[email protected] Glaucoma Surgery
[email protected] Published in 2005 by Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2005 by Taylor & Francis Group, LLC No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-10: 0-8247-2743-6 (Hardcover) International Standard Book Number-13: 978-0-8247-2743-7 (Hardcover) This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. No part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC) 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Catalog record is available from the Library of Congress
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[email protected] This book is dedicated to all the great teachers who made me think including Robert and Adele Trope, Wallace Foulds, Jeffery L. Jay, John Dudgeon, and William S. Lee Graham E. Trope
[email protected] Preface
Why a new Glaucoma surgery text at this time? A review of currently available texts reveals a paucity of readily available information for the Glaucoma Specialist. Although there are some excellent surgical texts for general ophthalmologists, there are few indepth texts available to help the Glaucoma specialist deal with complications seen after adult glaucoma surgery. This book is divided into two sections. A “How to” section and a section on management of complications. Topics covered in the latter section include management of the postoperative eye with high intraocular pressure with deep chamber, the flat anterior chamber with high intraocular pressure and the flat chamber with low intraocular pressure. To aid learning surgery we have also included a surgical DVD. This DVD covers a number of important topics including Peng Khaw’s method of doing a trabeculectomy, how to insert an Ahmed valve and how to manage bleb problems. I am indebted to Professor Peng Khaw, Dr. Garry Condon and especially Dr. Wai-Ching Lam for their important contributions to the DVD. I would like to thank all the surgeons who gave their valuable time to the preparation of this book. This book contains an international approach to glaucoma surgery and the management of complications. I make no apology for extensively utilizing Canadian expertise. My Canadian colleagues are expert in dealing with complications and as a result they have made substantial contributions to this new surgical text. I sincerely hope this text will help practicing glaucoma specialists decide on the most appropriate surgery for their patients and help surgeons deal rationally with complications seen postoperatively in the adult eye. Graham E. Trope, M.B., B.Ch., Ph.D., F.R.C.S.(C.), F.R.C.Ophth., F.R.C.S. (E.D.), D.O. (R.C.P.&S.)
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[email protected] Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Biography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Section I 1.
Surgical Techniques
Indications, Pre-operative Evaluation, and Outcomes of Filtering Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arthur J. Sit and Graham E. Trope
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2.
Glaucoma: Surgical Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maurice H. Luntz and Graham E. Trope
13
3.
Modern Anesthesia for Adult Glaucoma Filtration Surgery . . . . . . . . . . . . . Monica M. Carrillo and Graham E. Trope
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4.
Advances in the Modulation of Wound Healing Including Large Treatment Areas and Adjustable Sutures: The Moorfields Safe Surgery System . . . . . . . . . . . . . . . . . . . . . . Peng Tee Khaw and Graham E. Trope
5.
How to Do a Trabeculectomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Clive Migdal and Graham E. Trope
6.
Nonpenetrating Glaucoma Surgery: Indications, Techniques, and Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tarek Shaarawy, Graham E. Trope, and Andre´ Mermoud
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45
51
7.
How to Insert a Glaucoma Implant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jeffrey Freedman and Graham E. Trope
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8.
Management of Glaucoma Implant Complications . . . . . . . . . . . . . . . . . . . Jeffrey Freedman, Shlomo Melamed, and Graham E. Trope
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Contents
9.
Pars Plana Insertion of Ahmed Glaucoma Valve . . . . . . . . . . . . . . . . . . . . . Roland Ling, Wai-Ching Lam, and Graham E. Trope
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10.
Full-Thickness Filtering Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . . . . . Maurice H. Luntz and Graham E. Trope
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11.
How to Do a Surgical Iridectomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Maurice H. Luntz and Graham E. Trope
12.
Combined Cataract and Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . . . . . . 107 Ruth Lapid-Gortzak, David S. Rootman, Yvonne M. Buys, and Graham E. Trope
13.
Ultrasound Biomicroscopy in Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . 119 Charles J. Pavlin and Graham E. Trope
Section II
Management of Complications
14.
Overview: An Approach to the Diagnosis of Early Postoperative Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Yvonne M. Buys and Graham E. Trope
A.
Management of High Intraocular Pressure with a Deep Chamber
15.
Massage: Techniques and Complications . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Yvonne M. Buys and Graham E. Trope
16.
Glaucoma Suture Lysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Graham E. Trope
17.
Releasable Sutures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Ruth Lapid-Gortzak, David S. Rootman, and Graham E. Trope
18.
The Failing Bleb: Risk Factors and Diagnosis Paul R. Healey and Graham E. Trope
19.
Encapsulated Bleb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 Adael S. Soares, Marcelo T. Nicolela, Paul E. Rafuse, and Graham E. Trope
20.
Needling Procedures in Postoperative Management of Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Tarek Shaarawy, Pieter Gouws, Graham E. Trope, and Andre Mermoud
B. 21.
. . . . . . . . . . . . . . . . . . . . . . 159
Management of Flat Anterior Chamber with High Intraocular Pressure Suprachoroidal Hemorrhage in Filtering Surgery and Practical Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 Ravikrishna Nrusimhadevara, R. G. Devenyi, and Graham E. Trope
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22.
Malignant Glaucoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Dimitrios Kourkoutas, Charles J. Pavlin, and Graham E. Trope
C.
Management of a Flat Chamber with Low Intraocular Pressure
23.
Management of the Leaking Bleb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 Andrew C. Crichton, Garry P. Condon, and Graham E. Trope
24.
Remodeling the Filtration Bleb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 J. E. Morgan and Graham E. Trope
25.
Management of Flat Anterior Chambers and Choroidal Effusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Ridia Lim, Ivan Goldberg, and Graham E. Trope
26.
Hypotony Maculopathy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Catherine M. Birt and Graham E. Trope
D.
Management of Bleb Infection
27.
Blebitis and Bleb-Associated Endophthalmitis: Diagnosis and Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 Fani Segev, Allan R. Slomovic, and Graham E. Trope
Index
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
[email protected] Biography
Dr. Graham E. Trope is Professor of Ophthalmology at the University of Toronto. He has directed the Glaucoma Service at University Health Network since 1984. Dr. Trope is the past Chairman of Ophthalmology at the University of Toronto. He has published over 115 scientific articles, has been involved in Glaucoma Research and Treatment for over 20 years and is the Founder and Scientific Director of Glaucoma Research Society of Canada. He is incoming Editor-in-Chief of the Canadian Journal of Ophthalmology and he sits on a number of editorial boards including the Journal of Glaucoma. He has won a number of awards including The Ontario College of Physicians and Surgeons Council Award for his contributions to patient care. He has trained more than 20 glaucoma fellows from all over the world and is a past examiner for the Royal College of Physicians and Surgeons of Canada. He is a member of a number of learned societies and has published a book entitled Glaucoma, A Patient’s Guide to the Disease which is in its 3rd edition. xi
[email protected] Contributors
Catherine M. Birt, M.A., M.D., F.R.C.S.(C.) Associate Professor, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Yvonne M. Buys, M.D., F.R.C.S.(C.) Associate Professor of Ophthalmology, University Health Network and University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Monica M. Carrillo, M.D. Clinical and Research Fellow, Department of Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada Garry P. Condon, M.D. Clinical Associate Professor, Drexel University College of Medicine, Allegheny General Hospital, Pittsburgh, Pennsylvania, USA Andrew C. Crichton, M.D., F.R.C.S.(C.) Calgary, Calgary, Alberta, Canada
Clinical Associate Professor, University of
R. G. Devenyi, M.D., F.R.C.S.(C.) Professor of Ophthalmology & Ophthalmologist in Chief and Director of Retinal Services, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Jeffrey Freedman, M.B., B.Ch., Ph.D., F.C.S.(S.A.), F.R.C.S.E. Professor of Clinical Ophthalmology, Department of Ophthalmology, S.U.N.Y. Brooklyn, Brooklyn, New York, USA Ivan Goldberg, M.B.B.S., F.R.A.N.Z.C.O., F.R.A.C.S. ates and Sydney Eye Hospital, Sydney, Australia
Ophthalmologist, Eye Associ-
Pieter Gouws, M.B., B.Ch., F.R.C.Ophth. Glaucoma Fellow, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Paul R. Healey, M.B.B.S.(Hons.), B.Med.Sc. (Cell Biology), M.Med. (Clinical Epidemiology), F.R.A.N.Z.C.O. Ophthalmic Surgeon, Director of Glaucoma Services and Clinical Senior Lecturer, Western Sydney Eye Hospital; University of Sydney, Centre for Vision Research (Westmead Millennium Institute); and Save Sight Institute, Sydney, Australia xiii
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Contributors
Peng Tee Khaw, Ph.D., F.R.C.P., F.R.C.S., F.R.C.Ophth., F.R.C.Path., F.I.Biol., FMed.Sci. Professor of Glaucoma and Ocular Healing & Consultant Ophthalmic Surgeon, Director, Department of Glaucoma and Ocular Healing, ORB Ocular Repair and Regeneration Biology, Glaucoma, Pathology and Cell Biology, Moorfields Eye Hospital and Institute of Ophthalmology, London, UK Dimitrios Kourkoutas, M.D. Consultant in Ophthalmology, Department of Opthalmology, 401 Hellenic Army General Hospital, Athens, Greece Wai-Ching Lam, M.D., F.R.C.S.(C.) Associate Professor, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Ruth Lapid-Gortzak, M.D. Cornea Fellow, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada and Lecturer in Ophthalmology, Ben Gurion University of the Negev, Israel Ridia Lim, M.B.B.S., F.R.A.N.Z.C.O., M.P.H. Ophthalmologist, Eye Associates and Prince of Wales and Westmead Hospitals, Sydney, Australia Roland Ling, B.A., B.M., B.Ch., F.R.C.Ophth. Consultant Opthalmologist & Vitreoretinal Surgeon, The Royal Devon & Exeter Hospital, Exeter, UK Maurice H. Luntz, M.D., F.A.C.S., F.R.C.S. (E.D.), F.R.C.Ophth., D.O. (R.C.P.&S.), D.O.M.S. (R.C.S.I.), Diplomate A.B.O., Hon. F.C.S. (S.A.) Ophth. Attending and Director Emeritus, Glaucoma Services, Manhattan Eye, Ear and Throat Hospital, New York; Attending, New York Eye, Ear Infirmary, New York; Director Emeritus Department of Ophthalmology, Beth Israel Medical Center, New York; Clinical Professor of Ophthalmology, Mount Sinai School of Medicine, New York; Clinical Professor of Ophthalmology, New York University School of Medicine, New York, New York, USA Shlomo Melamed, M.D. Tel Hashomer, Israel
The Sam Rothberg Glaucoma Center, Sheba Medical Center,
Andre´ Mermoud Professor and Head, Glaucoma Unit, Jules Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland Clive Migdal, M.D., F.R.C.S., F.R.C.Ophth.
Western Eye Hospital, London, UK
J. E. Morgan, M.A., D.Phil., F.R.C.Ophth. Reader, Department of Ophthalmology, School of Medicine, Cardiff University, Cardiff, UK Marcelo T. Nicolela, M.D. Associate Professor in Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada Ravikrishna Nrusimhadevara, M.B.B.S., D.N.B. (India) Retina Fellow, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Charles J. Pavlin, M.D., F.R.C.S. Professor, Department of Ophthalmology and Visual Science, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Paul E. Rafuse, M.D., Ph.D. Assistant Professor in Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada
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David S. Rootman, M.D., F.R.C.S.(C.) Associate Professor of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Fani Segev, M.D. Department of Ophthalmology, University Health Network and University of Toronto, Toronto, Ontario, Canada Arthur J. Sit, M.D., P.Eng., F.R.C.S.(C.) Glaucoma Fellow, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Allan R. Slomovic, M.A., M.D., F.R.C.S.(C.) Associate Professor of Ophthalmology, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Tarek Shaarawy, M.D. Head, Glaucoma Sector, Ophthalmology Service, University of Geneva, Geneva, Switzerland Adael S. Soares, M.D. Nova Scotia, Canada
Clinical Fellow in Glaucoma, Dalhousie University, Halifax,
Graham E. Trope, M.B., B.Ch., Ph.D., F.R.C.S.(C.), F.R.C.Ophth., F.R.C.S. (E.D.), D.O. (R.C.P.&S.) Professor of Ophthalmology, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
[email protected] Section I: Surgical Techniques
[email protected] [email protected] 1 Indications, Pre-operative Evaluation, and Outcomes of Filtering Surgery Arthur J. Sit and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Indications for Surgery 1.1. Target Pressures: A Review of Recent Clinical Trials 1.2. Risk Factors for Progression 1.3. Compliance 1.4. Quality of Life and Lifestyle Factors 1.5. Diurnal Variations 1.6. The Case for Early Surgery 2. Pre-operative Evaluation 2.1. Patient Age 2.2. External Disease 2.3. General Health Status 3. Surgical Outcomes 4. Summary References
1.
3 3 5 6 6 7 8 9 9 9 9 9 10 11
INDICATIONS FOR SURGERY
Glaucoma surgery is indicated when target pressures are not achieved, or when neural tissue or visual function is progressively lost despite maximally tolerated medical and laser therapies.
1.1.
Target Pressures: A Review of Recent Clinical Trials
Target pressure is generally accepted to be the pressure at which progression of glaucomatous optic neuropathy is unlikely to continue. It is an attempt to prevent progression in a prospective manner. Target pressures need to be re-evaluated periodically and re-set at a lower level if progression continues. At the present time, the success of target pressure 3
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estimates can only be determined in a retrospective manner after many years of treatment. Recent multi-center, randomized controlled trials have demonstrated the efficacy of lowering intraocular pressure (IOP) in reducing both the risk of developing glaucoma and progression of the disease, and provide some help in choosing the initial target pressure. The Collaborative Normal-Tension Glaucoma Study (CNTGS) evaluated the efficacy of a 30% reduction of IOP on the rate of progression of open-angle glaucoma with normal IOP (,24 mmHg). Over a 5-year follow-up period, 35% of untreated eyes had evidence of progression of disease compared with 12% of treated eyes. The investigators concluded that IOP is related to the pathogenesis of normal-tension glaucoma, and lowering IOP by 30% decreases the risk of progression (1). On the basis of this study, we recommend trying to achieve an initial target reduction of IOP of 30% in all normal-tension glaucoma cases. Surgery may be indicated in cases when this target level is not reached. The Advanced Glaucoma Intervention Study (AGIS) was originally designed to compare the efficacy and prognosis of two different surgical treatment protocols in white and black patients. Although the original objective of the study has become somewhat irrelevant due to changes in surgical techniques, the data collected has provided important insights into the selection of target pressures. After 7 years of follow-up, the investigators reported a “dose –response” between IOP and visual field loss, in which the amount of visual field progression increased with IOP (2). In the “predictive” analysis, the patients were stratified into three groups based on average pressure. The group with average IOP ,14 mmHg had significantly less visual field deterioration than the group with average IOP .17.5 mmHg. In the “associative” analysis, the patients were stratified into four groups based on the proportion of IOP measurements that were ,18 mmHg. The group that was ,18 mmHg for all visits had an average IOP of 12.3 mmHg and demonstrated no visual field progression. The three groups that were ,18 mmHg for ,100% of visits demonstrated visual field progression. It is noteworthy that even in the first group, 14.4% of patients demonstrated visual field progression, which was balanced on average by 18.0% of patients who demonstrated improvement in their visual fields. On the basis of this evidence, we set initial target pressures in the low teens for all patients with advanced glaucomatous optic neuropathy. Clearly, if this is not achieved with medical and laser therapies, surgery may be indicated in such cases. The Ocular Hypertension Treatment Study (OHTS) compared the rates of progression for treatment vs. no treatment in patients with ocular hypertension, but no clinical evidence of glaucoma as indicated by normal optic discs and visual fields. In this study, 1636 patients with a mean IOP of 24 –32 mmHg were randomized to medical treatment with a target of 20% reduction, or observation. At 5 years, the mean reduction in IOP for the treatment arm was 22.5%. In this study, the probability of developing primary openangle glaucoma (POAG), as demonstrated by progression in visual fields or optic discs, was 4.4% for treated patients when compared with 9.5% of controls (3). This study supports lowering IOP in ocular hypotensives especially those at risk for progression, but clearly surgery is not indicated in these cases unless there are very unusual circumstances present. These studies clearly show the benefit of IOP reduction in the management of glaucoma and selected patients with ocular hypertension, and help us to set initial target pressures. Lower pressures 12 –15 mmHg clearly result in a lower risk of progression, but even reducing IOP by 20% has a protective effect. Advanced disease requires lower pressure when compared with early disease in order to halt or minimize the risk of progression. It is for this latter group that surgery should be considered sooner than later. The risk of progression posed by IOP must always be balanced with the risks of treatment. This is especially true when surgery is being considered. There is even some
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discussion as to whether patients are being over-treated in the zeal to reach the target pressure, particularly with early glaucoma. It is instructive to consider that the OHTS found that 90% of untreated ocular hypertensives did not progress over 5 years. Clearly, however, patients with advanced disease require aggressive therapy. However, not all glaucoma patients require an IOP of 12– 14 mmHg. For example, an 85-year-old with a 0.75 cup-to-disc ratio and an IOP of 18 mmHg will likely not go blind from progressive optic neuropathy despite this IOP level. However a 55-year-old with a 0.9 cup-to-disc ratio and the same IOP level with a life expectancy of at least another 20 years is at greater risk of blindness if IOP is not dropped into the low teens. Spaeth has suggested that the goal of treatment is not to prevent disease progression, but to prevent patients from becoming symptomatic or from becoming more symptomatic (4). 1.2.
Risk Factors for Progression
The decision to proceed with glaucoma surgery must include an evaluation of risk factors other than IOP alone. Table 1.1 lists the risk factors for glaucoma progression other than IOP that were found in the major recent randomized controlled trials of glaucoma treatment. In addition, factors that were assessed and found to be noncontributory, and factors that were found to be protective are listed. All of these factors should be considered prior to proceeding to surgery. Normal-tension glaucoma appears to have different risk factors than other types of glaucoma (5). Among the studies of elevated-pressure glaucoma, age is the only factor identified universally. Note that none of the studies found family history to be a significant factor for progression, and only the Collaborative Initial Glaucoma Treatment Study (CIGTS) identified race as a factor (6). This is likely a result of the high prevalence of the disease, but seems to contradict population surveys that clearly show race and family history to be associated with the presence of glaucoma. Race is clearly an important Table 1.1 Factors for Progression Other than IOP Protective factors
Study (Ref.)
Risk factors
CNTGS (5)
Disc hemorrhage, migraine, female, race (black)— tendency Better baseline VF (MD), male, age, less formal education, diabetes
AGIS (11)
EMGT (9)
Exfoliation, age, both eyes affected, worse baseline VF (MD), disc hemorrhages
CIGTS (6)
Age, race (nonwhite), diabetes, worse baseline VF (MD) Central corneal thickness (thin), age, cup-to-disc ratio, worse baseline VF (PSD)
OHTS (10)
Asian
Noncontributory factors Age, family history, hypertension, cup-to-disc ratio Race (black, nonblack), marital status, systemic hypertension, vascular disease, systemic beta-blockers, refractive error Sex, central corneal thickness, refractive error, family history, hypertension, vascular disease, migraine, smoker Sex, type of glaucoma
Diabetes
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Sit and Trope
factor in glaucoma, because blacks have four to five times the prevalence of disease as whites (7). Race may simply be an indicator for other risk factors. Family history as a risk factor may be more useful in glaucoma that occurs at a younger age. Central corneal thickness may also be an important independent risk factor for progression (8). Advanced disease is generally considered to be more susceptible to further glaucomatous damage than early disease. This is supported by the EMGT (9), CIGTS (6), and OHTS (10), which examined early glaucoma and ocular hypertension. However, the opposite result was found with AGIS (11) which examined advanced glaucoma and found that patients with better baseline visual fields were more likely to demonstrate progression. The investigators suggested that this might be due to greater difficulty in detecting visual field changes in advanced disease when compared with early disease.
1.3.
Compliance
Compliance with glaucoma medications, as with medications for any type of chronic diseases, is a major risk factor for progression. In the study by Kass et al. (12) using an eyedrop medication monitor, compliance with pilocarpine was found to be very poor. Fifteen percent of patients administered less than one-half of the prescribed doses. Twenty-five percent of patients missed at least 1 day per month. When interviewed, however, patients reported taking an average of 97% of prescribed doses. In general, compliance with medications decreases with the frequency of dosing and the number of medications. However, even with newer medical therapies with less frequent dosing, compliance continues to be very poor (13). This is further exacerbated by the fact that glaucoma is an asymptomatic disease until the very late stages, and therapy does not result in any subjective improvement in their condition. Other major reasons for noncompliance include medication side effects (both local and systemic) and difficulty administering the medication. In a patient where target IOP cannot be achieved consistently due to noncompliance, surgery must be seriously considered but only after patient education has been tried. The majority of the reasons sited by patients for noncompliance is not related to social or environmental factors and may be amenable to patient education or modification of medications (13). These include regimen factors (e.g., cost, complexity and side effects), patient factors (lack of knowledge/skill, forgetfulness, lack of motivation, and complexities created by co-morbidities), and medical provider factors (e.g., dissatisfaction with care and lack of communication). Some situational compliance factors may be difficult to remedy. Patients who live in parts of the world where drops are not available or are prohibitively expensive, or live alone and have difficulty in administering the drops for physical reasons require earlier glaucoma surgery in order to achieve target pressures (14,15). However, caution must be exercised since good compliance with medications is required postoperatively in order to reduce potential surgical complications and enhance the chance of successful surgery.
1.4.
Quality of Life and Lifestyle Factors
Both medical and surgical therapies have an impact on patient quality of life. Multiple medical therapy presents problems for elderly patients who often have difficulty in instilling drops, whereas, younger, active patients often have difficulty in maintaining a schedule for their medications. Surgical therapy often results in fewer medications in
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the long-term, but requires intense patient participation in the postoperative period. Complications of surgery can also affect patient quality of life. In the CIGTS, quality of life factors was evaluated between initial medical and initial surgical therapies (16). Symptoms and vision specific factors were evaluated at baseline, 2 months and 6 months postrandomization, and then at 6 month intervals. Visual function symptoms included evaluation of glare disability, light/dark adaptation, acuity/spatial vision, visual search, visual processing speed, depth perception, color discrimination, and peripheral vision. The results indicated lower IOP in the surgical group (14 – 15 mmHg) vs. the medical group (17 – 18 mmHg) but visual field progression was not statistically different between the two groups. Patients in the surgical group reported being bothered by more visual function symptoms than the medical group. Systemic and local eye symptoms were also evaluated. No consistent differences were found in systemic symptoms. The most persistent differences were in the local eye symptoms, which were reported more frequently in the surgical group. However, differences in symptoms between the treatment groups did not result in differences in broader measures of quality of life. Therefore, unless further information to the contrary arises, quality of life should not be used as a major factor in the decision to postpone or proceed with glaucoma surgery. 1.5.
Diurnal Variations
IOP has long been known to undergo diurnal variations (17). As well, IOP can undergo short-term fluctuations in response to environmental factors such as food or fluid intake. Consumption of large amounts of water results in an osmotic shift into the aqueous resulting in increased IOP. The opposite effect occurs when hyperosmotic solutions are used in the treatment of glaucoma. Current evidence suggests that IOPs normally peak at the end of the sleep cycle or upon awakening, and decrease through the course of the day (18). The reason for IOP increase at night is unclear, as there are currently no studies of human 24 h IOP measurements that do not require opening the eyes of the patient and/or waking the patient. It is unlikely to be related to aqueous production, since production is actually higher during the day than at night (19,20). Diurnal IOP variation has been implicated as an independent risk factor for glaucoma progression (21). In a study by Asrani et al., patients used a self-tonometer to measure IOP five times a day for 5 days at home. The diurnal IOP range and the IOP range over multiple days were found to be significant risk factors for progression, even after adjusting baseline factors including for office IOP, age, race, gender, and visual field damage at baseline. Further studies are indicated to confirm these results. Interestingly, glaucoma patients seem to have larger diurnal/waking IOP variations, but may actually have smaller nocturnal/sleeping IOP variations when compared with normals. Twenty-four-hour IOP measurements on newly diagnosed, untreated glaucoma patients show a peak at night similar to normal patients (22). However, after taking into account the change in positioning of the patient (i.e., upright while awake and supine while asleep), the diurnal-to-nocturnal IOP change was less in glaucoma patients than in normal patients. Although the role of diurnal and nocturnal IOP variations in the pathogenesis and progression of glaucoma is still not fully elucidated, it is reasonable to target therapy towards reducing diurnal IOP variations, as well as lowering mean IOP. Although any measure to lower the IOP will decrease the pressure variations, therapy that increases outflow facility, instead of decreasing aqueous production, may result in more stable measurements (23). A recent study has suggested that trabeculectomy results in reduced IOP variations compared with medical therapy, likely due to improved outflow facility
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(24). In the study by Asrani et al. (21), the risk of progression was 5.76 times higher in patients with a diurnal IOP range of 5.4 mmHg (75th percentile) compared with a range of 3.1 mmHg (25th percentile). Therefore, in a patient with progression of glaucoma on maximally tolerated medical therapy, surgical treatment may be indicated if there is evidence of large diurnal pressure range (.5 mmHg) even if the mean IOP is within the target range. 1.6.
The Case for Early Surgery
Early surgical intervention has been advocated by the European glaucoma community. This approach was initially supported by a study from Scotland that compared initial medical therapy with initial surgical therapy for newly diagnosed POAG (25). In this study, 116 patients were randomized to either trabeculectomy at diagnosis or initial medical therapy followed by trabeculectomy in unsuccessful cases. No difference in visual acuity was detected, but greater visual field loss was found in patients with initial medical therapy. The investigators suggested that this was due to delay of surgery, whereas medical therapy was modified in patients with minimal visual field loss at diagnosis. The Moorfields Primary Treatment Trial also evaluated medical therapy vs. surgical therapy for the primary treatment of glaucoma. This study randomized 48 patients to initial surgery and 40 patients to initial medical therapy. Surgery as primary treatment resulted in a lower mean IOP than medicine as primary treatment, although the visual fields were not statistically different (26). The investigators suggested that initial surgery is a safe and more cost-effective method for treating glaucoma. CIGTS evaluated initial medical therapy vs. initial surgical therapy for the primary treatment of glaucoma (6,16). In that study, the surgical group achieved a lower average IOP than the medical group, but there was no statistically significant difference in the visual field scores between the two groups. As well, the medical treatment group had a better average visual acuity than the surgical group, and was less likely to have a clinically substantial visual loss (15 letters or more). This was partially due to the surgical group having a cataract extraction rate almost three times higher than the medical group. However, the difference remained even after adjusting for cataracts. The investigators speculated that the differences in the results of this study compared with the European studies might be related to having patients with glaucoma earlier in the disease course, as well as the availability of newer, more effective medical treatments. They did not suggest changing current treatment protocols based on their 5 year results indicating that longer-term studies were required for a chronic diseases such as glaucoma. These studies suggest that both medical and surgical therapies as initial treatment for glaucoma are effective and safe. In general, surgery results in a slightly lower IOP than medical treatment alone. However, the importance of this additional IOP lowering in early glaucoma must be considered in relation to potential complications and effect on central vision. Since the potential for vision threatening complications is real, we feel surgical treatment should still be reserved for second- or third-line therapy until conclusive evidence becomes available to show that surgical treatment of glaucoma results in better visual function outcomes. The exception to this rule is in developing countries, where early surgical intervention is often indicated. With limited health care resources, there is often limited access to long-term follow-up care. In addition, life-long medical treatment is commonly prohibitively expensive for the patient. Under these circumstances, primary surgical treatment for glaucoma is a cost-effective solution despite the increased potential for complications (14,15).
[email protected] Indications, Pre-operative and Outcomes of Filtering Surgery
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9
PRE-OPERATIVE EVALUATION
Once the decision to proceed with glaucoma surgery has been made, several factors should be considered during surgical planning. 2.1.
Patient Age
Younger patients tend to have a more vigorous healing response making them more susceptible to failure. This may indicate the use of antifibrotic agents, although they should be used with caution in young myopes due to the risk of hypotonous maculopathy. By the virtue of their longer life expectancy, younger patients are more likely to have surgical failure within their lifetimes, requiring repeat surgery. We therefore advise initial surgery in one upper quadrant leaving the other quadrant for repeat surgery at a later date. It is important to remember that surgery in younger patients may result in an increased risk of blebitis and endophthalmitis due to their longer life expectancy. Older patients may have a decreased healing response and may be more susceptible to complications in the short-term. In addition, elderly patients may have difficulty with postoperative care without assistance from caregivers. 2.2.
External Disease
Evidence of ocular surface disease, including dry eye, conjunctival scarring, symblepharon, and previous ocular surgery, should be noted. These conditions make the surgical procedure more difficult, and also increase the risk of postoperative scarring, and complications. Lack of suitable conjunctiva may require an alteration in both the type and the site of surgery planned (e.g., from a trabeculectomy to a seton). The lids should always be examined for epiphora, entropion, or distachiasis. These should be dealt with prior to glaucoma surgery. Temporary measures, such as Quickert sutures for entropion or epilation for distachiasis, may be sufficient. Chronic infections, such as staphylococcal blepharitis or purulent discharge from the lacrimal sac, must be addressed prior to glaucoma surgery. 2.3.
General Health Status
Although most glaucoma surgery is performed with local anesthetic, including topical anesthetic, general health status should be known. In particular, patients with cardiovascular disease, systemic hypertension and diabetes are at increased risk of suprachoroidal hemorrhage. Surgery should be performed with caution in such cases. Patients with liver dysfunction or patients on anticoagulation therapy will have increased intraoperative bleeding. Such patients should be advised of the increased risk and be assessed by the relevant specialists before recommending discontinuation of anticoagulation therapy. Most glaucoma surgery can be successfully performed with patients on anticoagulation therapy but informed consent is important in such cases.
3.
SURGICAL OUTCOMES
Success rates for incisional glaucoma surgery depend on patient factors as discussed earlier, but are also affected by surgical techniques. The use of antimetabolites has significantly improved both the success rate and the survival rate of trabeculectomies. Two types
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Figure 1.1 Success rates with and without 5-FU (27). [Reprinted from Ref. (27), with permission from Elsevier.]
of antimetabolites are commonly used in glaucoma surgery. 5-Fluorouracil (5-FU) inhibits DNA replication but is reversible and may be used intraoperatively, as well as multiple times postoperatively. Mitomycin-C permanently binds DNA, and can only be used once with maximal effect after 5 min. The Fluorouracil Filtering Surgery Study examined the success rates of trabeculectomies with and without the use of postoperative 5-FU. Success was defined as IOP ,21 mmHg with or without medications and no need for re-operation to control IOP. The 5 years success rate of trabeculectomies was 49% with 5-FU use, but only 26% without antimetabolite use (Fig. 1.1) (27). One of the major causes of failure in both groups was early postoperative wound leak (within 2 weeks of surgery). At 5 years, the success rate for the 5-FU group was 54% in eyes without a leak and 28% in those with a leak. The 5 year success rate in the group without antimetabolites was 24% without a wound leak and 15% with a leak (28). Risk factors for wound leaks include the use of antimetabolites, one-layer (vs. two-layer) conjunctiva-Tenon capsule closure, inferiorly located trabeculectomy, and older patients. More recent studies have demonstrated similar efficacy with intraoperative mitomycin-C without the need for postoperative injections of antimetabolites (29). With the use of any antimetabolite, caution must be exercised as these patients may be more susceptible to complications from glaucoma surgery such as wound leaks or blebrelated infections (30 – 32). 4.
SUMMARY
The decision to proceed with glaucoma surgery is usually straightforward: surgery is indicated when target pressures are not achieved or when optic disc and/or visual field loss occurs despite maximally tolerated medical and laser therapies. However, risk factors
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for progression other than IOP must be evaluated as well. The presence of numerous risk factors in addition to IOP suggests the need for more aggressive target pressures and treatment. Early surgery may be indicated when compliance with medical therapy is a problem, or in developing countries where the cost of medications may be prohibitive. Large diurnal pressure variations in a patient with severe disc damage may also be an indication for earlier surgery even if the mean IOP is at target. Conversely, quality of life issues should not be used in the decision to either proceed with or delay with surgery. Once the decision to proceed with surgery has been made, careful pre-operative evaluation must be performed to determine the optimal site and type of glaucoma surgery, including the use of antifibroblastic agents. This will help to improve the success of the surgery and minimize potential complications.
REFERENCES 1.
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Collaborative Normal-Tension Glaucoma Study Group (CNTGS). The effectiveness of intraocular pressure reduction in the treatment of normal-tension glaucoma. Am J Opthalmol 1998; 126:498 – 505. The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration. Am J Opthalmol 2000; 130:429 – 440. Kass MA, Heuer DK, Higginbotham EJ, Johnson CA, Keltner JL, Miller JP et al. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Arch Ophthalmol 2002; 120:701 – 713. Spaeth GL. OHTS one year later: has it reduced my threshold for treatment? American Academy of Ophthalmology Subspecialty Day Glaucoma Meeting. Anaheim, CA, Nov 15, 2003. Drance S, Anderson DR, Schulzer M. Collaborative Normal-Tension Glaucoma Study Group. Risk factors for progression of visual field abnormalities in normal-tension glaucoma. Am J Ophthalmol 2001; 131:699 – 708. Lichter PR, Musch DC, Gillespie BW, Guire KE, Janz NK, Wren PA et al. Interim clinical outcomes in the Collaborative Initial Glaucoma Treatment Study comparing initial treatment randomized to medications or surgery. Ophthalmology 2001; 108:1943 – 1953. Tielsch JM, Sommer A, Katz J, Royall RM, Quigley HA, Javitt J. Racial variations in the prevalence of primary open-angle glaucoma. The Baltimore Eye Survey. JAMA 1991; 266:369 – 374. Herndon LW, Weizer JS, Stinnett SS. Central corneal thickness as a risk factor for advanced glaucoma damage. Arch Ophthalmol 2004; 122:17 – 21. Leske MC, Heijl A, Hussein M, Bengtsson B, Hyman L, Komaroff E, EMGT Group. Factors for glaucoma progression and the effect of treatment: The Early Manifest Glaucoma Trial. Arch Ophthalmol 2003; 121:48 – 56. Gordon MO, Beiser JA, Brandt JD, Heuer DK, Higginbotham EJ, Johnson CA et al. The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma. Arch Ophthalmol 2002; 120:714 –720. The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): 12. Baseline risk factors for sustained loss of visual field and visual acuity in patients with advanced glaucoma. Am J Ophthalmol 2002; 134:499 – 512. Kass MA, Meltzer DW, Gordon M, Cooper D, Goldberg J. Compliance with topical pilocarpine treatment. Am J Ophthalmol 1986; 101:515 – 523. Tsai JC, McClure CA, Ramos SE, Schlundt DG, Pichert JW. Compliance barriers in glaucoma: a systematic classification. J Glaucoma 2003; 12:393 – 398.
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Thomas R, Kumar RS. Primary open-angle glaucoma: the developing world perspective. American Academy of Ophthalmology Subspecialty Day Glaucoma Meeting. Anaheim, CA, Nov 15, 2003. Thomas R, Sekhar GC, Kumar RS. Glaucoma management in developing countries: medical, laser, and surgical options for glaucoma management in countries with limited resources. Curr Opin Ophthalmol 2004; 15(2):127 –131. Janz NK, Wren PA, Lichter PR, Musch DC, Gillespie BW, Guire KE et al. The Collaborative Initial Glaucoma Treatment Study: interim quality of life findings after initial medical or surgical treatment of glaucoma. Ophthalmology 2001; 108:1954 – 1965. Wilensky JT. The role of diurnal pressure measurements in the management of open angle glaucoma. Curr Opin Ophthalmol 2004; 15:90 – 92. Liu JHK, Bouligny RP, Kripke DF, Weinreb RN. Nocturnal elevation of intraocular pressure is detectable in the sitting position. Invest Ophthalmol Vis Sci 2003; 44:4439 – 4442. Larsson LI, Rettig ES, Brubaker RF. Aqueous flow in open-angle glaucoma. Arch Ophthalmol 1995; 113:283 – 286. Liu JHK. Diurnal measurement of intraocular pressure. J Glaucoma 2001; 10(suppl 1):S39–S41. Asrani S, Zeimer R, Wilensky J, Gieser D, Vitale S, Lindenmuth K. Large diurnal fluctuations in intraocular pressure are an independent risk factor in patients with glaucoma. J Glaucoma 2000; 9:134 – 142. Liu JH, Zhang X, Kripke DF, Weinreb RN. Twenty-four-hour intraocular pressure pattern associated with early glaucomatous changes. Invest Ophthalmol Vis Sci 2003; 44:1586 – 1590. Brubaker RF. Targeting outflow facility in glaucoma management. Surv Ophthalmol 2003; 48(suppl 1):S17 –S20. Medeiros FA, Pinheiro A, Moura FC, Leal BC, Susanna R Jr. Intraocular pressure fluctuations in medical versus surgically treated glaucomatous patients. J Ocul Pharmacol Ther 2002; 18:489 – 498. Jay JL, Allan D. The benefit of early trabeculectomy versus conventional management in primary open angle glaucoma relative to severity of disease. Eye 1989; 3:528 –535. Hitchings RA, Migdal CS, Wormald R et al. The Primary Treatment Trial: changes in the visual field analysis by computer-assisted perimetry. Eye 1994; 8:117– 120. The Fluorouracil Filtering Surgery Study Group. Five-year follow-up of the fluorouracil filtering surgery study. Am J Ophthalmol 1996; 121:349– 366. Parrish RK II, Schiffman JC, Feuer WJ, Heuer DK. Fluorouracil Filtering Surgery Study Group. Prognosis and risk factors for early postoperative wound leaks after trabeculectomy with and without 5-fluorouracil. Am J Ophthalmol 2001; 132:633 – 640. Singh K, Mehta K, Shaikh NM, Tsai JC, Moster MR, Budenz DL, Greenfield DS, Chen PP, Cohen JS, Baerveldt GS, Shaikh S. Trabeculectomy with intraoperative mitomycin C versus 5-fluorouracil. Prospective randomized clinical trial. Ophthalmology 2000; 107:2305– 2309. Lehmann OJ, Bunce C, Matheson MM, Maurino V, Khaw PT, Wormald R, Barton K. Risk factors for development of post-trabeculectomy endophthalmitis. Br J Ophthalmol 2000; 84:1349 – 1353. DeBry PW, Perkins TW, Heatley G, Kaufman P, Brumback LC. Incidence of late-onset bleb-related complications following trabeculectomy with mitomycin. Arch Ophthalmol 2002; 120:297 – 300. Mac I, Soltau JB. Glaucoma-filtering bleb infections. Curr Opin Ophthalmol 2003; 14:91– 94.
15.
16.
17. 18. 19. 20. 21.
22. 23. 24.
25. 26. 27. 28.
29.
30.
31.
32.
[email protected] 2 Glaucoma: Surgical Anatomy Maurice H. Luntz Manhattan Eye, Ear and Throat Hospital, New York; New York Eye, Ear Infirmary, New York; Beth Israel Medical Center, New York; Mount Sinai School of Medicine, New York; New York University School of Medicine, New York, New York, USA
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
Glaucoma filtering surgery is performed at the surgical limbus. The anatomical limbus is situated where the peripheral cornea meets the sclera externally. This is a well-demarcated zone. Conjunctiva and Tenon’s Fascia are fused and inserted here. The transition from peripheral cornea to sclera in the deeper layers is not well demarcated but is a broad area of transition 1 mm in width, has a bluish-grey appearance and constitutes the surgical limbus. The bluish-grey appearance of the surgical limbus is due to the extension of the deeper corneal lamellae beyond the external margin of the
Figure 2.1 Line drawing of dissected 1/3 thickness scleral flap. 13
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Figure 2.2 (See color insert) Photograph of dissected 1/3 thickness scleral flap with anatomical landmarks.
peripheral cornea. Viewing the scleral bed of a 1/3 thickness scleral flap at the limbus, one can note the deep corneal lamellae extending beyond the edge of the corneal periphery and this is well illustrated in Figs. 2.1 and 2.2. Figure 2.1 is a drawing and Fig. 2.2 is a photograph of the same dissection of a 1/3 thickness scleral flap which is anteriorly rotated onto the cornea. This dissection
Figure 2.3
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exposes the deeper layer of the scleral bed at the surgical limbus. In the upper part of the scleral bed, there are transparent corneal lamellae through which brown iris is visible. This is also recognizable in the photograph (Fig. 2.2) which records the surgeons view. Note that the corneal tissue in the scleral flap does not reach as far as the corneal lamellae in the deeper scleral bed (Fig. 2.1). Posterior to the cornea in the scleral bed is a grey band, which is the trabecular meshwork, and at the posterior border of this grey band dense scleral tissue is visible. The junction of the posterior limit of the grey band and the sclera is the external landmark for the scleral spur and canal of Schlemm. Deeper dissection at this landmark will lead the surgeon directly to the canal of Schlemm (e.g. for trabeculotomy). The scleral spur extends slightly posterior to this junction. It is important to recognize these landmarks, particularly when performing trabeculotomy or nonpenetrating filtration surgery. The ciliary body is attached to the junction of the trabecular band and the sclera at the scleral spur. Dissection through the sclera posterior to this junction will expose the ciliary body and the pars plicata which if cut may result in significant bleeding. In planning filtration surgery, bear in mind that the extraocular rectus muscles are inserted around the limbus area. As the muscle insertions are placed well back from the limbus, for example, the superior rectus is 7.75 mm behind the limbus, the extraocular muscles do not interfere with filtration surgery which for the most part is performed within 3 –4 mm posterior to the limbus. With a limbus-based conjunctival flap, if the scleral flap is dissected further back, great care must be taken not to cut the extraocular muscles (especially superior rectus) (Fig. 2.3).
[email protected] [email protected] 3 Modern Anesthesia for Adult Glaucoma Filtration Surgery Monica M. Carrillo Dalhousie University, Halifax, Nova Scotia, Canada
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. 2. 3. 4.
Introduction Pre-operative Evaluation General Anesthesia Local Anesthesia for Glaucoma Surgery 4.1. Monitored Anesthesia Care with Local Anesthesia 4.1.1. Intravenous Medications 4.1.2. Technique 4.1.3. Adverse Effects 4.2. Local Anesthesia 4.2.1. Advantages 4.3. Local Anesthetics 4.4. Retrobulbar Anesthesia 4.4.1. Technique 4.4.2. Complications 4.5. Subconjunctival/Sub-Tenon’s Anesthesia 4.5.1. Introduction 4.5.2. Advantages 4.5.3. Technique 4.5.4. Complications 4.5.5. Recommendation 4.6. Topical Anesthesia with Unpreserved Lidocaine 2% Jelly 4.6.1. Introduction 4.6.2. Advantages 4.6.3. Disadvantages 4.6.4. Technique of Topical Jelly Anesthesia 4.7. Topical Anesthesia with Eye Drops 4.7.1. Technique 4.7.2. Disadvantages of Local Drops
18 18 19 20 20 20 20 21 21 21 21 22 22 23 24 24 24 25 25 26 26 26 26 27 27 27 27 27 17
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5. Conclusion Acknowledgments References
1.
27 27 28
INTRODUCTION
Anesthetic techniques for filtration surgery have evolved over the years. Table 3.1 shows this evolution. Selection of the appropriate anesthetic method for glaucoma surgery depends on the pre-operative assessment of the patient, surgeon’s technique, and the complexity of the surgical procedure. Although glaucoma surgery is relatively low-risk, glaucoma patients represent a high-risk population, as they tend to be at extremes of age and to have concomitant systemic disease. Mortality for ophthalmic surgery is significantly lower than for general surgery (1 – 4). General anesthesia is more likely to cause adverse systemic effects. The incidence of anesthesia-related deaths in the operating room for all types of surgery is approximately 1 in 3000. The mortality rate associated with ophthalmic surgery is lower at 1 in 5000 or less (5). Prior to surgery, every glaucoma patient should be carefully evaluated so that potential complications can be identified and reduced to as close to zero as possible.
2.
PRE-OPERATIVE EVALUATION
The goals of pre-operative evaluation are to psychologically prepare the patient, to establish a doctor – patient relationship, to plan peri-operative management, to assess local and systemic risk, to obtain informed consent, and to meet other legal requirements. When approaching a pre-operative patient, it is important to consider the following points: .
Every patient undergoing a surgical procedure must have a comprehensive and timely medical history and physical examination and the results should be inserted in the medical record preferably by the patient’s personal physician. A thorough review of all medications should also be included. The interaction
Table 3.1 Evolution of Anesthetic Techniques for Filtration Surgery Technique
Year
Author
General anesthesia Topical cocaine Retrobulbar Posterior peribulbar Facial nerve block Anterior peribulbar Sub-Tenon’s Topical with eye drops Topical with lidocaine 2% jelly
1846 1884 1884 1985 1914 1991 1992 2002 2003
Koller Knapp Davis and Mandel van Lint, O’Brien Bloomberg Ritch R, Liebman JM Jonas et al. Trope et al.
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of glaucoma medications with general anesthetics should be considered. Complications such as tachycardia, extra systoles, hypertension, and syncope have been reported in patients on therapy with topical epinephrine (6,7). Special precautions should also be taken with patients on chronic acetazolamide therapy, as patients may be hypokalemic and hyponatremic and therefore at risk of significant arrhythmias especially under general anesthesia. Preanesthetic assessment with an anesthesiologist or a member of the anesthesia care team is advisable. This evaluation should include: a review of the patient’s medical history, a decision regarding further laboratory tests or consultations, development of an anesthetic plan, and discussion with the patient. The role of pre-operative blood tests and electrocardiogram on post-operative outcome is controversial. Evidence from a large, multi-centre trial reported no benefit of pre-operative tests on post-operative outcome (8–10). Our pre-operative testing and consultation protocol for patients scheduled for glaucoma surgery in Toronto is guided by each patient’s particular anesthetic risk provided by the patient’s medical history, that is, if under 65 with no history of heart, respiratory, or other problems, routine x-ray chest and electrocardiogram are not done. The risks associated with anesthesia and the procedure itself should be carefully discussed with the patient and detailed informed consent should be completed.
Guidelines to encourage consistency of care and to minimize disruption to patients have been published by the British Ophthalmic Anesthesia Society, specifically addressing pre-operative management of patients with cardiovascular disease (8). Adequate pre-operative evaluation is a medical, ethical, and legal duty of the ophthalmic medical care team.
3.
GENERAL ANESTHESIA
Many ophthalmic procedures including filtration surgery traditionally performed under general anesthesia (GA) are now routinely performed under topical anesthesia with monitored anesthesia care. There are, however, occasions when local anesthesia is not appropriate and GA is still the best option. Although a discussion on the details of general anesthetic technique and medications are beyond the scope of this chapter, we will briefly describe the indications, contraindications, risks, and goals of GA. Indications for GA include: .
. . . . . .
Inability of the patient to cooperate with monitored local anesthesia care (e.g., children, adults with mental or psychological deficits, nystagmus, general movement disorders, excessive anxiety or claustrophobia, tremor, inability to lie supine). Surgeons or patient preference. Surgical field not amenable to regional, local, or topical anesthesia. Regional block technically difficult or contraindicated (e.g., large globe from myopia or congenital glaucoma, coagulopathy). Allergy or sensitivity to topical anesthesia. Following intrathecal or intravascular injection of local anesthetic. Previous retrobulbar hemorrhage.
General anesthesia should be avoided in the following cases:
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. . .
Patients with Marfan’s syndrome as they have a high prevalence of cardiovascular and pulmonary abnormalities (11). Myotonic dystrophy patients as they may develop significant bradycardia and respiratory complications (12). Patients with previous severe reactions to general anesthesia or a family history of malignant hyperthermia.
It is prudent to avoid general anesthesia in patients with severe cardiovascular or pulmonary disease, and those who are particularly prone to post-operative nausea and vomiting. Ocular complications of GA include: . . .
4.
Retinal or optic nerve ischemia from profound hypotony (rare) (13). Retinal or suprachoroidal hemorrhages due to vomiting and straining on the endotracheal tube. These are of importance in filtration surgery. Exposure keratitis in the fellow eye (incidence as high as 44%) (14).
LOCAL ANESTHESIA FOR GLAUCOMA SURGERY
4.1.
Monitored Anesthesia Care with Local Anesthesia
In Toronto, virtually all filtration surgery is done under local anesthesia with monitored anesthesia care (MAC) utilizing a respiratory therapist under the supervision of an anesthesiologist to monitor the patient. The patient should ideally be awake or rousable during the procedure and able to communicate. The level of monitoring required during local anesthesia depends on the anesthetic technique and the medical condition of the patient. Appropriate facilities for monitoring in the post-operative period must be available.
4.1.1.
Intravenous Medications
An intravenous ultra short hypnotic such as propofol and very small doses of a short-acting narcotic such as alfentanyl, remifentanyl, fentanyl, or sufentanyl can be combined to accomplish most of the goals of MAC (15). Propofol provides sedation, decreased awareness, antiemesis (counteracting the pro-emetic effects of the narcotic), and amnesia. The narcotic provides a brief period of intense analgesia. This combination yields cardiopulmonary stability during stress and painful stimuli and return to baseline mental status within 10 min. Intravenous benzodiazepines such as midazolam can be used as an alternative anesthetic providing adequate sedation for patients who require anxiolysis or a small amount of sedation after the application of topical anesthesia.
4.1.2.
Technique
At the University Health Network, Toronto, intravenous sedation is, virtually, always used in conjunction with topical anesthesia for glaucoma surgery. Our sedation protocol includes a combination of: . . .
Fentanyl 1– 2 mg/kg I.V. (1 or 2 bolus depending on each patient). Propofol 0.24 –0.40 mg/kg I.V. (one dose). Occasionally midazolam, just one dose 0.75 –0.2 mg I.V. in total is utilized along with the previous two agents.
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Doses should be individualized. Patients generally do not need any further sedation and are ready for discharge when they leave the recovery room.
4.1.3.
Adverse Effects . . . .
4.2.
Sudden movement and restlessness. Airway obstruction. Lack of response to command and mild stimulation. Induction of anesthesia.
Local Anesthesia
Local anesthesia is the procedure of choice for most anterior segment ophthalmic surgeries. The use of local anesthesia in United Kingdom has risen from around 20% in 1991 (16,17) to 86% in 1997 (18).
4.2.1. . . . . . .
Advantages Less post-operative nausea and vomiting. Greater cardiopulmonary stability. Morbidity and mortality lower than with GA. Quick return to ambulation. Prolonged post-operative analgesia. Cost.
Local anesthesia includes: . . . . . .
Retrobulbar anesthesia. Peribulbar anesthesia. Sub-Tenon’s or subconjunctival anesthesia. Topical and peribulbar anesthesia. Topical and intraocular anesthesia. Topical anesthesia.
In this chapter, only the most frequently used anesthesia techniques for filtration and Seton surgery are described including retrobulbar, sub-Tenon’s, and topical anesthesia with lidocaine jelly. Ophthalmic regional anesthesia can be nonakinetic and akinetic. Akinetic blocks include retrobulbar, peribulbar, and combined retro/peribulbar techniques (19 – 23). Motor, sensory, and autonomic fibers are all blocked, resulting in regional motor paralysis and anesthesia.
4.3.
Local Anesthetics
Clinicians who use local anesthetics must be familiar with three different groups: short-acting local anesthetics (20 – 45 min), including procaine and chlorprocaine; intermediate-acting anesthetics (60 – 120 min, longer with epinephrine), including lidocaine (xylocaine) and mepivacaine; and long-acting anesthetics (400 – 450 min or longer), including bupivacaine, etidocaine, and ropivacaine (24,25) (Table 3.2).
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Table 3.2 Commonly Used Local Anesthetic Drugs (24,25) Anesthetic
Concentration (%)
Lidocaine
0.5– 1
Mepivacaine Bupivacaine Ropivacaine Etidocaine Procaine Chlorprocaine
15
0.5– 1 0.25– 0.5 0.25– 1 1 1– 2 1– 2
15 – 30 1 – 15 15 2–5 ,15
Tetracaine
4.4.
Onset (min)
15 s
Duration (h) No epinephrine: 1.5 – 2.5 With epinephrine: 2 – 4 45 – 90 min 2 –4 2 –6 2 –3 1 No epinephrine: 30 – 45 min With epinephrine: 60 – 90 min 15 min
Retrobulbar Anesthesia
4.4.1. .
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.
.
Technique For retrobulbar anesthesia, light general sedation and analgesia should be started before the retrobulbar is started. It is important that the patient remains cooperative during the retrobulbar. After the retrobulbar, more sedation can be supplied. A 1:1 mixture of lidocaine (2%, 1.5 mL) without epinephrine and bupivacaine (0.5%, 1.5 mL) should be used, with or without hyaluronidase (5 U/mL). There is poor evidence that adding hyaluronidase increases the effectiveness of these blocks at producing akinesia (26). We do not use hyaluronidase in our unit. A maximum of 3 mL retrobulbar injection is administered with the globe in primary position preferably via a short blunt 25 –27-gauge (31 mm) needle on a 5 –10 mL syringe. This provides consistent tactile feedback for both insertion of the needle and injection of the anesthetic, which in turn, provides reliable and safe blocks. Several techniques for the administration of retrobulbar block have been described, however, no single method has established a striking advantage in safety or efficacy. We recommend an entry site through the lower lid at the junction of the lateral and middle third of the inferior orbital rim with the eye in the primary position with the needle initially directed parallel to the floor of the orbit aimed at the opposite mandibulary process. It is very important to feel the lower border of the globe through the lid prior to needle insertion. The globe size is determined and only then the needle inserted 1– 2 mm below the lowest edge of the globe. Once passed the equator the needle can be tilted 208 with the tip towards superior orbit to facilitate entry to the muscle cone. A slight “give” from the inferior rectus can sometimes be felt. The hub of the needle should not go beyond the inferior orbital rim. Any pain reported by the patient may signal contact with the sclera and should prompt partial withdrawal and redirection of the needle. After aspiration to rule out intravascular placement, 1 –3 mL of anesthetic solution is injected slowly (1 mL/10 s) (27). It is important not to deliver a large bolus into the muscle cone, as the increased pressure around an atrophic glaucomatous nerve can damage it. There should be little resistance to injection. Fullness and mild ptosis of the upper lid will be evident towards the end of the injection. The tension in the orbit should be monitored manually. On no account
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should pressure be applied to the glaucomatous eye to disperse the anesthetic. Pressure from a Honan’s balloon with orbital pressure from the injection bolus can cause dangerous reduction in optic nerve head perfusion possibly leading to “wipe out” of remaining field. On withdrawal, orbicularis akinesia is achieved with injection of 1.5 mL of the same anesthetic solution slowly (1 mL/s) anterior to the septum orbitale.
Supplementary injections may be needed in 10% of cases. It takes around 10 min for most retrobulbar injections to exert their maximal effect. Evaluation of the block involves: .
Paralysis in all positions of gaze and ptosis help you to decide whether there is adequate anesthesia.
If there is excessive movement or if more than two muscles are still active at 10 min, a further 1.0 mL of the anesthetic mixture should be given in the same manner. Some activity of the superior oblique persists after the recti are completely blocked, probably from incomplete spread of the anesthetic to the superonasal/posterior aspect of the orbit where cranial nerve IV supplies the superior oblique (28). 4.4.2. Complications As the retrobulbar technique involves blind insertion of a needle into a space occupied by a number of neural and vascular structures, significant complications can and do threaten the patient’s vision or life. Complications can be divided into systemic and ocular. Systemic Complications. The systemic toxicity of local anesthetics on the central nervous and cardiovascular systems are often due to inadvertent intravascular or subarachnoid injection of the drug via the sheaths of the optic nerve or via the superior orbital fissure, with immediate transit via the bloodstream to brain or heart, or due to systemic absorption of an excess dose of the drug. This can result in brainstem anesthesia (incidence as high as 0.79%), respiratory depression, apnea, and even death (25,29 – 31). The development of toxic blood levels depends, to some degree, on the total dose, location of the block, the addition of epinephrine to the anesthetic, and the skill of the physician administering the anesthetic. Within the central nervous system, toxicity is a spectrum, extending from “excitation” to convulsions. This can serve as a warning of impending local anesthetic-induced cardiovascular collapse, characterized by profound hypotension, cardiac arrhytmias, and even death (32). It is therefore crucial that resuscitation equipment be on hand when this form of anesthesia is used. Also an experienced member of the anesthetic team should be available on short notice if retrobulbar anesthesia is to be performed. It is important to remember the maximum dosage for each anesthetic when considering local anesthesia. Table 3.3 shows the maximum dosage for local anesthetics. Ocular Complications. Rare but serious complications including amaurosis, akinesia, retinal vascular occlusion, scleral perforation, sight-threatening retrobulbar hemorrhage (incidence of 1 –5%), and even “ocular explosion” (35 –37) have all been reported (38 – 40). Post-operative ptosis, diplopia, and transient loss of vision in both eyes have also been described. Although these are less serious and transient, they are disturbing to patient and physician (41,42). Methods to reduce complications include: . .
Using a short needle with a blunted tip. Aspirating the syringe prior to injection.
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Carrillo and Trope
Table 3.3 Maximum Doses for Local Anesthetics (Illustrated in the Case of a 70 kg Patient) (24,33,34)
Anesthetic Long duration Bupivacaine Ropivacaine Moderate duration Lidocaine Mepivacaine Short duration Procaine Chlorprocaine
. .
Maximum adult dose
Concentration (%)
Without epinephrine (cc)
With epinephrine (cc)
0.5 0.5
35 40
45
2 1
15 28
25 50
2 2
40 40
50 50
Reducing the bolus volume. Reducing the force with which the local anesthetic is injected.
In Toronto, we never use retrobulbar blocks for trabeculectomy surgery, but we do use them in selected Seton cases.
4.5.
Subconjunctival/Sub-Tenon’s Anesthesia
4.5.1.
Introduction
Sub-Tenon’s local anesthesia, an alternate to retrobulbar anesthesia, has the advantage of being performed under direct observation potentially reducing the numerous complications associated with retrobulbar anesthesia (43 – 49). Parabulbar block, pinpoint anesthesia, single quadrant injection, episcleral block, and subconjunctival injection are different names or modifications of this technique (50 –53). A recent survey of the members of United Kingdom and Ireland Cataract and Refractive Society (UKISCRS) suggests that the sub-Tenon’s block is now practiced in 51% units (23). This suggests that large numbers of surgeons still use retrobulbar or general anesthesia, methods we stopped using many years ago.
4.5.2.
Advantages . . . . . .
.
Provides prolonged anesthesia and adequate akinesia for filtration surgery. Smaller volume of local anesthetic is required compared with retrobulbar block. No risk of retrobulbar hemorrhage and minimizing the risk of ocular perforation. Reduced surgical time. No need to wait for the retrobulbar to work. Excellent patient and surgeons acceptance of the technique. Allows the surgeons to check for conjunctival mobility in filtration and Seton surgery in cases of re-operation as the infiltration of anesthetic fluid separates Tenon’s capsule and conjunctiva from episclera. Easy and safe anesthetic technique not only for trabeculectomy (49,54) but also for cataract surgery (46,55,56).
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4.5.3. Technique There are many variations of this block but they have similar principles. The techniques differ in access to the sub-Tenon’s space, cannula used, local anesthetic agent, volume and the use of adjuvant. Our technique (49) involves the following steps: . . .
.
.
Insertion of tetracaine eyedrops 5 min before prepping and draping and one drop before the anesthetic injection followed by insertion of the lid speculum. For virtually painless anesthesia place a tetracaine soaked cotton bud tip on the proposed injection site for 3 – 5 min prior to injecting subconjunctival lidocaine. The most commonly used agent is 2% lidocaine without epinephrine. With the patient looking down, 0.5 – 1 cc of 2% lidocaine is injected under direct vision into the sub-Tenon’s or subconjunctival space utilizing the operating microscope via a 30-gauge needle (with a length of 0.5 in.) 8 mm from the limbus to avoid buttonholing the surgical area. With a fornix-based flap insert the needle 3 –4 mm from the limbus outside the area operation site. Insert enough anesthetic to elevate the conjunctiva over the planned operation site. It is essential to ensure that the needle tip is visualized by the surgeon throughout the procedure; this avoids the possibility of scleral perforation. Excellent globe anesthesia for trabeculectomy is usually provided by 0.25– 0.5 mL, but larger volumes (using cannulae) are required if akinesia is required (4 – 5 mL). Akinesia is not a prerequisite in our hands. Prior to final conjunctival closure, a further injection of anesthetic is administered into the conjunctival wound edges. This considerably reduces closure discomfort.
Different sub-Tenon’s anesthetic techniques have been described as follows: .
.
Fukasaku reported rapid, complete anesthesia with no akinesia utilizing placement of a specially designed curved 24-gauge blunt, metal cannula through an incision in conjunctiva and Tenon’s capsule 8 – 12 mm posterior to the limbus in the superotemporal quadrant. The cannula is introduced into the subTenon’s space and advanced posteriorly along the eye wall to its fullest extent and 1 mL of 2% lidocaine is infused. As the incision is made far from the limbus, this technique is used by some during limbal-based filtration surgery (51). Another technique described by Greenbaum involves performing an incision 2 mm behind the limbus followed by sub-Tenon’s infusion of anesthetic through a specially designed, flexible cannula (50). This conjunctival limbal incision can be eventually enlarged to incorporate a fornix-based conjunctival flap.
Cannulae for sub-Tenon’s anesthesia are either made of metal or plastic. Metal cannulae come in various sizes ranging from 19 to 23 gauges. The selection of a cannula depends on the availability and the preference of the surgeon and anesthetist. SubTenon’s anesthesia with a retained polyethylene catheter has been described for surgery of long duration (57). Access to sub-Tenon’s space has been described from the superotemporal quadrant (51), medial canthus (52), and via inferonasal quadrant dissection (58). 4.5.4.
Complications . Pain during injection (reported in up to 44% of patients) (53,59). . Subconjunctival hemorrhage (incidence: 20– 100%) (49,53).
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. . . . . .
Chemosis. Loss of local anesthetic volume during injection (53). Conjunctival injection buttonholes. Scleral perforation (60). Temporary muscle paresis. Trauma by metal cannula to inferior and medial rectus muscles leading to fibrosis and diplopia (61).
Other blocks not involving blind use of sharp needles include intracameral, deep fornix nerve block, and various combinations of two or more of these. These are usually performed by surgeons only and do not provide akinesia. 4.5.5. Recommendation We recommend subconjunctival placement of local anesthetic. This works well, raises the conjunctiva, is safe (as long as the needle tip is visualized), and effectively controls pain during surgery (49). 4.6.
Topical Anesthesia with Unpreserved Lidocaine 2% Jelly
4.6.1.
Introduction
Topical jelly anesthesia has been used by us for over 5 years for patients needing filtration surgery (62). Lidocaine 2% jelly is a widely used agent for topical anesthesia in urogenital, laryngotracheal, and even skin anesthesia and has recently been described in cataract, trabeculectomy, and phacotrabeculectomy surgery (63 – 65). Recent evidence suggests that topical anesthesia with lidocaine 2% jelly is a safe and effective alternative for clear cornea cataract surgery (66), trabeculectomy (62), and phacotrabeculectomy, even without systemic sedation (67). 4.6.2. . . . .
. . . . .
Advantages Pain control equal to sub-Tenon’s anesthesia (62). Provides adequate anesthesia and patient comfort (65 –68). Excellent patient and surgeon acceptance (62). Compared with regional anesthetic techniques such as peribulbar anesthesia, this topical approach does not increase vitreous pressure and there is no effect on the optic nerve perfusion. Post-operative recovery is quick and post-operative pain is minimal. No subconjunctival hemorrhage. Eye look is cosmetically better. Promotes efficient use of operating time (62). Preserved ocular motility can be used to optimize the wound access. The gel formulation has an increased contact time with the ocular surface, providing prolonged release of lidocaine, thus creating a sustained effect.
We conducted a prospective randomized clinical trial comparing lidocaine 2% jelly vs. sub-Tenon’s injection in 59 trabeculectomy patients (62). Anesthesia with lidocaine 2% jelly was not associated with any significant complications. For trabeculectomy surgery, 2% jelly was found to be as effective as sub-Tenon’s anesthesia. In addition, it may be safer as it does not involve injections. Topical jelly anesthesia is our preferred technique for filtration surgery. Topical anesthesia is the preferred technique for cataract surgeons in the USA
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(37%; range: 22 – 63%) according to a survey conducted by David Learning in 1998 (20). Topical anesthesia for ophthalmologic surgery has been successfully used by different authors for cataract surgery (69 – 71), trabeculectomy (62,72,73), vitrectomy (74), and phaco-trabeculectomy surgery (67,75). We find it possible to perform Seton surgery with topical jelly, but suggest addition of subconjunctival anesthesia for routine cases. A modified topical anesthesia technique has also been described for Ahmed valve placement surgery (Ayala R. Seven easy steps allow Ahmed glaucoma valve implantation under modified topical anesthesia. Ocular Surgery News 2003). 4.6.3. . . 4.6.4.
Technique of Topical Jelly Anesthesia .
. .
4.7.
Disadvantages Slightly sticky jelly covering the surgical field. Possible increased expense.
Lidocaine 2% jelly, 0.2 cc, is instilled into the conjunctival fornices 5 min before surgery. Use a 5 cc syringe with a size 20 angiocath on its end. The angiocath facilitiates application of the jelly. The Lidocaine jelly is directed over the operation site and cornea at the start of surgery and supplemented during surgery as required. Prior to final conjunctival closure, a further application of jelly must be administered to the edges of the open conjunctival wound to reduce pain.
Topical Anesthesia with Eye Drops
Topical anesthesia with eyedrops alone has been reported to be a safe and effective alternative for trabeculectomy surgery (72,73). 4.7.1.
Technique
For topical anesthesia administration with eyedrops, use preservative-free single-dose unit (minims) of tetracaine containing 0.5 mL. For each case, the entire contents of a single unit should used and administered 5 –10 min prior to surgery. One drop more should be additionally administered after draping the patient just before start of surgery and during the procedure as required (73). 4.7.2.
Disadvantages of Local Drops . . .
5.
Need for administration of several doses prior and during surgery. Short anesthetic effect without elimination of ocular movement. Potential for cumulative corneal toxicity.
CONCLUSION
Subconjunctival and, more recently, topical jelly anesthesia are rapidly replacing older forms of anesthesia for filtration surgery. ACKNOWLEDGMENTS The authors acknowledge the support of Dr. Frances Chung from the Department of Anesthesia, Toronto Western Hospital, University Health Network.
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et al., eds. New Frontiers in Ophthalmology. Proceedings of the XXVI International Congress of Ophthalmology, Singapore, March 1990, Exerpta Medica 1991:103 –106. Hessemer V, Jacobi B, Kaufman H. Motorische blockade durch retrobulbaranesthesie title: phanomenologie and mechanismen. Ophthalmologe 1995; 92:307– 310. Javitt JC, Addiego R, Friedberg HL. Brainstem anesthesia after retrobulbar block. Ophthalmology 1987; 94:718 – 724. McGalliard JN. Respiratory arrest after two retrobulbar injections (letter). Am J Ophthalmol 1978; 96:847. Meyers EF, Ramirez RC, Boniuk I. Grand mal seizures after retrobulbar block. Arch Ophthalmol 1978; 96:847. Binnion PF. Toxic effects of lignocaine on the circulation. British Medical Journal 1968; 2:470 – 472. White PF. Outpatient Anesthesia. New York: Churchill Livingston, 1990. Duke J, Rosenberg S. Local anesthetics. Anesthesia Secrets. Philadelphia: Hanley & Belfus Inc., 1995:96 – 101. Rathi V, Basti S, Gupta S. globe rupture during massage after peribulbar anesthesia. J Cat Refract Surg 1997; 23:297 – 299. Magnate DO, Bullock JD, Green WR. Ocular explosion after peribulbar anesthesia. Ophthalmology 1997; 104:608– 615. Bullock JD, Warwar RE, Green WR. Ocular explosions from periocular anesthetic injections. Ophthalmology 1999; 106:2341– 2353. Sullivan KL, Brown GC, Forman AR et al. Retrobulbar anesthesia and retinal vascular obstruction. Ophthalmology 1983; 90:373– 377. Ramsay RC, Knobloch WH. Ocular perforation following retrobulbar anesthesia for retinal detachment surgery. Am J Ophthalmol 1978; 86:61 – 64. Morgan CM, Schatz H, Vine AK. Ocular complications associated with retrobulbar injections. Ophthalmology 1988; 95:660– 665. Kaplan LJ, Jaffe NS, Clayman HM. Ptosis and cataract surgery. Ophthalmology 1985; 92:237 – 242. Rainin EA, Carlson BM. Post-operative diplopia and ptosis. A clinical hypothesis based on the myotoxicity of local anesthetics. Arch Ophthalmol 1985; 103:1337 – 1339. Smith RJH. Editorial: Why retrobulbar anesthesia? Br J Ophthalmol 1988; 72:1. Redmond RM, Dallas NL. Extracapsular cataract extraction under local anesthesia without retrobulbar injection. Br J Ophthalmol 1990; 74:203– 204. Smith R. Cataract extraction without retrobulbar anesthetic injection. Br J Ophthalmol 1990; 74:205 – 207. Furuta M, Toriumi T, Kashiwagi K, Satoh S. Limbal anesthesia for cataract surgery. Ophthalmic Surg 1990; 21:22 – 25. Petersen WC, Yanoff M. Subconjunctival anesthesia: an alternative to retrobulbar and peribulbar techniques. Ophthalmic Surg 1991; 22:199 – 201. Ritch R, Liebman JM. Sub-Tenon’s anesthesia for trabeculectomy. Ophthalmic Surg 1992; 23:502 – 504. Buys YM, Trope GE. Prospective study of sub-Tenon’s versus retrobulbar anesthesia for inpatient and day-surgery trabeculectomy. Ophthalmology 1993; 100:1585 –1589. Greenbaum S. Parabulbar anesthesia. Am J Ophthalmol 1992; 114:776. Fukasaku H, Marron JA. Sub-Tenon’s pinpoint anesthesia. J Cataract Refrac Surg 1994; 20:468 – 471. Ripart J, Metfe L, Prat-Pradal D. Medial cantus single-injection episcleral (sub-Tenon anesthesia): computed tomography imaging. Anesth Analg 1998; 87:42 – 45. Stevens JD. A new local anesthesia technique for cataract extraction by one quadrant infiltration. Br J Ophthalmol 1992; 76:670– 674. Ritch R, Liebmann JM. Sub-Tenon’s anesthesia for trabeculectomy. Ophthalmic Surg 1992; 23:502 – 504.
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Redmond RM, Dallas NL. Extracapsular cataract extraction under local anaesthesia without retrobulbar injection. Br J Ophthalmol 1990; 74:203– 204. Smith R. Cataract extraction without retrobulbar anaesthetic injection. Br J Ophthalmol 1990; 74:204 – 207. Behndig A. Sub-Tenon’s anesthesia with a retained catheter in ocular surgery of longer duration. J Cataract Refract Surg 1998; 24:1307 – 1309. Kumar CM. An update: sub-Tenon’s block. Ophthalmic Anaesthesia News 2001; 5:13– 16. Roman SJ, Chong Sit DA, Boureau CM. Sub-Tenon’s anesthesia: an efficient and safe technique. Br J Ophthalmol 1997; 81:673 – 676. Frieman BJ, Firedberg MA. Globe perforation associated with subtenon’s anesthesia. Am J Ophthalmol 2001; 131:520 – 521. Jaycock PD, Mather CM, Ferris JD, Kirkpatrick JNP. Rectus muscle trauma complicating sub-Tenon’s local anaesthesia. Eye 2001; 15:583 – 586. Carrillo MM, Buys YM, Faingold D, Trope GE. Prospective study comparing Lidocaine 2% jelly versus sub-Tenon’s anaesthesia for trabeculectomy surgery. Br J Ophthalmol 2004; 88(8):1004– 1007. Bardocci A, Lofoco G, Perdicaro S, Ciucci F, Manna L. Lidocaine 2% gel versus Lidocaine 4% unpreserved drops for Topical anesthesia in cataract surgery. Ophthalmology 2003; 110:144 – 149. Bellucci R, Morselli S, Pucci V, Zordan R, Magnolfi G. Intraocular penetration of topical lidocaine 4%. J Cataract Refract Surg 1999; 25:643– 647. Assia EI, Pras E, Yehezkel M et al. Topical anesthesia using lidocaine gel for cataract surgery. J Cataract Refract Surg 1999; 25:635 – 639. Koch PS. Efficacy of lidocaine 2% jelly as a topical agent in cataract surgery. J Cataract Refract Surg 1999; 25:632 –634. Lai JSM, Tham CCY, Lam DSC. Topical Anesthesia in Phacotrabeculectomy. J Glaucoma 2002; 11:271 – 274. Barequet IS, Soriano ES, Green R, O’Brien TP. Provision of anesthesia with single application of lidocaine 2% gel. J Cataract Refract Surg 1999; 25:626– 631. MacLean H, Burton T, Murray A. Patient discomfort during cataract surgery with modified topical and peribulbar anesthesia. J Cataract Refract Surg 1997; 23:277 – 283. Vicary D, McLennan S, Sun XY. Topical plus subconjunctival anesthesia for phacotrabeculectomy: one year follow-up. J Cataract Refract Surg 1998; 24(9):1247– 1251. Zehetmayer M, Radax U, Skorpik C et al.Topical versus peribulbar anesthesia in clear corneal cataract surgery. J Cataract Refract Surg 1996; 22(4):480 – 484. Sauder G, Jonas JB. Topical anesthesia for penetrating trabeculectomy. Graefe’s Arch Clin Exp Ophthalmol 2002; 240:739 – 742. Zabriskie NA, Ahmed IIK, Crandall AS, Daines B et al. A comparison of topical and retrobulbar anesthesia for trabeculectomy. J Glaucoma 2002; 11(4):306 – 314. Yepez J, Cedeno de Yepez J, Arevalo JF. Topical anesthesia in posterior vitrectomy. Retina 2000; 20(1):41– 45. Ahmed IK, Zabriskie NA, Crandall AS et al. Topical versus retrobulbar anesthesia for combined phacotrabeculectomy. J Cataract Refract Surg 2002; 28:631– 638.
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[email protected] 4 Advances in the Modulation of Wound Healing Including Large Treatment Areas and Adjustable Sutures: The Moorfields Safe Surgery System Peng Tee Khaw Moorfields Eye Hospital and Institute of Ophthalmology, London, UK
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Introduction 2. Which Antifibrotic Agent(s) 3. Clinically Used Agents 3.1. 5-Fluorouracil 3.2. Mitomycin-c 3.3. Other Agents 4. Application Technique 4.1. Intraoperative Application of Antimetabolite 4.1.1. Type of Incision/Dissection 4.1.2. Scleral Flap 4.1.3. Conjunctival Clamp 4.1.4. Type of Sponge 4.1.5. Antimetabolite Treatment Duration and Washout 4.1.6. Scleral Flap Sutures—New Adjustable, Releasable, and Fixed 4.1.7. Conjunctival Closure 4.2. Postoperative Application of Antimetabolites 4.2.1. Indications 4.2.2. Technique for Postoperative 5FU Injection 5. Summary Acknowledgments References
32 32 32 32 32 33 35 35 35 37 38 38 39 39 39 40 40 40 42 42 42 31
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Khaw and Trope
INTRODUCTION
Agents that modulate healing such as the antimetabolites 5-fluorouracil (5FU) and mitomycin-c (MMC) have revolutionized glaucoma surgery, in patients with a high risk of surgical failure. There is increasing evidence from long-term prospective trials, that intraocular pressures in the 10–15 mmHg range best preserve long-term vision in glaucoma (1,2). However, vision threatening complications occur with the use of these agents (3,4). Changes in clinical techniques of antimetabolite application can increase the safety and considerably reduce complications while maintaining effectiveness. In this chapter, we describe how our surgical technique has been changed to make the use of antimetabolites as safe as possible—the Safe Surgery System. This technique has evolved at Moorfields on the basis of both clinical observation and experimental studies to reduce complications and to enhance success. Some changes in surgical technique are necessary to take full advantage of these improvements. The techniques and materials described are straightforward and have been designed to be easily available to ophthalmologists. 2.
WHICH ANTIFIBROTIC AGENT(S)
There are many antifibrosis agents available for use and these range from steroids used in virtually every patient, through to antimetabolites and newer experimental agents. The full details of all antiscarring agents are too extensive for this chapter and are covered elsewhere. However, the many potential agents are summarized in Table 4.1 and the risk factors, risks of antimetabolite complications, and regimen we use in Tables 4.2– 4.4. 3.
CLINICALLY USED AGENTS
The most commonly used agents are 5FU and MMC, with other agents such as betaradiation occasionally used. Newer agents currently undergoing clinical trials in humans include Trabiow human antibody to transforming growth factor beta2, photodynamic therapy and suramin. 3.1.
5-Fluorouracil
5FU is most commonly thought of as an agent preventing DNA synthesis and therefore cell proliferation, but it also has other effects including interference with RNA function. 5FU was first used after glaucoma filtration surgery in the 1980s by Parrish and the Miami group. More recently, 5FU has been used as a single intraoperative sponge application, stimulated in part by laboratory experiments suggesting that long-term effects of 5FU could be achieved from convenient single, short intraoperative applications in vitro and in vivo (7,8) and the the intraoperative use of MMC. 3.2.
Mitomycin-c
MMC is an antibiotic antimetabolite that damages DNA by alkylation and possibly crosslinking. Free radicals are also generated that can damage many nonspecific aspects of cell function including DNA, RNA, and protein synthesis. MMC is more effective than 5FU, essentially, because at the clinical doses currently used, more cell death than cell growth arrest occurs, resulting in tissues that are relatively acellular and unable to respond to healing stimuli.
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Table 4.1 Sequence of Events in Tissue Repair and Possible Types of Modulation After Glaucoma Filtering Surgery (Events and Agents Have Overlapping Time Duration and Action) Modified from Khaw et al. (5,6) Event
Possible modulation
Activated conjunctiva “pre-activated” cells
Conjunctival/episcleral/scleral incisions Damage to connective tissue Release of plasma proteins and blood cells Activation of clotting and complement Fibrin/fibronectin/blood cell clot Release of growth factors from blood
Aqueous released from eye Breakdown of blood aqueous barrier Release of growth factors into aqueous Aqueous begins to flow through wound Migration and proliferation of polymorphonuclear neutrophil cells, macrophages, and lymphocytes
Activation, migration, and proliferation of fibroblasts
Wound contraction Fibroblast synthesis of tropocollagen glycosaminoglycans and fibronectin Collagen cross linking and modification Blood vessel endothelial migration and proliferation Resolution of healing Apoptosis Disappearance of fibroblasts Fibrous subconjunctival scar
3.3.
Stop medical therapy (especially drops causing red eye) Pre-operative steroids Minimal trauma Less invasive surgical techniques Hemostasis (blood can reverse MMC) Agents preventing/removing fibrin (e.g., heparin, tissue plasminogen activator, hirudin) Antagonists to growth factor production (e.g. antibodies to growth factors humanized antiTGF-beta2 antibody (CAT 152 Trabiow) or receptors) Anti-sense oligonucleotides, ribozymes, siRNA Less specific antagonists (tranilast, genistein, suramin) Blood aqueous barrier stabilising agents (e.g. steroids) Non-steroidal anti-inflammatory agents Anti-inflammatory agents (e.g., steroids, cyclosporine, glucosamine dendrimers) Anti-metabolites (e.g., 5FU/MMC) Antibodies to inflammatory mediators Angiotensin converting enzyme or chymase inhibitors Pre-operative steroids to reduce activation Anti-metabolites MMC 5FU Methylxanthine derivatives, Mushroom lectins Antiproliferative gene p21(WAF-1/Cip-1) Photodynamic therapy Anti-contraction agents (e.g., colchicine, taxol lectins, MMP inhibitors) Interferon alpha, MMP inhibitors, fibrostatin-c Anti-cross linking agents (e.g., beta-aminopropionitrile/penicillamine) Inhibitors of angiogenesis (e.g., fumagillin analogs, heparin analogs) MMC 5FU death receptor ligands Stimulants of apoptosis pathways
Other Agents
In photodynamic therapy, the area is sensitized with a photosensitizing dye (carboxyfluorescein) and then the bleb area to be treated exposed to appropriate wavelength of light (blue 450– 490 nm) protecting other areas (9). Beta-radiation is delivered using a
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Table 4.2 Risk Factors for Failure Due to Scarring After Glaucoma Filtration Surgery Risk factors
Risk 1 –3þ
Ocular Neovascular glaucoma (active) Previous failed filtration surgery Previous conjunctival surgery Chronic conjunctival inflammation Previous cataract extraction (conj incision) Aphakia (intracapsular extraction) Previous intraocular surgery Uveitis (active, persistent) A red, injected eye Previous topical medications (beta-blockers þ pilocarpine) (beta-blockers þ pilocarpine þ adrenaline) New topical medications High preoperative intraocular pressure (higher with each 10 mmHg rise) Time since last surgery (especially if within last 30 days) Inferiorly located trabeculectomy Patient Afro-Caribbean origin may vary (e.g., West vs. East Africans) Indian subcontinent origin Hispanic origin Japanese origin young þ (þ) (particularly children) þþ
þþþ þþ(þ) þþ þþ(þ) þþ(þ) þþþ þþ þþ þþ þ(þ) þþþ þ(þ) þ(þ)
Comments
Uncertain
Depends on type of surgery
Particularly if they cause a red eye
þ þþ(þ) þ þþ þ (þ) (þ)
Strontium-90 probe, which is applied to the bleb area at the end of surgery. A dose of 1000 cGy is normally given—the time of exposure depends on the emission rate of the probe. Trabiow is given as a subconjunctival injection of antibody just before opening the conjunctiva, at the end of surgery, on day 1 and day 7 after surgery. Beta-irradiation has also been used effectively to inhibit wound healing after filtration surgery, principally by causing cellular growth arrest (10). A summary of the currently used intraoperative agents is shown in Table 4.5.
Table 4.3 Possible Risk Factors for Antimetabolite Related Complications † † † † †
Elderly patient Primary surgery no previous medications Poorly supportive scleral tissue prone to collapse (e.g., Myopia/buphthalmos/Ehlers Danlos) Thin conjunctiva or sclera Bleb placed in interpalpebral or inferior position
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Table 4.4 Moorfields Eye Hospital (More Flow) Intraoperative Single Dose Anti-scarring Regimen v2005 (Continuously Evolving). Lower Target Pressures Would Suggest that a Stronger Agent May be Required Low risk patients (nothing or intraoperative 5FU 50 mg/mL )a No risk factors Topical medications (beta-blockers/pilocarpine) Afro-Caribbean (elderly) Youth ,40 with no other risk factors Intermediate risk patients (intraoperative 5FU 50 mg/mL or MMC 0.2 mg/mL)a Topical medications (adrenaline) Previous cataract surgery without conjunctival incision (capsule intact) Several low-risk factors Combined glaucoma filtration surgery/cataract extraction Previous conjunctival surgery (e.g., squint surgery, detachment surgery, trabeculotomy) High risk patients (intraoperative MMC 0.5 mg/mL)a Neovascular glaucoma Chronic persistent uveitis Previous failed trabeculectomy/tubes Chronic conjunctival inflammation Multiple risk factors Aphakic glaucoma (a tube may be more appropriate in this case) Intraoperative beta-radiation 1000 cGy can also be used. CAT-152 (Trabiow) or humanized anti-TGF-beta2 antibody may be appropriate in the low and intermediate risk groups in the future on the basis of the results of current studies. These groups account for the majority of patients undergoing glaucoma surgery. a Postoperative 5FU injections can be given in addition to the intraoperative applications of antimetabolite.
4.
APPLICATION TECHNIQUE
The variations in the technique used to deliver intraoperative antimetabolites may account for some of the variations in efficacy and complications seen in the literature. It is very important for individual users to maintain a consistent technique and to build up experience with one technique. Changes in area of treatment, conjunctival and scleral flap construction, and adjustable sutures have led to a dramatic difference in terms of reducing short and long term complications (Fig. 4.1). This has led to a reduction in cystic areas within the bleb from 90% to 29%. The blebitis and endophthalmitis rate over 3– 5 years was 20% for older limbus based techniques with a smaller treatment area vs. 0% over the same period for the current technique (11). Falls in complication rate have also been seen in the USA in lower risk populations from 6% to 0.5% to date (Paul Palmberg, personal communication). If these figures were extrapolated to an approximate figure of 50,000 trabeculectomies with antimetabolite per year in the United States it is possible that bleb related complications could be avoided in many thousands of patients (Fig. 4.2). 4.1.
Intraoperative Application of Antimetabolite
4.1.1. Type of Incision/Dissection Dr. Khaw has changed to a fornix-based incision for either intraoperative 5FU or MMC. The cut length is 8 mm. He does not make a relieving incision to avoid any restricting
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Table 4.5 Various Intraoperative Anti-scarring Agents Applied Directly to the Bleb Site 5FU (50 or 25 mg/mL)
Beta-radiation (1000 cGy)
Delivery
2 – 5 min
20 s – 3 min depending on output rate Approximately UK£3000 for probe but lasts 10þyears Special ordering and licensing required Lead shielded area
Cost
UK£1.50 (10 mL vial)
Availability
Good
Storage
Room temperature ready constituted
Duration effect on fibroblast proliferation
Several weeks Clinical effects several years
Several weeks
Primary effect Control over area treated
Growth arrest Moderate
Growth arrest Precise
MMC (0.2– 0.5 mg/mL) 2 – 5 min
UK£8 (2 mg vial makes 5 mL of 0.4 mg/mL) Good
Powder stable at room temperature Unstable once reconstituted Months/permanent cell death at higher range concentrations Growth arrest and cell death Moderate
Note: There have been reports of 5FU given intraoperatively directly into the filtration site during surgery. However, the risk of intraocular penetration is great and commercial 5FU is alkaline with a pH 9.0. Injected MMC has also been occasionally reported but one case of combined central retinal artery and vein occlusion has been reported following MMC injection. An aliquot of 50 mL of MMC (one drop) irreversibly damages the cornea.
incision. He dissects backwards with Westcott scissors to make a pocket of 10 – 15 mm posteriorly and wide for the antimetabolite sponges. When he dissects over the superior rectus tendon he lifts the conjunctiva to cut attachments avoiding the tendon itself (Fig. 4.3).
Figure 4.1 (See color insert) Changes in technique leading to improvements in outcome following the use of antimetabolites.
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Figure 4.2 (See color insert) Patient’s left eye treated with smaller area of mitomycin-c 0.4 mg/mL showing focal cystic bleb. Left eye treated with mitomycin-c 0.5 mg/mL and large area showing diffuse noncystic bleb.
Explanation. Dr. Khaw previously used a limbus-based incision with antimetabolite as he was worried about postoperative leaks. However, his clinical observation of cystic blebs led him to the hypothesis that they had two things in common. The first was restricted posterior flow “the ring of steel.” The second was anterior aqueous flow. Even cystic blebs from preantimetabolite days have these. The restricted flow from the posterior incision resulting in more focal cystic blebs led him to change. The effects of treatment are very focal (8,12), the cells at the edge of the treatment area although growth arrested (13,14), can make scar tissue, and encapsulate the area resulting in thinning and a cystic bleb. A fornix-based incision allows a larger area of antimetabolite treatment, without a posteriorly placed restricting scar. Similar blebs can be achieved with a limbus-based flap but the incision has to be very posteriorly placed and this result is not as consistent. This does make the subsequent scleral flap and sutures more difficult. 4.1.2. Scleral Flap Dr. Khaw now cuts the scleral flap before he applies antimetabolite. He tries to cut the largest flap possible and leave the side cuts at the limbus incomplete (1 –2 mm from limbus). This forces the aqueous backwards over a wider area to get a diffuse bleb.
Figure 4.3 (See color insert) Fornix dissection to ensure large surface area of treatment.
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Explanation. An aqueous jet at the limbus predisposes to an anterior focal cystic bleb, whereas posteriorly directed diffuse flow of aqueous from incompletely cut sides of a large scleral flap results in a more diffuse noncystic bleb. There is also evidence that treatment under the flap increases the success rate (15). Finally, if dissection occurs before the antimetabolite treatment and if there is any defect in the flap the use of intraoperative agents, particularly mitomycin can be avoided and postoperative injections used instead. 4.1.3. Conjunctival Clamp Dr. Khaw uses a special conjunctival T clamp he designed (Duckworth and Kent 2-686 Duckworth-and-Kent.com) to hold back the conjunctiva and to prevent antimetabolite touch. This clamp maintains a pocket for antimetabolite treatment. Explanation. Our experiments have shown that the antimetabolite affects mainly the area it touches (8), therefore protecting the edge prevents wound leaks and dehiscence. 4.1.4.
Type of Sponge
Dr. Khaw uses circular medical grade polyvinyl alcohol sponges used for lasik and corneal shields rather than other sponges. He cuts the sponges in half and folds them like a foldable lens. They fit through the entrance to the pocket without touching the sides (5 mm 3 and insert about 6 of these) (Fig. 4.4). He attempts to treat as large an area as he can. He also treats under the scleral flap. He has used polyvinyl alcohol sponges for many years as they maintain their integrity and do not fragment. In contrast, other sponges (e.g., Weck Cell) fragment relatively easily, with an increased chance of leaving small pieces of sponge behind in the wound. The large area of treatment results in more diffuse noncystic blebs clinically. Dr. Khaw treats under the flap as there is evidence that it improves the success rate. In addition, when he has re-explored failed surgery he has found adhesions between the scleral flap and bed in addition to episcleral fibrosis.
Figure 4.4 (See color insert) Special clamp protecting conjunctiva while folded sponges are being inserted.
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Increasing the surface area of treatment results in a much more diffuse noncystic area clinically. A large area prevents the development of a ring of scar tissue (the “ring of Steel”), which restricts flow and promotes the development of a raised cystic avascular bleb. 4.1.5. Antimetabolite Treatment Duration and Washout Dr. Khaw treats for 3 min. If he needs to vary the effect of MMC, he varies the concentration. He uses only two concentrations (0.2 and 0.5 mg/mL). For intraoperative 5FU he always uses 50 mg/mL. He washes out with 20 mL of balanced salt solution. Explanation. Pharmacokinetic experiments we have done show a rapid uptake over 3 min after which there is a plateau when relatively little drug is added for extra minutes. In the period from 1 to 3 min there is considerable variation in the dose delivered (16). 4.1.6.
Scleral Flap Sutures—New Adjustable, Releasable, and Fixed
The sclerostomy is created and secured with a mixture of fixed and releasable sutures. Dr. Khaw has developed a new type of adjustable suture which he has evolved for about 2 years. These allow the tension to be adjusted postoperatively through the conjunctiva. Specially designed forceps with very smooth edges are used for this adjustment of pressure (Duckworth and Kent 2-502) (Fig. 4.5). Explanation. If strong antimetabolites such as MMC are used, complete suture removal can lead to a sudden drop in intraocular pressure even many months after surgery. An adjustable suture system allows a gradual titration of the intraocular pressure—more gradual than that seen with suture removal or massage (17). 4.1.7. Conjunctival Closure The main reason fornix-based flaps are not popular despite the increased speed, much better exposure, and absence of a scar in the line of aqueous flow leading to more cystic blebs is the inconvenience of aqueous leakage at the limbus in the postoperative period. To get rid of this problem and take advantage of a fornix-based bleb
Figure 4.5 (See color insert) New adjustable sutures being adjusted through the conjunctiva using special finely machined forceps. For video, see http://www.ucl.ac.uk/ioo/research/khaw.htm
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Dr. Khaw has used several strategies . . . .
4.2.
No side cut in the conjunctiva—this minimizes manipulation and side leakage. Ensure Tenons is engaged in every stitch rather than just conjunctiva. Minimize any contact with antimetabolites, for example, with clamp. Side purse string sutures and deep attachment sutures buried in corneal grooves; 10/0 nylon is used throughout.
Postoperative Application of Antimetabolites
Postoperative injections of 5FU can be used postoperatively on their own, or even after intraoperative MMC or 5FU have been used. Subconjunctival injections of MMC have been given, but occasionally significant complications have been reported, so we do not use MMC injections routinely. 5FU was originally used as a planned regimen following surgery, but with the advent of intraoperative metabolites, the 5FU injections are now usually used according to the clinical situation at each post operative visit. 4.2.1.
Indications 1. 2. 3. 4. 5.
As part of a planned regimen in a patient with a significant risk of scarring or requiring a low postoperative intraocular pressure. In a patient showing signs of scarring and imminent bleb failure. Following a needling or re-exploration procedure. To prevent failure of an existing bleb after a healing stimulus (e.g., cataract extraction surgery). Injections may be given up to several months after surgery, if there is a persistent healing response and the intraocular pressure is rising.
4.2.2. Technique for Postoperative 5FU Injection The technique of postoperative injection is important. Laboratory experiments show that the degree of effect of antimetabolites on fibroblasts depends on either concentration or duration of exposure, hence the logic for using a very high concentration of 5FU intraoperatively in the surgical area (7,8). 1.
2.
3.
4. 5.
The eye is anaesthetized with several drops of topical amethocaine. It may also be useful to blanch the conjunctiva with a drop of adrenaline 0.01% or pheneylephrine 2.5% if there is no contraindication, as this may reduce the incidence of postinjection subconjunctival hemorrhage. Quantity and concentration. The original regime involved injections of 5 mg of 5FU diluted with 0.5 mL of saline. 5FU is now generally given in a concentration directly from the bottle, which is either 0.1 mL of a 50 mg/mL solution or 0.2 mL of a 25 mg/mL solution (i.e., injection dose ¼ 5 mg). A thin needle is advantageous as it reduces the reflux of 5FU into the tear film. For convenience we use a presterilized insulin syringe with an integral 27-gauge needle. A lid speculum is inserted to improve access. Site of injection. 5FU was originally given 1808 from the bleb to minimize the risk of intraocular entry of the 5FU solution which has an alkaline pH of 9. Dr. Khaw now gives the injection about 908 from the bleb to maximize the effect. Occasionally, the injection can be given deep in the upper fornix away from the drainage bleb if there is very good exposure. The conjunctiva is
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Figure 4.6 (See color insert) Injection of 5FU being given through a viscoelastic wall.
6.
gently lifted with a nontoothed forceps and the needle inserted subconjunctivally. If the needle is too deep, there is a danger of scleral bleeding and direct tracking into the eye. The bleb resulting from the injection is slowly raised and watched as it advances towards the drainage bleb area, and injecting should stop just before the injection bleb meets the drainage area. Great care should be taken, particularly in a soft eye, as 5FU may enter the eye much more easily in a soft eye. The needle should be left in place for a few seconds as this helps to seal off the entry site and reduce leakage of 5FU into the tear film.
Figure 4.7 (See color insert) Example of diffuse noncystic bleb with intraocular pressure of 12 mmHg 5 years after surgery using mitomycin 0.5 mg/mL and described techniques. This result may be possible for the majority of patients having filtration surgery with improvements of current techniques, and can lead to a dramatic reduction in complications.
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7.
8.
5.
Any remnant 5FU in the tear film should be irrigated out. If amethocaine eyedrops are used after a 5FU injection, a fine white precipitate in the tear film indicates that there is 5FU present. Washing out the fornix may reduce the incidence of corneal complications. Dr. Khaw has developed a new technique of 5FU preceded by subconjunctival Haelon GVTM. This “viscoelastic wall” prevents leakage of 5FU back into the tear film and enhances the effect of the 5FU (Fig. 4.6).
SUMMARY
Simple changes in the method of intraoperative antimetabolite application coupled with changes in surgical technique can very greatly increase the long-term safety of filtration surgery (Fig. 4.7).
ACKNOWLEDGMENTS Dr. Khaw research has been supported in part by the Medical Research Council (G9330070), the Guide Dogs for the Blind, the Wellcome Trust, Fight for Sight, the RNIB, Eranda Trust, Hayman Trust, Moorfields Trustees, the Healing Fund, and the Michael and Ilse Katz Foundation, who have supported our glaucoma and ocular repair and regeneration research program. Without them newer safer techniques for surgery would not have been developed. Mr. Alan Lacey produced the diagrams. This chapter is dedicated to Ilse Katz who inspired and helped us to help others. The author has no financial interest in any of the products listed in this review including the instruments which he has designed.
REFERENCES 1.
2.
3. 4. 5. 6. 7.
8.
The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration.The AGIS Investigators. Am J Ophthalmol 2000; 130(4):429– 440. Collaborative Normal-Tension Glaucoma Study Group. The effectiveness of intraocular pressure reduction in the treatment of normal-tension glaucoma. Am J Ophthalmol 1998; 126(4):498– 505. Higginbotham EJ, Stevens RK, Musch DC, Karp KO, Lichter PR, Bergstrom TJ et al. Blebrelated endophthalmitis after trabeculectomy with mitomycin C. 1996; 103(4):650– 656. Greenfield DS, Suner IJ, Miller MP, Kangas TA, Palmberg PF, Flynn HW. Endophthalmitis after filtering surgery with mitomycin. Arch Ophthalmol 1996; 114(8):943 –949. Khaw PT, Chang LPY. Antifibrotic agents in glaucoma surgery. In: Duker D, Yanoff M, eds. Ophthalmology—A Practical Textbook. London: Churchill Livingston, 2003. Khaw PT, Occleston NL, Schultz GS, Grierson I, Sherwood MB, Larkin G. Activation and suppression of fibroblast activity. Eye 1994; 8:188– 195. Khaw PT, Ward S, Porter A, Grierson I, Hitchings RA, Rice NSC. The long-term effects of 5-fluorouracil and sodium butyrate on human Tenon’s fibroblasts. Invest Ophthalmol Vis Sci 1992; 33:2043 – 2052. Khaw PT, Sherwood MB, MacKay SLD, Rossi MJ, Schultz G. 5-Minute treatments with fluorouracil, floxuridine and mitomycin have long-term effects on human Tenon’s capsule fibroblasts. Arch Ophthalmol 1992; 110:1150 – 1154.
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11.
12.
13.
14. 15.
16. 17.
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Diestelhorst M, Grisanti S. Photodynamic therapy to control fibrosis in human glaucomatous eyes after trabeculectomy: a clinical pilot study. Arch Ophthalmol 2002; 120(2):130– 134. Siriwardena D, Khaw PT, King AJ, Donaldson ML, Overton BM, Migdal C et al. Human antitransforming growth factor beta(2) monoclonal antibody—a new modulator of wound healing in trabeculectomy: a randomized placebo controlled clinical study. Ophthalmology 2002; 109(3):427– 431. Wells AP, Cordeiro MF, Bunce C, Khaw PT. Cystic bleb formation and related complications in limbus versus fornix based conjunctival flaps in paediatric and young adult trabeculectomy with mitomycin C. Ophthalmology 2003; 110:2192 – 2197. Khaw PT, Doyle JW, Sherwood MB, Grierson I, Schultz G, McGorray S. Prolonged localized tissue effects from 5-minute exposures to fluorouracil and mitomycin C. Arch Ophthalmol 1993; 111(2):263 –267. Occleston NL, Daniels JT, Tarnuzzer RW, Sethi KK, Alexander RA, Bhattacharya SS et al. Single exposures to antiproliferatives: long-term effects on ocular fibroblast wound-healing behavior. Invest Ophthalmol Vis Sci 1997; 38(10):1998– 2007. Daniels JT, Occleston NL, Crowston JG, Khaw PT. Effects of antimetabolite induced cellular growth arrest on fibroblast-fibroblast interactions. Exp Eye Res 1999; 69(1):117 –127. El Sayyad F, Belmekki M, Helal M, Khalil M, El Hamzawey H, Hisham M. Simultaneous subconjunctival and subscleral mitomycin-C application in trabeculectomy. Ophthalmology 2000; 107(2):298 –301. Wilkins MR, Occleston NL, Kotecha A, Waters L, Khaw PT. Sponge delivery variables and tissue levels of 5-fluorouracil. Br J Ophthalmol 2000; 84(1):92 – 97. Wells AP, Bunce C, Khaw PT. Flap and suture manipulation after trabeculectomy with adjustable sutures: titration of flow intraocular pressure in guarded filtration surgery. J Glaucoma 2004; 13:400 – 406.
[email protected] [email protected] 5 How to Do a Trabeculectomy Clive Migdal Western Eye Hospital, London, UK
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Technique 2. Postoperative Care 3. Conclusion References
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Trabeculectomy is currently the most frequently performed surgical procedure for glaucoma. The modern trabeculectomy is a safe and effective procedure, with a high success rate. The chief aim is to allow aqueous to bypass the trabecular meshwork into the subconjunctival space, but at the same time, ensuring an optimum intraocular pressure (IOP) (i.e., not too high or too low) as well as maintaining the anatomy of the globe (i.e., preventing shallowing of the anterior chamber) (1,2). It is important to assess each patient individually before undertaking trabeculectomy. Aiming for a target pressure specific for each individual eye should be an important consideration. There are many different modifications of the trabeculectomy technique (3). To obtain optimum results, however, careful attention to detail at every step of the procedure is essential. In this way, outcomes can be improved and complications minimized. In general, everything possible to minimize fibroblast proliferation should be done, with as little tissue manipulation as possible.
1.
TECHNIQUE 1.
Selecting the site: All trabeculectomies should be sited superiorly (either centrally or superonasal or superotemporal). A superonasal or superotemporal quadrant site allows preservation of the adjacent superior quadrant for 45
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2.
3.
4.
subsequent filtering or cataract surgery. Avoid the interpalpebral area as this predisposes to infection. If the patient has had previous surgery that has involved the conjunctiva, choose a site where the conjunctiva is mobile, if possible. Anesthesia: We prefer doing trabeculectomy surgery utilizing topical 2% xylocaine jelly (4); however, the procedure can be performed with subtenons/ subconjunctival anesthesia. We do not recommend retrobulbar, peribulbar, or general anesthesia unless there are specific indications for these. (See chapter on anesthesia for glaucoma surgery.) Positioning the globe: A corneal traction suture allows the best positioning of the globe (Fig. 5.1). A superior rectus traction suture can also be used, but care must be taken not to put unnecessary traction on the muscle, which might cause damage, leaving the patient with a slight ptosis. Any hemorrhage in the area might also promote postoperative fibrosis, which is undesirable. Conjunctival flap: The conjunctival flap can either be fornix- or limbal-based (5,6). It is suggested that the success and safety of these two surgical approaches are similar. A fornix-based flap is currently the most popular. Advantages include better exposure (allowing better visualization and easier forward dissection of the scleral flap), technically easier (less time and less bleeding, thus reducing fibrosis), a more diffuse bleb (as there is no posterior scar line to limit the bleb), less manipulation of the conjunctiva, easier wound closure, and less chance of buttonholing the conjunctiva. The main disadvantage of the fornix-based flap is the risk of postoperative wound leak at the limbus. This can be minimized with careful closure of the conjunctiva at the end of the operation.
Figure 5.1 Conjunctival flap.
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47
The limbal incision can either be linear, or with a relieving incision [Fig. 5.1(A) and (B)]. It is usually about 2’O clock hours in length. The incision is made through both the conjunctiva and the Tenon’s capsule, entering into the plane just above the sclera, and allowing separation of the conjunctiva and Tenon’s from the sclera. A small amount of oozing from the episcleral blood vessels usually stops spontaneously. Persistent bleeders should be individually cauterized using bipolar cautery. If a limbal-based incision is used, make sure that the incision is sufficiently posterior to avoid overlying the scleral flap, as this may cause scarring/ walling off of the bleb. In addition, care must be taken not to damage the underlying superior rectus muscle. Application of antimetabolites: This subject is covered in a separate chapter and therefore will not be discussed here. Scleral flap: This can be either square, rectangular, or triangular in shape (1 in Fig. 5.2). The size of the flap can vary. Most square flaps are 4 mm 4 mm, and rectangular 4 mm 2 mm. The flap is usually half scleral thickness. After delineating the flap and performing the linear posterior incision, the flap is carefully dissected forwards, using an angled crescent blade. This is less sharp than a diamond knife, and thus avoids inadvertent perforation. It is necessary to follow a pathway parallel to the wall of the globe, thus maintaining a scleral flap of uniform thickness. As the flap is retracted, the underlying bed should have a white color similar to the surrounding sclera, although slightly grayer due to the underlying ciliary body. If it is very gray, the flap is too deep and the bed too thin. As the flap is dissected forward, a
Figure 5.2 Scleral flap, sclerostomy, and iridectomy.
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7.
8.
9.
10.
definitive white line is encountered, marking the anterior extent of the sclera. This lies approximately over the scleral spur, or the posterior extent of the trabecular meshwork. The grayish blue zone anterior to the white line is the oblique junction between the cornea and the sclera and overlies the trabecular meshwork. About 1 mm further forward, the bluish gray area gives way to the more translucent clear cornea. This junction corresponds approximately to Schwalbe’s line. The dissection is stopped when clear cornea is encountered. Cautery should be kept to a minimum order to avoid promoting postoperative fibrosis. Tip: Avoid extending the side cuts of the scleral flap too anteriorly. This will prevent excessive leakage immediately postoperatively, which risks causing hypotony and/or a flat anterior chamber. Paracentesis: This is an essential part of the procedure and should be placed in the horizontal meridian. Tip: Avoid incising into an eye with a very high IOP. The sudden decompression risks choroidal detachment or an expulsive hemorrhage. If the IOP is .30 mm Hg preoperatively, consider administering mannitol, or other IOP reducing medications in order to reduce the IOP. Sclerostomy: The sclerostomy incision should be at least 1 mm clear of either side of the scleral flap (Fig. 5.2). After the initial linear incision into the anterior chamber, there are a number of different options for completing the sclerostomy: this can either be fashioned with a scleral punch (e.g., the Kelly Descemet’s membrane punch) (4 in Fig. 5.2), or a second parallel linear incision performed with the diamond knife, and the two then joined, enabling the removal of a block of scleral tissue (3 in Fig. 5.2). A fistula of 0.5– 1 mm in height and 1.5 –2 mm in width is created. Tip: Ensure that a full-thickness block of scleral tissue is removed, and that Descemet’s membrane, which is transparent, does not remain. Peripheral iridectomy: This is performed by grasping the peripheral iris through the sclerostomy with a fine-toothed forceps, then using a scissors (e.g., De Wecker’s) to excise a small portion of the iris (5 in Fig. 5.2). Tip: Ensure that the peripheral and not central iris is gripped. Holding the scissors blade in the horizontal meridian allows a wide v-shaped iridectomy, rather than a narrow one. The iridectomy should be visible through the clear cornea and the pupil should be round. Should bleeding from the iris occur, instilling air into the anterior chamber at this point will stop the bleeding immediately and prevent a hyphema forming (this works via a tamponade effect). The air can be withdrawn through the paracentesis at the end of the procedure. Closure of the scleral flap: This is done using various combinations of fixed and/or releasable sutures. Dr. Migdal’s preference is one fixed and one releasable suture using 10/0 monofilament nylon. Other methods include using three 10/0 nylon sutures, one at each corner of the rectangular flap (or tip of the triangle) and one on each side, 1 – 2 mm from the limbus. Tip: Always place the fixed suture first as manipulation of the flap for the second suture may loosen the first suture if this is of the releasable type. The suture is placed at 458 across the angle of the flap. The suture should be rotated to bury the knot.
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11.
12.
13.
2.
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See the chapter on releasable sutures for methods to close the flap utilizing this technique. Suturing the conjunctival flap: In the case of a fornix-based flap, it is very important to execute closure carefully, avoiding any conjunctival laxity and thus postoperative leakage. Two sutures are inserted in a purse-string fashion at either end of the incision, drawing the conjunctiva tightly across the limbus. The suture ends are buried, thus avoiding postoperative discomfort. If there is still laxity or retraction of the flap, a mattress suture can be used, spanning the two end sutures. Some surgeons prefer a continuous suture to close fornix-based flaps plus two wing sutures. With a limbal-based flap, it is essential to ensure that the incision is tightly sutured, making it water-tight. A useful method is to use a mattress stitch (absorbable 8.0 vicryl suture), taking bites of the conjunctiva and Tenon‘s capsule of the distal edge of the incision, followed by Tenon’s and conjunctiva of the proximal edge in turn. Each bite is locked in succession. If Mitomycin is used, we recommend closing limbal flaps in two separate layers using 8/0 vicryl sutures. Reformation of the anterior chamber: At the end of the procedure, it is important to reform the anterior chamber, using saline injected through the paracentesis, ensuring that the chamber is of good depth and the tension reasonable (tested by pressing gently on the central cornea with a blunt instrument). This avoids a shallow anterior chamber postoperatively, and possibly also helps prevent hypotony or choroidals. Antibiotics/steroids/patch: Some surgeons use subconjunctival antibiotics at the conclusion of the procedure, but we recommend a topical antibiotic/ steroid combination (Tobradex). We do not patch the eye after surgery (7). A plastic shield is used to cover the eye and the patient is instructed to start their postoperative drops (Tobradex QID and Atropine 1% BID) 4 h postsurgery. We recommend discontinuing the atropine after a few days if the chamber is deep. We discontinue the antibiotic steroid combination after 4 days and switch to a topical steroid drop (prednisone QID or more often if needed) for an additional 6 weeks or until the bleb is quiescent without active vacularization (8).
POSTOPERATIVE CARE
At the first postoperative visit, it is important to check the IOP, the state of the anterior chamber and fundus, and the morphology of the drainage bleb. If the IOP is raised on the first day, it is possible to apply gentle localized pressure with a sterile cotton bud to the edge of the scleral flap, thus separating the edges of the wound and allowing egress of aqueous into the subconjunctival space. If this fails to reduce the IOP to a satisfactory level, the releasable suture can be adjusted, or, if all else fails, fully released. A fixed suture can also be released, if necessary, by means of laser suture lysis (9,10), using the argon laser. See relevant chapters for further descriptions of these techniques. In most cases, the releasable suture is removed at the first or second postoperative week. However, if the IOP is at an optimum level, the releasable suture described earlier can be left in situ permanently, as the exposed parts of the suture usually become covered by epithelium within about 4 weeks.
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The approach to the management of postoperative problems such as shallowing of the anterior chamber, bleb leakage, and so on is dealt with in another chapter.
3.
CONCLUSION
Trabeculectomy is an effective procedure that maintains IOP control at a satisfactory target level for a long period of time. It is essential to develop a safe and careful surgical technique, keeping in mind the aims and potential pitfalls of the procedure, in order to ensure good results and prevent complications.
REFERENCES 1. 2. 3. 4.
5. 6. 7. 8.
9.
10.
Cairns JE. Trabeculectomy: preliminary report of a new method. Am J Ophthalmol 1968; 66:673 – 679. Watson PG. Surgery of the glaucomas. Br J Ophthalmol 1972; 56:299– 305. Lerner SF. Small incision trabeculectomy avoiding Tenon’s capsule: a new procedure for glaucoma surgery. Ophthalmology 1997; 104:1237 – 1241. Carrillo M, Buys Y, Faingold D, Trope GE. Prospective randomized study comparing lidocaine 2% jelly versus subtenons anesthesia for trabeculectomy surgery. Brit J Ophthalmol 2004; 88:1004 – 1007. Shuster JN, Krupin T, Kolker AE, Becker B. Limbus- versus fornix-based conjunctival flap in trabeculectomy: a long-term randomized study. Arch Ophthalmol 1984; 102:361 – 362. Traverso CE, Tomey KF, Antonios S. Limbal- vs fornix-based conjunctival trabeculectomy flap. Am J Ophthalmol 1987; 104:28– 32. Trope GE, Buys YM, Flanagan J, Wang L. Is a tight patch necessary after trabeculectomy? Br J Ophthalmology 1999; 83:1006– 1007. Roth SM, Spaeth GL, Starita RJ et al. The effect of postopertive corticosteroids on trabeculectomy and the clinical course of glaucoma: five-year follow-up study. Ophthamic Surg 1991; 23:724 – 729. Lewis RA. Laser suture lysis and releasable sutures. In: Weinreb RN, Mills RP, eds. Glaucoma Surgery. Principles and Techniques. 2nd ed. San Francisco: American Academy of Ophthalmology, 1991:60 – 63. Macken P, Buys Y, Trope GE. Laser suture lysis. Br J Ophthalmol 1996; 8:398– 401.
[email protected] 6 Nonpenetrating Glaucoma Surgery: Indications, Techniques, and Complications Tarek Shaarawy University of Geneva, Geneva, Switzerland
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
Andre´ Mermoud University of Lausanne, Lausanne, Switzerland
1. Principles of Nonpenetrating Glaucoma Surgery 2. Indications for NPGS 2.1. Open-Angle Glaucoma 2.2. Glaucoma Patients with High Myopia 2.3. Pigmentary Glaucoma 2.4. Exfoliative Glaucoma 2.5. Congenital Glaucoma 3. Relative Contra-indications to NPGS 4. Absolute Contra-indications 4.1. Neovascular Glaucoma 5. Surgical Technique of NPGS 5.1. Deep Sclerectomy 5.1.1. Anesthesia 5.1.2. Technique 5.1.3. The Use of Implants 5.2. Viscocanalostomy 6. Nd:YAG Goniopuncture After NPGS 7. Complications of Nonpenetrating Surgery 7.1. Intraoperative Complications 7.1.1. Perforation of the TDM 7.2. Early Postoperative Complications 7.2.1. Wound Leak 7.2.2. Inflammation 7.2.3. Hypotony 7.3. Postoperative Increase in IOP
52 52 52 52 53 53 53 53 53 53 54 54 54 54 56 57 57 58 58 58 58 58 59 59 59 51
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7.4. Late Postoperative Complications 7.4.1. Late Rupture of the TDM 7.4.2. Descemet’s Detachment 7.4.3. Peripheral Anterior Synechia 7.4.4. Scleral Ectasia 8. Results of NPGS References
1.
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PRINCIPLES OF NONPENETRATING GLAUCOMA SURGERY
Nonpenetrating glaucoma surgery (NPGS) selectively targets the pathological structures responsible for the increase in intraocular pressure (IOP) (1,2). This is done without penetration into the eye (3). In this respect, NPGS is essentially extraocular surgery as opposed to other surgical modalities that necessitate eye penetration. The avoidance of penetration into the eye reduces the risk of hypotony and its sequelae. In primary and in some cases of secondary open-angle glaucoma, the main aqueous outflow resistance is thought to be located at the level of the juxtacanalicular trabeculum and the inner wall of Schlemm’s canal (4). These two anatomic structures are removed during NPGS. The principal behind this technique was first proposed by Zimmerman (1,2), and he used the term ab externo trabeculectomy to describe it. Kozlov (5) suggested a variation on ab externo trabeculectomy in an attempt to increase the aqueous outflow facility. He extended the dissection anteriorly into peripheral corneas for an extra 1– 2 mm removing the corneal stroma behind Descemet’s membrane (Fig. 6.1). This has been termed deep sclerectomy. Postoperatively, the main aqueous outflow occurs at the level of the anterior trabeculum and Descemet’s membrane, the so-called trabeculo-Descemet’s membrane (TDM). In viscocanalostomy, as described by Stegmann et al. (6), the aqueous filters through the TDM to the surgically created scleral space, as in deep sclerectomy, but it does not form a subconjunctival filtering bleb because the superficial scleral flap is tightly closed. From the scleral space, the aqueous reaches Schlemm’s canal ostia, which are surgically opened, and dilated with viscoelastic. 2.
INDICATIONS FOR NPGS
Most published trials have evaluated efficacy of NPGS in primary and secondary openangle glaucoma. In cases where the angle is grossly distorted or closed, NPGS should not be performed. 2.1.
Open-Angle Glaucoma
NPGS has been advocated as a safer option to trabeculectomy in open-angle glaucoma (7). Instead of excising a portion of peripheral cornea and trabecular meshwork, NPGS targets the presumed site of pathology, namely the inner wall of Schlemm’s canal and the juxtacanalicular meshwork. 2.2.
Glaucoma Patients with High Myopia
Conventional glaucoma surgery in patients with high myopia carries a higher risk of complications. One study (8) reported on the results of NPGS in highly myopic
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Figure 6.1 (See color insert) Sclerectomy, ab externo trabeculectomy, deep sclerectomy.
glaucoma patients. Two out of 21 patients developed choroidal detachments, one of which was secondary to blunt trauma to the operated eye. This low rate of complication is attributed to the gradual intraoperative IOP reduction with NPGS. 2.3.
Pigmentary Glaucoma
NPGS is a potential therapy for pigmentary glaucoma; NPGS targets the site of the pathology, namely the pigment loaded trabecular meshwork. 2.4.
Exfoliative Glaucoma
NPGS is an option in exfoliative glaucoma. One study (9) reported 2-year acceptable IOP control rates in patients with exfoliative glaucoma. They also reported a low incidence of complication with NPGS. 2.5.
Congenital Glaucoma
Tixier and co-workers (10) were the first to report on NPGS in congenital glaucoma. Nine of 12 operated eyes were ,16 mmHg at 10 months without medications. They concluded that NPGS is at least as effective as trabeculectomy in congenital glaucoma with fewer complications.
3.
RELATIVE CONTRA-INDICATIONS TO NPGS
There are no published reports on NPGS in primary angle closure glaucoma. This is not surprising considering the principles behind NPGS and its presumed mechanisms of function. Likewise, secondary angle closure aetiological entities are a relative contraindication. The descision, though, depends on the degree of angle closure.
4. 4.1.
ABSOLUTE CONTRA-INDICATIONS Neovascular Glaucoma
Neovascular glaucoma is an absolute contra-indication to NPGS. The condition of the angle structures and the pathological state of the trabeculum provide little chance of surgical success.
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SURGICAL TECHNIQUE OF NPGS
5.1. 5.1.1.
Deep Sclerectomy Anesthesia
Three to four milliliters of a solution of bupivacaine 0.75% and xylocaine 4% are usually sufficient for a successful retrobulbar anesthesia. A combination of topical and subconjunctival anesthesia is possible with cooperative patients.
5.1.2.
Technique
Exposure. A superior rectus muscle traction suture or a superior intracorneal suture is used to expose the upper nasal or supero-temporal surgical quadrant. The corneal suture should not be inserted too near the limbus so that the anterior dissection of the deep sclerectomy is not obscured. Optionally, two 7/0 vicryl tangential intracorneal sutures may be placed on either side of the potential surgical site in order to reduce tension on the corneal stroma during dissection. The conjunctiva is opened as either a limbalbased flap or a fornix-based flap. A fornix-based incision offers better scleral exposure, but needs careful closure, especially when antimetabolites are used. The sclera is exposed, and moderate hemostasis is performed. To facilitate the scleral dissection, all Tenon’s capsule residue should be removed with a knife (e.g., beaver 64 or 57). Sites with large aqueous drainage veins should be avoided, to preserve the aqueous-humor physiological outflow pathways. Often gentle and continuous pressure on a bleeding vessel for 1 min stops the bleeding. Scleral Dissection. A superficial scleral flap measuring 5 5 mm2 is dissected, 1/3 scleral thickness (300 mm) (Fig. 6.2).
Figure 6.2 (See color insert) Dissection of superficial scleral flap.
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The initial scratch incision is done with a No. 11 stainless-steel blade. The horizontal dissection is done with a crescent blade. In order to later dissect the corneal stroma down to Descemet’s membrane, the scleral flap is dissected anteriorly 1 –1.5 mm into clear cornea. In patients at high risk of sclero-conjunctival scar formation (young, secondary glaucoma or African-origin), a sponge soaked in mitomycin-C 0.02% may be placed for 45 s in the scleral bed between the sclera and the conjunctiva. Deep sclero-keratectomy is done by performing a second deep scleral flap (4 4 mm2) (Fig. 6.3). The two lateral and the posterior deep scleral incisions are made using a 15-degree diamond blade or a No. 11 stainless-steel blade. The deep flap is smaller than the superficial one leaving a step of sclera on the three sides. This allows for tight closure of the superficial flap in case of intraoperative perforation of the TDM. Tip: While dissecting, the deep flap start at one corner and deepen the scratch incision till the choroid is identified, then begin the dissection in the sclera a few microns above this level. The remaining scleral layer should be as thin as possible (50 –100 mm). A second important tip involves holding the deep flap firmly so as to stretch it. Use gentle side-to-side dissection, while the flap is stretched maintaining this deep level of dissection. Maintaining a consistent straight deep level of dissection allows for successful bisection of Schlemm’s canal. As one dissects past the scleral spur (the anterior part of the dissection), Schlemm’s canal is unroofed. Schlemm’s canal is located anterior to the scleral spur where the scleral fibers are regularly oriented, parallel to the limbus. Schlemm’s canal is opened and the sclero-corneal dissection is continued anteriorly into peripheral cornea for another 1 – 1.5 mm in order to remove the roof of Schlemm’s canal and stromal tissue superficial to Descemet’s membrane. This surgical step is challenging as there is a high risk of perforation of the anterior
Figure 6.3 (See color insert) Dissection of deep flap, excision, and exposure of Schlemm’s canal.
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chamber (AC) at this point. In patients with congenital glaucoma, Schlemm’s canal localization is more difficult to find, because it is often more posteriorly situated. Tip: The best way to perform this last part of the dissection is to make two careful radial corneal cuts without penetrating down to anterior trabecular meshwork or Descemet’s membrane. This is performed with a 15-degree diamond knife or with No. 11 stainless-steel blade with the bevel side facing up. When the anterior dissection between corneal stroma and Descemet’s membrane is completed, the deep scleral flap is cut at its anterior edge using the diamond knife. At this stage, there should be a diffuse percolation of aqueous through the remaining TDM. The juxtacanalicular trabeculum and Schlemm’s endothelium are then removed using a small blunt forceps (Fig. 6.4). Tip: Just before attempting to grasp the inner wall of Schlemm’s canal with the forceps, the area should be dried, this greatly facilitates the process of stripping. Finally, the superficial scleral flap is closed and secured with two loose 10/0 nylon sutures. Note that the procedure has evolved into a combined deep sclerectomy and ab externo trabeculectomy. 5.1.3.
The Use of Implants
The original idea (5,11) behind using implants in NPGS was to avoid collapse of the superficial flap over the TDM and the remaining sclera. The first implant was a collagen implant placed in the scleral bed and secured with a single 10/0 nylon suture (Fig. 6.5). The implant was processed from porcine scleral collagen. It increased in volume after contact with aqueous and is slowly resorbed within 6– 9 months leaving a patent scleral space for aqueous filtration. Other implants currently available are the reticulated
Figure 6.4 (See color insert) Peeling of the innerwall of Schlemm’s canal and juxtacanalicular trabeculum.
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Figure 6.5 (See color insert) Implantation of a collagen implant.
hyaluronic (12) acid implant resorbing in 3 months or the T-shaped hydrophilic acrylic implant, which is nonabsorbable. The role of implants in nonpenetrating surgery is still controversial, but studies comparing deep sclerectomy with an implant vs. without (13) seems to show greater success rates with implant use. 5.2.
Viscocanalostomy
In the case of viscocanalostomy, high viscosity hyaluronic acid is injected into the two surgically created ostia of Schlemm’s canal, aiming at dilating both the ostia and the canal. The viscoelastic agent is also placed in the scleral bed. The superficial scleral flap is tightly sutured in order keep the viscoelastic in place and to force the aqueous percolating through the TDM into the two ostia.
6.
Nd:YAG GONIOPUNCTURE AFTER NPGS
When filtration through the TDM is insufficient, Nd:YAG goniopuncture is performed (14). Using a gonioscopy contact lens, the aiming beam is focused on the semitransparent TDM. Using the free running Q-switched mode, with a power of 4– 5 mJ, 2 – 15 shots are applied. This results in the formation of microscopic holes through the TDM allowing direct passage of aqueous from the AC to the subsuperficial flap space (also termed decompression chamber or intrascleral bleb). The success rate of Nd:YAG laser goniopuncture is 50%. The success of goniopuncture depends mainly on the thickness of the TDM, hence the importance of sufficiently deep dissection.
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By opening the TDM, however, goniopuncture converts a nonperforating filtration procedure into a perforating one. Nevertheless, the combined complication rates of deep sclerectomy and goniopuncture are significantly lower than the complication rates associated with trabeculectomy (15). 7.
COMPLICATIONS OF NONPENETRATING SURGERY
Nonpenetrating surgery has a lower complication rate than conventional trabeculectomy (16,17), with or without antimetabolites. Complications of NPGS are considered intraoperative, early postoperative or late postoperative. Comprehensive knowledge of these complications, as well as an understanding of the best ways to deal with them, help to make appropriate management decisions. 7.1.
Intraoperative Complications
7.1.1. Perforation of the TDM The commonest intraoperative complication of nonpenetrating surgery is perforation of the TDM. Perforations occur in 30% of the first 10 – 20 cases. After the initial learning phase, surgeons can expect perforations in 2 – 3% of cases. Different types of perforations are as follows. Transverse Tear. This occurs at the junction of the anterior meshwork and Descemet’s membrane, the weakest point of the TDM corresponding to Schwalbe’s line on gonioscopy. A perforation at this level will usually lead to the formation of a long tear, followed by immediate iris prolapse. TDM Holes. Holes may occur in the TDM during the anterior deep dissection with the knife. Holes may be small with no loss of depth of the AC or large and accompanied by shallow or flat AC and/or iris prolapse. Management. The two factors that determine the management of a TDM perforation are the depth of the AC and the presence of iris prolapse. Small holes with no iris prolapse or loss of AC depth should be ignored, and the surgery continued. Perforations with shallow or flat AC and no iris prolapse should be dealt with in order to prevent subsequent iris prolapse or peripheral anterior synechia formation. Viscoelastic material should be injected through a paracentesis, into the AC under the TDM window to reform the AC and reposition the iris. The smallest possible amount of viscoelastic material should be used to avoid postoperative ocular pressure spikes. In addition, an implant can be placed on the perforation site to tamponade the hole. The superficial scleral flap should be tightly sutured with 6– 8 10/0 nylon sutures once the AC has been reformed and the iris pushed back. Iris prolapse accompanying a larger hole is an indication for a peripheral iridectomy. The superficial flap should be tightly closed after viscoelastic material has been inserted into the surgically created scleral space so as to increase the outflow resistance. Because the scleral space left after deep sclerectomy decreases the aqueous-humor outflow resistance, very tight superficial scleral-flap closure is of great importance (18). 7.2.
Early Postoperative Complications
7.2.1. Wound Leak Wound leaks or positive Seidel test occurs with the same frequency after trabeculectomy and nonpenetrating surgery and are often due to inadequate conjunctival wound closure.
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In most cases, leaking stops after a week and after discontinuing steroid therapy. Rarely, surgical intervention is necessary to repair the wound leak. 7.2.2. Inflammation The degree of inflammatory reaction following nonpenetrating surgery is usually less than that seen with trabeculectomy. This is due to the fact that the AC is not penetrated and an iridectomy is not performed. Inflammation is treated with topical steroids for 6 weeks. 7.2.3.
Hypotony
Early hypotony without perforation is an excellent indicator of good surgical dissection. Low postoperative IOP is expected in the early postoperative period because of the surgically induced increase in outflow facility. Ideally, the TDM should always offer enough resistance to prevent anterior-chamber collapse; flat anterior chambers are not expected with successful nonpenetrating filtering surgery. On the first postoperative day, mean IOP after nonpenetrating filtering surgery usually measures 5 mmHg (19,20). IOP usually increases over the next few days without specific treatment. 7.3.
Postoperative Increase in IOP
Because the main site of postoperative aqueous-humor outflow resistance after nonpenetrating filtering surgery is located at the TDM level, this complication should not occur if the dissection of the membrane has been performed correctly. Early postoperative IOP spikes are due to the following causes. 1.
2. 3. 4.
5. 6.
Insufficient surgical dissection. In such cases, the operative site can possibly be revised. A revision though is usually difficult, many surgeons opt for a re-operation in a different site. Hemorrhage in the scleral bed. This usually spontaneously resolves without treatment within a few days. Excess viscoelastic remaining in the AC, mainly after combined surgery or AC reformation with a microperforation. This usually resolves in a few days. Postoperative rupture of the TDM with iris prolapse, secondary to increased IOP from eye rubbing, Valsalva’s maneuver, and so on. This should be managed with miotics and gonio Yag laser to the prolapsed iris. If this does not work, surgical iridectomy is indicated. Peripheral anterior synechia (PAS) formation at the site of the filtering window, often secondary to intraoperative microperforation. Steroid induced IOP increase within the first postoperative weeks.
Overall, IOP spikes are unusual postoperative complications and should be managed according to each specific cause. 7.4. 7.4.1.
Late Postoperative Complications Late Rupture of the TDM
The risk of membrane rupture decreases with time because the postmembrane outflow resistance slowly builds for several weeks. However, rupture can occur after ocular trauma or after goniopuncture. With rupture, iris prolapses into the tear leading to a
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distorted pupil and darkening of the subconjunctival area. If the IOP remains under control, no further treatment is needed. However, if the iris prolapse blocks the aqueous-humor outflow and the IOP rises, medical or surgical therapy including gonio laser or surgical iridectomy and AC reformation should be performed. 7.4.2.
Descemet’s Detachment
Descemet’s membrane detachment is a rare complication after nonpenetrating filtering surgery. We estimate it occurs in about 1 out of 250 –300 operated eyes. With viscocanalostomy, detachment is related to misdirected viscoelastic injection. The detachment is noticed during the procedure or generally shortly afterwards. After deep sclerectomy, this complication may be explained by the passage of aqueous humor from the scleral space to the sub-Descemet space at the anterior edge of Descemet’s window, secondary to increased intrableb pressure from trauma, encysted bleb, and vigorous ocular massage. This is usually a transient complication, but if it becomes prolonged, Descemetopexy has been tried successfully in such cases. 7.4.3.
Peripheral Anterior Synechia
The iris may adhere to trabeculo-Descemet’s window and form PAS (21) in the following situations: intraoperative microperforation with microiris prolapse; iris entrapment into a goniopuncture hole, which usually occurs rapidly after laser treatment, and rupture of the TDM (e.g., blunt trauma) with subsequent iris prolapse. There may be an associated increase in IOP if there is insufficient aqueous-humor flow through the membrane. Yag laser lysis should be attempted to remove the iris from the osteum. If this fails, medical or surgical treatment should be considered. 7.4.4.
Scleral Ectasia
In the literature, there is a single reported case (22) of scleral ectasia following deep sclerectomy in a12-year-old girl with chronic arthritis complicated with glaucoma secondary to a chronic uveitis. As rare as it is, this complication should be considered in patients with high myopia and chronic uveitis, especially in association with rheumatoid or juvenile arthritis. The use of antimetabolites intra- or postoperatively may also increase the risk of this complication.
8.
RESULTS OF NPGS
Prospective nonrandomized trials of deep sclerectomy (23 – 27) and viscocanalostomy (28 –30) provide sufficient evidence that the procedure can reduce IOP to acceptable levels. Randomized controlled trials (15,31 –35) comparing NPGS with trabeculectomy have a consensus on the superior safety profile of NPGS. On efficacy, we have controversial reports. This disparity in results can be attributed to a number of factors, namely the fundamental differences between various NPGS techniques, the long-learning curves, and the use of goniopunctures to achieve target IOPs. One should keep in mind though as he browses between results that it is all about technique. Issues related to which technique is superior to which in the wide spectrum of NPGS is of paramount importance. The fact of an existing long learning curve could not be over-stated. It is neither meaningful nor scientifically sound to compare one’s last twenty cases of trabeculectomy to one’s first twenty
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deep sclerectomies. What is valid is that with its apparent mechanisms of function that seems to target specific pathological structure in glaucoma, NPGS is quite promising. It would be prudent to remember that from the weight of evidence that we have available, it is of absolute importance to achieve proper depth of dissection, to use implants, and to perform goniopuncture whenever target IOPs are not achieved.
REFERENCES 1.
2.
3. 4. 5. 6. 7.
8. 9. 10. 11. 12. 13.
14.
15.
16.
17.
18.
Zimmerman TJ, Kooner KS, Ford VJ, Olander KW, Mandlekorn RM, Rawlings EF et al. Trabeculectomy vs. nonpenetrating trabeculectomy: a retrospective study of two procedures in phakic patients with glaucoma. Ophthalmic Surg 1984; 15:734 –740. Zimmerman TJ, Kooner KS, Ford VJ, Olander KW, Mandlekorn RM, Rawlings FE et al. Effectiveness of nonpenetrating trabeculectomy in aphakic patients with glaucoma. Ophthalmic Surg 1984; 15:44– 50. Mermoud A. Sinusotomy and deep sclerectomy. Eye 2000; 14:531– 535. Johnson DH, Johnson M. How does nonpenetrating glaucoma surgery work? Aqueous outflow resistance and glaucoma surgery. J Glaucoma 2001; 10:55– 67. Kozlov VI, Bagrov SN, Anisimova SY, Osipov AV, Mogilevtsev VV. Deep Sclerectomy with collagen. Eye Microsurg 1990; 3:44– 46. Stegmann R, Pienaar A, Miller D. Viscocanalostomy for open-angle glaucoma in black African patients [see comments]. J Cataract Refract Surg 1999; 25:316– 322. Mermoud A, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Faggioni R. Comparison of deep sclerectomy with collagen implant and trabeculectomy in open-angle glaucoma. J Cataract Refract Surg 1999; 25:323 – 331. Hamel M, Shaarawy T, Mermoud A. Deep sclerectomy with collagen implant in patients with glaucoma and high myopia. J Cataract Refract Surg 2001; 27:1410 – 1417. Drolsum L. Deep sclerectomy in patients with capsular glaucoma. Acta Ophthalmol Scand 2003; 81:567 – 572. Tixier J, Dureau P, Becquet F, Dufier JL. Deep sclerectomy in congenital glaucoma. Preliminary results. J Fr Ophtalmol 1999; 22:545– 548. Kozlov VI, Bagrov SN, Anisimova SY, Osipov AV, Mogilevtsev VV. Nonpenetrating deep sclerectomy with collagen. Eye Microsurg (In Russian) 1990; 3:157– 162. Detry-Morel M. Non penetrating deep sclerectomy (NPDS) with SKGEL implant and/or 5-fluorouracile (5-FU). Bull Soc Belge Ophtalmol 2001; 280:23– 32. Shaarawy T, Nguyen C, Schnyder CC, Mermoud A. Comparative study between deep sclerectomy with and without collagen implant: long-term follow up. Br J Ophthalmol 2004; 88(1):95– 98. Mermoud A, Karlen ME, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE et al. Nd:Yag goniopuncture after deep sclerectomy with collagen implant. Ophthalmic Surg Lasers 1999; 30:120 – 125. Gandolfi S, Quaranta L, Cimino L, Bettelli S. Deep sclerectomy versus trabeculectomy. Prospective Randomized Clinical trial. 4-Year interim analysis. Proceedings of the Second International Congress on Glaucoma Surgery, Luxor, Egypt, 2003. Karlen ME, Sanchez E, Schnyder CC, Sickenberg M, Mermoud A. Deep sclerectomy with collagen implant: medium term results [see comments]. Br J Ophthalmol 1999; 83:6 – 11. Mermoud A, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Faggioni R. Comparison of deep sclerectomy with collagen implant and trabeculectomy in open-angle glaucoma [see comments]. J Cataract Refract Surg 1999; 25:323 – 331. Sanchez E, Schnyder CC, Mermoud A. Comparative results of deep sclerectomy transformed to trabeculectomy and classical trabeculectomy. Klin Monatsbl Augenheilkd 1997; 210:261 – 264.
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19.
Shaarawy T, Karlen M, Schnyder C, Achache F, Sanchez E, Mermoud A. Five-year results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2001; 27:1770– 1778. Ambresin A, Shaarawy T, Mermoud A. Deep sclerectomy with collagen implant in one eye compared with trabeculectomy in the other eye of the same patient. J Glaucoma 2002; 11:214 – 220. Kim CY, Hong YJ, Seong GJ, Koh HJ, Kim SS. Iris synechia after laser goniopuncture in a patient having deep sclerectomy with a collagen implant. J Cataract Refract Surg 2002; 28:900 – 902. Milazzo S, Turut P, Malthieu D, Leviel MA. Scleral ectasia as a complication of deep sclerectomy. J Cataract Refract Surg 2000; 26:785– 787. Sanchez E, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Mermoud A. Deep sclerectomy: results with and without collagen implant. Int Ophthalmol 1996; 20:157– 162. Karlen ME, Sanchez E, Schnyder CC, Sickenberg M, Mermoud A. Deep sclerectomy with collagen implant: medium term results. Br J Ophthalmol 1999; 83:6– 11. Hamard P, Plaza L, Kopel J, Quesnot S, Hamard H. Deep nonpenetrating sclerectomy and open angle glaucoma. Intermediate results from the first operated patients. J Fr Ophtalmol 1999; 22:25 – 31. Shaarawy T, Karlen M, Schnyder C, Achache F, Sanchez E, Mermoud A. Five-year results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2001; 27:1770– 1778. Yamin M, Quentin CD. Results and complications after deep sclerectomy. Ophthalmologe 2002; 99:171 – 175. Sunaric-Megevand G, Leuenberger PM. Results of viscocanalostomy for primary open-angle glaucoma. Am J Ophthalmol 2001; 132:221 – 228. Wishart MS, Shergill T, Porooshani H. Viscocanalostomy and phacoviscocanalostomy: long-term results. J Cataract Refract Surg 2002; 28:745 – 751. Shaarawy T, Nguyen C, Schnyder CC, Mermoud A. Five-year results of viscocanalostomy in Caucasians. Br J Ophthalmol 2003; 87(4):441 – 445. Carassa R. Viscocanalaostomy versus trabeculectomy: a 12 months prospective randomized study. American Society of Cataract and Refractive Surgery, Boston, USA, 2000. Netland PA. Nonpenetrating glaucoma surgery. Ophthalmology 2001; 108:416 – 421. Jonescu-Cuypers C, Jacobi P, Konen W, Krieglstein G. Primary viscocanalostomy versus trabeculectomy in white patients with open-angle glaucoma: a randomized clinical trial. Ophthalmology 2001; 108:254– 258. Luke C, Dietlein TS, Jacobi PC, Konen W, Krieglstein GK. A prospective randomized trial of viscocanalostomy versus trabeculectomy in open-angle glaucoma: a 1-year follow-up study. J Glaucoma 2002; 11:294 – 299. El Sayyad F, Helal M, El-Kholify H, Khalil M, El-Maghraby A. Nonpenetrating deep sclerectomy versus trabeculectomy in bilateral primary open-angle glaucoma. Ophthalmology 2000; 107:1671 – 1674. Dietlein TS, Luke C, Jacobi PC, Konen W, Krieglstein GK. Variability of dissection depth in deep sclerectomy: morphological analysis of the deep scleral flap. Graefes Arch Clin Exp Ophthalmol 2000; 238:405 – 409.
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22. 23. 24. 25.
26. 27. 28. 29. 30. 31. 32. 33.
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[email protected] 7 How to Insert a Glaucoma Implant Jeffrey Freedman S.U.N.Y. Brooklyn, Brooklyn, New York, USA
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Introduction 2. Surgical Technique 2.1. Anesthesia 2.2. Conjunctival Incision 2.3. Plate Attachment 2.4. Valve Priming 2.5. Tube Preparation and Patch Graft 2.5.1. Tube Stent 2.5.2. Patch Graft 2.5.3. Tube Suture 2.5.4. Tube Trimming 2.6. Insertion of a Double Plate Molteno Implant 3. The Express Glaucoma Shunt 4. General Principles Regarding the Insertion of All Glaucoma Draining Implants References
1.
63 64 64 64 64 66 66 66 66 68 68 72 72 73 73
INTRODUCTION
The contemporary glaucoma implants are all modeled on the long tube Molteno implant introduced in 1973 (1). The implants most commonly used are the Molteno single and double plate devices, the Baerveldt, Ahmed, and the Krupin implants. The Ahmed and Krupin implants are valved, whereas the Baerveldt and Molteno implants are nonvalved. Insertion techniques for valved and nonvalved implants differ. In that, nonvalved implants require additional techniques to be applied on insertion to prevent hypotony. The different implants do require minimal modifications regarding their individual insertions, and these will be described. 63
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SURGICAL TECHNIQUE Anesthesia
We prefer performing glaucoma implant surgery under local anesthesia. Our preference is for retrobulbar anesthesia, but this surgery can be done utilizing subtenons and even local anesthetic jelly if required. 2.2.
Conjunctival Incision
The single plate implant may be inserted superonasally or superotemporally, between the superior rectus and the medial or lateral rectus muscles. A limbal or fornix-based incision can be utilized. We prefer fornix-based conjunctival incisions. The conjunctiva is ballooned up at the limbus by the injection of balanced salt solution (BSS). If the conjunctiva is adherent to the sclera for a distance .1 mm as a result of previous surgery, a different site needs to be chosen for the placement of the implant. The fornix-based conjunctival flap is then formed by incising the conjunctiva at the limbus for a length of 12 mm. A relieving incision of 5 mm is then made parallel to the upper border of medial or lateral rectus muscle, depending on which quadrant the implant is to be inserted. The two edges of the cut limbal conjunctiva are identified for reattachment, by placing two marker sutures at their extremities. This allows for accurate reattachment at the conclusion of the insertion of the implant. The conjunctiva is then undermined, by opening with Westcott scissors between sclera and conjunctiva. The dissection extends posteriorly for about 10 –12 mm. A pocket is thereby created for the insertion of the drainage plate. The posterior widespread dissection is to be avoided, as the space created should not be larger than the diameter of the plate. This can be achieved by pushing a Weck cell sponge into the area designated for the plate, creating a limited space, and thereby decreasing the chances for hypotony in the immediate post-operative period, particularly when using a nonvalved implant (3). If a Baerveldt implant is to be used, isolation of the medial or lateral rectus muscle, as well as the superior rectus muscle, is achieved by the use of muscle hooks. This needs to be done as the lateral and medial wings of the implant need to be placed beneath the muscles. Prior to the insertion of the implant, two 8/0 silk sutures on Alcon cu5 needles are inserted through the two anterior suture holes located on all the implants (Fig. 7.1). The steep curve of the needles enables the exit path of the needle to be very close to its entry, allowing for accurate placement of the anterior edge of the implant distance wise from the limbus. A less curved needle would exit a greater distance from the plate, moving it forward towards the limbus. 2.3.
Plate Attachment
The Ahmed and Molteno implants may be slid back into the pocket created between Tenons-conjunctiva and sclera, by using a curved Harms tying forceps placed on either side of the silicone tube, at its junction with the plate, and gently pushing the plate posteriorly into the previously created pocket (Fig. 7.2). The Baerveldt implant requires retraction of the superior and medial or lateral rectus muscles, so that the wings of the implant can be placed underneath two of these muscles, depending on which quadrant the implant is being placed. The plate is then fixed to the sclera with the preplaced 8/0 silk sutures. The anterior edge of the plate should be 8 –10 mm from the limbus (Fig. 7.3) Tip 1: If a preplaced suture is not used prior to placing the plate into the conjunctival pocket, it is still possible to suture the plate to sclera. However, in this situation, first place the plate into position. Then, place the first suture into the sclera 10 mm from the limbus in
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Figure 7.1 (See color insert) Needles preplaced through anterior needle holes. Supramid suture inserted from plate side.
Figure 7.2 (See color insert) Harms forceps used to insert plate.
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Figure 7.3 (See color insert) Placing sutures through sclera 8 – 10 mm from limbus.
front of one of the holes on the leading edge of the plate. Then, pass the blunt side of the suture (the side with the suture) through the lower plate hole while holding the plate to exit through the upper opening last, that is, backwards. Tie the suture and repeat the process with the second hole. This maneuver prevents inadvertent scleral perforation that can occur if the suture is passed from plate into sclera. Tip 2: If fibrosis or poor visualization prevents access to one or the other plate holes, it is still possible to firmly tie the plate by passing a suture through the anterior lip of one of the newer silicone Ahmed valves. The lip is soft enough to easily pass a sharp needle through it to facilitate plate adhesion to sclera. 2.4.
Valve Priming
Using the Ahmed implant, the implant should be examined and primed prior to implantation. Priming is accomplished by injecting 1 cc of BSS or sterile water through the drainage tube and valve using a 30 gage cannula. The BSS should be seen to flow through the valve to ensure that it is open prior to inserting the implant. The valve site should not be touched with forceps, as this may lead to damage resulting in failure of valve function. 2.5. 2.5.1.
Tube Preparation and Patch Graft Tube Stent
If a Baerveldt or Molteno implant is being used, then prior to insertion of the plate, a 3/0 supramid suture is placed into the silicone tube from its opening onto the plate (Fig. 7.1). A section of 3/0 supramid suture 15 –20 mm in length is cut, and one end is grasped with a tying forceps and gently inserted into the silicone tube from the opening on the plate side. The suture is inserted for a distance of 6 – 10 mm into the tube. This suture will be used as a temporary valve to be removed during the post-operative period (2). 2.5.2. Patch Graft Prior to the trimming and insertion of the tube, donor or preserved sclera or pericardium used to cover the tube is brought onto the operative field and cut to size, so that it will cover
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Figure 7.4 (See color insert) Pericardium cut to cover tube from plate to limbus.
the tube from its insertion into the anterior chamber to its attachment to the plate (Fig. 7.4). The graft is sutured to the sclera prior to the insertion of the tube into the anterior chamber. This is done by suturing one side of the graft and preplacing the sutures into the other side but leaving them untied, so that the graft can be retracted to one side leaving access to the underlying tube (Fig. 7.5). Preplacing the sutures allows the graft to be fixated into place immediately after the tube is inserted into the anterior chamber. Furthermore, if hypotony occurs, as it occasionally does after tube insertion, having preplaced the sutures eliminates the need to insert sutures into an hypotonous eye, which can be difficult. The sutures used for the graft are 10/0 nylon sutures placed at the anterior and posterior corners of the graft. Tip 1: If a seton is inserted in the infero-temporal quadrant, cover the tube with half thickness donor cornea. Cornea, being clear, has a much better cosmetic appearance than
Figure 7.5 (See color insert) Pericardium retracted to side following insertion of preplaced sutures. Suture preplaced around silicone tube.
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sclera that is cosmetically unacceptable in this potentially exposed areas because of its white color. 2.5.3.
Tube Suture
It is important to fixate the tube to the sclera. This is done by passing a 10/0 suture through sclera beneath the tube, again left untied, until the tube has been inserted, at which time this preplaced suture should be tied to fixate the tube to the sclera (Fig. 7.5). Be careful not to tie this suture too tightly as you may block aqueous flow; however, this is highly unlikely with the use of a 10/0 nylon suture. 2.5.4. Tube Trimming Prior to inserting the silicone tube into the anterior chamber, it needs to be trimmed. The length of tubing to be inserted depends on the condition being treated. Usually, the tube should be 1– 3 mm in length in the anterior chamber. However, if neovascular glaucoma is being treated, the tube needs to be longer to avoid blockage by fibrous tissue. The tube should extend almost to the pupil margin. As this measurement is done over the exterior of the cornea, one should ensure that no traction is placed on the tube when estimating the future internal length, as this will result in a shorter than desired result. The tube is then cut with a scissors, the blades facing upwards to ensure a bevel on the tube that is facing upwards and away from the iris preventing it from blocking the tube (Fig. 7.6). Prior to inserting the tube, a paracentesis should be done at the lateral aspect of the limbus with a microsharp blade (Fig. 7.7). This allows for reformation of the anterior chamber, if this become necessary during insertion of the tube, as well as possible manipulation of the tube with an iris repositor, again if this become necessary. A 22 or 23 gage needle is then used to enter the anterior chamber. The needle is inserted immediately posterior to the limbus, unless peripheral anterior synechiae are present, as seen in neovascular glaucoma, in which case the needle needs to be inserted anterior to the peripheral anterior synechiae, thus avoiding obstruction of its insertion into the anterior chamber (Fig. 7.8). The needle is inserted parallel to the iris and mid-way between iris and
Figure 7.6 (See color insert) Cutting of tube with scissor blades facing upwards to ensure bevel of tube is facing up.
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Figure 7.7 (See color insert) Paracentesis with microsharp blade.
cornea. This creates the path through which the silicone tube will be passed. The distal cut end of the silicone tube is then grasped with a tying forceps, while at the same time the anterior lip of the entry tunnel is elevated, allowing the eye to be steadied, facilitating the entry of the tube into the anterior chamber (Fig. 7.9). A tube inserter manufactured by ASSI may also be used for this purpose. If peripheral anterior synechiae are present, the tube may have to be passed more anteriorly to avoid the peripheral iris. If this become necessary, it is imperative to ensure that the anterior edge of the graft is far enough anterior to totally cover the tube. The preplaced 10/0 suture around the tube is now tied, fixating the tube to the sclera. If a 3/0 supramid suture had been placed into the tube, then prior to inserting the tube, venting slits are made in the sides of the tube, which will lie beneath the graft. These slits may be made by passing the needle of the 10/0 suture through the tube or by slitting
Figure 7.8 (See color insert) Use of 22 or 23 gage needle to create passage for silicone tube into anterior chamber.
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Figure 7.9 (See color insert) Inserting silicone tube into anterior chamber.
with a microsharp blade. BSS may then be injected into the tube from its distal end to test the flow of fluid through these slits that will allow drainage to occur in the immediate postoperative period, during which the tube will be temporarily tied off to prevent hypotony (Fig. 7.10). The tube is now tied down to sclera. Again, ensure that this suture is not so tight as to obstruct flow of aqueous through the tube. The preplaced graft is then sutured into place over the tube by tying the final two preplaced 10/0 sutures. Where a 3/0 supramid suture was preplaced, a 7/0 vicril suture is placed around the tube at its junction with the plate and gently tied down onto the internal suprapramid suture, thus blocking the tube (Fig. 7.11). The supramid suture can be removed at any time post-operatively, re-establishing the lumen of the silicone tube, as the vicril suture will only close the tube to the position of the supramid suture.
Figure 7.10
(See color insert) Testing patency of slits made in silicone tube by injecting BSS.
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Figure 7.11 (See color insert) Pericardium sutured to sclera. Tube tied off with 70 Vicril at junction with plate.
The conjunctiva is then closed by suturing the free ends of the conjunctiva, located by the preplaced sutures, to their original position at the limbus (Fig. 7.12). Two wing sutures are needed for the limbal reattachment of the conjunctiva, using an episcleral insertion at the limbus, and then passing the needle through the free edge of the conjunctiva close to where the preplaced marker sutures were placed. The conjunctiva is brought forward to completely cover the scleral/pericardial patch and if this is not achieved, a further one or two sutures placed at the limbus may needed to accomplish this. The relieving incisions of the conjunctivae are also sutured. All of these suturings being done with 7/0 vicril sutures. Prior to closure of the conjunctiva, the previously placed supramid suture protruding from the plate end of the draining implant is brought forward under the conjunctiva, so that it protrudes beyond the limbus. After the conjunctiva has been
Figure 7.12 (See color insert) Suturing conjunctiva to limbus and showing availability of supramid suture for removal at a later date.
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sutured at the limbus, the supramid suture is trimmed, so that it just protrudes beyond the limbus from under the conjunctiva (Fig. 7.12). Edema of the conjunctiva will just cover the suture and it may easily be grasped at a later date, when it needs to be removed from the tube. This allows the suture to be removed from the tube without having to disturb the conjunctiva. Tip 1: If the tube and scleral patch are bulky and apply pressure to the overlying conjunctiva, the limbal wound can retract exposing the graft. To prevent this, we recommend using half thickness scleral patch grafts. In such situations, we prefer to close the conjunctiva at the limbus with a continuous 8/0 vicryl limbal suture. If a fornix-based conjunctival flap is used, we recommend closure of tenons first (using a continuous suture) followed by a continuous conjunctival suture (i.e., closed in two layers). This is particularly important if the tube has been inserted from below, as conjunctival wound healing is often poor in the inferior quadrants. 2.6.
Insertion of a Double Plate Molteno Implant
The use of a double plate Molteno implant requires modification of the insertion technique. The device is labeled right or left side, indicating that the plate to which the tube entering the anterior chamber is attached will be placed on the nasal side. However, it is more practical to have the primary plate placed in the supero-temporal quadrant, where more space allows for easier placement of the plate, the tube, and the scleral patch. This is achieved by placing a left-labeled double plate implant in the right eye and vice-versa. In placing a double plate, a fornix-based conjunctival flap is once again fashioned from the limbus, but is now extended 1808. Relieving incisions are made parallel to the upper borders of the lateral and medial rectus muscles. The nasally placed plate is sutured to the sclera between the medial and the superior rectus muscles 7 –10 mm behind the limbus, using the same technique as described for a single plate. The superior rectus muscle is isolated with a muscle hook, and the conjunctiva is carefully dissected from the muscle sheath. This allows the second plate to be passed over the muscle and to be placed in the temporal quadrant between superior and lateral rectus muscles. The laterally placed plate is sutured to the sclera 7– 10 mm behind the limbus, in the manner described for the medial plate. The silicone tube is handled in the same manner as described for a single-plate implant. In addition, the tube connecting the two plates is tied off with a 7/0 vicril suture, which will release in about 2 –3 weeks, at which an adequate capsule over the second plate will prevent excessive hypotony. The conjunctiva is resutured to the limbus utilizing the preplaced 4/0 silk suture markers to ascertain correct anatomical placement of the conjunctiva to the limbus. The conjunctiva is sutured with two interrupted 7/0 vicril sutures, the initial placement of the suture being from the limbus through episcleral tissue. If the conjunctiva does not fit snugly to the limbus, further interrupted 7/0 vicril sutures can be inserted. The relieving incisions along the upper borders of the medial and lateral rectus muscles are sutured with a continuous 7/0 vicril suture. The previously placed supramid suture is handled as described for single-plate implants.
3.
THE EXPRESS GLAUCOMA SHUNT
Within the past few years, a new mini-glaucoma shunt has been introduced (4), labeled the Express Mini-glaucoma Shunt. The shunt is a stainless steel “tube” that measures ,3 mm in length and 400 mm in diameter. The device has a penetrating tip that is inserted into the anterior chamber. Behind the tip is a spur to prevent extrusion of the device and at the
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proximal end, there is an external flange that prevents over-penetration. The Express is intended to reduce IOP in patients with glaucoma, where medical and conventional surgical treatments have failed, indications similar to those for other drainage implants. Originally designed for insertion as a minimally invasive procedure, more recently the insertion of the Express under a trabeculectomy flap has been described. The Express is implanted through a simple four-step procedure. 1. 2. 3.
4.
Inject viscoelastic material into the anterior chamber through a paracentesis opening. A small 1– 2 mm incision is made in the conjunctiva, 10 mm from the limbus. A 25 gage needle is inserted through the conjunctival incision and guided subconjunctivally to the limbus, where it is used to penetrate into the anterior chamber. The Express is then introduced into the anterior chamber, via the introducer, which is passed along the same subconjunctival pathway. The introducer is then withdrawn, the spur keeping the Express in position.
An alternative method of implantation, is to place the Express under a scleral flap (5). A standard trabeculectomy is performed up to the stage of entry into the anterior chamber. Instead of removing corneoscleral tissue, the Express shunt is inserted into the anterior chamber beneath the scleral flap, without the addition of a peripheral iridectomy. If so desired, an antimetabolite such as mitomycin C or 5 Fu may be used, as one might do in a standard trabeculectomy. The flap is then sutured over the mini-shunt with interrupted sutures or a releasable suture. The use of the shunt in this way is a modified nonpenetrating and penetrating glaucoma procedure. Early results with the shunt placed under a flap have been encouraging, particularly with regard to eliminating such complications as hypotony and erosion associated with the original technique of subconjunctival insertion.
4.
GENERAL PRINCIPLES REGARDING THE INSERTION OF ALL GLAUCOMA DRAINING IMPLANTS
Utilize a fornix-based flap, as this places the conjunctival incision at the furthest distance from the draining bleb eliminating the possibility of erosion and leakage through the conjunctiva. In nonvalved implants, a stent within the silicone tube needs to be placed to prevent post-operative hypotony. If deciding to place the tube via the pars plana, a total vitrectomy needs to be done to avoid blockage of the tube by vitreous (see chapter elsewhere in this book). If superior quadrants are not available, the implant may be placed inferiorly. In doing so, the patient should be warned of the possibility of diplopia where binocular vision is present. When placing the implant inferiorly instead of using sclera or pericardium, half thickness cornea should be used to cover the silicone tube as this affords a better cosmetic result. If an Ahmed valve is used inferiorly using a limbal-based flap, the conjunctiva must be and closed in two layers. REFERENCES 1.
Molteno ACB, Straughn JL, Anker E. Long tube implants in the management of glaucoma. SA Fr Med J 1976; 50:1062 –1066.
[email protected] 74 2. 3. 4.
5.
Freedman and Trope Sherwood MD, Smith MF. Prevention of early hypotony associated with Molteno implants by a new occluding stent technique. Ophthalmology 1993; 6:515– 520. Freedman J. Drainage implants. In: Yanoff M, Duker J, eds. Ophthalmology. London: Mosby, Section 12, 32.1– 32.6. Kaplan-Messas A, Traverso C, Sellem E, Zagorski Z, Belkin M. The Ex-Press minature glaucoma implant in combined surgery with cataract extraction: prospective study. ARVO, Fort Lauderdale, FL, 2002. Dahan E, Carmichael T. The Ex-Press minature glaucoma implant: implantation under a scleral flap. Fourth IGS Meeting, Barcelona, Spain, March 2003.
[email protected] 8 Management of Glaucoma Implant Complications Jeffrey Freedman S.U.N.Y. Brooklyn, Brooklyn, New York, USA
Shlomo Melamed The Sam Rothberg Glaucoma Center, Sheba Medical Center, Tel Hashomer, Israel
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Introduction 2. Intraoperative Complications 2.1. Conjunctival “Button Hole” or Laceration 2.2. Tube Problems 2.2.1. Tube Misdirection 2.2.2. Vitreous Loss 2.2.3. Bleeding 3. Early Postoperative Complications 3.1. Flat Anterior Chamber 3.2. Blocked Tube 3.3. Tube-Corneal Touch 3.4. The Hypertensive Phase 3.5. Iritis 4. Late Postoperative Complications 4.1. Implant Drainage Failure 4.2. Tube Erosion 4.3. Plate Erosion 4.4. Diplopia 4.5. Corneal Decompensation 4.6. Other Complications References
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INTRODUCTION
Currently, most surgeons use glaucoma implants in cases of refractory glaucoma with scarred conjunctiva and active inflammation as well as in cases of neovascular glaucoma. 75
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Consequently, there is a higher risk for intraoperative and postoperative complications. Complications associated with glaucoma implants can be classified as intraoperative, early postoperative, and late postoperative.
2. 2.1.
INTRAOPERATIVE COMPLICATIONS Conjunctival “Button Hole” or Laceration
Manipulation of a friable conjunctiva may result in tearing or laceration of the conjunctiva, especially as these patients have often had previous surgical procedures involving conjunctival manipulation. Elevating the conjunctiva with balanced salt solution prior to cutting it allows the surgeon to delineate the areas of conjunctiva that are adherent to the underlying sclera and therefore more likely to perforate if elevated and thus can be avoided, decreasing the probability of lacerating the conjunctiva. If a tear is noted during surgery, attempts must be taken to close it with a 10/0 nylon on a BV needle. If the tear will not close, care should be taken to ensure the entrance to the anterior chamber is well covered by the patch graft under the tear and ensure there is no external aqueous leak. If there is none, it is likely that the conjunctiva will heal with vascularization of the patch. If there is an external leak, the implant may have to be removed, the wound tightly closed and the tube inserted in a new quadrant. Inability to accomplish adequate conjunctival closure at the end of the procedure can occur, especially if a thick patch graft is used such as full-thickness sclera or cornea. We recommend half-thickness cornea or sclera to cover the tube. Also, the conjunctiva has a tendency to contract, particularly in elderly patients. This problem can be minimized by marking the cut ends of the conjunctivae with sutures on disinsertion from the limbus, so that the ends can be identified at the end of the procedure and reattached to their correct anatomical area. If it still does not close, care must be taken to ensure the entrance wound is well covered by the patch graft. Then the conjunctiva is closed as close as possible to the limbus, as a small area of exposed patch graft does not pose a problem. The drainage occurs in a posterior situation so that if conjunctiva covers the plate and most of the patch graft, aqueous leakage is unlikely. 2.2.
Tube Problems
The silicone tube may be cut too short and cannot adequately enter the anterior chamber. This can be remedied by splicing on more tube, utilizing a tube extender such as the one made by Ahmed (model TE), which is commercially available. It is advisable to always have a spare tube extender in case it is needed. 2.2.1. Tube Misdirection A tube can be inserted too anteriorly or too posteriorly. If inserted too anterior, corneal endothelium will be damaged, and if inserted too posterior, iris or lens can be damaged. This complication is best avoided by correct placement of the introducing needle. The needle tract needs to be carefully planned, with the eye in the primary position with the needle track parallel to the iris plane. The needle track should start 1– 2 mm posterior to the limbus in order to position the tube away from the corneal endothelium. The tube should enter the anterior chamber parallel to, but in front of the iris and lens, 1 –2 mm behind the corneal endothelium. Careful assessment of the tube position is essential at the end of surgery and the tube should be repositioned anterior or posterior to the initial incision if it is too close to the endothelium or iris before the patient leaves the operating
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room. In the postoperative period, if the tube is noted to touch the endothelium but this touch is localized, such as just the tip of the tube, this will not usually cause diffuse endothelial damage and may be left. If the tube touch is more extensive, that is, the whole intraocular portion of tube touches the endothelium, repositioning of the tube in the operating room should be seriously considered as extensive endothelial damage may result. If the tube is noted to touch the iris and is not blocked, it may be left alone. Misdirection of the tube into the posterior chamber is likely to happen in the presence of posterior synechiae, where the flexible tube follows the path of least resistance. This can be remedied by inserting an iris spatula through a limbal paracentesis opening to the site of entry of the tube and by guiding the tube above the spatula into the anterior chamber. 2.2.2.
Vitreous Loss
A rare complication associated with plate insertion is the very deep placement of the fixating sutures with vitreous presentation at the insertion site. Should this occur, the sutures must be removed and the plate reattached at a different site. Should the eye become hypotonous, a careful examination of the retinal area is indicated and even if nothing is seen cryoablation at the perforation site is indicated. The patient should be followed up by a vitreoretinal specialist. 2.2.3.
Bleeding
Bleeding into the anterior chamber can occur, especially on introducing the tube into the anterior chamber where rubeosis iridis is present. To avoid this complication, the hypotony associated with tube insertion needs to be avoided, and this can be accomplished by either the use of an anterior chamber maintaining cannula attached to a bottle of balanced salt solution or the insertion of a viscoelastic substance prior to the tube introduction. The rubeotic vessels bleed when the surrounding pressure is lowered, therefore maintaining the intraocular pressure by balanced salt solution through the cannula or by inserting a viscoelastic material decreases the potential for bleeding from these vessels. The complication of suprachoirodal hemorrhage is more likely to occur in neovascular glaucoma or when there is uncontrolled intraocular pressure. The hemorrhage occurs when the eye is suddenly decompressed following tube introduction into the anterior chamber. This can be avoided by lowering the intraocular pressure preoperatively with appropriate medications and decompressing the eye slowly with a paracentesis prior to tube insertion. A small amount of aqueous should be removed in a controlled fashion until the eye is no longer hard. A prophylactic posterior sclerotomy can also be done prior to insertion of the tube. Intraocular pressure should be kept constant during insertion of the tube by inserting viscoelastic prior to tube insertion or with the use of an anterior chamber maintainer.
3. 3.1.
EARLY POSTOPERATIVE COMPLICATIONS Flat Anterior Chamber
The commonest postoperative complication is the absence of the anterior chamber. This is most likely to occur with nonvalved implants, where no precaution has been taken to prevent postoperative hypotony. Nonetheless, this complication can occur with valved implants as well even with ligaturing of the tube. If the anterior chamber is shallow with iris corneal touch, it should be treated in the usual way with cycloplegics and aqueous suppressants. Transient shallow chambers usually resolve after a few days. If
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still shallow, the anterior chamber may be reformed 7 –10 days postoperatively with air or sooner if the tube seems to be damaging the endothelium or is in contact with the lens. If the anterior chamber is flat, it may be reformed with the injection of a viscoelastic material through the paracentesis opening that was created intraoperatively. This may have to be repeated, but if the hypotony persists, the tube may have to be ligated in the operating room. Hypotony may be associated with the development of a suprachoroidal effusion. Large effusions may require the use of systemic steroids to eliminate them. Kissing choroidals will require suprachoroidal fluid drainage with the injection of gas and elimination of the cause of the hypotony, which usually means the tying off of the tube. The tube may be tied off by exposing it in its anterior position beneath the patch, which is where it is most accessible. A 5/0 vicryl suture may be used. This will dissolve at a later time. Alternatively, the tube may be removed from the anterior chamber, occluded with a prolene suture, and then reinserted. This suture can be released at an appropriate time using a YAG laser. 3.2.
Blocked Tube
The tube may become blocked resulting in elevation of the intraocular pressure. The blockage may be due to blood, iris, or fibrin. Blood usually dissolves unless there is a full hyphema that may have to be washed out. Iris plugging the tube opening may be removed with a YAG laser. Fibrin responds well to intensive use of topical steroids, and if persistent can also be removed with a YAG laser. A large fibrinous exudate in the anterior chamber will respond to topical steroid use but may need a subconjunctival injection of steroid. Occasionally, an intense vitreitis is seen, particularly in neovascular glaucoma, which may require systemic steroid use. 3.3.
Tube-Corneal Touch
Tube-corneal touch, if very localized and peripheral, can be left alone. It may produce some peripheral corneal decompensation in the region of contact without affecting the rest of the cornea. More extensive corneal touch can produce generalized corneal decompensation and the tube may need to be removed and repositioned. 3.4.
The Hypertensive Phase
The hypertensive phase seen in most but not all glaucoma implant surgeries occurs 4 –6 weeks postoperatively. The elevation of intraocular pressure may be treated with reduction of topical steroids and anti-glaucoma medications, but if very high, is best treated by draining using a 29 gage needle which is passed into the bleb under local anesthesia at the slit lamp, with the withdrawal of a quarter to a half cc of aqueous, without loss of the anterior chamber. This may have to be repeated on a weekly basis until the pressure returns to normal level. By decreasing the pressure within the bleb around the plate, ongoing fibrosis due to TGFb production is prevented, with the likelihood of a more successful outcome in bleb formation. 3.5.
Iritis
Occasionally, a recurrent uveitis is seen in association with glaucoma implants. Care should be taken to ensure the tube is not eroding the peripheral iris or angle structures. If the iritis or iris erosion is mild it can be left alone or treated with low doses of
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topical steroids. If severe, the tube may be repositioned or replaced. However, in most postoperative cases the cause for the persistent uveitis is unknown, and the treatment is that of any anterior uveitis in a glaucoma patient.
4. 4.1.
LATE POSTOPERATIVE COMPLICATIONS Implant Drainage Failure
The most significant late complication is failure of the implant due to bleb fibrosis. Excision of the capsule with the application of an anti-metabolite such as mitomycin has been attempted but with moderate success. We do not recommend this approach. Placement of a second implant in a separate quadrant can lead to good success. J. Freedman, utilizes a supratenons position for the second implant with the view for trying to prevent fibrosis over the plate. This has been done with good success in a number of patients. Prevention of late encapsulation can be achieved by the use of fibrosis suppression medication as described by Molteno and colleagues (1,2). The medication consists of a nonsteroidal anti-inflammatory, a systemic steroid, colchicine and topical adrenaline. These medications need to be given no later than 14 days after insertion, and to be continued for 6 weeks thereafter. This systemic approach will need supervision by a rheumatologist or someone expert at dealing with the side effects of these toxic drugs. The removal and replacement of an existing implant is inadvisable, as fibrosis will occur very rapidly over the new implant. 4.2.
Tube Erosion
Erosion of the tube through the sclera or overlying patch material can occur. This complication requires recovering of the tube with patch material, such as sclera or pericardium, to prevent the possibility of endophthalmitis from occurring. If the coverings fail to prevent recurring erosion of the tube, this is an indication to remove the tube from the eye (you can leave the plate) and a new implant should be inserted at a different site. Removal of the tube can be difficult as the tube is usually encased in a sleeve of connective tissue. When removing the tube, it is important to dissect carefully over the tube so as not to cut it, open the sleeve on its surface, and extend the opening to the limbus. Before removing the tube an 8/0 suture should be placed around the tube and the sleeve. On removal of the tube, the suture must be tied tightly to prevent the fistula from leaking. It is usually not necessary to remove the plate. The tube should be cut as close to the plate as possible and the plate should be left. 4.3.
Plate Erosion
Erosion of the conjunctiva overlying the plate may occur especially if the tube is blocked purposely or accidentally. This allows the conjunctiva to constantly contact the plate, giving rise to the erosion. If there is a patent connection between the anterior chamber and the plate, in the presence of an erosion, the eye will become extremely hypotonous and the chances for endophthalmitis to develop are high. The best treatment for the erosion is to remove the implant. Erosions are more likely to occur in those cases where the conjunctiva over the implant has been treated with an anti-metabolite, particularly mitomycin C. Erosion through the conjunctiva is also more likely to occur if the original conjunctival incision is limbal based with the wound close to the plate. Erosions in such cases can be associated with epithelial down growth over the plate. This down
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growth inhibits often repeated wound closure attempts including patch grafting necessitating removal of the plate and tube on occasion. 4.4.
Diplopia
Limitation of eye movements may occur particularly in the presence of large blebs. As the plates are usually superiorly positioned, the limitation of movement is usually in upward gaze with little effect on the patient clinically. Placement of implants inferiorly is more likely to cause restriction of down-gaze with associated diplopia and such placement should be avoided if vision is good in both eyes (5). Certain implants may produce motility problems even if placed in the superior quadrants (3). Diplopia is common in the early postoperative period, but often resolves with time. Prisms are helpful if the diplopia is troublesome. 4.5.
Corneal Decompensation
Another late complication of glaucoma implants is the development of corneal decompensation. This occurs particularly in aphakic and pseudophakic eyes. Many of these eyes have undergone previous glaucoma filtering procedures prior to the use of the glaucoma implant surgery, and these multiple surgeries invariably result in endothelial cell loss, added to by the further surgical trauma induced by the use of the glaucoma implant. It is possible that the silicone tube per se has some toxic effect on the endothelium, although this has never been proven. Extensive tube endothelial touch (direct touch or touch with eye movements) can precipitate endothelial cell decompensation in an eye with a low endothelial cell count. Corneal transplantation is needed when corneas decompensate. If it is well away from the endothelium, the tube needs to be left in situ. If the tube is close to the endothelium, a suture may be placed across the tube within the anterior chamber thus deflecting it away from the cornea (4). Alternatively, the tube may be repositioned prior to the penetrating keratoplasty. Other options include removing the tube and inserting a new valve in another quadrant, preferably before the corneal transplant (or in conjunction with the PKP). One of us (GT) has had success removing the tube from the anterior chamber repositioning it into the vitreous chamber, a maneuver requiring total vitrectomy, which potentially increases the morbidity of the procedure. Although not proven, this maneuver may prevent further corneal decompensation or allow for later corneal grafting. In postpenetrating keratoplasty, two further complications can occur. The first of these is greater difficulty in controlling the glaucoma, as corneal transplants are often associated with the development of raised intraocular pressure. This is often seen even in the presence of a previously placed glaucoma implant. The second problem often seen is the development of a fibrous membrane seen covering the iris, as well as covering the intraocular lens. A possible cause is the formation of TGFb in the bleb, which then induces an inflammatory reaction in the anterior chamber. Management often requires removal of the membrane with total iridectomy and removal of the intraocular lens as well. 4.6.
Other Complications
Although infrequent, complications that have been associated with glaucoma implants include retinal detachments (5), cataract formation, and the more serious complication of endophthalmitis. A rare form of sterile endophthalmitis is seen in glaucoma implants,
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especially where an intratubal stent has been used to prevent postoperative hypotony (6). The cause is unknown. Attention to meticulous surgical technique as well as adequate, frequent, and continued follow up of all glaucoma implant patients will result in a diminution of complications related to glaucoma implant surgery.
REFERENCES 1. 2.
3.
4. 5. 6.
Molteno ACB, Straughn JL, Ancker E. Control of bleb fibrosis after glaucoma drainage surgery. S Afr Med J 1976; 102:91 – 97. Molteno ACB, Dempster AG. Methods of controlling bleb fibrosis around draining implants. In: Mills KB, ed. Glaucoma: Proceedings of the Fourth International Symposium of the Northern Eye Institute, Manchester, UK. Oxford: Pergamon Press, 1988:192– 211. Smith SL, Starita RJ, Fellman RL, Lynn JR. Early clinical experience with the Baerveldt 350 mm glaucoma implant and associated extraocularmuscle imbalance. Ophthalmology 1933; 100:914 – 918. Freedman J. Management of the Molteno silicone tube in corneal transplant surgery. Ophthalmic Surg Lasers 1988; 29:432– 434. Waterhouse WJ, Lloyd MAE, Dugel PU et al. Rhegmatogenous retinal detachment after Molteno glaucoma implant surgery. Ophthalmology 1994; 101:665 –671. Ball SF, Latfield K, Scharfenberg J. Molteno ripcord suture hypopyon. Ophthalmic Surg 1991; 22:82 – 86.
[email protected] [email protected] 9 Pars Plana Insertion of Ahmed Glaucoma Valve Roland Ling The Royal Devon & Exeter Hospital, Exeter, UK
Wai-Ching Lam and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Introduction 2. Indications for Pars Plana Tube Placement 3. Surgical Technique 3.1. Placement of the Ahmed Glaucoma Valve Plate 3.2. Pars Plana Vitrectomy 3.2.1. The Infusion Port 3.2.2. The Superotemporal Port 3.2.3. The Superonasal Port 3.3. Placement of the Pars Plana Tube 3.4. Closure 4. Results and Complications of Pars Plana GDI References
1.
83 84 84 85 86 86 87 87 87 88 90 92
INTRODUCTION
Refractory glaucoma, defined as glaucoma not responsive to medical therapy and/or conventional filtration surgery, can be a management challenge. In addition to trabeculectomy with adjuvant antifibrotic agents (1,2) and cyclodestructive procedures (3,4), glaucoma drainage implant (GDI) surgery has emerged as a management option in these difficult cases (5 –7). Conventional GDI surgery aims to create an alternative pathway for aqueous outflow between the anterior chamber and the equatorial subconjunctival space through the artificial channel of the drainage implant (5 – 7). However, implantation of the tube in the anterior chamber may be difficult for anatomical reasons and contraindicated in certain situations. For example, extensive peripheral anterior synaechiae or new vessels 83
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of the iridocorneal angle may make placement of the tube in the anterior chamber very difficult or even impossible (8). Furthermore, tube-corneal endothelial touch has been observed in up to 23% of cases with anterior chamber tube, resulting in endothelial decompensation in as many as 35% of cases (9). Anterior chamber tube placement may therefore be contraindicated in eyes with existing corneal grafts or those with severe corneal disease awaiting penetrating keratoplasty. Because of these difficulties, placement of the tube in the vitreous cavity by combining the GDI surgery with pars plana vitrectomy has been advocated (8,10 –15). In this chapter, we aim to review the indications, surgical technique, results, and complications of GDI surgery with pars plana seton placement.
2.
INDICATIONS FOR PARS PLANA TUBE PLACEMENT
The indications for pars plana tube placement are generally limited to cases in the following categories: 1.
2.
3.
4. 5.
3.
Cases with shallow and/or extensively closed anterior chamber angle (10 –13): These include anterior cleavage syndromes (Axenfeld/Reiglers syndrome, Aniridia), iridocorneal endothelial (ICE) syndrome, epithelial downgrowth, neovascular glaucoma, chronic angle closure glaucoma with shallow anterior chamber, uveitic and traumatic glaucoma with extensive peripheral anterior synaechiae, and disorganized anterior segment secondary to trauma. Cases of previous GDI surgery and anterior chamber tube, with tube-related anterior segment complications (14): Repositioning of the implant tube from the anterior chamber into the vitreous cavity can be carried out in cases with anterior segment tube-related complications such as tube erosion, tube obstruction, or corneal decompensation. Cases of postpenetrating keratoplasty or those with severe corneal disease requiring penetrating keratoplasty (15): In eyes with refractory glaucoma and existing corneal graft or severe corneal disease awaiting penetrating keratoplasty (such as pseudophakic bullous keratopathy, aphakic bullous keratopathy, corneal scarring secondary to trauma, herpes simplex keratitis, and ulcerative keratitis), pars plana tube surgery is one option for simultaneously achieving IOP control and avoiding anterior chamber tube-related complications such as tube-corneal touch and corneal decompensation, therefore potentially enhancing the rate of corneal graft survival. Aphakic and pseudophakic cases with shallow anterior chambers and/or vitreous prolapse into the anterior chamber (8). Cases with concurrent indication for pars plana vitrectomy (13): Concurrent glaucoma and retinal indications for vitrectomy includes macular pucker, dropped nucleus, vitreous hemorrhage, and endophthalmitis.
SURGICAL TECHNIQUE
In Toronto, we use the Ahmed Glaucoma Valve with a Pars Plana Clip (Model PS2) (New World Medical, Inc. Rancho Cucamonga, CA) for pars plana tube surgery, although other GDIs such as Molteno, Schocket, and Baerveldt have also been described (8,10 – 15).
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We recommend a combined approach, with both a vitreoretinal and a glaucoma surgeon performing the surgery together, as this is a technically complicated surgery. The following description of the surgical technique is for the pars plana insertion of the Model PS2 Ahmed Glaucoma Valve. This implant consists of a Model S2 Ahmed Glaucoma Valve with an additional Pars Plana ClipTM. The Pars Plana ClipTM imposes a smooth “bend” in the tube and provides the curvature required for insertion through the pars plana. The Pars Plana ClipTM can slide along the length of the tube, and the distance from the receptacle plate to the Pars Plana ClipTM can therefore be adjusted accordingly.
3.1.
Placement of the Ahmed Glaucoma Valve Plate Following Retrobulbar or sub-Tenon’s local or general anesthesia, a 7/0 vicryl corneal traction suture is used to expose the superotemporal or inferotemporal quadrant. Subconjunctival injection of lidocaine 2% is given in the superotemporal or inferotemporal quadrant, raising a conjunctival bleb to facilitate the creation of a conjunctival and Tenon’s flap. The conjunctival and Tenon’s capsule is then incised 5 – 7 mm posterior to the limbus, for 3 –4’O clock hours parallel to the limbus to create a limbal-based flap. The Ahmed Glaucoma Valve is primed by introducing a 23-gage cannula on a 3 cc syringe, 3 – 4 mm into the tube, and balanced salt solution (BSS) is flushed with at least 1 mL through the tube until the initial spurt of BSS is observed to flow from the valve in the receptacle plate (Fig. 9.1). The receptacle plate is tucked underneath the conjunctival flap in the relevant quadrant (Fig. 9.2). The plate is anchored to the episclera 10 mm posterior to the limbus with interrupted 8/0 silk sutures through each of the two eyelets on the receptacle plate (Fig. 9.3). Two additional 8/0 silk sutures can be passed, one through each eyelet, to further anchor down the receptacle plate, if it is not securely fixed to the sclera.
Figure 9.1 (See color insert) The Ahmed valve is primed with balanced salt solution.
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Figure 9.2 (See color insert) The Ahmed valve is tucked underneath the limbral-based conjunctival flap.
3.2.
Pars Plana Vitrectomy Three-port pars plana vitrectomy is then performed by a vitreoretinal surgeon (Fig. 9.4).
3.2.1. The Infusion Port In an aphakic or pseudophakic eye with the seton in the superotemporal quadrant, the infusion port is made through the inferotemporal limbus with a 20-gage MVR blade. An anterior chamber maintainer is inserted and the infusion is started once the tip of the infusion is in the anterior chamber. In a phakic eye, an inferotemporal sclerotomy is made with a 20-gage MVR blade 4 mm posterior to the limbus through a separate inferotemporal peritomy. A 7/0 vicryl suture is preplaced at the sclerostomy to facilitate closure at the
Figure 9.3 (See color insert) The Ahmed valve is anchored to the episclera with interrupted 8/0 silk sutures through the eyelets on the receptacle plate.
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Figure 9.4 (See color insert) Sclerostomy is made with MVR blade 3 mm posterior to the limbus.
end of the vitrectomy. A posterior chamber infusion line is inserted, and the infusion started following confirmation that the tip of the infusion is in the vitreous cavity. 3.2.2.
The Superotemporal Port
A superotemporal sclerostomy is made with a 20-gage MVR blade 3 mm posterior to the limbus in an apakic/pseudophakic eye or 4 mm posterior to the limbus in a phakic eye, at a location that is in line with the tube of the preplaced Ahmed Glaucoma Implant. This allows for the tube to be inserted into the pars plana through the same sclerostomy at the end of the vitrectomy. The placement of the superotemporal sclerostomy is therefore more superior than usual compared to a standard three-port pars plana vitrectomy. 3.2.3. The Superonasal Port A superonasal sclerostomy is made with a 20-gage MVR blade 3 mm posterior to the limbus in an apakic/pseudophakic eye or 4 mm posterior to the limbus in a phakic eye, through a separate superonasal peritomy. A complete vitrectomy is then performed. Particular attention must be paid to thoroughly remove the vitreous in the area of the tube insertion to prevent tube blockage by vitreous. Air – fluid exchange is then performed at the end of the vitrectomy. This is to ensure that the tube is “pneumatically stented” in the immediate postoperative period inside the vitreous cavity, preventing residual vitreous from plugging the pars plana end of the tube. With the air-pump maintaining the intraocular pressure, the superonasal port is plugged with a scleral plug. Attention is now turned to the placement of the tube into the pars plana. 3.3.
Placement of the Pars Plana Tube The Pars Plana ClipTM is slide along the tube until the “bend” is at the correct distance for insertion through the superotemporal sclerostomy (Fig. 9.5).
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Figure 9.5 (See color insert) Set up for Pars Plana sclerostomy with Landers ring suture in place.
Excess amount of tube is trimmed so that the tube extends 5 mm into the vitreous cavity when inserted through the sclerostomy. After inserting the tube through the superotemporal sclerostomy, the sclerostomy is narrowed with an interrupted 10/0 nylon to ensure that the sclerostomy is water-tight around the tube (Fig. 9.6). The Pars Plana ClipTM is then anchored to the episclera with interrupted 8/0 silk through the two eyelets (Fig. 9.7). 3.4.
Closure The Ahmed Glaucoma Valve tube and Clip is then covered by a graft of eye bank cornea, sclera, or other material. If cornea is used, it should be prepared in
Figure 9.6 (See color insert) The tube of the Ahmed valve is inserted through the superotemporal sclerostomy.
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Figure 9.7 (See color insert) The Pars Plana ClipTM is anchored to the episclera with 8/0 silk sutures through the eyelets.
advance by dissecting off the epithelial half of the cornea through the midstroma with a 57 blade using only the endothelial half. The half-thickness cornea graft is sutured to the episclera with interrupted 10/0 nylon sutures, to prevent postoperative erosion of the implant tube and Clip through the conjunctiva (Fig. 9.8). Water-tight closure of Tenon’s capsule and conjunctival flap, in separate layers with a continuous 7/0 vicryl sutures is then performed (Fig. 9.9). The superonasal sclerostomy and peritomy is closed in turn with 7/0 vicryl suture. In cases where an anterior chamber maintainer is used, this is now removed followed by hydration of the limbal wound with BSS. In cases where a pars plana infusion is used, the infusion cannula is removed with immediate closure of the sclerostomy by the preplaced 7/0 vicryl suture.
Figure 9.8 (See color insert) Half-thickness cornea graft is sutured to the episclera with interrupted 10/0 nylon sutures to cover the tube and the Pars Plana ClipTM .
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Figure 9.9 (See color insert) Water-tight closure of Tenon’s capsule and conjuctival flap.
Top-up with filtered air can be injected on a short 30-gage needle through the inferotemporal limbal wound into the anterior chamber, or through the closed inferotemporal sclerostomy into the vitreous cavity, if the eye is soft. Subconjunctival injection of steroid and antibiotic should be placed inferonasally.
4.
RESULTS AND COMPLICATIONS OF PARS PLANA GDI
Various studies (8,10 – 15) in the last decade have reported the experience of combined GDI surgery with pars plana vitrectomy and pars plana tube insertion. These are summarized in Table 9.1. A wide variety of different glaucoma diagnosis were reported in these studies. In addition, variability in the definition of surgical success, difference in the surgical techniques, and the different types of GDI used make interpretation of the results difficult. There are significant postoperative complications, some secondary to hypotony, shared with conventional GDI surgery with anterior chamber tube placement. Serous choroidal effusions were reported in 36% in one series (13). Suprachoroidal hemorrhage occurred in up to 6% of cases (15). In addition, complications specific to pars plana vitrectomy are also encountered, specifically, rhegmatogenous retinal detachment in 6– 12% of cases (12,15). Patient should be fully informed about potential complications prior to surgery. Nevertheless, satisfactory intraocular pressure control without further glaucoma surgery (with or without glaucoma medication) is achieved in 72.5– 94% of the cases (8,10 –15). Considering the severity of the glaucoma treated, these results show promise for the management of these selected cases of refractory glaucoma. Before proceeding with combined GDI surgery and pars plana tube insertion, considerations should be given to ensure that the advantages associated with the reduced risk of anterior segment problems outweighs the additional risk of posterior segment complications of the pars plana vitrectomy.
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13
17
50
9
34
Smiddy et al. (11)
Varma et al. (8)
Kaynak et al. (12)
Luttrull et al. (13)
Joos et al. (14)
Sidoti et al. (15)
NVG Aphakic G Pseudophakic G ACG Congenital G Angle recession G Aphakic G Pseudophakic G Aphakic G Pseudophakic G Angle recession G 28 ACG NVG POAG CACG Uveitic G Aphakic G AC tube with AC complications CACG, POAG, Uveitic G, NVG with PKP or PBK
Glaucoma diagnosis
PPV þ tube reposition PPV þ PPT + PKP
85
76
Baerveldt Molteno Ahmed
72
78
94
Baerveldt
88
100
94
Molteno Schocket
69
70
65
% Stable or improved VA
Baerveldt
100
Baerveldt
PPV þ PPT þ tube ligation PPV þ PPT
PPV þ PPT þ pneumatic stenting
90
75
% IOP control
Molteno Baerveldt
Molteno Schocket
GDI type
PPV þ PPT þ tube ligation
PPV þ PPT 8 PPV þ ACT 12
Type of surgery
6 – 32
2 – 42
3 – 41
4 – 71
12– 28
3 – 24
4.2 – 28
F/U interval (months)
SCE 12% SCH 6% VH 6% RRD 6%
No retinal complications Hypotony 12% SCE 6% VH 6% RRD 12% SCE 36% SCH 4% VH 2% RRD 8% NLP 10% RRD 11%
SCE 20%
Complications
Note: G, glaucoma; NVG, neovascular glaucoma; ACG, angle closure glaucoma; POAG, primary open angle glaucoma; CACG, chronic angle closure glaucoma; PKP, penetrating keratoplasty; PBK, pseudophakic bullous keratopathy; PPV, pars plana vitrectomy; PPT, pars plana tube; ACT, anterior chamber tube; SCE, serous choroidal effusion; SCH, suprachoroidal hemorrhage; VH, vitreous hemorrhage; RRD, rhegmatogenous retinal detachment; NLP, no light perception.
20
No. of eyes
Granham et al. (10)
Reference
Table 9.1 Results and Complications of Pars Plana Glaucoma Damage Implant Surgery
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REFERENCES 1. 2. 3. 4. 5.
6. 7. 8. 9. 10. 11. 12. 13.
14. 15.
Katz GJ, Higginbotham EJ, Lichter PR et al. Motomycin C versus 5-fluorouracil in high-risk glaucoma filtering surgery. Ophthalmology 1995; 102:1263 – 1269. The Fluorouracil Filtering Surgery Study Group. Five-year follow-up of the fluorouracil filtering surgery study. Am J Ophthalmol 1996; 121:349– 366. Patel A, Thompson JT, Michels RG, Quigley HA. Endolaser treatment of the ciliary body for uncontrolled glaucoma. Ophthalmology 1986; 93:825 –830. Trope GE, Ma S. Mid-term effects of neodymium:YAG transcleral cyclophotocoagulation in glaucoma. Ophthalmology 1990; 97:73 – 75. Schocket SS, Nirankari VS, Lakhanpal V et al. Anterior chamber tube shunt to an encircling band in the treatment of neovascular glaucoma and other refractory glaucomas; a long-term study. Ophthalmology 1985; 92:553 – 562. Lloyd MA, Sedlak T, Heuer DK et al. Clinical experience with the single-plate Molteno implant in complicated glaucomas: update of a pilot study. Ophthalmology 1992; 99:679 – 687. Lloyd MA, Baervrldt G, Heuer DK et al. Initial experience with the Baerveldt implant in complicated galucomas. Ophthalmology 1994; 101:651 – 658. Varma R, Heuer DK, Lundy DC et al. Pars plana Baerveldt tube insertion with vitrectomy in glaucomas associated with pseudophakia and aphakia. Am J Ophthalmol 1995; 119:401 – 407. Siegner SW, Netland PA, Urban RC Jr et al. Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology 1995; 102:1298 –1307. Grandham SB, Costa VP, Katz LJ et al. Aqueous tube-shunt implantation and pars plana vitrectomy in eyes with refractory glaucoma. Am J Ophthalmol 1993; 116:189– 195. Smiddy WE, Rubsamen PE, Grajewski A. Vitrectomy for pars plana placement of a glaucoma seton. Ophthalmic Surg 1994; 25:532 – 535. Kaynak S, Tekin NF, Durak I et al. Pars plana vitrectomy with pars plana tube implantation in eyes with intractable glaucoma. Br J Ophthalmol 1998; 82:1377– 1382. Luttrull JK, Avery RL, Baerveldt G, Easley KA. Initial experience with pneumatically stented Baerveldt implant modified for pars plana insertion for complicated glaucoma. Ophthalmology 2000; 107:143 – 150. Joos KM, Lavina AM, Tawansy KA, Agarwal A. Posterior repositioning of glaucoma implants for anterior segment complications. Ophthalmology 2001; 108:279 – 284. Sidoti PA, Mosny AY, Ritterband DC, Seedor JA. Pars plaa tube insertion of glaucoma drainage implants and penetrating Keratoplasty in patients with coexisting glaucoma and corneal disease. Ophthalmology 2001; 108:1050 –1058.
[email protected] 10 Full-Thickness Filtering Glaucoma Surgery Maurice H. Luntz Manhattan Eye, Ear and Throat Hospital, New York; New York Eye, Ear Infirmary, New York; Beth Israel Medical Center, New York; Mount Sinai School of Medicine, New York; New York University School of Medicine, New York, New York, USA
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Introduction 2. Subscleral Scheie Procedure 3. Surgical Technique 3.1. Conjunctival Flap (5 Magnification) 3.2. Scleral Flap and Paracentesis (7 to 10 Magnification) 3.3. Fistula and Iridectomy (10 Magnification) 3.4. Closure (5 Magnification) 4. Subscleral Trephine 5. Surgical Technique 5.1. Conjunctival Flap (5 Magnification) 5.2. The Scleral Flap (7 to 10 Magnification) 5.3. Corneal-Scleral Trephining (7 to 10 Magnification) 6. Sclerectomy 6.1. Anterior Lip Sclerectomy 6.2. Posterior Lip Sclerectomy References
1.
93 94 94 95 95 96 97 98 98 98 98 99 99 99 99 100
INTRODUCTION
Prior to 1968, glaucoma filtering operations were full-thickness procedures, that is, a fistula was made at the limbus through the full thickness of the sclera and aqueous drained freely into the subconjunctival space. In 1968, John Cairns (1) described trabeculectomy. In the trabeculectomy procedure, an one-third thickness lamellar scleral flap is 93
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fashioned to cover the scleral fistula. The scleral flap retards the aqueous outflow through the fistula and significantly reduces the risk of postoperative complications, in particular, over-filtration, flat anterior chamber (AC), hypotony, and suprachoroidal hemorrhage. Owing to its greater safety compared with full-thickness procedures, trabeculectomy has become the standard filtration procedure for glaucoma surgery. Although trabeculectomy adds to the safety of filtering surgery, reducing the risk of postoperative complications, it also slows and restricts aqueous drainage. The result is that trabeculectomy only infrequently achieves intraocular pressure (IOP) reduction into the low teens (10 –12 mmHg) when compared with full-thickness procedures. Recent longitudinal studies have demonstrated the importance of achieving IOP levels into the low teens in patients with optic nerve head cupping and visual field loss (2). The ability to achieve these IOP levels with trabeculectomy became feasible when antimetabolites were used in conjunction with trabeculectomy. At present, the most effective antimetabolite in use is mitomycin C. The higher success rate has come with a price. The effect of these antifibrotic agents is not confined to fibroblasts entering the area of bleb formation, but destroys cells in the surrounding conjunctiva and the surrounding blood vessels. Postoperatively, a thin-walled bloodless bleb forms, which is prone to hypotony, suprachoroidal hemorrhage (2), and leakage of aqueous through poor healing of the conjunctival incision and/or breaks in the bleb (positive Seidel) and risk of endophthalmitis (3,4). These are serious and sightthreatening complications and have led to a resurgence of interest in full-thickness procedures without the use of antimetabolites as a means of achieving low IOP levels. The full-thickness procedures most popular at this time are trabeculectomy but without suturing the lamellar scleral flap, the subscleral Scheie, the subscleral trephine procedure, and setons, because of their relative safety when compared with other full-thickness procedures. These full-thickness procedures have been modified and are performed under a small scleral flap which acts as a “ball valve,” restricts aqueous flow and protects the limbal conjunctiva.
2.
SUBSCLERAL SCHEIE PROCEDURE
The subscleral Scheie procedure, first described by Soll in 1973 (5) is a modification of the procedure which was first described by Harold Scheie in 1958 (6). The procedure was subsequently modified and used with excellent results by Luntz et al. (7). The operation interposes a lamellar flap of sclera between the classical Scheie fistula and the limbal conjunctiva. The scleral flap is designed to reinforce the conjunctiva at the limbus, to reduce the rate of aqueous flow through the fistula, in this way to reduce the incidence of over-filtration and minimize postoperative flat or shallow AC. By deflecting aqueous humor posteriorly, the flap also results in a more posterior and diffuse bleb (Fig. 10.1). The scleral flap is not sutured as in trabeculectomy and this operation is a partially guarded full-thickness procedure as opposed to a trabeculectomy, which is a fully guarded procedure.
3.
SURGICAL TECHNIQUE
A suitable area of conjunctiva is selected. The best site is virgin, untraumatized conjunctiva, preferably the upper nasal quadrant. Where conjunctival scarring is present, an area
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Figure 10.1
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Aqueous flow in subscleral Scheie.
of normal or near-normal conjunctiva is selected, but only in the superior conjunctiva. If the superior conjunctiva is severely scarred, this procedure is contraindicated and a seton should be used.
3.1.
Conjunctival Flap (53 Magnification)
A limbus-based conjunctival flap is preferred to a fornix-based flap for this operation. Using Westcott scissor, a conjunctival incision 7 mm in width is made in the fornix, 7 mm behind and parallel to the surgical limbus. The incision is carried through the conjunctival tissue and Tenon’s to sclera, and scleral surface is laid bare. Hemostasis is obtained using a pencil bipolar cautery. Dissection is then carried forward using either a Westcott or Troutman scissors toward the surgical limbus, separating conjunctiva and Tenon’s fascia from sclera. As the limbus is approached, Tenon’s capsule and episcleral tissue fuse, and a disposable Beaver knife (#75 or #69) is used to dissect into the limbal area, dissecting just forward of the surgical limbus. The limbus-based conjunctival flap is rotated forward onto the cornea and held there by an assistant using a #28 Hoskins forceps (Katena). 3.2.
Scleral Flap and Paracentesis (73 to 103 Magnification)
A scleral flap hinged at the limbus, extending posteriorly from the limbus for 1.5 mm and 5 mm in length, is marked out on the sclera beneath the conjunctival flap using the bipolar cautery. A 5 mm incision is made 1.5 mm posterior and parallel to the limbus along this marked-out area, extending through one-third of the scleral thickness, and each end of the incision is joined to the limbus by two radial incisions, also extending through one-third of the scleral thickness. Using a diamond blade, the scleral flap is dissected from the posterior incision to the limbus, raising a 1/3 thickness scleral flap, 5 mm in length and 1.5 mm in width, hinged at the limbus. A temporal paracentesis is made with a 158 superblade (Alcon).
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Fistula and Iridectomy (103 Magnification)
The scleral flap is rotated forward and held there by the assistant, exposing the underlying scleral bed. Using the diamond knife, a 5 mm long incision is made in the deep scleral bed, parallel to the limbus and immediately posterior to the hinged area of the scleral flap (Fig. 10.2). This incision is carried through 1/3 the thickness of the deep scleral bed and a row of cautery burns using a bipolar cautery is applied to the posterior wall of this incision (Fig. 10.3). The cautery causes retraction of the posterior lip of the incision, widening the incision area. The incision is then deepened to Descemet’s membrane using the diamond knife and a second row of cautery applications is made along the posterior lip, deep to the first row of cauteries, further retracting the posterior lip of the incision. The next step is to enter the AC using the diamond knife across the full 5 mm length of the incision (Fig. 10.4). To perform this safely, the surgeon lifts the anterior lip of the incision with a #19 Hoskins forceps and the assistant lifts the posterior lip of the scleral incision with a second pair of forceps. Using the diamond blade, the AC is entered at one end of the 5 mm long scleral incision, and with the sharp edge of the blade pointing upward, the incision can be carried across to the other end, completing the opening into the AC. Using pressure on the posterior lip of the incision in the deep scleral bed, iris is prolapsed into this incision. If iris does not prolapse, it should be carefully grasped and pulled through the fistula with a #28 Hoskins forceps. Holding the iris with the Hoskins forceps, a peripheral iridectomy is made. The iris is then allowed to slip back into the AC, ensuring that it is not incarcerated in the incision. If this occurs, iris can be freed
Figure 10.2
Dissection scleral flap—subscleral Scheie.
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Figure 10.3
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Cautery to incision—subscleral Scheie.
by using a jet of balanced salt solution (BSS) through the incision. Healon or a comparable viscoelastic is injected through the paracentesis incision to maintain the AC.
3.4.
Closure (53 Magnification)
The conjunctival flap is rotated back into the fornix, covering the 1/3 thickness scleral flap which is not sutured. The incision in Tenon’s capsule is sutured with interrupted #10/0 nylon sutures using 10 interrupted sutures. Approximately 10 interrupted or continuous #10/0 nylon sutures unite the cut conjunctival edges. A drop of an antibiotic–steroid combination is instilled into the conjunctival sac at the completion of surgery. BSS is injected through the temporal paracentesis incision to deepen the AC. The BSS egresses through the scleral fistula and fills the bleb. Ensure a negative Seidel using a Fluorescein strip. The steroid–antibiotic combination is used for 1–10 days postoperatively, depending on the extent of postoperative iritis. As soon as the AC reaction is improved to a level of 1þ flare and no cells, and postoperative infection is no longer anticipated, this medication is replaced with a topical steroid for another month. By this time, the eye should be quiet and the patient can be weaned off the steroid drops. If the AC shallows postoperatively, homatropine 5% twice daily is added. The treatment of postoperative complications is reviewed elsewhere. Transient ocular hypertension may follow some fistulizing procedures, lasting from 2 days to 6 weeks. The reason for this is obscure, but may be related to postsurgical edema of the trabecular meshwork, to obstruction of the fistula by blood, to early failure of the bleb, or to the use of steroids or cycloplegics. If blood is a factor, the pressure will gradually drop to a normal postoperative level once the blood is resorbed. Massage used three to four times a day may be helpful during the ocular hypertensive period and the technique of massage is described elsewhere in this book.
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Figure 10.4
4.
Subscleral Scheie—completed incision.
SUBSCLERAL TREPHINE
For the first half of the 20th century, corneal-scleral trephine, which is a full-thickness filtration, was the most popular procedure for the treatment of chronic open angle glaucoma. It fell into disuse when trabeculectomy became popular because of the smaller risk of complications with trabeculectomy. The corneal-scleral trephine operation was first described by Robert Elliot in 1909 (8). The procedure has become popular once again as fullthickness procedures have increased in popularity over the past few years. The modern corneal-scleral trephine procedure should be a partially guarded procedure performed under 1/3 thickness lamellar-scleral flap, similar to that described for subscleral Scheie.
5. 5.1.
SURGICAL TECHNIQUE Conjunctival Flap (53 Magnification)
Using Westcott scissors, a conjunctival incision 7 mm in width is made in the fornix 7 mm behind and parallel to the surgical limbus. The conjunctival dissection is then carried out in the same way as described in the previous section for subscleral Scheie. When the surgical limbus is reached, the dissection is carried forward into the surgical limbus and just anterior to the vascular arcade in the corneal periphery.
5.2.
The Scleral Flap (73 to 103 Magnification)
A 1.5 mm wide by 5 mm long 1/3 thickness scleral flap is raised in the same way as described in the previous section for the subscleral Scheie procedure, except that the
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dissection toward the limbus is carried across the surgical limbus for 0.5 mm exposing deep corneal lamellae. 5.3.
Corneal-Scleral Trephining (73 to 103 Magnification)
A 1.5 mm trephine is used. The scleral flap is rotated forward using a #19 Hoskins forceps, exposing the surgical limbus and anterior corneal lamellae, and the trephine is placed so that one-third of the diameter of the trephine lies anterior to the surgical limbus in the corneal lamellae and two-thirds behind the surgical limbus in the sclera. The trephine is rotated alternately clockwise and anti-clockwise slowly. As the trephine proceeds, it is slightly tilted to the temporal side and careful watch is maintained for penetration of the AC on the temporal side. As the trephine enters the AC, there is a flow of aqueous humor from this area and the AC will shallow. Great care must be taken not to continue the trephining once the AC is perforated because of the danger of a collapsed AC, in which case the trephine may damage the anterior lens capsule, causing a traumatic cataract. The trephine is removed and trephine incision is completed using Vannas scissors. The trephine disk is then removed and a peripheral iridectomy is performed using a Hoskins forceps to pull iris through the opening in order to do the iridectomy. The conjunctivaTenon’s flap is then replaced and the conjunctival incision in the fornix is sutured, separately suturing Tenon’s capsule with #8/0 vicryl or #10/0 nylon continuous suture, and suturing the conjunctiva separately with a continuous #10/0 nylon suture.
6.
SCLERECTOMY
The partially guarded subscleral Schei procedure and trephine are the most widely used full-thickness procedures at present. However, there are other types of sclerectomy that have been described, particularly in the first half of the 20th century. These have for the most part fallen into disuse. 6.1.
Anterior Lip Sclerectomy
Anterior lip sclerectomy is performed using a conjunctival and 1/3 thickness scleral flap, exactly as described in the trephine and subscleral Scheie procedures. In this procedure, the 1/3 thickness scleral flap is rotated forward, exposing the surgical limbus area. An incision is made as described for subscleral Scheie procedure, 5 mm long and 1.5 mm behind the limbus, but no cautery is used. The incision is carried through into the AC using a diamond knife. Using a punch specially designed for the purpose, the sclera is punched out in the anterior lip of this incision, creating a fistula in the anterior lip of the scleral incision. Closure of the conjunctiva is performed in the same method as described for subsceral Scheie. 6.2.
Posterior Lip Sclerectomy
This procedure is performed in exactly the same way as that described for anterior lip sclerectomy, except that the punch in this instance is used in the posterior lip of the sclerectomy, producing a fistula in the posterior lip of the scleral incision. Care must be taken not to punch into the ciliary body. As previously noted, the anterior lip sclerectomy and posterior lip sclerectomy are not widely used at this time.
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REFERENCES 1. 2.
3. 4. 5. 6. 7. 8.
Cairns JE. Trabeculectomy—preliminary report of a new method. Am J Ophthamol 1968; 66:673 – 679. The AGIS Investigators. The advanced glaucoma intervention study (AGIS) VII: The relationship between control of intraocular pressure and visual field deterioration. Am J Ophthalmol 2000; 130:429 – 440. Greenfield DS, Suner IJ, Miller MP. Endophthalmitis after trabeculectomy with mitomycin C. Ophthalmology 1996; 103:650 – 656. Higginbotham EJ, Stevens RK, Musch DC. Bleb-related endophthalmitis after trabeculectomy with mitomycin C. Ophthalmology 1996; 103:650 – 656. Soll DB. Intrascleral filtering procedure for glaucoma. Am J Ophthalmol 1973; 75:392– 394. Scheie HS. Retraction of scleral wound edges as a fistulizing procedure in glaucoma. Am J Ophthalmol 1958; 45:220 – 229. Luntz MH, Harrison R, Schenker H. Glaucoma Surgery. Baltimore: Williams and Wilkins, 1984:84 – 90. Elliot RH. Ophthalmoscope 1909; 7:804 – 807.
[email protected] 11 How to Do a Surgical Iridectomy Maurice H. Luntz Manhattan Eye, Ear and Throat Hospital, New York; New York Eye, Ear Infirmary, New York; Beth Israel Medical Center, New York; Mount Sinai School of Medicine, New York; New York University School of Medicine, New York, New York, USA
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Surgical Treatment for Angle Closure Glaucoma 2. Surgical Techniques for Peripheral Iridectomy for Angle Closure Glaucoma 2.1. Mechanism of Action 2.2. Surgical Techniques 2.2.1. Surgical Incision (10 Magnification) 2.2.2. Iridectomy (10 Magnification) 2.3. Return of the Iris to Anterior Chamber 2.4. Suturing the Incision 3. Results 4. Peripheral Iridectomy (Alternative Technique) 5. Complications 6. Recurrence—Acute Angle Closure References
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SURGICAL TREATMENT FOR ANGLE CLOSURE GLAUCOMA
In 1857, the German ophthalmologist Albrecht von Graefe announced at the first International Congress of Ophthalmology held in Brussels, that he had discovered a surgical cure for acute glaucoma (1). This involved a sector iridectomy, which he observed to effect a long lasting cure. He published this observation in 1869. This discovery represented a major milestone in the history of ophthalmic surgery. Before von Greafe’s discovery, acute glaucoma had been a blinding disease treated by leeches and venesection. von Graefe had observed the hypotensive effect of a sector iridectomy performed for corneal staphyloma, and this led him to try it for acute glaucoma. It was not until 1920 that E.J. Curran, an American, noted that angle closure glaucoma was associated with pupil block and suggested that peripheral iridectomy was as effective in curing acute glaucoma as was sector iridectomy (2). This has remained until recently 101
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the specific surgical treatment, but today the increased use of the argon or YAG laser to create a hole in the iris (laser iridectomy) has largely replaced surgical iridectomy. In geographic areas where a laser is not available, surgical peripheral iridectomy is the only option. Some patients (e.g., Laplanders) have very thick irides, in which a laser has difficulty in penetrating, and in these patients surgical peripheral iridectomy is an option. Surgical peripheral iridectomy is performed under local anesthesia as an ambulatory operation.
2. 2.1.
SURGICAL TECHNIQUES FOR PERIPHERAL IRIDECTOMY FOR ANGLE CLOSURE GLAUCOMA Mechanism of Action
Peripheral iridectomy is a safe surgical procedure and is highly successful. The objective is to create an opening for unhampered aqueous flow from the posterior to the anterior chamber, reducing the pressure build-up in the posterior chamber from relative pupil block, thereby allowing the iris to fall backward and open the angle. It is unnecessary to make the opening in the iris either basal or sector as long as the aqueous can flow freely through it. The equalization of pressure between the posterior and the anterior chambers, following iridectomy, will separate the iris from the posterior corneal surface if the apposition has not become permanent. The effect of iridectomy on these irido-corneal attachments is to open localized areas of the angle where the closure is not permanent. The angle might only open adjacent to the iridectomy. This is due to loculation of the aqueous behind the iris as a result of widespread scar formation in the angle, limiting the free flow of aqueous. In these longstanding cases, it is useful to do two peripheral iridectomies, one in each superior quadrant, because this may reach more than one locule of aqueous and open more of the angle than would be achieved by only one iridectomy. Nevertheless, even in the earlier situation, one iridectomy, by equalizing anterior and posterior chamber pressures, will in most cases prevent further acute angle closure attacks. Any residual ocular hypertension after peripheral iridectomy is due to either chronic angle closure or an open angle mechanism (primary or secondary).
2.2.
Surgical Techniques
Anesthesia: Topical anesthesia (alcaine-proparacaine hydrochloride 0.5% from Alcon) with intracameral preservative-free lidocaine 1% from Astra. Alternatively, the procedure can be performed using only topical 2% xylocaine jelly. 2.2.1. Surgical Incision (10 Magnification) The operation is preferably performed through a corneal incision leaving the conjunctiva unmolested. A 3 mm long incision is made in the cornea just anterior to the limbus and at the anterior edge of the limbal corneal vessels. The incision is best sited in the upper nasal quadrant using a #75 Beaver microblade. The corneal stroma is dissected down to Descemet’s membrane. At this point, the incision is grasped with Hoskin #28 forceps (Keeler) and, keeping the cornea pulled slightly upward and away from the iris, the anterior chamber is entered with the knife over the full 3 mm length of the incision (Fig. 11.1).
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Figure 11.1
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Corneal incision.
2.2.2. Iridectomy (10 Magnification) Once the anterior chamber is entered, pressure is applied on the scleral side of the incision (Fig. 11.2) with a flat iris spatula in an attempt to prolapse the iris into the incision, in which case it is pulled through the incision using a #28 Hoskin forceps. When the iris does not prolapse into the incision, the forceps is carefully introduced into the anterior chamber, using 10 magnifications for good visualization of the iris surface. The iris is grasped with the forceps held in the left hand and pulled into the incision. The iris is then grasped at a point closer to the pupil with a second #28 Hoskin forceps held in the right hand and pulled out of the incision. Failure to hold the iris nearer the pupil before pulling it through the incision may result in tearing the iris base, in irido-dialysis, and in intraocular bleeding. With the iris exteriorized, the surgeon ensures that both the stromal and the pigment layers are held in the forceps (pigment layer is usually easily visible through the iris stroma). Using DeWecker scissors and cutting parallel to the limbus, the portion of the iris held in the forceps is removed (Fig. 11.3).
Figure 11.2
Prolapse iris into incision.
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Figure 11.3
Surgical iridectomy.
A peripheral iredectomy results at the junction of the outer and middle third of the iris surface. This is the ideal position for the peripheral iridectomy because the major iris vessels are avoided.
2.3.
Return of the Iris to Anterior Chamber
In most cases, the iris, once released, will slip back through the incision into the anterior chamber, and the peripheral iridectomy can be visualized through the cornea. In the event the iris becomes incarcerated in the incision, pressure on the scleral side of the incision with a flat iris spatula will generally dislodge it. Failing that, the cornea is stroked with an iris spatula from the center of the cornea upward to the limbus. When the iris still remains incarcerated in the incision, the two edges of the incision are held apart and a jet of balanced salt solution directed into the incision will dislodge the iris. Once the iris is back in the anterior chamber, the surgeon should ascertain that the iridectomy included the pigment layer by demonstrating a red reflex through the iridectomy with retroillumination using the co-axial microscope light and also ensure that the pupil is round.
2.4.
Suturing the Incision
One or two 10-0 nylon sutures are placed across the center of the corneal incision at full corneal depth and tied to provide good apposition but not too tightly. The sutures are cut on the knot which is buried on the corneal side of the incision. There is no necessity to reform the anterior chamber as it is not lost during the procedure. The surgeon also must ensure that the pupil is round. Subconjunctival injection of antibiotics and steroids is unnecessary. An antibiotic – steroid combination is used for a few days, postoperatively. The suture can be left indefinitely or removed after 3 months. Suture-induced astigmatism is minimal because of the small size of the incision. There is minimal postoperative uveitis or discomfort. An eye patch is not necessary.
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RESULTS
Peripheral iridectomy is the most satisfying surgical procedure. When meticulous surgical technique is used, a patent iridectomy is always obtained, and this will cure .80% of primary angle closure glaucoma (3). Late cataract formation is the commonest complication. This may develop years later. Other complications are exceptionally rare but include wound leak, iritis, hyphema, malignant glaucoma, and endophthalmitis. Failure to excise the pigment layer of the iris will result in a nonfunctioning iridectomy. This is readily corrected using bursts of an argon laser set at 50 mm, 0.5 W power, and 0.2 s exposure, which will remove the pigment layer. 4.
PERIPHERAL IRIDECTOMY (ALTERNATIVE TECHNIQUE)
A conjunctival flap including Tenon’s fascia is made 4 mm from cornea and 5 mm in length. Incision into the anterior chamber is made for 3 mm with a diamond knife or #75 Beaver microblade. The incision line is in the mid-limbal position. A “knuckle” of iris is prolapsed by gentle pressure on the posterior lip. Full thickness iridectomy is performed with DeWecker scissors applied tangentially, the iris being grasped with #28 Hoskin forceps. Loose iris pigment is irrigated away. A single suture of 10-0 nylon is usually adequate to close the incision, which should be tested for watertight closure by pressing with the tip of a fine forceps. The conjunctival flap is closed with a short continuous 10-0 nylon suture. The anterior chamber is usually not lost but must be seen to be formed before allowing the patient to leave the operating room table. An antibiotic – steroid combination is used for a few days, postoperatively. 5.
COMPLICATIONS
Complications are few. There is a danger of injury to the ciliary body and hemorrhage if the limbal incision is made too far posteriorly. Failure to obtain a watertight closure of the incision can lead to a flat anterior chamber, and immediate surgical repair is mandatory. The other complications listed under peripheral iridectomy with a corneal incision can also occur. 6.
RECURRENCE—ACUTE ANGLE CLOSURE
Acute angle closure may recur in the presence of a patent peripheral iridectomy in patients with plateau iris or a plateau iris component to a primary pupil block mechanism. Patients with this anomaly should be warned that there may be a recurrence. Plateau iris can be treated by combining peripheral iridectomy with laser gonioplasty. REFERENCES 1. 2. 3.
von Graefe A. Arch Ophthalmol 1869; 15:108, 228. Curran EJ. Arch Ophthalmol 1920; 49:131. Luntz MH. In: Turtz AL, ed. Ophthalmology. Vol. 1. Saint Louis, USA: The C.V. Mosby Company, Chapter 9, 1969:100.
[email protected] [email protected] 12 Combined Cataract and Glaucoma Surgery Ruth Lapid-Gortzak University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada and Ben Gurion University of the Negev, Israel
David S. Rootman, Yvonne M. Buys, and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Indications 2. Outcomes of Phacotrabeculectomy 3. Contra-Indications 4. Patient Information and Informed Consent 5. Techniques 6. Operative Technique: One-Site Phacotrabeculectomy 7. Two-Site Phacotrabeculectomy Technique 8. Postoperative Care 9. Comments 10. Tips 11. Complications References
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INDICATIONS
Combined cataract and glaucoma filtration surgery is indicated in: 1.
2.
Patients with vision impairing cataract and uncontrolled or marginally controlled glaucoma with maximum tolerated medical therapy or patients with medically uncontrolled glaucoma and a cataract which is likely to become visually significant in the near future. Patients with vision impairing cataract and glaucoma controlled with multiple medications.
There are several advantages of combined surgery over staged procedures including decreased risk with one operation and anesthetic compared to two, decreased cost both in terms of health care costs and costs to the patient, faster visual rehabilitation, and decreased incidence of early postoperative pressure spikes, which is of major importance in patients 107
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with advanced optic nerve cupping or visual field loss (1,2). Phacotrabeculectomy is also beneficial in that it may reduce the long-term need for glaucoma medications (1,3).
2.
OUTCOMES OF PHACOTRABECULECTOMY
Combined phacotrabeculectomy has been shown in several studies to result in long-term intra-ocular pressure reduction and improved vision (4,5). The visual success rates range between 62.5% and 98% (visual acuity better than 20/40). Pressure control without medication ranges between 66% and 96% (5 – 12). Evidence, however, suggests that trabeculectomy alone achieves better long-term pressure control than combined phacotrabeculectomy (13 –18). This has led some surgeons to advocate a two-step approach, surgically controlling pressure first, followed later by phacoemulsification. The effect on bleb function and IOP of subsequent cataract surgery in the presence of a filtering bleb is debatable. Several published studies have reported failure rates (usually defined as the need for additional glaucoma medication or further filtration surgery) of 0 – 33%, 15 – 24 months following phacoemulsification in a previously filtered eye (19 – 25). These studies were mostly retrospective. Two of these (19,23) compared the success rate with matched control groups of trabeculectomy only, and did not find a statistically significant difference suggesting that the failure rate of filtration following subsequent phacoemulsification may be the same as the natural course of a trabeculectomy.
3.
CONTRA-INDICATIONS
In certain circumstances, combined procedures should not be performed: 1. 2. 3.
4.
If the lens opacity is not significantly affecting vision, or likely to do so soon. When the optic nerve is healthy and the pressure well controlled on one or two medications. When glaucoma surgery is likely to fail because of bleb fibrosis, for example, neovascular glaucoma.
PATIENT INFORMATION AND INFORMED CONSENT
The patient should be informed that the goal of surgery is to improve vision by cataract surgery and to gain better short and possibly long-term control of IOP. The patient should be told that surgery may not free them indefinitely from use of medication or possible future glaucoma surgery to control pressure. The patient should be made aware that the filtration procedure will not cure the glaucoma or reverse existing visual field loss. Together with the usual consent information pertaining to possible complications from cataract surgery, the patient should also be informed about the issues relating to filtration surgery such as the need for digital massage or suture removal or lysis, anterior chamber reformation, bleb problems including infection, and the increased risk of choroidal hemorrhage, along with the expected fluctuation in visual acuity that accompanies such interventions. It is important that patients are made aware that visual recovery is usually slower than that experienced after phacoemulsification alone and good vision is not expected for 2– 6 weeks after surgery. Post-operative visual acuity can be influenced by astigmatism induced by the operative wound and sutures.
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TECHNIQUES
Combined cataract with filtration surgery can be performed with varying techniques. The more commonly utilized techniques are 1. 2. 3. 4. 5.
phacotrabeculectomy, one site, phacotrabeculectomy, two sites, scleral tunnel phacotrabeculectomy, scleral tunnel ECCE (Blumenthal technique) with trabeculectomy, combined nonpenetrating surgery, for example, phacoviscocanulostomy.
Other variations in technique include limbal vs. fornix based flaps; variations in suturing techniques such as suture-less and releasable suture technique; incision variations with scleral tunnels, smile incisions, large vs. small incisions; and the use of antimetabolites. In terms of IOP lowering, there is modest evidence to suggest that two-site phacotrabeculectomy achieves lower IOP than one-site surgery and combined surgery augmented with mitomycin-C (MMC) and not with 5-fluorouracil results in lower IOP (26). There is no evidence to suggest that fornix- or limbal-based flaps influence the final IOP in phacotrabeculectomies (27 – 29). Presently, there is insufficient scientific evidence to recommend newer alternatives such as phacoemulsification combined with trabecular aspiration, viscocanalostomy, deep sclerectomy, endoscopic laser cycloablation, or trabeculectomy in the surgical management of coexisting cataract and glaucoma. We will describe a standard one-site combined phacotrabeculectomy technique with releasable sutures, which we have used with good success for more than a decade, and a two-site procedure, which evidence-based analysis has shown to have some advantages in terms of long-term management of glaucoma over the one-site procedure (17).
6.
OPERATIVE TECHNIQUE: ONE-SITE PHACOTRABECULECTOMY 1. 2.
3. 4. 5. 6. 7. 8.
9.
Neurolept anesthesia is administered by an accompanying anesthesiologist. Topical 0.5% tetracaine is instilled. A 0.5 cc of xylocaine 1% with epinephrine is injected in the sub-Tenon space of in upper right quadrant, as far superiorly as possible (for a right-handed surgeon). Skin prep with 10% povidone iodine. Lashes are draped. The speculum is inserted. A 8/0 silk corneal bridle suture is placed at the 11:30 o’clock position partial thickness through peripheral cornea. A 158 blade is used to create a paracentesis at the 2 o’clock position. At 11:30 o’clock, a fornix-based peritomy is performed, using a crescent blade and a nontoothed forceps, at the posterior limbus with the knife edge following the contor of the globe. Dissection under the conjunctiva and Tenon’s capsule is done with a Wescott scissors. The dissection is carried posteriorly into the upper right-handed quadrant in the space between the superior and medial (or lateral in the right eye) rectus muscle (Fig. 12.1). If the Tenon capsule is very dense or fibrotic, a tenonectomy is performed, by excision with Wescott scissors. If MMC use is planned, the tenonectomy is usually omitted. Hemostasis of the vessels in the area of the planned scleral flap is done, using wet-field cautery. Vessels should be coagulated without
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Figure 12.1
10.
11.
12.
Peritomy with the crescent blade at the limbus, following the contor of the globe.
charring of the underlying tissues. By applying cautery through a wet methylcellulose sponge, hemostasis without charring can usually be achieved. This technique decreases the amount of cautery energy applied directly to the tissues. A Weck-cell soaked in 0.4 mg/mL of MMC is then applied. MMC is applied for 1–3 min, on the sclera where the scleral flap is planned and posteriorly under the conjunctiva and Tenon’s capsule. A narrow long pledget 2 4 mm is useful to direct the application posteriorly. The scleral surface exposed to MMC is irrigated with 40 cc of BSS. This can be done by inserting the phacoemulsification probe under the conjunctiva and applying irrigation only. Dissection of the scleral flap: A half-thickness rectangular flap of 3.5 4 mm is dissected, using a 0.12 forceps and a crescent-shaped knife held with the blade at 908 to the sclera to outline the flap. Take care to keep the same plane for the whole flap (Fig. 12.2).
Figure 12.2
Formation of the scleral flap.
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18.
19.
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A standard scleral type dissection is done with the blade parallel to the surface directed anteriorly into clear cornea. Enter the anterior chamber at the limbal base of the scleral flap with a 3.0 mm keratome. Intra-ocular nonpreserved xylocaine 1% is injected, this being particularly important if iris manipulation is required. Fill the anterior chamber with viscoelastic through the paracentesis. In cases of small nondilating pupils, a pupil-widening procedure is performed, either with the use of iris hooks, or with flexible Grieshaber hooks. A bimanual maneuver with a cyclodialysis spatula in the left hand through the paracentesis incision and a Kuglin hook through the incision at 12 o’clock works well by dilating the pupil horizontally and vertically and is sufficient to increase lens exposure in most cases. In cases where the iris is floppy, thin, or iridoschisis is present, it is preferred to use flexible iris hooks to keep the iris dilated and away from the aspiration of the phacoemulsification handpiece. Perform a circular curvilinear capsulorrhexis with a cystotome, and an Uttrata forceps. Vision blue enhancement of the anterior capsule can be used if needed. In patients with pseudoexfoliation, this maneuver should be done with extreme caution because of the weakened nature of the zonules in these patients. Hydrodissection of the lens, with the 27 gage canula on a 2 cc syringe filled with BSS. Elevate the anterior capsule with the canula. Take care to mobilize the nucleus, while avoiding intra-operative capsular block or tears in the posterior capsule, by depressing the posterior lip of the operative wound while injecting steadily. This will allow the excess viscoelastics to be released from the eye, and eliminate pressure build-up which can potentially rupture the posterior capsule. Phacoemulsification of the nucleus and its removal from the bag is performed with the surgeon’s bimanual phaco-chop technique of choice (Fig. 12.3).
Figure 12.3 Nuclear cracking during phacoemulsification. The phacoemulsification probe is inserted through the ostium for the trabeculectomy.
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21. 22.
23. 24.
25. 26.
27.
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Irrigation and aspiration (I/A) of the cortical remnants is then performed. Polishing of the posterior capsule is performed if needed, with the automated I/A or manually with the hydrodissection needle. Digital pressure on the syringe will regulate the amount of vacuum applied, and allows for the gentle removal of cortical remnants. Inject viscoelastic into the bag via the paracentesis wound, and reform the anterior chamber. Insert a foldable intra-ocular lens with the technique varying with the type of lens and injector-tube used. We prefer an acrylic lens (Acrysof, SA60, Alcon, Fort Worth, TX) as it is nonreactive and has an excellent injector system. Miochol is then injected via the paracentesis to constrict the pupil prior to the iridectomy. With a 158 blade, the trabeculectomy is performed under the scleral flap by excising a rectangular 3 2 mm piece of tissue including trabecular meshwork. Radial incisions are made from posterior to anterior into the anterior chamber, with the trabeculectomy excision between these two radial incisions (Fig. 12.4). A wide peripheral iridectomy is performed by grasping the peripheral iris tissue and exteriorizing it towards the trabeculostomy site, followed by cutting it with a De Wecker scissors parallel to the limbus. The base of the peripheral iridectomy should be slightly wider than the width of the scleral flap incision at the limbus to avoid iris incarceration in the ostium. Avoid excess traction on the iris and the ciliary body as this may cause hemorrhage or an excessively large iridectomy that can be visually disturbing. Evacuate the intra-ocular viscoelastics using I/A through the main incision (Fig. 12.5). Reform the anterior chamber with BSS via the paracentesis, as needed. Suture the scleral flap with 3 –4 interrupted buried 10/0 nylon sutures. The length of the bites should be relatively long, to make post-operative laser suture lysis easier to perform. Our preferred technique, however, is to utilize a “U”-shaped releasable suture (30). This technique is described elsewhere in this book. Pressure applied with a dry methyl-cellulose sponge over the scleral flap should not cause a leak. The function of the trabeculectomy
Figure 12.4
Trabeculectomy performed with a 158 blade.
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Figure 12.5 Conjunctival sutures with buried knots. Notice the loop of the releasable suture on the cornea (inverted U).
31.
7.
fistula is assessed by injecting BSS into the anterior chamber via the paracentesis checking for depth of the anterior chamber, the tension of the globe, and leakage of fluid across the scleral flap sutures. The conjunctiva is then repositioned and closed with 10/0 nylon sutures in a water-tight manner. Two-wing sutures with bites through the peripheral cornea and one central horizontal mattress suture work best in our hands. Take extra care to burry all knots for patient comfort. Although closure with a continuous 8/0 vicryl is an option, we believe nylon causes less irritation than a braided absorbable suture with less tendency to suture erosion.
TWO-SITE PHACOTRABECULECTOMY TECHNIQUE
The phacoemulsification is performed through a clear corneal incision at the temporal limbus. We describe the technique for surgery on the right eye by a right-handed surgery. 1.
2.
3.
The sites of the trabeculectomy and phacoemulsification are determined according to whether the eye operated upon is the right or the left, and on which hand the surgeon is used to holding the phaco-probe. For example, a right-handed surgeon operating on a right eye could make the trabeculectomy in the upper nasal or upper temporal quadrant and the phaco would be done through temporal clear cornea. The trabeculectomy site is prepared to the point prior to entering the anterior chamber as described in the previous chapter or as described in the chapter on trabeculectomy. The phacoemulsification site is prepared as follows: At the 9 o’clock position (for the right-handed surgeon), a clear corneal incision is made with a 3.0 mm keratome. The tunnel is made in a self-sealing beveled fashion: the first part 908 to the corneal surface, than a section parallel to the corneal surface, till the whole anterior triangular part of the keratome is intra-corneal, then the posterior stroma and Descemet’s membrane are penetrated and the
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4. 5.
8.
anterior chamber is entered. Phacoemulsification and intra-ocular lens implantation are completed. Viscoelastic is left in the anterior chamber. The trabeculectomy is then completed. The viscoelastic is removed from the anterior chamber and the corneal wound closed with one 10/0 nylon suture. At the end of surgery, there should be: a. No leak from the trabeculectomy site. b. The anterior chamber should be deep. c. The eye should not be firm to palpation. d. The bleb should easily be inflated by injection of BSS via the paracentesis site.
POSTOPERATIVE CARE
At the end of surgery, apply an antibiotic and steroid drops, and a protective shield. A patch is not needed as the lid function is normal owing to the absence of lid akinetic block (31). Combined antibiotic and steroid eye-drops are commenced, instilled every 2 h, with a shield for protection on the day of surgery. The antibiotic is stopped on day 4, the steroid is tapered after 6 weeks. The patient is seen the following day when the visual acuity, the IOP, and the bleb are assessed. See other chapters in this book for postoperative management of filtration surgery. 9.
COMMENTS 1.
2.
3.
4.
5.
6.
We do not recommend a tenonectomy when releasable sutures are employed, especially if MMC is used. If Tenon’s capsule is very hypertrophic or if laser suturelysis is planned, it can be excised. Small pupils: Many techniques are available to mechanically dilate small pupils, such as iris stretching with hooks, Grieshaber flexible iris hooks, or sphincterotomies. Stretching results in small tears to the iris sphincter and enlargement of the pupil. Iris hooks are sometimes useful in patients with thin irides such as seen in nanophthalmic eyes or those with pale irides and in patients who have been on miotics for many years. IOL types: Different IOLs exhibit different biocompatibility. Braga-Mele et al. reported that some types of silicone foldable lenses may prolong the inflammatory response after combined procedures compared with PMMA lenses (32). One study suggested that some acrylic lenses may be associated with IOP elevation, compared with silicone lenses (33). Acrylic lenses have a good record of biocompatibility, with a similar profile to PMMA lenses. The newer generation silicone lenses may be more biocompatible and thus one may consider their use if the surgeon prefers, however the literature does not support this. MMC—The use of MMC enhances the success rate of the phacotrabeculectomy, especially in patients who have risk factors for failure (34,35). We routinely use MMC in phacotrabeculectomies, as the cataract surgery itself is a risk factor for failure. MMC use is also associated with a higher incidence of blebitis, wound leaks, and hypotony (36,37). In our experience, flat chambers occur less commonly with phacotrabeculectomy, than with trabeculectomy, likely because of the support of the IOL and decrease in volume compared with the crystalline lens. Avascular cystic blebs seem to occur less often after phacotrabeculectomy compared with trabeculectomy alone.
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TIPS 1.
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Hydrodissection should always be done carefully. Excess fluid must be allowed to egress by pressing the nucleus down a little, allowing fluid to escape from the bag into the anterior chamber and from there out of the eye through the incision. This avoids rupture of the posterior capsule. (The pseudoexfoliative capsule is especially prone to this.) Phacoemulsification of the nucleus should be done using low vacuum, and 50% ultrasound, making short-deep grooves before cracking. This prevents interfering with the edge of capsulorrhexis and breaching the posterior capsule. It is important to make the groove deep rather than long to enable cracking of the nucleus. Leave sufficient lens material at the 6 o’clock position to enable grasping of the lens with aspiration and fragmentation with a chopper. Should you suspect a rent in the posterior capsule, then visco-dissection may help stem the defect and prevent the downward movement of the nucleus. If the vitreous does prolapse into the anterior chamber, an anterior vitrectomy should be done protecting as much capsule as possible. If capsular support is adequate, a posterior chamber IOL can be placed in the bag or in the sulcus. The lens should be placed with the haptics at right angles to the rent so that the IOL will be stable and not enlarge the hole in the capsule. When placement in the capsular bag is impossible, the IOL should be placed in the sulcus. Make sure to switch to an appropriately sized lens for sulcus fixation. In those rare cases that the capsular support is entirely lacking, the IOL may need to be sutured trans-sclerally, as an AC lens may not be the best choice in POAG. In the case of a nucleus dropped into the vitreous, do not chase it posteriorly. Resist the temptation to do a large vitrectomy through the anterior segment incision. Consult a vitreo-retinal surgeon, and have the nucleus retrieved from the vitreous. This should be done as soon as possible, but does not necessarily have to take place the same day. Extensive removal of the vitreous through the anterior segment can be dangerous and may result in retinal problems. Pseudoexfoliation: The zonules in pseudoexfoliation are often unstable. They can be stabilized by use of an intra-capsular tension ring. Another technique of stabilizing the lens is using Grieshaber hooks that grasp the bag at the capsulorrhexis edge, together with the iris edge. The downside of this technique is that the hooks can cause shallowing of the anterior chamber, making manipulation more difficult. Post-operative problems: Early post-operative pressure elevation is often related to retention of viscoelastics. Avoid release of scleral flap sutures at this time, as this may result in a flat anterior chamber with hypotony. Treat this IOP spike with ocular massage or a paracentesis.
COMPLICATIONS
See the relevant chapters on intra-operative, early, and late complications of filtration surgery. Complications of cataract surgery: Intra-operative complications and methods to avoid them are mentioned in the technique section. Early postoperative complications include wound leak, increased IOP, IOL dislocation, and endophthalmitis. The major late complications of cataract surgery include endophthalmitis, cystoid macular edema,
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and retinal detachment. 1.
2.
3.
4.
5.
6.
Conjuntival wound leak: Can be treated by administering an aqueous suppressant and/or a bandage contact lens or by suturing the wound, if the wound edges dehisce. Most leaks around the sutures resolve within 48 h. We do not recommend a patch to manage this condition. Early pressure spikes should be treated by digital massage and/or topical antiglaucoma medication. Sutures should not be removed early, as this may lead to shallowing of the anterior chamber. Dislocation or malposition of the IOL. If there is capture of the IOL by the iris in the AC, then dilation of the pupil, with supine positioning of the patient, followed by pupil constriction with pilocarpine after the IOL has returned to its position is a good remedy to try. More severe dislocations of the lens usually need surgical intervention with repositioning with or without securing the lens with a suture through the iris or sclera. Acute post-operative endophthalmitis is rare. This should be suspected if there is markedly decreased vision, pain, extraordinary anterior chamber reaction, and cellular reaction in the vitreous. See relevant chapter in this book for management of blebitis or endophthalmitis. Cystic macular edema (CME) occurs in 1– 2% of patients and is clinically relevant in 10% of these cases. CME should be treated with a course oral acetazolamide 125 –250 mg TID – QID, and topical NSAID, for a few weeks. Beware of using topical NSAID in a patient with dry eyes, or a connective tissue disease as this can lead to corneal melting. Retinal detachment complicates 1 in 1000 cataract surgeries.
In summary, combined phacotrabeculectomy achieves short- and long-term pressure control in glaucoma patients undergoing cataract surgery. In our experience, there is a lower incidence of flat chambers after combined phacotrabeculectomy than after trabeculectomy alone. Ischemic and leaking blebs seem to be less common. Early post-operative pressure spikes are more easily controlled with combined phacotrabeculectomy compared with cataract surgery alone (1,38). Long-term pressure control is often better with combined phacotrabeculectomy than after cataract surgery alone (18,39,40). However, evidence suggests trabeculectomy alone probably achieves better long-term pressure control than combined phacotrabeculectomy (13 –15).
REFERENCES 1. 2. 3. 4. 5. 6.
Hopkins JJ, Apel A, Trope GE, Rootman DS. Early intraocular pressure after phacoemulsification combined with trabeculectomy. Ophthalmic Surg Lasers 1998; 29:273– 279. Porges Y, Ophir A. Surgical outcome after early intraocular pressure elevation following combined cataract extraction and trabeculectomy. Ophthalmic Surg Lasers 1999; 30:727– 733. Storr-Paulsen A, Bernth-Petersen P. Combined cataract and glaucoma surgery. Curr Opin Ophthalmol 2001; 12:41 – 46. Mamalis N, Lohner S, Rand AN, Crandall AS. Combined phacoemulsification, intraocular lens implantation, and trabeculectomy. J Cataract Refract Surg 1996; 22:467– 473. Perasalo R, Flink T, Lehtosalo J, Ralli R, Sulonen J. Surgical outcome of phaco-emulsification combined with trabeculectomy in 243 eyes. Acta Ophthalmol Scand 1997; 75:581 – 583. Beckers HJ, De Kroon KE, Nuijts RM, Webers CA. Phacotrabeculectomy. Doc Ophthalmol 2000; 100:43 – 47.
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Lederer CM Jr. Combined cataract extraction with intraocular lens implant and mitomycinaugmented trabeculectomy. Ophthalmology 1996; 103:1025 – 1034. Berestka JS, Brown SV. Limbus- versus fornix-based conjunctival flaps in combined phacoemulsification and mitomycin C trabeculectomy surgery. Ophthalmology 1997; 104:187 – 196. Honjo M, Tanihara H, Negi A et al. Trabeculotomy ab externo, cataract extraction, and intraocular lens implantation: preliminary report. J Cataract Refract Surg 1996; 22:601 – 606. Manners TD, Mireskandari K. Phacotrabeculectomy without peripheral iridectomy. Ophthalmic Surg Lasers 1999; 30:631– 635. Anand N, Menage MJ, Bailey C. Phacoemulsification trabeculectomy compared to other methods of combined cataract and glaucoma surgery. Acta Ophthalmol Scand 1997; 75:705 – 710. Arnold PN. No-stitch phacotrabeculectomy. J Cataract Refract Surg 1996; 22:253– 260. Bellucci R, Perfetti S, Babighian S, Morselli S, Bonomi L. Filtration and complications after trabeculectomy and after phaco-trabeculectomy. Acta Ophthalmol Scand Suppl 1997; 44 – 45. Caprioli J, Park HJ, Weitzman M. Temporal corneal phacoemulsification combined with superior trabeculectomy: a controlled study. Trans Am Ophthalmol Soc 1996; 94:451 – 463; discussion 463– 468. Derick RJ, Evans J, Baker ND. Combined phacoemulsification and trabeculectomy versus trabeculectomy alone: a comparison study using mitomycin-C. Ophthalmic Surg Lasers 1998; 29:707 – 713. Wyse T, Meyer M, Ruderman JM et al. Combined trabeculectomy and phacoemulsification: a one-site vs a two-site approach. Am J Ophthalmol 1998; 125:334– 339. Friedman DS, Jampel HD, Lubomski LH et al. Surgical strategies for coexisting glaucoma and cataract: an evidence-based update. Ophthalmology 2002; 109:1902 –1913. Gimbel HV, Meyer D, DeBroff BM, Roux CW, Ferensowicz M. Intraocular pressure response to combined phacoemulsification and trabeculotomy ab externo versus phacoemulsification alone in primary open-angle glaucoma. J Cataract Refract Surg 1995; 21:653 –660. Park HJ, Kwon YH, Weitzman M, Caprioli J. Temporal corneal phacoemulsification in patients with filtered glaucoma. Arch Ophthalmol 1997; 115:1375– 1380. Chen PP, Weaver YK, Budenz DL, Feuer WJ, Parrish RK II. Trabeculectomy function after cataract extraction. Ophthalmology 1998; 105:1928– 1935. Manoj B, Chako D, Khan MY. Effect of extracapsular cataract extraction and phacoemulsification performed after trabeculectomy on intraocular pressure. J Cataract Refract Surg 2000; 26:75 – 78. Crichton AC, Kirker AW. Intraocular pressure and medication control after clear corneal phacoemulsification and AcrySof posterior chamber intraocular lens implantation in patients with filtering blebs. J Glaucoma 2001; 10:38– 46. Casson R, Rahman R, Salmon JF. Phacoemulsification with intraocular lens implantation after trabeculectomy. J Glaucoma 2002; 11:429 – 433. Rebolleda G, Munoz-Negrete FJ. Phacoemulsification in eyes with functioning filtering blebs: a prospective study. Ophthalmology 2002; 109:2248 – 2255. Derbolav A, Vass C, Menapace R, Schmetterer K, Wedrich A. Long-term effect of phacoemulsification on intraocular pressure after trabeculectomy. J Cataract Refract Surg 2002; 28:425 – 430. Jampel HD, Friedman DS, Lubomski LH et al. Effect of technique on intraocular pressure after combined cataract and glaucoma surgery: an evidence-based review. Ophthalmology 2002; 109:2215 – 2224, quiz 2225, 2231. Lemon LC, Shin DH, Kim C, Bendel RE, Hughes BA, Juzych MS. Limbus-based vs fornixbased conjunctival flap in combined glaucoma and cataract surgery with adjunctive mitomycin C. Am J Ophthalmol 1998; 125:340 – 345. Shingleton BJ, Chaudhry IM, O’Donoghue MW, Baylus SL, King RJ, Chaudhry MB. Phacotrabeculectomy: limbus-based versus fornix-based conjunctival flaps in fellow eyes. Ophthalmology 1999; 106:1152– 1155.
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Lapid-Gortzak et al. Kozobolis VP, Siganos CS, Christodoulakis EV, Lazarov NP, Koutentaki MG, Pallikaris IG. Two-site phacotrabeculectomy with intraoperative mitomycin-C: fornix- versus limbusbased conjunctival opening in fellow eyes. J Cataract Refract Surg 2002; 28:1758 – 1762. Maberley D, Apel A, Rootman DS. Releasable “U” suture for trabeculectomy surgery. Ophthalmic Surg 1994; 25:251– 255. Trope GE, Buys YM, Flanagan J, Wang L. Is a tight patch necessary after trabeculectomy? Br J Ophthalmol 1999; 83:1006 – 1007. Braga-Mele R, Cohen S, Rootman DS. Foldable silicone versus poly(methyl methacrylate) intraocular lenses in combined phacoemulsification and trabeculectomy. J Cataract Refract Surg 2000; 26:1517 –1522. Lemon LC, Shin DH, Song MS et al. Comparative study of silicone versus acrylic foldable lens implantation in primary glaucoma triple procedure. Ophthalmology 1997; 104:1708 – 1713. Shin DH, Ren J, Juzych MS et al. Primary glaucoma triple procedure in patients with primary open-angle glaucoma: the effect of mitomycin C in patients with and without prognostic factors for filtration failure. Am J Ophthalmol 1998; 125:346– 352. Shin DH, Kim YY, Sheth N et al. The role of adjunctive mitomycin C in secondary glaucoma triple procedure as compared to primary glaucoma triple procedure. Ophthalmology 1998; 105:740 – 745. Yang KJ, Moster MR, Azuara-Blanco A, Wilson RP, Araujo SV, Schmidt CM. Mitomycin-C supplemented trabeculectomy, phacoemulsification, and foldable lens implantation. J Cataract Refract Surg 1997; 23:565 – 569. Zacharia PT, Schuman JS. Combined phacoemulsification and trabeculectomy with mitomycin-C. Ophthalmic Surg Lasers 1997; 28:739 – 744. Tezel G, Kolker AE, Kass MA, Wax MB. Comparative results of combined procedures for glaucoma and cataract: II. Limbus-based versus fornix-based conjunctival flaps. Ophthalmic Surg Lasers 1997; 28:551– 557. Anders N, Pham T, Holschbach A, Wollensak J. Combined phacoemulsification and filtering surgery with the ‘no-stitch’ technique. Arch Ophthalmol 1997; 115:1245– 1249. Storr-Paulsen A, Pedersen JH, Laugesen C. A prospective study of combined phacoemulsification-trabeculectomy versus conventional phacoemulsification in cataract patients with coexisting open angle glaucoma. Acta Ophthalmol Scand 1998; 76:696– 699.
[email protected] 13 Ultrasound Biomicroscopy in Glaucoma Surgery Charles J. Pavlin and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Introduction 2. Theoretical Considerations 3. Clinical Use of Ultrasound Biomicroscopy 3.1. Technique 3.2. Measuring Ocular Structures 4. Ultrasound Biomicroscopy in Glaucoma Surgery 4.1. Filtering Surgery 4.2. Assessing Filtration 4.3. Other Forms of Filtering Surgery 4.4. Blood in the Filter 4.5. Valves 4.6. Overfiltration 4.7. Malignant Glaucoma 5. Conclusion References
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INTRODUCTION
The use of ultrasound frequencies in the 40 –100 MHz range is a relatively new development in ultrasound imaging of the eye. This technique has been developed and refined at the University of Toronto over the past decade (1– 3). We have applied the term ultrasound biomicroscopy to this technique because of similarities to optical biomicroscopy, that is, the observation of living tissue at microscopic resolution. Such systems have provided resolution approaching that of optical microscopy, which is not available using any other imaging means. The ability to image subsurface phenomenon at microscopic resolution has brought new understanding to a variety of glaucoma entities. The ability to 119
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image the relationship of subsurface structures in real time can clarify mechanisms and aid in understanding complications in glaucoma surgery.
2.
THEORETICAL CONSIDERATIONS
Mechanical waves and vibrations occur over a wide range of frequencies called the acoustic spectrum. This spectrum extends from the audible range (10–20,000 Hz), with which we are all familiar, to the range of phonons (.1012 Hz) that comprise the vibrational states of matter. Higher frequency ultrasound provides higher resolution on the order of 20 – 40 mm, but the penalty to be paid is loss of penetration. All human tissues exhibit ultrasound attenuation coefficients that increase with frequency. The maximum penetration that could be achieved for a 10 MHz system is 50 mm. For a 60 MHz system, penetration is only 5 mm. The penetration limits prevent imaging of the posterior pole, but are sufficient to gain valuable information on events in the anterior segment of glaucoma entities (4 – 8).
3.
CLINICAL USE OF ULTRASOUND BIOMICROSCOPY
High resolution ultrasound scans used in this chapter have been performed with the original instrument constructed in our laboratories and the commercial instrument based on this design. In the laboratory, we use instruments with frequencies between 40 and 100 MHz. The commercial instrument uses a 50 MHz transducer, which is a good compromise between resolution and penetration. Several other instruments are currently available with frequencies varying from 20 to 50 MHz. 3.1.
Technique
The technique of eye examination using ultrasound biomicroscopy is similar to conventional B-scan examination of the anterior segment. A fluid immersion technique is required to provide an adequate standoff from the structures being examined. This is necessary to avoid distortion of the image close to the transducer and to prevent contact of the transducer with the eye. An eyecup is used to hold the eyelids open and allow more rapid patient preparation. These eyecups resemble those used in conventional ultrasound biometry, with a lip that slides under the eyelids and holds the cup in place. They differ from biometry eyecups in being shallower and having a distinct flair that allows a view of scanning head position. Figure 13.1 shows an examination being performed with one of these eyecups. A solution of 1% methyl cellulose is an excellent coupling medium with sufficient viscosity to prevent fluid loss during examination. Air bubbles have to be carefully avoided, both in the fluid and on the concave surface of the transducer. Unlike conventional 10 MHz B-scan, high frequency transducers are generally not covered by a membrane. A membrane would provide excessive sound attenuation and defeat the purpose of doing examinations at this frequency. Since the transducer is moving, contact with the eye and resulting corneal abrasion must be carefully avoided. The presence of an articulated arm is valuable in improving control of the scanning head. Careful attention must be paid to the screen image to prevent the scanning head from getting too close to the eye. In practice, we have found that contact with the eye has been an extremely rare occurrence. Any part of the eye that can be approached directly over the surface can be examined. The cornea and anterior segment structures are easily examined in any meridian. The most easily interpreted images are radial and orientated, so that the sclera is on the
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Figure 13.1 Ultrasound biomicroscopic examination being performed in an eye cup filled with 1% methylcellulose.
left side of the screen. The conjunctiva, underlying sclera, and peripheral retina can be examined by rotating the eye as far as possible away from the region being examined. 3.2.
Measuring Ocular Structures
Ultrasound biomicroscopy expands our ability to accurately measure ocular structures (4,9). Measurement accuracy is improved by ultrasound biomicroscopy, which has an axial resolution 5– 10 times that of conventional 10 MHz ultrasound. We perform measurements on the screen during examination using electronic calipers. Stored images can be transferred to a computer and measured using imaging software. Measuring a structure accurately with ultrasound requires a knowledge of the speed of sound in the structure being examined. We have used a speed of sound of 1540 m/s to make the majority of measurements. This speed is used in conventional ultrasound scanning to measure distances in most tissue. Conventional ultrasound is capable of measuring relatively large distances such as anterior chamber depth. However, ultrasound biomicroscopy increases measurement accuracy of such structures because the shorter wavelength allows a finer positioning of end points and the exact measurement position can be defined more precisely. A number of ocular structures such as the ciliary body, sclera, and iris cannot be measured by other techniques because of inadequate resolution and the inability to differentiate these structures from adjacent tissue. 4. 4.1.
ULTRASOUND BIOMICROSCOPY IN GLAUCOMA SURGERY Filtering Surgery
Ultrasound biomicroscopy can be used to image at depth the surgical site of filtering surgery. Features that can be defined include the internal scleral ostium, the intrascleral
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Figure 13.2 A medium reflective filtering bleb (B). The scleral opening (arrow) is imaged communicating with a intrascleral pathway.
pathway, and the filtering bleb itself (Fig. 13.2). The internal ostium usually appears as a wedge-shaped opening with clear fluid in the gap. The intrascleral pathway varies in size. At times, there is a distinct fluid filled pathway through the sclera that can be measured. At other times, this pathway can be discerned as a more subtle lower reflective line
Figure 13.3 (See color insert) A filtering bleb (B) contains clear spaces and low reflective episcleral tissue.
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Figure 13.4 In pupillary block, the iris shows anterior bowing narrowing the angle (arrow) and a small iris lens contact. S, sclera, C, cornea, I, iris, CP, ciliary processes, z, zonule, L, lens.
intrasclerally without obvious separation of the superior and inferior scleral walls. The intrascleral pathway can generally be traced back to the superficial entry point below the bleb. The bleb itself is quite variable in appearance. The height of the bleb can be measured from the conjunctival surface, to the highly reflective underlying sclera. The internal reflectivity can vary. The usual appearance is medium reflective tissue interspersed with some clear fluid spaces (Fig. 13.3). The medium reflective areas indicate the fluid filled, spongy episcleral tissue. Rarely is the entire bleb filled with clear fluid
Figure 13.5 In plateau iris the ciliary processes (CP) are forward supporting the peripheral iris producing peripheral angle narrowing (arrow).
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Figure 13.6 Anterior synechiae show an angled appearance of the iris with attachment to the trabecular meshwork (arrow).
except in the case of an encapsulated bleb. This type of bleb is usually thin walled and can be imaged by transillumination clinically. Other features that can be imaged include the state of the surrounding angle, the presence of anterior synechiae, and the relationship of residual iris and ciliary processes to the internal ostium. The angle appearance is distinctive in pupillary block (Fig. 13.4), plateau iris (Fig. 13.5), and anterior synechia (Fig. 13.6). In the case of the pseudophakic eye, the position of the optics and haptics and their relationship to the surgical site can be imaged (Fig. 13.7).
Figure 13.7
A case of an anterior chamber IOL with haptics buried in the angle (arrow).
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Assessing Filtration
Ideally, ultrasound biomicroscopy could be used to predict the functional status of filtering blebs and to help ascertain the site of failure of filtration. This is often possible, but not always. Yamamoto et al. (10) classified blebs into four categories: low reflective, high reflective, encapsulated, and flattened. They found that good control was generally associated with low reflective blebs and poor control with encapsulated and flattened blebs. McWhae and Crichton (11) used a blinded study to predict filtering function in postsurgical eyes. They used the presence of a patent filtration pathway from the anterior chamber to the bleb and the presence of a bleb space to indicate good bleb function. Evidence of obstruction of the internal orifice, obstruction of the trapdoor flap, and absence of bleb cavity were evidence of poor function. Several cases did not fit clearly into these categories. They found a correlation of 86% between ultrasound biomicroscopy grade and clinical findings. Correlation was weakest in those in which medication was still required to control intraocular pressure. Other authors have found varied correlation of ultrasound biomicroscopy appearance and function (12 – 15). 4.3.
Other Forms of Filtering Surgery
Various types of nonpenetrating filtering surgery have evolved over the past several years. These include deep sclerectomy with collagen implant and viscocanalostomy. Ultrasound biomicroscopy has been used to image these entities (16 – 18). In deep sclerectomy with implants, the presence of a filtering bleb, a supraciliary hypoechoic area, and hyporeflectivity of the scleral tissue around the decompression space have been associated with good control. In viscocanalostomy, the presence of a nonreflective scleral chamber has been associated with good glaucoma control. 4.4.
Blood in the Filter
Autologous injection of blood has been used to prevent overfiltration. In eyes that have had this procedure, ultrasound biomicroscopic imaging shows the presence of red cells in the passageways of the filtering procedure (Fig. 13.8). Red cells can be imaged in the bleb, the intrascleral pathway, and the anterior chamber. 4.5.
Valves
Various valves have been used to improve the results of filtering surgery in difficult cases. Ultrasound biomicroscopy can be a valuable means of detecting the position of these valves, and to determine the cause of nonfunctioning valves. The valve itself is easily imaged in its path into the anterior chamber because of the high reflectivity of the plastic used, and its distinctive tubular appearance. The position of the tip of the valve and its relationship to intraocular structures is easily determined (Fig. 13.9). Causes of nonfiltration that can be detected by imaging include failure of the valve to enter the anterior chamber, occlusion of the tip of the valve by iris, or obstruction of the tip of the valve by other materials. 4.6.
Overfiltration
In patients with shallow chambers and hypotony following filtering surgery, several distinct features can be imaged with ultrasound biomicroscopy. The shallowing of the chamber can be imaged and quantitatively measured. A very common finding is the
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Figure 13.8 Ultrasound biomicroscopy image of filtering bleb with injected blood (B) above the sclera (S).
presence of a supraciliary effusion. The appearance of an effusion consists of a separation of the ciliary body from the overlying sclera (Fig. 13.10). The effusion extends forward close to the scleral spur. Such an effusion can be part of a larger choroidal effusion or be confined to the ciliary body region. The space between the ciliary body and sclera is low reflective, and crossed by thin lines representing cross-sections of the thin connective tissue septae that join the ciliary body and sclera, which are now expanded by
Figure 13.9 (See color insert) Ultrasound biomicroscopy image of Ahmed valve. The iris is partially obstructing the opening of the tube (arrow).
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Figure 13.10 A supraciliary effusion (E). The effusion appears as a low reflective space between the pars plana and sclera with cross sections of tissue septa.
fluid. The ciliary processes and iris are imaged as being rotated forward around the scleral spur. Grigera et al. (19) presented 15 patients with flattening of the anterior chamber following filtering surgery. All patients were low or normotensive when examined, and
Figure 13.11 Ultrasound biomicroscopy image cyclodialysis cleft. The ciliary body is disinserted from the scleral spur (arrow).
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Figure 13.12 (See color insert) Ultrasound biomicroscopy image of anterior chamber in malignant glaucoma. The anterior chamber (AC) is extremely shallow. C, cornea, L, lens.
all patients displayed a supraciliary effusion on ultrasound biomicroscopy. These effusions were not detected clinically and were not apparent on B-scan in a large number. These findings show that supraciliary effusions are an integral part of the sequelae of overfiltration, and that detection of these effusions is dependant on the sophistication of the method one uses to look for them (20). Other causes of possible hypotony can be imaged and ruled out. This includes wound leaks, particularly at cataract sites with combined or sequential procedures (21).
Figure 13.13 (See color insert) Ultrasound biomicroscopic image in malignant glaucoma. The iris (I) and ciliary processes (CP) are rotated forward closing the angle. The lens is forward. There is a supraciliary effusion (E) present. C, cornea, S, sclera.
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Such sites are indicated by a gap in the surgical incision site internally, possibly combined with a shallow bleb at the surgical site. Cyclodialysis caused by surgical procedures can be imaged as a separation of the ciliary body from the scleral spur (22) and the extent of the dialysis measured (Fig. 13.11). In patients with inflammatory conditions, ciliary body membranes can be detected if present, and their relationship to the ciliary processes and presence of traction ascertained. 4.7.
Malignant Glaucoma
The ultrasound biomicroscopic appearance in the acute stage of malignant glaucoma shows several distinct features. The ciliary processes and iris are rotated forward closing the angle. The chamber is extremely shallow with the anterior position of the lens (Fig. 13.12). A supraciliary effusion is present (Fig. 13.13). We have previously shown that supraciliary effusions are found by ultrasound biomicroscopy (23), and postulated that effusions may have a major role in the clinical presentation of malignant glaucoma. We have subsequently examined a number of patients with malignant glaucoma and found supraciliary effusions, in the majority, in the acute phase. Other authors have reported similar findings (24). Supraciliary effusions can occur in other settings such as venous obstruction (e.g., vein occlusions and retinal detachment surgery) and following inflammatory episodes (25 –28). Some of these patients develop angle closure glaucoma characterized by shallow anterior chambers. Ultrasound biomicroscopy in these cases shows effusions with anterior rotation of the ciliary processes and iris. This is identical to the ultrasound biomicroscopic appearance in cases of malignant glaucoma. The clinical presentation is essentially identical to that of malignant glaucoma with shallow or flat anterior chambers. Medical treatment that includes hypotensive agents and cycloplegics is the same. The similarity of the clinical presentation of malignant glaucoma and effusion-based glaucoma has been noted in the past. These two entities, however, have been divided essentially by the presence or absence of an effusion as detected by the methods available at the time. If the effusion was not detected by clinical or B-scan examination, then the clinical case was assumed to be caused by aqueous misdirection. The increased precision of ultrasound biomicroscopy in detecting these effusions forces us to reassess our classification of these entities (29). Further clinical research will be required in future to fully verify these mechanisms. Ultrasound biomicroscopy will be an important tool as it is the only method available at this time that consistently detects small effusions. A greater understanding of the sequence of events in malignant glaucoma should lead to an improved treatment approaches. 5.
CONCLUSION
Ultrasound biomicroscopy allows subsurface imaging of various sequelae in glaucoma surgery. This imaging method can be helpful in determining the cause of underfiltration and overfiltration, and in the diagnoses and follow up of complications. REFERENCES 1.
Pavlin CJ, Sherar MD, Foster FS. Subsurface ultrasound microscopic imaging of the intact eye. Ophthalmology 1990; 97:244– 250.
[email protected] 130 2. 3. 4. 5. 6. 7. 8.
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20. 21. 22. 23.
Pavlin and Trope Pavlin CJ, Harasiewicz K, Sherar MD, Foster FS. Clinical use of ultrasound biomicroscopy. Ophthalmology 1991; 98:287– 295. Pavlin CJ, Foster FS. Ultrasound Biomicroscopy of the Eye. New York: Springer Verlag Inc, 1994. Pavlin CJ, Harasiewicz K, Foster FS. Ultrasound biomicroscopy of anterior segment structures in normal and glaucomatous eyes. Am J Ophthalmol 1992; 113:381 – 389. Pavlin CJ, Ritch R, Foster FS. Ultrasound biomicroscopy in plateau iris syndrome. Am J Ophthalmol 1992; 113:390 – 395. Potash SD, Tello C, Liebmann J, Ritch R. Ultrasound biomicroscopy in pigment dispersion syndrome. Ophthalmology 1994; 101:332 –339. Pavlin CJ, Foster FS. Plateau iris syndrome: changes in angle opening associated with dark, light, and pilocarpine administration. Am J Ophthalmol 1999; 128:288 – 291. Woo EK, Pavlin CJ, Slomovic A, Taback N, Buys YM. Ultrasound biomicroscopic quantitative analysis of light– dark changes associated with pupillary block. Am J Ophthalmol 1999; 127:43 – 47. Tello C, Liebmann J, Potash SD, Cohen H, Ritch R. Measurement of ultrasound biomicroscopy images: intraobserver and interobserver reliability. Invest Ophthalmol Vis Sci 1994; 35:3549 – 3552. Yamamoto T, Sakuma T, Kitazawa Y. An ultrasound biomicroscopic study of filtering blebs after mitomycin C trabeculectomy. Ophthalmology 1995; 102(12):1770 – 1776. McWhae JA, Crichton AC. The use of ultrasound biomicroscopy following trabeculectomy. Can J Ophthalmol 1996; 31(4):187– 191. Avitabile T, Russo V, Uva MG, Marino A, Castiglione F, Reibaldi A. Ultrasoundbiomicroscopic evaluation of filtering blebs after laser suture lysis trabeculectomy. Ophthalmologica 1998; 212(suppl 1):17– 21. Martinez-Bello C, Rodriguez-Ares T, Pazos B, Capeans C, Sanchez-Salorio M. Changes in anterior chamber depth and angle width after filtration surgery: a quantitative study using ultrasound biomicroscopy. J Glaucoma 2000; 9(1):51 – 55. Jinza K, Saika S, Kin K, Ohnishi Y. Relationship between formation of a filtering bleb and an intrascleral aqueous drainage route after trabeculectomy: evaluation using ultrasound biomicroscopy. Ophthalmic Res 2000; 32(5):240 – 243. Ito K, Matsunaga K, Esaki K, Goto R, Uji Y, Supraciliochoroidal fluid in the eyes indicates good intraocular pressure control despite absence of obvious filtering bleb after trabeculectomy. J Glaucoma 2002; 11(6):540 – 542. Chiou AG, Mermoud A, Underdahl JP, Schnyder CC. An ultrasound biomicroscopic study of eyes after deep sclerectomy with collagen implant. Ophthalmology 1998; 105(4): 746– 750. Marchini G, Marraffa M, Brunelli C, Morbio R, Bonomi L. Ultrasound biomicroscopy and intraocular-pressure-lowering mechanisms of deep sclerectomy with retculated hyaluronic acid implant. J Cataract Refract Surg 2001; 27(4):507 – 517. Negri-Aranguren I, Croxatto O, Grigera DE. Midterm ultrasound biomicroscopy findings in eyes with successful viscocanalostomy. J Cataract Refract Surg 2002; 28(5): 752– 757. Grigera D, Moreno C, Fava O, Girado SG. Ultrasound biomicroscopy in eyes with anterior chamber flattening after trabeculectomy. Can J Ophthalmol 2002; 37(1):27 – 32 (discussion 32– 33). Sugimoto K, Ito K, Esaki K, Miyamura M, Sasoh M, Uji Y. Supraciliochoroidal fluid at an early stage after trabeculectomy. Jpn J Ophthalmol 2002; 46(5):548 – 552. Sicco thoe Schwartzenburg GW, Pavlin CJ. Occult wound leak diagnosed by ultrasound biomicroscopy in patients with post-operative hypotony. J Cataract Refract Surg 2001. Gentile RC, Pavlin CJ, Liebmann JM et al. Diagnosis of traumatic cyclodialysis by ultrasound biomicroscopy. Ophthalmic Surg Lasers 1996; 27:97– 105. Trope GE, Pavlin CJ, Bau A, Baumal CR, Foster FS. Malignant glaucoma: clinical and ultrasound biomicroscopic characteristics. Ophthalmology 1994; 101:1030 – 1035.
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Liebmann JM, Weinreb RN, Ritch R. Angle closure glaucoma associated with occult annular ciliary body detachment. Arch Ophthalmol 1998; 116:731 – 735. Fourman S. Angle closure glaucoma complicating cilio-choroidal detachment. Ophthalmology 1989; 96:646 – 653. Pavlin CJ, Easterbrook M, Harasiewicz K, Foster FS. An ultrasound biomicroscopic analysis of angle-closure glaucoma secondary to ciliochoroidal effusion in IgA nephropathy. Am J Ophthalmol 1993; 116:341 – 345. Pavlin CJ, Rutnin SS, Devenyi R, Wand M, Foster FS. Supraciliary effusions and ciliary body thickening after scleral buckling procedures. Ophthalmology 1997; 104:433– 438. Yuki T, Kimura Y, Nanbu S, Kishi S, Shimizu K. Ciliary body and choroidal detachment after laser photocoagulation for diabetic retinopathy: a high-frequency ultrasound study. Ophthalmology 1997; 104:1259– 1264. Pavlin CJ. The importance of supraciliary effusions in the pathophysiology of malignant glaucoma. Can J Ophthalmol 2002; 37(1) (discussion 32 – 33).
[email protected] [email protected] Section II: Management of Complications
[email protected] [email protected] 14 Overview: An Approach to the Diagnosis of Early Postoperative Complications Yvonne M. Buys University Health Network and University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
1. Introduction 1.1. Formed Anterior Chamber and High Intraocular Pressure 1.2. Formed Anterior Chamber and Low Intraocular Pressure 1.3. Shallow/Flat Anterior Chamber and High Intraocular Pressure 1.4. Shallow/Flat Anterior Chamber and Low Intraocular Pressure
1.
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INTRODUCTION
The success of filtration surgery depends greatly on the early recognition and appropriate management of postoperative complications. Although the list of potential complications following filtration surgery is extensive, in most scenarios a short differential can be obtained by knowing only three key elements; anterior chamber depth, intraocular pressure, and bleb status. Figure 14.1 details a useful algorithm to assist in correctly diagnosing complications in the early postoperative period. The first differentiation occurs with the anterior chamber, which is either formed or shallow/flat. The second is the intraocular pressure which is either elevated or low and final assessment is the filtration bleb. Using this systematic approach, complications during the early postoperative period are easy to diagnose.
1.1.
Formed Anterior Chamber and High Intraocular Pressure
Following Fig. 14.1 to the left, in the presence of a formed anterior chamber, the next differentiation occurs with the intraocular pressure, which will be high, normal or low. In the case of a formed anterior chamber and elevated intraocular pressure, the bleb status will narrow the differential. If the bleb is elevated, the intraocular pressure high, 135
[email protected] [email protected] Blocked Osteium
nonpatent
iridectomy
Aqueous Shutdown
No Seidel
Wound Leak
Seidel positive
check for leak
Pupil Block
flat/shallow
high
bleb
low
Aqueous Misdirection
check for leak
shallow/flat
Aqueous Shutdown
Suprachoroidal Hemorrhage
No Seidel
Wound Leak
Seidel positive
Overfiltration
elevated
IOP
shallow/flat
patent
mass
bleb formed or shallow funduscopy no mass
Anterior Chamber
Figure 14.1 Early postoperative trabeculectomy complications—diagnostic considerations.
Tight Flap
formed
bleb
low
Expected Outcome or Overfiltration (IOP
