cataract Surgery and Age-Related Macular Degeneration RETINAL BREAKS AND RETINAL DEGENERATIONS PRIOR TO CATARACT SURGERY Cataract Surgery in Patients with Uveitis Method of Choice Diagnosing the Type of Uveitis in the Pre-Operative Phase Preoperative Management The Intraocular Lens Cataract Surgery in Adult Strabismus Patients Preoperative Judgment

11 11 11 12 13 14 15 21 21 21 21 21 24 24 25 27 28 28 31 32 32 32 33 33 33

IX

CHAPTER 3 PREPARING FOR SURGERY Making Patients Confident Patients Encounter with the Physician Ingredients of a Strong Relationship Evaluating the Patient's Cataract Approaching the Day of Surgery Patient's Expectations

37 37 37 38 38 39 39

IOL POWER CALCULATION IN STANDARD AND COMPLEX CASES

39

Postop Refractive Errors No Longer Admissible The Challenge of the Complex Cases The Most Commonly Used Formulas Main Causes of Errors Targeting Post-Op Refraction Monocular Correction Binocular Correction Good Vision in the Non-Operated Eye When Cataracts in Both Eyes IOL POWER CALCULATION IN COMPLEX CASES Specific Methods to Use in Complex Cases Practical Method for Choosing Formulas in Complex Cases High Hyperopia The Use of Piggyback Lenses in Very High Hyperopia High Myopia DETERMINING IOL POWER IN PATIENTS WITH PREVIOUS REFRACTIVE SURGERY Methods Most Often Used The Clinical History Method The Trial Hard Contact Lens Method Example as Provided by Holladay The Corneal Topography Method THE IMPORTANCE OF DETECTING IRREGULAR ASTIGMATISM IOL POWER CALCULATION IN PEDIATRIC CATARACTS Different Alternatives Alternatives of Choice IOL POWER CALCULATION FOLLOWING VITRECTOMY

40 43 44 44 45 45 46 46 46 47 47 47 47 48 49 49 52 52 53 53 54 54 54 55 55 57

CHAPTER 4 PREVENTING INFECTION AND INFLAMMATION Use of Antiseptics, Antibiotics and Antiinflammatory Agents Effective Preoperative Antibiotic Treatments Regimens Recommended Gills Formulas to Prevent Infection 1) For High Volume Cataract Surgery 2) Non-Complex, Effective and Safe Alternative for Prevention of Infection

X

63 63 64 64 64 65

CHAPTER 5 PROCEEDING WITH THE OPERATION PREPARATION, SEDATION AND ANESTHESIA Preparation of Patient Sedation Pupillary Dilation ANESTHESIA Topical Selection of Anesthetic Method Unassisted Topical Anesthesia The Anesthetic Procedure of Choice Technique for Irrigation of Lidocaine in AC Injection of Viscoelastic What Can be Done with the Combined Anesthesia Side Effects of the Combined Anesthesia How to Manage Patients Who Feel Pain and Discomfort PHOTOTOXICITY IN CATARACT SURGERY

71 71 71 72 72 72 72 74 75 75 75 75 75 75 75

CHAPTER 6 PHACOEMULSIFICATION - WHY SO IMPORTANT? COMPARING PLANNED EXTRACAPSULAR WITH PHACO EXTRACAPSULAR ADVANTAGES OF THE PHACO TECHNIQUE MAIN TECHNICAL DIFFERENCES ASSOCIATED WITH PHACO LIMITATIONS OF PHACOEMULSIFICATION

83 83 84 86

CHAPTER 7 PREPARING FOR THE TRANSITION GENERAL OVERVIEW AND STEP BY STEP CONSIDERATIONS Equipment - Dependent and Phase-Dependent Technique Mental Attitude UNDERSTANDING THE PHACO MACHINE Becoming Familiar with the Equipment Two Hands, Two Feet and Special Sounds Main Elements of Phaco Machines - Their Action on Fluid Dynamics COMPARISON OF SURGICAL TECHNIQUES FOR TRANSITION VS EXPERIENCED SURGEONS Techniques Which Are the Same for the Transition and for Advanced Surgeons Techniques that Vary According to the Skill of the Surgeon

93 93 93 94 94 95 95 96 96 96

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SURGICAL TECHNIQUE IN THE TRANSITION Anesthesia The Incision How to Make a Safe Transition from Large to Small Incision Role of Conjunctival Flap Anterior Capsulorhexis Hydrodissection THE MECHANISM OF THE PHACO MACHINE Getting Ready to Use Phaco During Transition Optimal Use of the Phaco Machine The Rationale Behind It - Main Functions Parameters of the Phaco Machine How to Program the Machine for Optimal Use Fluid Dynamics During Phaco Fluidics and Physics of Phacoemulsification Importance of and Understanding the Surge Phenomenon Lessening Intraoperative Complications from the Surge NUCLEUS REMOVAL - APPLICATION OF PHACO FRACTURE AND EMULSIFICATION The Divide and Conquer Technique Emulsification of the Nuclear Fragments FINAL STEPS Aspiration of the Epinucleus Aspiration of the Cortex Intraocular Lens Implantation Removal of Viscoelastic Closure of the Wound What to Do if Necessary to Convert Testing the Wound for Leakage Immediate Postoperative Management

97 97 97 97 101 102 104 106 106 106 106 112 114 114 116 119 121 121 123 123 124 126 126 126 126 128 128 129 130 131 131

CHAPTER 8 INSTRUMENTATION AND EMULSIFICATION SYSTEMS INSTRUMENTATION Eye Speculum Fixation Ring Knives and Blades Hydrodissection Cannula Cystotomes or Capsulorhexis Forceps Nuclear Manipulators or Choppers (Second Instrument) Forceps and Cartridge Injector Systems for Insertion of Foldable Intraocular Lenses THE PHACO PROBES AND TIPS Phaco Tips Surgical Principles Behind the Different Phaco Tips PHACOEMULSIFICATION SYSTEMS The Alcon Legacy The Allergan Sovereign The Bausch & Lomb - Storz Millennium

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137 137 137 137 140 141 142 144 147 148 149 150 150 150 150

The Pulse and Burst Modes Differences Between Them Clinical Applications of the Pulse Mode Clinical Applications of the Burst Mode Its Role in Transition to Chopping Advances with the Sovereign Phaco System

151 151 152 154 154 154

CHAPTER 9 MASTERING PHACOEMULSIFICATION The Advanced, Late Breaking Techniques General Considerations Trauma-Free Phacoemulsification Faster Operations Do They Sacrifice Patient Care? Readiness and Know-How to Become Efficient THE ADVANCED, LATE-BREAKING TECHNIQUES Anesthesia Fixation of the Globe THE INCISIONS The Primary Incision Essential Requirements for a Self-Sealing Corneal Incision Position of the Clear Cornea Tunnel Incision Reservations About the Clear Corneal Incision Advantages to the Temporal Approach Importance of the Length of the Tunnel Placing and Making the Primary Incision Surgeon's Position Controversy Over the Strength and Safety of the Wound Testing the Wound for Leakage Closing a Leaking Wound Without Sutures THE ANCILLARY INCISION ANTERIOR CAPSULORHEXIS Key Role Technique for Performing a First Class CCC Size of the Capsulorhexis STAINING THE ANTERIOR CAPSULE IN WHITE CATARACTS HYDRODISSECTION - HYDRODELAMINATION Technique of Hydrodissection Hydrodelamination

159 159 160 160 160 160 160 161 161 161 162 162 164 164 166 166 167 167 167 167 169 169 169 170 170 172 175 175 175

MANAGEMENT OF THE NUCLEUS

176

General Considerations Concepts Fundamental to All Techniques The Essential Principles THE ENDOCAPSULAR TECHNIQUES THE HIGH ULTRASOUND ENERGY AND LOW VACUUM GROUP THE GROOVING AND CRACKING METHODS

176 176 177 177 177 177

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The Divide and Conquer Four Quadrant Nucleofractis Technique Principles of the Divide and Conquer Techniques The Role of D & C Techniques in Cataracts of Different Nucleus Consistency Present Role of Original Four Quadrant Divide and Conquer THE LOW ULTRASOUND ENERGY AND HIGH VACUUM GROUP THE CHOPPING TECHNIQUES Main Instruments Used Surgical Principles of the Original Phaco Chop Chopping Techniques Presented in this Volume THE STOP AND CHOP TECHNIQUE Surgical Principles Absolute Requirements to Perform the Stop and Chop Importance of the Phaco Chopper Highlights of the Stop and Chop Technique FUNDAMENTAL DIFFERENCES BETWEEN CHOPPING AND DIVIDE AND CONQUER (D & C) TECHNIQUES THE CRATER PROCEDURES The Crater Divide and Conquer (Mackool) The Crater Phaco Chop for Dense, Hard Nuclei THE NUCLEAR PRE-SLICE OR NULL PHACO CHOP TECHNIQUE Disassembling the Nucleus How Is the Null-Phaco Chop Done Potential Complications Contributions of this Technique THE CHOO-CHOO CHOP AND FLIP PHACOEMULSIFICATION TECHNIQUE Origin of the Name “Choo-Choo” Comparison With Other Techniques Fine's Parameters THE TRANSITION TO CHOPPING TECHNIQUES REMOVAL OF RESIDUAL CORTEX AND EPINUCLEUS INTRAOCULAR LENS IMPLANTATION The Increased Interest in Foldable IOL's The Most Frequently Used IOL's MONOFOCAL FOLDABLE LENSES THE FOLDABLE ACRYLIC IOL'S THE FOLDABLE MONOFOCAL SILICONE IOL's OTHER MONOFOCAL LENSES The Hydrogel, Foldable Monofocal IOL The Foldable Toric Lens Bitoric Lens But Not Foldable THE FOLDABLE MULTIFOCAL IOL The Array Multifocal Silicone Lens How Does the Array Foldable Multifocal Lens Work? Quality of Vision with Array Multifocal Patient Selection and Results

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177 180 180 181 181 183 183 184 184 184 184 188 188 189 190 191 191 191 194 194 194 198 198 198 199 202 202 204 205 207 207 207 208 208 209 210 210 210 210 211 211 212 212 212

Specific Guidelines for Implanting the Array Lens Special Circumstances for Array Implantation Need for Spectacle Wear PostOp Halos at Night and Glare SURGICAL PRINCIPLES AND GUIDELINES FOR IOL IMPLANTATION PREFERRED METHODS OF IOL IMPLANTATION Use of Forceps vs Injectors Advantages and Disadvantages New Trends for Folding and Insertion of IOL's Guidelines for Insertion of Different Types of Lenses Surgical Technique with Array Lens Carreño's Technique of Acrylic IOL Implantation Through a 2.75 mm Incision Dodick's AcrySof's Implantation Technique Implantation Technique for Silicone Foldable IOL's Using Cartridge-Injector System TESTING THE WOUND FOR LEAKAGE

213 213 214 214 214 214 214 214 214 218 218 218 220 222 223

CHAPTER 10 FOCUSING PHACO TECHNIQUES ON THE HARDNESS OF THE NUCLEUS MULTIPLICITY OF TECHNIQUES The Essential Criteria for Success DIFFERENT NUCLEUS CONSISTENCY TECHNIQUES OF CHOICE Representative Experts LINDSTROM'S PROCEDURES OF CHOICE Advantages of the Supracapsular Disadvantages of the Supracapsular Contraindications of Supracapsular HIGHLIGHTS OF THE SUPRACAPSULAR IRIS PLANE TECHNIQUE CENTURION'S TECHNIQUES RELATED TO NUCLEUS CONSISTENCY CARREÑO'S NUCLEAR EMULSIFICATION TECHNIQUE OF CHOICE (PHACO SUB 3) Adjusting the Equipment Parameters to Remove Cataracts of Various Nuclear Density Three Sets of Values Programmed Into Memory Technique of Choice and Consistency of Cataract NISHI'S TECHNIQUES OF CHOICE FOR NUCLEI OF DIFFERENT CONSISTENCIES

229 229 229 230 230 231 232 232 233 234 237 237 237 238 245

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CHAPTER 11 COMPLICATIONS OF PHACOEMULSIFICATION INTRAOPERATIVE COMPLICATIONS General Considerations Main Intraoperative Complications Incidence Facing the Challenges COMPLICATIONS WITH THE INCISION COMPLICATIONS RELATED TO ANTERIOR CAPSULORHEXIS COMPLICATIONS WITH HYDRODISSECTION COMPLICATIONS DURING NUCLEUS REMOVAL COMPLICATIONS DURING REMOVAL OF THE CORTEX COMPLICATIONS DURING FOLDABLE IOL's IMPLANTATION COMPLICATIONS WITH POSTERIOR CAPSULE RUPTURE Pars Plana Vitrectomy for Dislocated Nucleus

XVI

249-268 249 249 249 250 250 254 258 259 260 260 262 266

POSTOPERATIVE COMPLICATIONS

269-290

MEDICAL Cystoid Macular Edema Diabetes and Cystoid Macular Edema PHOTIC MACULOPATHY AMINOGLYCOSIDE TOXICITY POSTERIOR CAPSULE OPACIFICATION Overview Role of IOL in PCO Role of Continuous Curvilinear Capsulorhexis in PCO Main Factors that Reduce PCO PERFORMING THE POSTERIOR CAPSULOTOMY Size of Capsulotomy Posterior Capsulotomy Laser Procedure Complications Following Nd:YAG Posterior Capsulotomy POSTOPERATIVE ASTIGMATISM IN CATARACT PATIENTS MANAGEMENT Procedure of Choice Highlights of AK Procedure EXPLANTATION OF FOLDABLE IOL'S RETAINING THE BENEFIT OF THE SMALL INCISION RETINAL DETACHMENT POSTOPERATIVE ENDOPHTHALMITIS INTRAOCULAR LENS DISLOCATION

269 269 273 273 275 277 277 277 278 278 279 279 279 281 281 281 282 283 284 284 286 286 288

CHAPTER 12 CATARACT SURGERY IN COMPLEX CASES Aims of this Chapter Broadening of Indications Complex Cases Already Discussed in Previous Chapters FOCUSING ON THE MAIN COMPLEX CASES THE DIFFERENT TYPES OF VISCOELASTICS Their Specific Roles Cohesive and Dispersive Viscoelastics The Cohesive VES - Specific Properties The Dispersive VES- Specific Properties PHACOEMULSIFICATION AFTER PREVIOUS REFRACTIVE SURGERY PHACOEMULSIFICATION IN HIGH MYOPIA CHALLENGES OF PHACOEMULSIFICATION IN HYPEROPIA REFRACTIVE CATARACT SURGERY Why and When Do Refractive Cataract Surgery TECHNIQUE FOR REFRACTIVE CATARACT SURGERY

295 295 296 296 296 296 296 296 297 298

CATARACT AND GLAUCOMA

302

Overview - Alternative Approaches COMBINED CATARACT SURGERY AND TRABECULECTOMY Indications Evolution of the Incision for Combined Cataract Extraction and Trabeculectomy A. Extracapsular Cataract Extraction with Trabeculectomy B. Phacoemulsification with Trabeculectomy Intraocular Lens Implants Preoperative Preparation SURGICAL TECHNIQUES STEP BY STEP ECCE and Trabeculectomy With Single, Unbroken Tunnel Incision Phacoemulsification With Trabeculectomy Antimetabolites in Combined Procedures Results of Combined Cataract Surgery and Trabeculectomy PHACOEMULSIFICATION IN DISEASED CORNEAS PHACOEMULSIFICATION AND IOL IMPLANTATION IN THE PRESENCE OF OPAQUE CORNEA Overview Padilha’s Timing and Technique Specific Recommendations PHACOEMULSIFICATION, IOL IMPLANTATION AND FUCHS’ DYSTROPHY Preoperative Evaluation Special Precautions During Phacoemulsification

298 299 299 299 300

302 303 303 303 304 308 308 308 310 310 315 318 320 322 322 322 322 324 325 325 325

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PHACOEMULSIFICATION IN SMALL PUPILS Pharmacological Mydriasis Mechanical Dilatation with Viscoelastics Mechanical Strategies TRAUMATIC CATARACTS Overview Assessment of the Injured Eye Highlights of Examination Diagnostic Imaging Combined Injuries of Anterior and Posterior Segment Traumatic Cataracts in the Presence of Anterior Segment Penetrating Wounds MANAGEMENT OF TRAUMATIC CATARACT HIGHLIGHTS OF SURGICAL TECHNIQUE The Incision Anterior Capsulorhexis Lens Removal Role of Intracapsular Tension Ring in Traumatic Cataracts Removal of Cortex Selection of IOL IOL Implantation Selection of Viscoelastic in Traumatic Cataracts Phacoemulsification Advantages in Traumatic Cataract PHACOEMULSIFICATION IN SUBLUXATED CATARACTS Strategic Management MANAGEMENT DEPENDING ON SIZE OF ZONULAR DIALYSIS Special Precautions with Subluxated Cataracts Increasing the Safety of Posterior Lens Implantation in Extensive Zonular Disinsertion Fixation of the Anterior Capsule to the Ciliary Sulcus CATARACT SURGERY IN CHILDHOOD Previous Controversies Now Resolved 1) Age and Timing for Surgery Bilateral Cataracts Unilateral Cataracts Preoperative Evaluation History Examination The Special Case of Lamellar Cataracts Rubella Cataracts The Need for Close Monitoring Preoperative Considerations The Decision to Implant IOL’s in Children with Cataract Surgery Surgical Technique The Posterior Approach to Cataract Extraction in Children CATARACT SURGERY IN UVEITIS

XVIII

328 328 328 328 333 333 333 333 333 334 334 334 334 334 334 334 335 336 339 339 339 340 340 340 340 342 344 345 347 347 347 347 347 348 348 349 350 350 350 350 351 351 355 355

CHAPTER 13 THE PRESENT ROLE OF MANUAL EXTRACAPSULARS Overview PERFORMING A FLAWLESS PLANNED EXTRACAPSULAR CATARACT EXTRACTION (with an 8 mm Incision and Posterior Chamber IOL Implantation) General Anesthesia Local Anesthesia Technique for Extracapsular Cataract Extraction with an 8 mm Incision (ECCE) THE MANUAL, SMALL INCISION EXTRACAPSULARS THE MINI-NUC TECHNIQUE SURGICAL TECHNIQUE Anesthesia, Paracentesis, ACM Capsulorhexis Conjunctiva Sclerocorneal Pocket Primary Incision and Tunnel Hydrodissection and Nucleus Dislocation Nucleus Expression Using Glide and High IOP Epinucleus and Cortex Extraction IOL Implantation Pupil Enlarged by Increased IOP Advantages of the Continuous Flow of BSS during Manual ECCE Complications THE SMALL INCISION PHACO SECTION MANUAL EXTRACAPSULAR TECHNIQUE

359 361

361 362 364

375 375 376 376 377 377 378 378 381 383 384 386 387 387 389

Overview Evolution of Technique Indications PHACO SECTION MOST IMPORTANT FEATURES Capsulorhexis Completing the Tunnel Incision Anterior Chamber Maintainer Aspiration of the Anterior Cortex and Epinucleus Phacosection Transition from Extracapsular Extraction to Phacosection

389 389 389 389 390 390 391 392 393 395

THE SMALL INCISION MANUAL PHACOFRAGMENTATION

400

Benefits of (MPF) Experiences with Other Phaco Fragmentation Techniques Why Use Gutierrez' Technique? Surgical Technique Complications

400 400 400 402 405

XIX

CHAPTER 14 THE NEW CATARACT SURGERY DEVELOPMENTS Overview DODICK’S PHOTOLYSIS SYSTEM THE CATAREX SYSTEM Aziz PhacoTmesis Water Jet Technology

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409 409 411 411 411

Fo c u s i n g a n d O v e r v i ew o f W h a t i s B e s t

FOCUSING AND OVERVIEW OF WHAT IS BEST Modern cataract surgery is definitely related to lens removal through small, short, valve like incisions and implantation of foldable intraocular lenses implanted through these short incisions.

Tackling the Challenges In this Volume we present what is best for our patients and how to tackle the challenges with vigor. We present the new developments in preoperative evaluation, the expansion of the indications as the outcomes have improved, the new, sometimes complex problems brought by refractive and vitreoretinal surgery in calculating IOL power. And we illustrate the steps that remain rather constant and which apply either to the surgeon in the process of transition or the experienced small incision surgeon, vs the methods that do change and require the skill of an experienced surgeon. We also present the anesthetic methods of choice, the understanding of the phaco machine, how it works and what the rationale is behind its optimal use. How to undergo the safe and successful transition from planned extracapsular to phaco. The incisions of choice for most surgeons, the methods that enhance the performance of capsulorhexis in complex cases, the modern techniques of hydrodissection, hydrodelineation and cortex removal that have stood the test of time and the advantages and disadvantages of the different methods of nucleus removal in phacoemulsification.

Role of Small Incision Manual Extracapsular Although we provide special emphasis on how to master phacoemulsification and foldable IOL implantation, including an indepth analysis of how to prevent and manage intraoperative and postoperative complications, we also present to you the small incision manual extracapsular techniques of proven and lasting value. For those surgeons who are prevented by practical considerations, or who simply prefer to not take the significant step of entering into small incision surgery, the chapter on how to perform a flawless planned extracapsular with 8 mm incision and its merits is superbly as presented by one of the world's master surgeons.

IOL's of Choice In modern cataract surgery it is essential to discuss the IOL's of choice and their merits. Selecting the correct lens implant (size of optic, chemical material, foldable vs non-foldable, mono vs multifocal) may play a more important role in the final patient's final visual outcome and satisfaction than the specific technique used for phacoemulsification of the nucleus.

The Best Phaco Technique The best phacoemulsification technique to use is based on the relation of the type

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of cataract to a specific method of nucleus removal for that specific stage of cataract. The divide and conquer in four quadrants continues to be the procedure of choice for the beginner in the transition period or for the surgeon who does not have a large volume of cataract surgery. The technique for nucleus removal with one hand continues to be fundamental for each phaco surgeon to learn. We will also present the phaco sub-3, phaco chop, phaco pre-chop, choo-choo chop and flip and the phaco burst, all of which are techniques for the more advanced or experienced surgeons. Each has its merits, effectiveness and limitations.

The Complex Cases Small incision cataract surgery has significantly changed the approach and management of the complex cases. It is the most important contribution made in years to a successful and safe combined glaucoma-cataract

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operation, to management of traumatic cataracts and cataract surgery in patients with corneal dystrophies. Pediatric cataracts have not been resolved with the improved management options and almost risk-free capabilities of the magnitude that we have available in adult patients. This, in part, may be related to the fact that the postoperative care depends more on the parents than on the surgeon. The previously highly controversial point of implanting intraocular lenses in children has shifted to a positive decision on the part of most surgeons who now agree to implant IOL's in children when the selection of cases has been done prudently. Let us now proceed to discuss each one of the highlights of modern cataract surgery. The field is exciting and a source of great satisfaction to the surgeon who does it well and with full dedication to the benefit of his or her patients.

C h a p t e r 1: S u r g i c a l A n a t o m y o f t h e H u m a n L e n s

SURGICAL ANATOMY OF THE HUMAN LENS Clinical Applications - Behaviour of Different Cataracts Understanding the three-dimensionality and concentric anatomy of the lens as originally conceived by Henry Clayman, M.D. for HIGHLIGHTS is fundamental for having a clear picture of some of the main steps in performing phaco. I refer to the dissection of the different structures of the nucleus with fluid, that is, hydrodissection of the anterior and posterior capsule from the cortex, separation of the nucleus and epinucleus with fluid and the different tissue reactions to the forces presented during phacoemulsification of the nucleus. The normal crystalline lens is an avascular structure. As pointed out by Howard Gimbel, M.D., lens fibers are surrounded by the lens capsule which is the basement membrane of the lens epithelial cells (Fig. 1). Lens epithelial cells are located just inside the capsule and exist as a single layer. The epithelial cells can differentiate into lens fibers, and this process occurs in an area just posterior to the lens equator. As new lens fibers are formed, the central fibers are compacted, forming the nucleus of the lens. The surrounding densely packed fibers form the cortex (Fig. 1). Due to the anatomical arrangement of cells and fibers, the Y sutures are formed within the lens nucleus. For a surgeon not experienced in small incision extracapsular techniques, there may be difficulties recognizing the hidden anatomy of the morbid cataract. It may be difficult to

distinguish what is really anterior capsule, what is cortex and where the posterior capsule is. When removing the cortex, we must keep in mind that its substance is three dimensional (Fig. 1). As described in this figure, the nucleus is the pit of the avocado. The pit in the avocado does not drop out because it is held in by adhesions between the flesh of the avocado and the pit. Figure 1 also shows that the cortex (C) adheres to the epinucleus and the nucleus. In order to remove the nucleus by whatever technique you prefer, these nuclear-cortical adhesions have to be broken and out comes the nucleus, whether by phacoemulsification or by planned extracapsular. The residual cortex, which is the flesh of the avocado, is wrapped around, three dimensionally, inside the skin of the avocado, which is the capsule (Fig. 1). When aspirating the cortex, it is prudent not to attack the cortex right on but to get a free edge, which you may attract to the aspiration port, and peel from its capsule support. In Fig. 1 you may see a conceptual cross section of the anterior globe, with all the structures of the human lens involved in the maneuvers hereby described. The capsule is like the skin of an avocado, both anterior (A) and posterior (P). The flesh of the avocado is comparable to the cortex (Fig. C). The pit of the avocado is comparable to the lens epinucleus and nucleus (Fig. E-N). In (1) the cortex (C), epinucleus (E) and nucleus (N) are shown removed from the capsule. (2) Shows the cortex (C) removed from the nucleus and epinucleus (E and N). The nuclear-cortical

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Figure 1: Three-Dimensionality of the Lens - Clinical Applications Figure 1 presents a conceptual cross section of the anterior globe and the three dimensional nature of the lens anatomy, with all the structures of the human lens involved in the surgical maneuvers. Think of the lens as if it were an avocado. The capsule is like the skin of an avocado, both anterior (A) and posterior (P). The flesh of the avocado is comparable to the cortex (Fig. C). The pit of the avocado is comparable to the lens epinucleus and nucleus (Fig. E-N). The pit in the avocado does not drop out because it is held in by adhesions between the flesh of the avocado and the pit. The cortex (C) adheres to the epinucleus (E) and the nucleus (N). The residual cortex, which is the flesh of the avocado, is wrapped around, three dimensionally, inside the skin of the avocado, which is the capsule (Fig. AP). When aspirating the cortex, it is prudent not to attack the cortex directly but to get a free edge, which you may attract to the aspiration port, and peel it from its capsule support. In (1) the cortex (C), epinucleus (E) and nucleus (N) are shown removed from the capsule. (2) Shows the cortex (C) removed from the nucleus and epinucleus (E and N). The nuclear-cortical adhesions have to be broken down before the nucleus can come out (2 and 3). In (E) the epinucleus is shown as an entity distinct from the nuclear core. This figure allows us to better understand the anatomical basis for the formation of grooves across the nucleus skillfully utilized by the surgeon in the technique of phacoemulsification.

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adhesions have to be broken down before the nucleus can come out (2 and 3). In (E) the epinucleus is shown as an, entity distinct from the nuclear core. This figure allows us to better understand the anatomical basis for the formation of grooves across the nucleus skillfully utilized by the surgeon in the technique of phacoemulsification.

Anatomical Characteristics of Different Types of Cataract The lens in cross section is made up of a concentric series of elliptical rings. Each one of these rings represents growth of the lens and the laying down of additional lens material from the epithelial cells located on the underside of the anterior capsule. In soft to medium density cataracts, the concentric lamellae of cataract tissue are not densely packed, so much of the space inside the cataract is taken up by

moisture. Medium to firm-density cataracts have concentric lamellae of tissue that are densely packed together, packed so tight that there is no room for moisture between lamellae.

How Cataracts Respond Differently Paul Koch, M.D. emphasizes that each one of these different types of cataracts responds differently, so surgical forces need to be applied differently. In breaking the nucleus the surgeon needs to individualize the operation to take advantage of the natural tendencies of each type of cataract. Soft to medium density cataracts are malleable and compliant. We can hold them in the capsular bag and squeeze them from between neighboring pieces. Medium to firm density cataracts are more like rocks. They have rigid form and are much more demanding of the surgeon's skill. If we

Figure 2: Dense, Nuclear Brunescent Cataract In dense, nuclear brunescent cataracts, as shown in Fig. 2, there is less water content, the capsule is dehydrated and there is a significant increase in the density and opacity of the nucleus (C). These nuclei are more like rocks, and are the hardest to manage with phacoemulsification in the transitional stage or by surgeons inexperienced in phaco. Difficulties during surgery may arise that can be characteristic in this type of cataract such as difficulty in identifying the capsulorhexis or with the hydrodissection.

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rub them against the capsule, the capsule can break. If we pull them up into the anterior chamber, the capsulotomy may split. If they touch the corneal endothelium, they abrade it. Understanding this surgical anatomy of the lens and its clinical applications helps significantly in recognizing that each type of cataract acts differently and that our approach should vary depending on the individual patient (Fig. 2).

INCIDENCE AND PATHOGENESIS It is widely known that cataracts constitute the major source of curable blindness worldwide. Not only do they seriously affect large segments of the population in developing or less economically fortunate regions but also the peri-urban areas of large and developed cities which are equipped with highly trained ophthalmologists and the latest technology. For psychological or social reasons difficult to understand, many blind or almost blind persons living in these peri-urban "belts" do not seek medical advice and treatment when easily available. This is one of the mysteries of people whose quality of life is significantly limited by partial or complete opacification of the crystalline lens. Figure 2 shows a brunescent, advanced, hard cataract which becomes sometimes very difficult to treat by phaco, even in skillful hands. Many patients allow their cataracts to become this much advanced even if they live near medical facilities that may provide proper care at a much more advantageous time. As pointed out by Howard Gimbel, M.D., there are a variety of causes and types of cataracts. By definition, all cataracts share the common feature of opacification of some portion of the crystalline lens which, if within the to cataract formation. 8

BIBLIOGRAPHY Assia, EI., Legler, UFC., Apple, DJ.: The capsular bag after short and long term fixation of intraocular lenses. Ophthalmology, 1995; 102:1151-7. Boyd, BF.: Cataract/IOL Surgery. World Atlas Series of Ophthalmic Surgery, published by HIGHLIGHTS, Vol. II, 1996; 5:5-13. Boyd, BF.: Cataract/IOL Surgery. World Atlas Series of Ophthalmic Surgery, published by HIGHLIGHTS,Vol. II, 1996; 5:34-38. Boyd, BF.: New developments for small incision cataract surgery. Highlights of Ophthalm. Journal, Volume 27, Nº 4, 1999;45-46. Gimbel, HV., Anderson Penno, EE: Cataracts: Pathogenesis and treatment. Canadian Journal of Clinical Medicine, September 1998. Koch, PS.: Simplifying Phacoemulsification, 5th ed., published by Slack; 1997; 7:85-86. Lens and Cataract, Basic and Clinical Science Course, Section 11. American Academy of Ophthalmology, 1998-99.

Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n

INDICATIONS AND PREOPERATIVE EVALUATION INDICATIONS To date there is no established medical treatment for the prevention or treatment of cataract formation and thus the treatment of cataracts remains surgical. Contrary to the commonly held belief that cataracts must reach a certain degree of density or become "ripe" prior to considering cataract surgery, today the crystalline lens can be removed at virtually any stage. In fact, refractive lensectomy in which the clear crystalline lens is removed may be used to surgically eliminate or significantly reduce the need for glasses in patients with very high myopia or hyperopia. In the latter condition, this may be achieved by implanting several piggyback lenses within the capsular bag following clear lensectomy.

Role of Quality of Life Cataract/IOL surgery improves quality of life better than any other medical procedure known to mankind. Cataract surgery is indicated when the patient's quality of life is being affected by visual impairment, when there is a diminution in vision if the patient is exposed to light or at night, and when the preoperative evaluation indicates that the potential for restoration of sight is good. How much a patient's quality of life is impaired from a cataract is relative, varying with the patient's occupation and age. The key factor is not to wait until a nuclear cataract becomes hard. With time, the lens fiber density becomes a hard nuclear brunescent cataract (Fig. 2) . With most modern phacoemulsification techniques it may be-

come increasingly difficult to perform surgery if the lens becomes extremely dense or brunescent. Waiting too long may require that the surgeon operate on dense nuclear cataracts, which increases the risk of posterior capsule tears, whether we perform planned extracapsular or a phacoemulsification. This complication may lead to other rather serious problems such as dislocated nucleus, retinal detachment, macular edema, bullous keratopathy and inflammation.

The Role of Visual Acuity There are very few strict criteria for recommending cataract surgery. In the United States, however, many professional review organizations have indicated that the reduction of Snellen distance acuity to 20/40 or worse as a result of cataract is sufficient indication in and of itself for cataract surgery. This is generally the minimum standard for driving. In some of the advanced, developed countries, being unable to obtain a driver's license may seriously affect a person's life because he/she may be disqualified to drive to the market or shop to purchase food and other materials essential to daily existence. However, in many cases surgery may be indicated without reduction of visual acuity to the level of 20/40 if the patient has difficulty performing activities of daily living. Because patients have varying occupational and recreational needs, some patients may need cataract surgery prior to having their vision reduced to 20/40 by standard tests. In addition, near vision in some cases may be

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compromised more than distance acuity particularly in the case of central posterior subcapsular cataracts. The trend toward early removal of cataract offers the advantage of operating on a younger age group, many of whom are still productive members of society. Their need for early return to their usual lifestyle is extremely important. The older population, often living alone, also benefits from early visual recovery. These high expectations and needs require that the ophthalmic surgeon perform superior surgery to obtain excellent postoperative visual acuity and early visual rehabilitation. As emphasized by Gimbel, symptoms of cataracts include complaints of a yellowing of vision, glare, halos, decreased night vision, and generally blurred vision in adults. Nuclear sclerosis which is a typical form of age-related cataracts may also induce a myopic shift and patients may give a history of having changed their glasses several times within a short period of time. In children cataracts may present as leukocoria and may result in strabismus and/or amblyopia if not treated promptly.

Contrast Sensitivity and Glare Disability In evaluating a patient with cataract and in the process of deciding when that person requires cataract/IOL surgery, it is fundamental to keep always in mind that standard Snellen acuity measurements do not give any information with regard to symptoms of disabling glare. As a matter of fact, very good visual acuity with the Snellen chart in the physician's examining room may lead the ophthalmologist to making the wrong decision and recommendations unless he or she takes other factors into consideration. In later years, we have become

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increasingly aware that diminished contrast sensitivity which interferes with sharp vision under different color backgrounds or target luminance, is an essential element of sight and a highly limiting factor in the presence of cataract. This is perceived by the patient for example when he or she is unable to read a computer screen at the airport if the background is light blue and the print is light yellow even though visual acuity in the physician's refracting lane was 20/30 or 20/25. The same for disabling glare. These are two additional very important issues in determining when the cataract should be removed. For many years this judgment has been based on Snellen visual acuity. But a patient can score quite well on Snellen acuity while suffering in real life. Posterior subcapsular cataracts are notorious for interfering with reading, even when distance vision is good, and may induce a great deal of glare. Snellen acuity may be 20/20 or 20/25, but against oncoming headlights while driving at night, for instance, the glare may diminish the functional vision to 20/100 or even 20/200. People with nuclear sclerosis, the most common form of cataract, tend to be bothered by decreased contrast sensitivity rather than glare. Although glare disability and contrast sensitivity are distinctly different, the terms often are erroneously interchanged. The testing characteristics of each, however, may overlap, and a reduction in one function often leads to a diminution in the other, further adding to the confusion of their differences. As clarified by Samuel Masket, M.D., glare disability is a light-induced visual symptom. Contrast sensitivity testing is a means of vision analysis, analogous to a markedly expanded form of Snellen acuity evaluation at varied amounts of target luminance.

Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n

Contrast Sensitivity Characteristics Like audiometry, which measures the sensitivity of the hearing apparatus to stimuli at different audio frequencies, contrast sensitivity analysis determines the ability of the visual system to perceive objects of differing contrasts as well as sizes.

A patient who has a reduction in contrast sensitivity might perceive the small, highly contrasted targets on a Snellen test line but be incapable of identifying larger objects at reduced contrast. There are alterations in the visual system that can cause visual loss that are not detected by the determination of Snellen visual acuity but may be evaluated by testing of contrast sensitivity function. This is unlike

Figure 3 B (below right): Contrast Sensitivity Recording Chart The contrast sensitivity recording chart provides four (4) rows of wave gratings. At the recommended test distance of 8 ft (2.5 meters), these gratings test the spatial frequencies of 3, 6, 12 and 18 cycles/degree. This chart provides a full contrast sensitivity curve. The functional acuity is determined by the lowest level of contrast sensitivity (gray band) that can be detected by the patient. The functional acuity score is shown in a bracket next to the contrast sensitivity score.

Figure 3 A (above left): Importance of Testing for Contrast Sensitivity The Contrast Sensitivity Test is used clinically to evaluate cataracts, glaucoma, diabetic eye disease, contact lens performance and refractive surgery. In the presence of cataract the clouding of the lens causes light scatter on the retina. This reduces image contrast and causes dimness of vision. One of the more difficult problems in evaluating how a cataract is affecting the patient's visual function is that many cataract patients preserve good visual acuity as tested in the refracting lane (Snellen chart) but complain about their visual disability. The true “real-world” vision of cataract patients can be established as a functional acuity score using contrast sensitivity and glare testing.

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disabling glare, which determines the effect of extraneous light on visual performance. Contrast sensitivity evaluation is a measurement of the resolving power of the eye at varied contrasts between image and background (Fig. 3 A-B). A number of useful contrast and glare sensitivity testing methods have been devised (Fig. 3 A-B). They are accessible and inexpensive. Unfortunately, standardization of these techniques has not yet been achieved. It is essential that the clinician be fully aware of these two factors that may impinge on the patient's real vision or quality of vision, in addition to the Snellen acuity test.

Relation of Glare to Type of Cataract Neumann et al. have determined that nuclear cataract is more likely to be associated with nighttime glare disability, while cortical cataract formation is associated with daylight glare, and posterior subcapsular cataracts may induce glare disability associated with bright, direct sunlight or bright central light sources. Cortical cataracts seem more likely to cause glare symptoms than nuclear cataracts. Masket points out that frequently, patients with dense central posterior subcapsular cataracts frequently retain excellent distance Snellen acuity as measured in the refracting lane, yet they perform poorly on any of the available glare testing devices. Such patients

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may have severely lower visual function during daylight driving although they do well with the Snellen acuity chart. In essence, the Snellen chart evaluates quantity of vision. Contrast sensitivity tests evaluate quantity and quality of vision. The equipment to perform the test is accessible and inexpensive. It is basically a chart about 0.3 meters in size and it costs about US$200.00

Preoperative Considerations In addition to determining visual acuity by the Snellen chart, contrast sensitivity and glare disability testing as outllined, all patients with cataracts should have a thorough history taken including any systemic or ocular medications being used and any systemic disease for which they receive treatment. A family history is also included. The ophthalmologic examination should include intraocular pressure (IOP) measurements, keratometry, pupil exam, routine motility testing, and dilated slit-lamp and funduscopic examinations including indirect ophthalmoscopy to examine the central and peripheral retina. Ancillary testing such as visual fields, topography, specular microscopy for endothelial cell counts, and fluorescein angiography should be considered in selected cases. There are many causes for decreased vision and ,especially in older patients, these causes may exist concurrently. Age-related macular degeneration is possibly the most important and difficult to detect because of the existing opacity of the cataract.

Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n

Evaluation of Macular Function The main preoperative tests to determine central visual acuity are: 1) the Potential Visual Acuity Meter (PAM) and 2) the Super Pinhole. They permit evaluation of the macular function in patients in whom examination of the macula is difficult due to media opacities. They are more useful when they are integrated into the total evaluation of the patient. One of the major problems that all of us confront as clinical ophthalmologists is that of patients with cataracts who correct to 20/100 or 20/200 and on whom we are planning to operate but cannot see the fundus, particularly the macula. This is aggravated when the patient has a few old small corneal opacities. The ever-present question is: what is the visual prognosis if we operate, either by a cataract extraction or combined with a corneal transplant? What can we anticipate for the patient or his/her family about future, postoperative vision even if we do not have any significant operative or postoperative complications? Ultrasonography and clinical tests will give us only a partial and limited answer. Since we cannot see the state of the macula or papilla, we are limited as to the prognosis. Sometimes we have the pleasant surprise of obtaining more vision postoperatively than we predicted; in other cases, we face the unpleasant reality of finding macular degeneration or other lesions in the macula or optic nerve that result in poor central vision in spite of a beautifully performed operation.

Any well trained ophthalmologist can diagnose major lesions of the optic nerve or retina preoperatively. The major problem is with the subtle lesions that nevertheless limit the patient's capacity to read or distinguish clear images at distance postoperatively. One of the most important tests for evaluating macular function in the presence of a lens opacity dense enough to make our clinical examination of the macula unreliable is the Guyton-Minkowski Potential Visual Acuity Meter (PAM). The Super Pinhole developed by David McIntyre, M.D., is another highly practical and useful method to evaluate macular function. The Laser Interference-Fringe Method has also been previoulsy used but it is less practical. Most clinical ophthalmologists prefer the PAM test or the Super Pinhole.

The PAM The Potential Acuity Meter (PAM) is an instrument which attaches to a slit lamp. It serves as a virtual pinhole by projecting a regular Snellen visual acuity chart through a very tiny aerial pinhole aperture about onetenth of a millimeter (0.1 mm) in diameter. The light carrying the image of the visual acuity chart narrows to a fine 0.1 mm beam and is directed through clearer areas in cataracts (or corneal disease), allowing the patient to read the visual acuity chart as if the cataract or corneal disease were not there (Figs. 4 and 5A and B). The PAM is taken from its stand and placed directly onto the slit lamp in the same

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Figure 4 : Concept of the Guyton-Minkowski Potential Acuity Meter With Cataractous Lens (PAM) The beam (arrow) of the projected Snellen chart is shown passing through a cataract (C) and forming the image of the chart on the retina (R). The beam of light can only strike the retina when the beam is able to pass through the lens, between opacities. With the chart successfully projected onto the retina, the patient can respond and we can determine the potential visual acuity as if the cataract were not there. The PAM serves as a superpinhole by projecting the regular Snellen chart along a tiny beam 0.1 mm in diameter.

manner as the detachable type of Goldmann tonometer. The examination takes from two to five minutes per eye, depending on the density of the cataract. As pointed out by Guyton, for the PAM to work adequately, there must be some small hole in the cataract for the light beam to pass through. You may find such a hole even in cataracts which have media clouding of up to 20/200 and better. When you find it, then you

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can avoid the light scattering produced by the opacities. It is this light scattering which washes out the retinal image and decreases vision behind cataracts. By projecting the image of the visual acuity chart through one tiny area, we avoid that scattering effect, and the patient can see the chart (Figs. 6 A-B and 7 A-B). How is the instrument operated by the clinician or an assistant? The device is mounted on a slit lamp so that the operator can see

Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n

Figure 5 A (above left): Concept of the Potential Acuity Meter (PAM) in Cases of Corneal Opacities and Cataract In Fig. 5-A the tiny beam of light (arrow) of the projected Snellen chart is shown striking a corneal opacity and failing to penetrate the cornea.

Figure 5 B (below right): Concept of the Potential Acuity Meter (PAM) in Cases of Corneal Opacities and Cataract In Fig.5-B, by moving the beam to a point between the corneal opacities, the projected Snellen chart can pass on through the cornea and onto the retina (arrow) so that the patient can see it and we can determine the visual acuity. The test as shown in Figs. 4-A and 4-B is particularly important if we are considering a combined cataract extraction and penetrating keratoplasty.

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exactly where the light beam is passing. The light beam is directed to various parts of the pupil (Fig. 4, 6-A, 6-B, 7-A, 7-B). It can be focused in between lens opacities. It is easy to see when the beam is going in because it practically disappears (Fig. 6-B). When it hits an opacity, you can see the opacity light up (Fig. 6-7). When you move the beam with the slit lamp control to lucent, non-opaque areas, you see the beam pierce through (Figs. 6-B and 7-B). It is valuable to observe this because if you know you are getting the beam through and the patient still reads poorly, you can be fairly confident that there will be a poor result after surgery. If you are not sure whether the beam is penetrating and the patient reads poorly, results of surgery will be uncertain. So, the slit lamp monitoring of the light beam is important.

It is sometimes difficult to find a small hole in a cataract with density greater then 20/200, although holes have been found in counting-fingers cataracts. If you obtain good vision behind any cataract, you have the information you need. As to the visual prognosis behind very dense cataracts, if you cannot obtain a good reading, you still do not know quite where you are. The instrument is best operated in a darkened room because it is easier to see the light beam. The best results are obtained with a dilated pupil because you have a better chance of finding an appropriate hole in the cataract. Ninety percent of patients whose best correctable vision is 20/200 and better preoperatively, achieve the predicted vision or within two lines

Figure 6-A: How the PAM Works - Slit Lamp View In Fig. 6-A the ophthalmologist directs the small beam of light through different parts of the dilated pupil in a patient with lens opacities. One can see here that the beam of light (arrow) is hitting a lens opacity. This light is strongly scattered by the opacity, lighting up the opacity, leaving little or no light remaining to penetrate on through to the retina.

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Figure 6-B: How the PAM Works - Slit Lamp View In Fig. 6-B the beam (arrow) is successfully penetrating the lens at a point where no lens opacities are present, and the beam disappears into the vitreous cavity (V). As the light beam broadens out, passing into the vitreous, it is no longer visible to the doctor. The examiner thus can be certain that the light beam of the projected Snellen chart is getting in to the retina. With the beam successfully projecting the Snellen chart image on the retina, the patient can respond accordingly so that the examiner can determine the potential visual acuity irrespective of the lenticular opacities.

than the predicted vision after surgery. When the preoperative visual acuity is worse than 20/ 200, only about 60% achieve vision within three lines of the vision predicted by the PAM. The vision obtained after surgery is generally equal to, or better than the vision predicted with the Potential Acuity Meter. False positives occur in 10-15% of cases. When the test is done in cases of cystoid macular edema, the instrument occasionally indicates better

potential vision than the patient can achieve with best refractive correction postoperatively. No single test of visual function, however, is sufficient to mandate surgery. Instead, it is the visual needs of the patient in combination with careful estimation of the potential for the return of visual function after surgery that finally serves as the basis for the ophthalmologist to decide whether surgery is indicated and useful.

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Figure 7 A: How the PAM Works Cross Section View Figures 7 A and 7 B demonstrate in cross-section the views shown in Figs. 6 A-B. In (A), the light beam (arrow) can be seen striking a lens opacity (C) and thus does not penetrate the lens. The patient in this case cannot see the projected Snellen chart.

Figure 7 B: How the PAM Works Cross Section View In Fig. 7-B the light beam is directed to another part of the pupil where it is focused between lens opacities so that the projected Snellen chart passes to the posterior pole. Hence the patient will see the chart and respond so that we can determine the effective potential visual acuity.

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PREOPERATIVE GUIDELINES FOR CATARACT SURGERY IN COMPLEX CASES HOW TO PROCEED IN PATIENTS WITH RETINAL DISEASE The Importance of Pre-Op Fundus Exam Thorough peripheral retinal examination should be done before cataract extraction. We are all proud to be first class clinical ophthalmologists and not think of cataract surgery only as a mechanical, technical procedure. As patients live longer, they are apt to have more preoperative diseases sometimes difficult to diagnose unless we are on the alert for them. Because the patient with an even moderate degree of cataract has reduced clarity of vision, it is easily possible that recent abnormalities may not have been observed or reported by the patient. This is particularly the case with retinal diseases.

CATARACT SURGERY IN DIABETIC PATIENTS Because of the increasing importance of diabetic retinopathy, both in incidence and severity, we provide special emphasis to this disease in considering cataract surgery in complex cases. Cataract and retinovascular complications often co-exist in diabetic patients. The combination can present problems in determining the cause of decreased vision. Cataract surgery can also result in rapid progression of diabetic retinopathy that may need treatment with photocoagulation (Figs. 8 and 9)..

Diabetic patients are very predisposed to developing cataracts. This is especially true of younger diabetic patients, who are also highly predisposed to developing diabetic retinopathy (diabetes Type I). In a series of diabetic retinopathy and maculopathy patients 15 years after laser treatment, only 22% of the eyes maintained clear lenses (Figs. 10 and 11). Cataracts will often form following vitrectomy surgery for diabetic retinopathy. Rarely retinopathy can cause cataracts. An example would be prolonged vitreous cavity hemorrhage that results in a partial opacification of the lens. (Very high risk proliferative diabetic retinopathy - Fig. 12)

Evaluating Diabetics Prior to Cataract Surgery Clinically significant macular edema (CSME) and less obvious macular changes in non-proliferative retinopathy may be the cause of decreased vision in addition to the cataract (Fig. 13). It is important to listen to the patient's history when evaluating the cause of visual deterioration. This can be helpful in deciding how much of the visual loss may be due to cataract as opposed to visual damage caused by retinovascular conditions. A good fundus examination through a dilated pupil is essential. In diabetic patients as in all patients, cataract should be removed when a patient's visual function does not meet his/her visual needs and the visual loss is consistent with the cataract. It is very rare that

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Figure 8 : Scatter Photocoagulation to Ischemic Retinal Area Invaded by Vessels in Diabetic Retinopathy Cataract extraction does not cause retinopathy to develop when it was not present before cataract removal, but it definitely may worsen pre-existent retinopathy, particularly if there is a proliferative retinopathy already present. This figure shows an ischemic area of the retina being treated with scatter photocoagulation. Please observe the large nets of vessels. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Practical Guide to Laser Photocoagulation", Italian Edition by Brancato, Coscas and Lumbroso, published by SIFI).

Figure 9: Significant Regression of Retinal Neovascularization Following Scatter Photocoagulation You may observe that the large nets of vessels shown in Fig. 8 have regressed following treatment with scatter photocoagulation of the proliferative neovascularization existing before cataract surgery. You may observe the laser burns. If the fundus is adequately visible in spite of the cataract, it is preferable to perform photocoagulation before doing cataract surgery. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Practical Guide to Laser Photocoagulation", Italian Edition by Brancato, Coscas and Lumbroso, published by SIFI).

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Figure 10 (above right): Focal Photocoagulation for Diabetic Maculopathy Previous to Cataract Surgery The laser applications are directed to the microvascular alterations responsible for chronic, leaking fluid which gives rise to macular edema. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Monografie della Societa Oftalmologica Italiana", Italian Edition by Brancato and Bandello, published by ESAM).

Figure 11 (below left): Grid Treatment with Photocoagulation for Diabetic Maculopathy Ophthalmoscopic appearance after grid pattern treatment of the macula in which diffuse rather than focal leakage is identified on the fluorescein angiogram. Only 22% of these eyes maintain clear lenses 15 years after laser treatment, particularly younger diabetics. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Monografie della Societa Oftalmologica Italiana", Italian Edition by Brancato and Bandello, published by ESAM).

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cataracts need to be removed so that treatment of the diabetic retinopathy can be performed. Occasionally, cataracts need to be removed when performing vitrectomy. It is important that we consider various diabetic factors in planning cataract surgery because the retinopathy can influence the result. We may see increased bleeding and fibrin formation, especially in the younger patients with active retinopathy and compromised retinal perfusion.

Importance of Maintaining the Integrity of the Lens Capsule Cataract surgery may not only result in rapid progression of diabetic retinopathy, but it may also complicate its management and treatment. Rapid deterioration often occurs

when the lens capsule and zonular integrity are sacrificed by the cataract surgery such as with rupture of the posterior capsule. Retained lens material may produce increased inflammation, which may further accelerate this process. While it is important to maintain an intact posterior lens capsule, it is equally important to have an easily dilatable pupil and a clear capsule to allow a good fundus view through which laser treatment can be performed.

Significant Increase in Complications Following Cataract Surgery The progression of retinopathy following cataract surgery may take several forms. We may see a patient with non-proliferative retinopathy rapidly develop macular edema (CSME) (Figs. 10, 11 and 13). Macular edema

Figure 12: Severe, Advanced Proliferative Diabetic Retinopathy, Very High-Risk - A Prolongued Vitreous Cavity Hemorrhage May Result in Partial Opacification of Lens Artistic rendition of severe, advanced, proliferative, very high risk diabetic retinopathy. (A) Shows a fundus view of a severe case of proliferative diabetic retinopathy. There are preretinal hemorrhages (H) in several locations. Note the extensive active fibrovascular proliferation causing a traction detachment (D) nasally due to traction from the fibrovascular tissue (A) on the retina. There is also active fibrovascular proliferation along the retinal vessel arcade (V) with detachment of the macular area. Note the active fibrovascular stalk (S) which obscures the optic nerve. (B) Shows the same eye with the surgeon's view as seen through the pupil, and accompanying cross section view of the tissue pathology. Note hemorrhage (H), traction (arrows) of the posterior hyaloid (C), traction detachment of the retina (D), and active fibrovascular stalk (S) on the optic nerve.

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Figure 13: Diabetic Macular Edema (A) Shows the fundus view of diabetic macular edema. Notice thickening of the macular area (F). From the oblique cross section (B), an area of the retina and choroid is magnified in (C) to show its relationship to the clinical ophthalmoscopic fundus view above. In (C), there is pooling of fluid (D) within the inner layers of the retina. This fluid is trapped between the ganglion cell layer (G) and the outer plexiform layer (P). Notice there is almost complete loss of the intermediary neurons (N) in this area.

may progress from being diffuse to being cystic. Rafael Cortez, M.D., has observed that diabetic patients with proliferative retinopathy (Fig. 12), or non-proliferative retinopathy (Fig. 13) or even without retinopathy, have a higher risk of developing a vitreous hemorrhage, rubeosis of the iris and neovascular glaucoma postoperatively. This risk is particularly high in those patients with proliferative retinopathy (Fig. 12).

Appropriate Laser Treatment Most diabetic retinopathy complications can be prevented by appropriate laser treatment before cataract surgery. Eyes with nonproliferative retinopathy that have clinically

significant macular edema (Figs. 13 and 14) should receive focal or grid laser treatment (Figs. 10, 11 and 14) to seal the leakage which is detectable through fluorescein angiography. Eyes with severe, non-proliferative (pre-proliferative) diabetic retinopathy (Fig. 15) and proliferative retinopathy (Fig. 16) should receive panretinal laser photocoagulation (Fig. 17) before cataract surgery. This treatment will reduce additional proliferation and deterioration. Even with a cataract, laser treatment can usually be performed with good pupillary dilatation. Krypton red wavelengths are often successful in penetrating somewhat dense nuclear sclerotic lenses (Fig. 14). Retrobulbar anesthesia may be necessary.

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Figure 14 (above right): Prevention of Diabetic Retinopathy Complications by Laser Treatment before Cataract Surgery Most diabetic retinopathy complications can be prevented by appropriate laser treatment before cataract surgery. Eyes with non-proliferative retinopathy that have retinal thickening from edema near the macula should receive focal treatment of the macular aneurysms to erase fluorescein leakage. As shown in this figure, even with a cataract, krypton red wavelengths are often successful in penetrating fairly dense nuclear sclerotic lenses. Laser treatment must be performed with good pupillary dilatation.

Figure 15 (center): Severe Non-Proliferative Diabetic Retinopathy (Pre-Proliferative). This photo shows a characteristic severe, nonproliferative diabetic retinopathy, previously known as pre-proliferative. Please observe prominent soft exudates, dot blot hemorrhages, venous beading, and microaneurysms. (Photo courtesy of Lawrence A. Yannuzzi, M.D., selected from his extensive retinal images collection with the collaboration of KongChan Tang, M.D.)

Figure 16 (below right): Proliferative Diabetic Retinopathy This photo shows the next stage in severity of the disease. Please observe a large subretinal hemorrhage surrounding soft cotton exudates at the lower temporal arcade. There are also multiple intraretinal hemorrhages with neovascularization elsewhere (NVE), which is defined as a proliferative retinopathy anywhere in the retina which is greater than 1 disc diameter from the optic disc margin. The macula is not shown. (Photo courtesy of Samuel Boyd, M.D., Clinica Boyd, Panama).

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Figure 17 (above right): Panretinal Laser Photocoagulation Before Cataract Surgery In treating diabetic retinopathy, panretinal photocoagulation covers all of the periphery and mid-periphery of the retina from the ora serrata to the vascular arcades, sparing only the posterior pole. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Practical Guide to Laser Photocoagulation", Italian Edition by Brancato, Coscas and Lumbroso, published by SIFI.

Main Options in Management of Co-existing Diabetic Retinopathy and Cataract The first and most successful is to defer the cataract surgery until laser treatment can be performed. If there is extensive vitreous hemorrhage or traction retinal detachment, you

may need to combine the cataract removal with a vitrectomy (Fig. 18). Intraocular lenses do not present a problem when a patient is going to have a vitrectomy. The visual results of pseudophakic eyes with diabetic retinopathy complications that have vitrectomy surgery are essentially identical to those of phakic eyes.

Figure 18: Need to Combine Cataract Removal with Vitrectomy (Vitreous Hemorrhage and Traction Retinal Detachment) The first indication for vitrectomy in the case of proliferative diabetic retinopathy is the presence of vitreous hemorrhage (H). This is conditional, however, depending on several factors such as status of retinopathy, visual loss, adequacy of previous photocoagulation, frequency of hemorrhage, vision in the fellow eye, advancing iris neovascularization, response to vitreous surgery in fellow eye, and systemic factors. In general, surgery for retinopathy is more likely to be indicated with hemorrhage in the presence of active fibrovascular proliferation or traction retinal detachment. This is the second indication for vitrectomy, namely a traction retinal detachment, but only when the macula (M) is detached as shown. Note contraction (arrows) of posterior hyaloid (P) causing a non-rhematogenous retinal detachment (D) due to traction from the fibrovascular tissue (A) on the retina.

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CATARACT SURGERY AND AGE-RELATED MACULAR DEGENERATION

RETINAL BREAKS AND RETINAL DEGENERATIONS PRIOR TO CATARACT SURGERY

Felix Sabates, M.D., has best outlined the precautions we must take when considering extracapsular extraction or phacoemulsification in eyes with already present age-related macular degeneration already present. These principles are: 1) It is important to study the macular area in detail prior to cataract surgery to detect the presence of age-related macular degeneration. 2) If cataract surgery is performed in the presence of age-related macular degeneration, special care should be taken to reduce the possibility of inflammation even if it would require immediate use of antiinflammatory drugs. 3) Cystoid macular edema should be aggressively treated, with careful follow-up emphasized. 4) Cataract surgery should not be performed on the patient with active "wet" macular degeneration (Fig. 19) until it has been brought to a dry stage (Fig. 20). If there is bleeding from a neovascular membrane, cataract surgery should be postponed until at least six (6) months after the blood has completely reabsorbed and there has been no recurrence of the bleeding has been present. 5) In patients with macular scars (Fig. 20) and opaque cataracts, surgical removal of the opacified lens with intraocular lens implantation may be of benefit in recovering some degree of pericentral or peripheral vision. The smaller the macular scar, the better the prognosis. No cataract surgery should be performed unless the cataract is opaque enough so that when it is removed, the patient will probably perceive the benefit of the operation.

The preoperative treatment of these retinal lesions has traditionally come into consideration as a possible means of preventing retinal detachments after cataract extraction, especially in myopes. I refer only to those peripheral retinal degenerations which can be clinically defined and identified, and which have statistically been linked with retinal detachment following posterior vitreous detachments. This, therefore, excludes senile retinoschisis, which has a higher prevalence in the general population than among patients with a retinal detachment. What needs to be clarified is the effect of cataract surgery on the risk retinal breaks and degenerations present and what recommendations should be given in regard to their management prior to cataract surgery. This requires therapeutic proof that prophylactic treatment significantly lowers this risk below that which the natural course of untreated lesions would present. There is an increasing tendency to support the concept that retinal detachments generally are associated with recent, not old, retinal breaks. At the present time the picture is not clear. We lack solid reports supporting the prophylactic treatment of preexisting retinal breaks prior to cataract surgery. What happens to an eye with lattice degeneration when cataract extraction is performed? Again, we face a lack of valid reports in the literature to support preventive treatment prior to cataract surgery. About 90% of eyes with lattice degeneration do not detach after small incision cataract extraction even when

Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n

Figure 19 (above right): Anatomy and Pathology of Exudative, ("Wet") Macular Degeneration with Extrafoveal Neovascularization Cataract surgery should not be performed in these cases. Wait until it has been brought to dry stage as shown in Fig. 20. Fundus view (A) shows an example of exudative "wet" macular degeneration with an extrafoveal neovascular membrane (N) and limited subretinal hemorrhage (H) just at the margin of the paramacular retinal vessels surrounding the fovea (F). From the oblique cross section (B), an area is magnified in (C) to show the direct relationship between clinical ophthalmoscopic fundus view above and its corresponding cellular pathology. Pathology reveals that the retina is slightly elevated over a neovascular membrane (N). Note vessels emanating from the choriocapillaris (J), into the neovascular membrane (N) and into the sub-RPE and subretinal spaces, passing through small breaks (T) in the retinal pigment epithelial cell layer (E). There is some atrophy of photoreceptors in this area (P). Subretinal blood (H) is seen to either side of the neovascular membrane. Large choroidal vessels (K).

Figure 20 (below left)): Anatomy and Pathology of Non-Exudative, Geographic ("Dry") Macular Degeneration In these patients, surgical removal of the opacified lens with IOL implantation may be of benefit in recovering some degree of peripheral vision. Fundus view (A) shows an example of non-exudative, geographic atrophic "dry" macular degeneration where atrophy of the retinal pigment epithelium predominates. The smaller the macular scar, the better the prognosis for cataract surgery. Notice the clinical signs of drusen (D) which can appear as discrete subretinal bodies, confluent masses or hard glinting lesions, usually yellowish in color. Darker intraretinal pigment (I) may or may not be present. Retinal pigment epithelium atrophy (E) is identified by prominence of the underlying choroidal vessels. From the oblique cross section (B), an area is magnified in (C) to show the direct relationship between the clinical ophthalmoscopic fundus view above and its corresponding cellular pathology. Pathology includes subretinal drusen (D) and atrophy of the RPE (E). Compare the disorganized RPE cell layer at (E) on the right to the more normal configuration at (N) on the left. Most importantly, though not clinically visible, there is definite loss of photoreceptors (P) in the area of degeneration (compare with normal photoreceptor layer on the left). Other anatomy: inner limiting membrane (L), choriocapillaris (J) and large choroidal vessels (K).

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YAG laser capsulotomy is later performed. Those that do develop a retinal detachment frequently do not detach from retinal breaks adjacent to or within the lattice lesions, but from unrelated areas which previously looked clinically normal. This has now been observed by numerous investigators. Sabates thinks that each case must be individualized. If a patient has a history of retinal detachment in one eye and lattice degeneration with retinal holes in the other eye, he performs cryosurgery or laser surgery and closes those holes in the second eye. Usually cryosurgery is required because the cataract

may preclude the use of laser. The type of tear present and other factors including the location of the tear and the existence of high myopia would influence the ophthalmologist's judgment in deciding when to treat. Fig. 21 shows the typical retinal tear that he treats, sealed with cryotherapy. Since seven to eight percent of the population has lattice degeneration, it is obvious that not all patients with lattice degeneration should be treated. Regardless of whether the patient is treated prior to cataract surgery, those patients should be followed closely with careful examination of the peripheral retina postoperatively following cataract removal.

Figure 21: Creating the Chorioretinal Adhesion of Retinal Tear with Cryotherapy Before Performing Cataract Surgery This figure presents the treatment with cryotherapy of a retinal tear that needs to be sealed prior to cataract surgery. The freezing and defrosting is observed with the indirect ophthalmoscope. (A conceptual slit beam has been added to this illustration to enhance the 3-dimensional nature of the view).

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CATARACT SURGERY IN PATIENTS WITH UVEITIS Rubens Belfort Jr.,M.D., in Sao Paulo, Brazil and Martinez Castro in Mexico have conducted extensive research on these patients. Cataracts develop frequently in patients with uveitis, either as a result of inflammation, the treatment of inflammation or both. There has been much controversy as to what to do, how to do it and when to operate in patients with cataract and uveitis, and whether intraocular lenses should be implanted in these patients. Professor Rubens Belfort Jr. considers that uveitis is one of the last categories for which surgeons have advised «don’t do it» when cataract surgery is considered. Cataract surgery has been regarded as contraindicated because of the initial bad results with intraocular lenses (IOLs) in patients with uveitis. Until about 10 years ago, most surgeons avoided cataract surgery with or without IOL implantation in these patients. There was concern about superimposing IOL implantation, with the inflammation which used to accompany it in many cases, on a seriously compromised and already inflamed eye. This concept has now changed. The development of current techniques for small incision cataract surgery, new types of IOLs, and advances in the management of patients with uveitis have changed the prognosis. The change is fortunate because cataracts are the major cause of loss of vision in patients with chronic uveitis (Fig. 22). Moreover, cataracts are potentially dangerous for patients with uveitis because they interfere with visualization of the fundus, denying the ophthalmologist the opportunity to identify macular lesions and to treat them adequately. When these pa-

Figure 22: Uveitic Cataract Cataracts caused by an inflammatory uveitic process generally occur with pigment deposits (P) on the anterior capsule of the lens (C) related to anterior synechiae that can immobilize the pupillary sphincter. The intensive use of topical steroids for the management of the uveitis can hasten the formation of such cataracts. Cataracts are the major cause of loss of vision in patients with chronic uveitis. Current techniques for small incision surgery, new types of IOL's and advances in management of uveitis enable their removal where previously this was contraindicated.

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tients finally undergo long-postponed surgery, usually with good anatomic success, central vision may not be recovered because of irreversible macular damage that had developed from chronic cystoid macular edema. Therefore it is critical for both the surgeon and the patient with uveitis to realize there is another reason for cataract surgery in addition to improving vision as much as possible. Removal of the cataract enables the the ophthalmologist to examine and treat the macula in order to forestall damage.

Method of Choice In theory, removal of the lens as a whole (intracapsular) could lead to less inflammation. In fact, careful extracapsular surgery with adequate cleaning of the lens material during surgery usually provides a better outcome. Most surgeons now prefer phacoemulsification to a classic extracapsular extraction of the cataract even in patients with uveitis. Belfort believes phacoemulsification leads to faster results and less inflammation, and he advocates phacoemulsification with or without an IOL. Intracapsular technique is no longer used except in some rare cases of lens-induced uveitis, in which inflammation is caused by the leakage of protein material from the lens.

Diagnosing the Type of Uveitis in the Pre-Operative Phase Belfort emphasizes that in the preoperative phase, it is very important for the surgeon to determine the exact type of uveitis the patient has in order to better predict the surgical outcome and minimize reaction. For

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instance, patients with ocular sarcoid have a much worse postoperative course than other patients. Therefore, a patient with sarcoidosis and uveitis, even in the absence of important uveitis, must be approached more carefully than patients with other types of uveitis. Other types of uveitis that can be effectively managed are Fuchs’ heterochromic cyclitis, intermediate uveitis, and posterior uveitis as well as most of the anterior essential uveities. Behcet’s disease and other vascular inflammations, which in the past were considered to have a bad prognosis, have shown much better results with current techniques.

Preoperative Management In general, the less inflamed the eye at the time of surgery, the better the prognosis. Ideally, every patient should be operated only after being inflammation-free for at least 3 months, although this is not possible in many cases. Uveitis is chronic, no matter what dose of steroids is used, and many patients must be operated even in the presence of some active uveitis. The goal is to have the eye as little inflamed as possible. Preoperative steroids, as eyedrops or even systemically, as well as immunosuppressive drugs have to be used in more severe cases. In patients who do not respond to steroids alone, Belfort uses systemic oral cyclosporin and oral prednisone therapy. In 20% of patients the use of an IOL is not advisable. This includes patients with granulomatous uveitis such as sarcoid, Vogt-Koyanagi-Harada syndrome, and sympathetic ophthalmia. Belfort also advises against using IOLs in patients with juvenile rheumatoid arthritis, who tend to have a chronic disease and may develop long-term complications.

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The Intraocular Lens Currently, IOLs can be used in at least 80% of patients with both uveitis and cataract. Selecting the right type of IOL is very important. Although PMMA lenses are well tolerated by the eye with uveitis, they may lead to more posterior capsule opacification than other lenses. Belfort recommends not using silicone in cases of uveitis because silicone lenses by themselves can cause uveitis and may aggravate previous intraocular inflammation, especially in heavily pigmented people. Belfort therefore prefers to use acrylic lenses in these patients. We do not yet have clinical trials or studies that establish conclusively the superiority of one lens material over another. Results appear not to be better with heparin-coated IOLs than with PMMA lenses in patients with uveitis. Considering that heparin-coated lenses are also more expensive, Belfort does not advocate using them in uveitis. CATARACT SURGERY IN ADULT STRABISMUS PATIENTS

Preoperative Judgment The treatment of co-existing cataract and strabismus traditionally has been managed with separate operations. Usually the cataract ex-

traction has been done first, followed later by a surgical correction of strabismus. As a matter of fact, we may even hesitate to remove a cataract in a patient who has had a deviated eye for a long period for two reasons: First, cataract removal may result in postoperative diplopia, and second, it is difficult to predict whether amblyopia may be present in the deviated eye, leaving us with a questionable prognosis. Successful combined cataract and strabismus surgery is highly feasible. The ideal patient for a combined approach must fill certain prerequisites: one, he or she must have a congenital strabismus rectifiable by surgery on a single muscle in each eye. Second, the patient must have an alternating deviation and equal fusion potential in each eye, determined either by knowing the patient's vision before the onset of the cataracts or by the results of the potential acuity meter (PAM) that should be about equal in both eyes (see figures 3 through 7). An equal potential acuity meter measurement in both eyes would seem to exclude amblyopia, thereby improving the chances for an optimal visual outcome. During combined cataract and strabismus surgery, if the patient continues to blink or squeeze the eyelids following the combined topical and intracameral anesthesia, you can obtain anesthetic control this a sub-Tenon's injection of lidocaine as illustrated in Figs. 33 and 34. The effect is almost instantaneous, and surgery can continue without delay.

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BIBLIOGRAPHY Boyd, BF.: Cataract Surgery in Diabetic Patients. World Atlas Series of Ophthalmic Surgery, published by HIGHLIGHTS,Vol. IV, 1999; 9:153-54. Boyd, BF.: Undergoing cataract surgery with a master surgeon: A personal experience. Highlights of Ophthalm. Journal, Vol. 27, Nº 1, 1999;2-3. Charlton, Judie: Cataract surgery and lens implantation. Editorial Overview, Current Opinion in Ophthalmology, 2000, 11:1-2. Fine, IH.: Cataract surgical problem: Consultation section. J Cataract Refractive Surg, 1997; 23:704. Gimbel, HV., Anderson Penno, EE: Cataracts: Pathogenesis and treatment. Canadian Journal of Clinical Medicine, September 1998. Gimbel HV., Basti S., Ferensowicz MA., DeBroff BM: Results of bilateral cataract extraction with posterior chamber intraocular lens implantation in children. Ophthalmology, 1997; 104:1737-1743. John K., Fenzl R.: Preoperative Workup. Cataract Surgery: The State of the Art. Edited by Gills, JP., Slack; 1998; 1:1-8. Lacava, AC., Caballero, JC., Medeiros, OA., Centurion, V.: Biometria no alto miope. Rev Bras de Oft. 1995;54:619-622. Masket S.: Preoperative evaluation of the patient with visually significant cataract. Atlas of Cataract Surgery, Edited by Masket S. & Crandall AS, published by Martin Dunitz Ltd., 1999, 1:3-5. Neumann D., Weissmann OD., Isenberg SJ., et al: The effectiveness of daily wear contact lenses for correction of infantile aphakia. Arch Ophthalmol. 1993;111:927-9.

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C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery

IOL POWER CALCULATION IN STANDARD AND COMPLEX CASES PREPARING FOR SURGERY Making Patients Confident From the minute the patient considers undergoing surgery, fear is present. There is fear of the unknown and fear of someone operating on your eye. Jack Dodick, M.D., from New York, believes in the important influence of office personnel and environment on making patients confident and comfortable. Dodick strongly advocates hiring and training highlevel professional staff. When patients interact with highly competent staff at every encounter, they tend to conclude that the doctor must be very good because he has selected and trained his staff so well. Many doctors pay too little attention to the impressions staff make on their patients. They are tempted to cut corners by hiring clerks at low pay if they fail to realize that patients’ impressions of staff are integral to their impressions of their physician. In addition, the office environment should be tasteful. The impression patients have when they enter the office influences their feelings about their physician. An office that is dirty and cluttered reflects poorly on the practice. Dodick believes that once patients feel respected and comfortable with the expertise of the physician and his/her staff, they relax and decide they have come to the right place.

Patients Encounter with the Physician And in the encounter with the physician patients should feel respected and important. Even though the waiting room is busy, everything should seem unhurried when the patient is sitting in the chair across from the physician. The ophthalmologist should convey the impression that, at this time, the patient is the most important person. The physician’s ability to project a confident manner is also critical to success. Dodick believes it is an art to convey this confidence and professionalism to patients. It is partly done through certain inflections in the voice; perhaps it is easier to explain in reverse. Sometimes the doctor who does not feel totally secure in his ability to produce results may become a little defensive, and give more emphasis to potential complications than the real positive benefits of the operation. “Well, you have a cataract. As you know, you can have it operated on or not, and there are some complications that sometimes occur. For example. . .” Although potential complications are in fact true, the chance that these complications will occur is minimal. Dodick does not dwell on these rare potential complications. Instead, he emphasizes the

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very high probability of positive results when communicating with patients. He retains a position of objectivity in order that his own perspective will not unduly influence the patient. The patient must be informed of potential risks but with modern small incision cataract surgery, they are very unusual.

Ingredients of a Strong Relationship The physician’s ability to instill confidence and trust in patients, and an ability to articulately convey his confidence through the spoken word are the basic ingredients of a strong relationship between physician and patient. A fundamental question is how should the ophthalmologist approach patients who measure well on Snellen acuity, but still complain about their vision because of the very important factors of contrast sensitivity and glare we have already discussed. Dodick follows these basic steps. He first listens to the patient and tries to make a historical determination about how happy or incapacitated they are because of their vision. If patients claim to be very happy with their vision, Dodick goes no further. He merely instructs them that they, like everyone over 50, have some lens changes. He explains the basic anatomy of the human eye (Fig. 1-A), with its clear windows inside and outside, and the tendency of the inside window to become cloudy. The treatment, of course, is to replace the cloudy window with a clear window and thereby restore their vision. In approaching the question of when a cataract should be removed, Dodick reinforces the concept that in nearly all conditions, cataract surgery is 100% elective. The time to remove a cataract is the time that

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patients decide they are unhappy with their vision. Most people understand this, but often Dodick hears the question, “What would you do in my position?” Dodick handles this by looking the patient in the eye and responding: “This is a very simple question. If I were very happy with my vision right now, I would do nothing. If I were unhappy, I would decide in a minute to have cataract surgery.” Then patients fully realize that cataract surgery is truly an elective procedure.

Evaluating the Patient's Cataract Of course, giving patients this choice is predicated upon the fact that the ophthalmologist has conducted a thorough examination. With slit lamp biomicroscopy posterior subcapsular cataracts which strongly interfere with vision by inducing a great deal of glare are very easy to evaluate, whereas nuclear sclerotic cataracts are often difficult to evaluate on the slit lamp. People with posterior subcapsular cataracts can measure 20/20 or 20/25 on Snellen acuity because they are really looking through the little pinholes of the posterior subcapsular cages (Fig. 23A-B). The minute they see oncoming headlights while driving at night, for instance, the glare may diminish their functional vision to 20/100 or even 20/200. On the other hand, people with nuclear sclerosis, the most common form of cataract, tend to complain about contrast sensitivity rather than glare (Fig. 23C-D). Over the years Dodick has found that a good way to evaluate lenticular or media changes is to examine the red reflex of the patient by holding an ophthalmoscope about 12 to 14 inches from the eye and determining whether it is a bright red reflex, a gray reflex,

C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery

Figure 23 A-D: Posterior Subcapsular Cataract (top, left and right). Cataract with Nuclear Sclerosis (bottom, left and right) Figures 23 A and B are three dimensional photographs of a characteristic posterior subcapsular cataract, seen with the slit lamp (top-left) and with indirect illumination also using the slit lamp (top-right). Patients with posterior subcapsular cataracts can measure 20/20 or 20/25 on the Snellen visual acuity chart in the examining room, because they are seeing through the little pinholes of the posterior subcapsular cages. When they are exposed to oncoming headlights while driving at night, the glare may diminish their functional vision to 20/100 or even 20/200. Figures 23 C and D are three dimensional photos of nuclear sclerotic cataract, viewed with diffuse illumination (left) and with the slit lamp beam (right). This is the most common form of cataract. Patients tend to be hindered more by loss of contrast sensitivity rather than glare. (Reproduced with permission from AAO's Basic and Clinical Science Course, Lens and Cataract, 1999, pp.42, 48, enhanced by HIGHLIGHTS).

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or a dark black reflex. This provides a good indicator of opacity. In some circumstances a

nuclear cataract can be better evaluated with this technique than with the slit lamp. Dodick does not rely on tests for contrast sensitivity when evaluating cataracts. Although conditions of glare can be simulated in a clinical setting, Dodick relies on the patient’s real life test experience instead.

Approaching the Day of Surgery Once Dodick and his patient have reached the mutual understanding that cataract surgery may be beneficial, the patient is in essence turned over to a series of highly trained, dedicated, professional staff who work closely with him. The next person the patient sees is a highly trained technician. The technician explains that a measurement is needed to determine the correct lens to implant into the eye, and they undergo an ultrasonography scan. When the test is completed, the patient is turned over to the surgical counselor, who has become a master at making patients comfortable and ready to approach the day of cataract surgery.

out glasses, by all means do not sacrifice their near vision just for providing 20/20. The availability of foldable multifocal IOL's makes this surgeon-patient understanding even more critical so that the visual advantages of these lenses need to be fully appreciated versus the disadvantages which exist but may be less significant. A similar situation presents with the alternative of monovision. If the surgeon contemplates using this method, which is a good alternative for many patients, it is important to make sure the patient understands how this works and be enthusiastic with this alternative. Final visual satisfaction with these methods, multifocal IOL's and monovision, will depend a great deal on the selection by the surgeon of the right patient for these alternatives. With multifocal IOL's patients are happier with bilateral implantation. With monocular implantation, it is preferable not to delay surgery in the fellow eye unless there is a major reason, because most patients feel very insecure with monocular vision and having only one eye operated.

DETERMINING IOL POWER (BIOMETRY)

Patient's Expectations It is essential to clarify to the patient what he/she may expect and what not to expect. Postoperative patient satisfaction is based on this pre-op surgeon-patient communication and understanding. What are the patient's daily needs and what final uncorrected visual acuity for distance and near he would prefer? Does he want to read without glasses? If so, then he must know he would not see perfectly clearly for distance. If he/ she are myopes and consequently read with-

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Ocular biometry must be performed prior to cataract surgery. There is no question that when well selected and properly done the ultrasonic methods afford us the best way of achieving the desired postoperative refraction. Determination of intraocular lens power through meaningful keratometer readings and axial length measurement through A-Scan ultrasonography has become a "standard of care". It is a challenging technique and crucial to the visual result and patient satisfaction.

C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery

Postop Refractive Errors No Longer Admissible This is particularly true considering the high patient's expectations and the minimal astigmatism created by small incision cataract surgery, particularly phacoemulsification. Patients look forward to wearing spectacles postoperatively only under special circumstances. As emphasized by Centurion and Zacharias, postoperative refractive errors are

no longer admissible. In small incision techniques, cataract surgery has attained the status of refractive surgery. Therefore, exact determination of the IOL power to end up with the specific planned postoperative refraction is essential. The advent of multifocal foldable IOL's makes this even more of an important, though complex subject, as well as operating on eyes with different axial lengths: normal (Fig. 24), short as in hyperopia (Fig. 25 A-B), long as in myopia (Fig. 26).

Figure 24: Determination of IOL Power in Patients with Normal Axial Length (Normal Eyes) - Mechanism of How Ultrasound Measures Distances and Determines Axial Length The use of ultrasound to calculate the intraocular lens power takes into account the variants that may occur in the axial diameter of the eye and the curvature of the cornea. The ultrasound probe (P) has a piezoelectric crystal that electrically emits and receive high frequency sound waves. The sound waves travel through the eye until they are reflected back by any structure that stands perpendicularly in their way (represented by arrows). These arrows show how the sound waves travel through the ocular globe and return to contact the probe tip. Knowing the speed of the soundwaves, and based on the time it takes for the sound waves to travel back to the probe (arrows), the distance can be calculated. The speed of the ultrasound waves (arrows) is higher through a dense lens (C) than through a clear one. Soft tipped transductors (P) are recommended to avoid errors when touching the corneal surface (S). The ultrasound equipment computer can automatically multiply the time by the velocity of sound to obtain the axial length. Calculations of intraocular lens power are based on programs such as SRK-II, SRK-T, Holladay or Binkhorst among others, installed in the computer.

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Figure 25 A (above right): IOL Power Calculation in Patients With Very Short Axial Length (Hyperopia) In eyes with short or very short axial lengths as shown in Fig. 25 the third generation formulas such as Holladay 2 and Hoffer-Q seem to provide the best results. Holladay has discovered that the size of the anterior and posterior segments is not proportional in extremely short eyes (