Convergent Strabismus

Monographs in Ophthalmology 6

Dr W. JUNK PUBLISHERS THE HAGUE - BOSTON - LONDON

Convergent Strabismus

edited by

L. EVENS

Dr W. JUNK PUBLISHERS THE HAGUE - BOSTON - LONDON

REPRINTED FROM Bull. Soc. beIge Ophtal. 196, 1982

Distributors:

for the United States and Canada

K1uwer Boston Inc. 190 Old Derby Street Hingham, MA 02043

USA

for all other countries

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3300 AH Dordrecht The Netherlands

ISBN-13: 978-94-009-8026-6 e-ISBN-13: 978-94-009-8024-2 001: 10.1007/978-94-009-8024-2

Copyright © 1982 Belgian Society of Ophthalmology, Leuven. Belgium and

Softcover reprint of the hardcover 1st edition 1982 Dr W. Junk Publishers, The Hague, The Netherlands.

All rights reserved. No part of this publication may be reproduced stored in a retrival system, or transmitted in any form or by any means, mechanical, photocopying, recording, or other­wise, without the prior permission of the publishers. Dr W. Junk Publishers, P.o. Box 13713,2501 ES The Hague, The Netherlands.

PREFACE

When the Board of Directors of the Belgian Ophthalmological Soci­ety, in its session of November 26th 1978, asked me to prepare a report on strabismus to be presented at the joint meeting of the Dutch and Belgian Ophthalmological Societies to be held on June 13th 1981, I felt greatly honored but still more overwhelmed by the immensity of the task.

I took advantage of the complete liberty given to me by the Board of Directors, first to limit the work to one particular form of strabismus, i.e. the convergent comitant form; second, to seek the help of what I thought to be the best strabologists in the Low Countries; third, to aim not at an encyclopedic treatise but at a practical volume destined to the general ophthalmologist.

This volume is thus limited to the various aspects of convergent strabismus, more accurately of comitant convergent strabismus. The omission of the word" comitant" is purposely made to avoid the dif­fic'ulties accompanying the explanation of this term and all the acroba­tics needed to explain that most comitant strabismus are not complete­ly comitant. The choice of this particular form of strabismus seems logical. First of all, it is the most common form of strabismus. On the other hand, most principles concerning examination and treatment can with some modifications be applied to other forms of strabismus.

Prof. R. C. Crone and Prof. A. Th. M. van Balen of the Netherlands, Dr. H. De Corte, Dr. M. Gobin and Dr. E. Vereecken of Belgium did me the great honor of accepting to collaborate in this entreprise. This volume then is the product of the cooperative efforts of these six authors, each of whom is entirely responsible for the chapters he has written. As strabismus treatment is an empirical matter and at the same time in full evolution, it cannot be expected that six independent authors have exactly the same ideas on each aspect of this treatment. If not all. many roads lead to Rome. In strabismus, different ways of treatment can lead to acceptable results and therapeutic variations can even be useful for progress in this still controversial field.

It was neither the goal of the authors to present an encyclopedic work nor to produce a volume so complicated as to be readable only by the

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elite of the strabological world. To the contrary, the purpose of this undertaking was to present a work that would be useful to the general ophthalmologist. I express the hope that this work will effectively help him to diagnose more accurately the different forms of esotropia, to elucidate the causes and contributing factors of each form, to define the aims and treatment possibilities of each form and to approach com­plete healing.

This volume will not be the last book on convergent strabismus but the efforts of the authors would be rewarded if it could bring us one step nearer to the "land where all is clarity, all is simplicity, all is logic ... "

Brussel, June 13th, 1981. Dr. Leo Evens, Editor Lakenselaan 36 1090 Brussels, Belgium

Mr. Vanhove of Janssen Pharmaceutica, 2340 Beerse, Belgium, corrected linguistic errors in chapters I, 2, 6, 8, 9, for which we are most grateful.

TABLE OF CONTENTS

Preface - L. Evens

CHAPTER I INTRODUCTION

L. EVENS

I. Definition. Classification II. Goals of treatment . . III. Goals and possibilities of treatment in the different forms of

convergent comitant esotropia A. Early esotropia . . . . . . B. Late esotropia . . . . . .

1. Accommodative esotropia 2. Acquired non-accommodative esotropia

C. Microstrabismus

CHAPTER II HISTORY OF STRABISMUS TREATMENT

L. EVENS

I. Introduction . . . . . . . . . . . . . . . II. Surgical procedures for convergent squint

A. Interventions on the medial rectus muscle 1. Myotomy and tenotomy . . 2. Partial tenotomy . . . . . 3. Controlled (bridled) tenotomy 4. Recession . . . . 5. Muscle lengthening 6. Faden-Operation 7. Other weakening procedures

B. Interventions on the lateral rectus muscle 1. Simple advancement ..... . 2. Resection .......... . 3. Tucking of the lateral rectus muscle 4. Malbran's screwlike twisting

V

1 3

5 5 8 8

11 11

19 22 22 22 23 24 27 28 30 31 32 33 33 33 34

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C. Interventions for A and V Phenomena 1. Interventions on the horizontal recti 2. Interventions on the vertical recti . 3. Interventions on the oblique muscles

D. Combined surgical procedures III. Non-surgical procedures

A. Optical corrections 1. Positive glasses 2. Bifocals 3. Prisms

B. Other procedures 1. Orthoptics . 2. Penalisation 3. Miotics

CHAPTER III NORMAL BINOCULAR VISION

R.A. CRONE

I. Introduction . . . . . . . . . . . . . . . . II. Psychophysics of spatial vision . . . . . . . .

A. The horopter. Binocular vision without depth B. Depth perception. Range of stereoscopic vision C. Cyclopean localization ..... D. Local and global stereoscopic vision

III. Neuroanatomy of binocular vision IV. Neurophysiology of binocular vision V. Motor aspects of binocular vision VI. Diagrammatic representation of binocular vision

CHAPTER IV NEUROMECHANICS OF THE HUMAN PERIPHERAL OCULOMOTOR SYSTEM

H. DE CORTE

34 35 36 37 39 40 40 40 41 41 42 42 43 44

53 55 56 57 60 60 63 66 69 71

I. Mechanical elements of the peripheral oculomotor system 75 II. Fixation 86 III. Saccades 97 IV. Smooth pursuit 110 V. Vergences . . 114

I.

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CHAPTER V SYMPTOMATOLOGY

R.A. CRONE

Definitions and terminology A. Definition . . . . . . B. Classification

125 125 126

II. Sensory anomalies I: suppression and amblyopia 127 A. Suppression .............. 127 B. Amblyopia .............. 129

III. Sensory anomalies II: anomalous binocular vision 129 A. Anomalous correspondence 130 B. Psychophysics ..... 133 C. Neuroanatomy and neurophysiology 135 D. Motor aspects ......... 135 E. Diagrammatic representation of anomalous binocular

vision . . . . . . . . IV. Sensory anomalies III: diplopia

A. Transient diplopia B. Persistent diplopia

V. Prevalence of convergent strabismus VI. Age of onset of convergent strabismus VII. Strabismus and convergence .

A. Types of convergence B. Accommodative aspects C. Tonic and spastic convergence

VIII. Nystagmus and related disturbances A. Occlusion nystagmus .... B. Occlusion hypertropia . . . .

IX. Incomitance in convergent strabismus X. Clinical syndromes . . . .

A. Strabismus, early onset B. Strabismus, late onset . C. Microstrabismus

XI. Pathogenesis of convergent strabismus A. Symptom or disease? B. Heredity ..... C. Theories concerning squint D. Inadequacy of the theories

137 138 138 139 142 143 145 145 146 150 152 152 154 155 159 159 162 163 165 165 168 169 171

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CHAPTER VI EXAMINATION METHODS

E. VEREECKEN

Introduction . . I. History. II. Inspection

III. IV.

V.

VI.

VII. VIII. IX. X.

Basic examination position A. Torticollis . . . . . B. The eyelid and palpebral fissures C. The pupils . . . . D. Nystagmus The corneal reflections The covertest .... A. Type I. The monolateral covertest B. Type II. The alternating covertest Prisms examinations A. Horizontal prism test B. Vertical prism test C. Prism bar . . . . Examination of ocular movements A. Versions ...... .

1. Horizontal movements 2. Vertical movements . 3. Diagonal movements

B. Ductions ..... C. The Bielschowsky test . . D. Convergence . . . . . .

1. The sliding convergence 2. The sudden convergence

Cycloplegia ..... . Ocular media and fundus Visual acuity test . . . . Measurement of the angle of deviation A. Estimation of the deviation

1. Non-foveal fixation (corneal reflection) Maddox scale

- Krimsky test - The synopthophore

2. Foveal fixation: Hirschberg test

179 181 182 182 184 185 186 187 188 191 191 197 198 198 200 200 201 201 203 204 206 206 206 207 207 208 209 212 213 214 214 214 214 214 216 216

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B. Measurement of the deviation 1. The objective methods

a. the manifest angle Maddox scale

- prism and simultaneous cover - the synoptophore

b. the maximum angle . . . . . Maddox scale ... . . .

- prism and alternating cover - the synoptophore

2. The subjective methods - the synoptophore - dark red glass and Maddox scale

XI. The sensorial status Children under 4 years Children above 4 years A. Foveal fixation . .

1. Less-dissociating examinations 1.1 Striated glasses ... . 1.2 Phasendifferenzhaploskop 1.3 Diplopia . . . .

red glass - vertical prism - prism compensation

1.4 Fusion and stereopsis 2. Dissociating examinations

2.1 the Worth four dot test 2.2 the synoptophore

2.2.1 real objects 2.2.2 entoptic phenomena

2.3 Dark red glass and after-image B. Non-foveal fixation . . . . . . . . .

l. the foveo-foveolar test . . . . . .

216 218 218 218 218 218 219 219 220 220 220 220 221 222 223 223 223 223 223 225 226 226 226 228 228 230 230 231 231 234 235 238 238

2. the synoptophore: Haidinger and after-image 238 XII. Preoperative examinations . . . . . . . . 241

A. The prism compensation test . . . . . 241 B. Tests to forecast post-operative diplopia 241

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CHAPTER VII AMBLYOPIA

A. Th. M. VAN BALEN

I. Introduction . II. Sensoric aspects

A. Psychophysics B. Electrophysiology C. Neuroanatomy

III. Motoric aspects IV. Conclusion V. The diagnosis of amblyopia

A. The" Ammann" effect B. The" Trennschwierigkeit" or crowding effect C. The visual acuity . . . D. The contrast sensitivity E. The VECP .....

VI. The treatment of amblyopia

CHAPTER VIII CONSERVATIVE TREATMENT

E. VEREECKEN

245 247 247 253 255 255 256 257 258 258 259 259 261 261

. Introduction . . . . . 269 I. Basic treatments 271

A. Optical treatment 271 B. Occlusion 277 C. Penalisation 280

II. Treatment adapted to the different strabismus groups 282 A. Early onset strabismus ..... 282 B. Late onset strabismus . . . . . . . . 284

1. Pure accommodative strabismus . . 286 2. Atypical accommodative strabismus 287 3. Partially accommodative strabismus 290

C. Microstrabismus 290 III. Complementary treatment 291

A. Prism treatment 291 B. Orthoptic treatment 292

IV. Postoperative conservative treatment 294

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CHAPTER IX SURGICAL MANAGEMENT OF ESOTROPIA

M.H. GOBIN

Introduction . . . . . . 301 Surgical techniques . . . 301

A. General directives 301 B. Specific directives 308

1. Strengthening procedures 308 Strengthening of a rectus muscle 308 Strengthening of an oblique muscle 310

2. Weakening procedures .... 310 Weakening of a rectus muscle 310 Weakening of an oblique muscle 313

3. Transpositioning procedures . . 314 Transpositioning of a rectus muscle 314 Transpositioning of an oblique muscle 315

Surgical effects .............. 317 I. Surgery of the horizontal rectus muscles 317 2. Surgery of the vertical rectus muscles 320 3. Surgery of the oblique muscles 321

Surgical indications ..... 321 1. Conventional surgery 321

A. General directives 321 B. Specific directives 324

1. Primary surgery 324 Treatment of horizontal deviations 324 Treatment of diagonal deviations 326 Treatment of torsional deviations 328 Treatment of vertical deviations 328

2. Secondary surgery 330 a. Undercorrections 330 b. Overcorrections 331

II. Simultaneous horizontal and cyclovertical surgery 333 A. General directives 333 B. Specific directives 334

1. Primary surgery 334 Treatment of horizontal deviations 334 Treatment of diagonal deviations 336 Treatment of vertical deviations 337

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2. Secondary surgery ........... 338 a. Undercorrections .......... 339

Treatment of horizontal undercorrections 339 Treatment of diagonal uridercorrections 339 Treatment of vertical undercorrections 340

b. Overcorrections . . . . . . . . .. 340 Treatment of horizontal overcorrections 340 Treatment of diagonal overcorrections 341 Treatment of vertical overcorrections 341

Surgical complications ........ 342 1. Conjunctiva and capsular tissue 342 2. Muscles 345 3. Bulbus . . . . 351 4. Eyelids . . . . 352 5. Palpebral fissure 353 6. Postoperative diplopia 354 7. Anaesthesia . . . . . 355