Binocular
Vision
and
Ocular
SIXTH
EDITION
Binocular
Vision
and
Ocular
Motility
THEORY AND MANAGEMENT
OF STRABISMUS
Gunter K. von Noorden, MD
Emeritus Professor of Ophthalmology
Cullen Eye Institute
Baylor College of Medicine
Houston, Texas
Clinical Professor of Ophthalmology
University of South Florida College of Medicine
Tampa, Florida
Emilio C. Campos, MD
Professor of Ophthalmology
University of Bologna
Chief of Ophthalmology
S. Orsola-Malpighi Teaching Hospital
Bologna, Italy
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Library of Congress Cataloging-in-Publication Data
Von Noorden, Gunter K., 1928–
Binocular vision and ocular motility : theory and management of strabismus / Gun-ter K. von Noorden, Emilio C. Campos.—6th ed.
p. cm.
Includes bibliographical references and index. ISBN 0–323–01129–2
1. Strabismus. 2. Binocular vision. 3. Eye—Movements. I. Title. RE771.V62 2001 616.7⬘62—dc21 2001042586
HERMANN MARTIN BURIAN
1906-1974
Preface to the Sixth Edition
A
major change with this edition is the addition
of co-author Dr. Emilio Campos, who is one
of the leaders of European strabismology and
widely respected for his scientific contributions.
Dr. Campos has written a new chapter on
Chemo-denervation and assisted me with the review and
revision of this sixth edition. I selected Dr.
Campos as a co-author because his scientific
back-ground is similar to mine. His mentor Bruno
Bag-olini was trained, as I was, by the late Hermann
Burian, with whom I co-authored the first edition.
Because of this common heritage we agree on all
major issues discussed in this text. Whenever an
occasional difference in opinions existed on minor
subject matters both of our views were stated.
As in previous editions, new material was added
and older text that had lost its relevance was
deleted, except when it was of historical interest.
Binocular Vision and Ocular Motility
has become
a major source of references to the older
strabis-mus literature that is not retrievable through
elec-tronic search techniques. With this in mind, we
have used a conservative approach in deleting
older references so that they would remain
avail-able to the researcher and interested clinician.
We have endeavored to improve clarity in the
text and tables, replaced several old figures with
better examples, and added illustration of surgical
techniques not covered in previous editions.
I
feel deeply honored for having been asked by
Dr. Gunter von Noorden to collaborate with
him on the sixth edition of
Binocular Vision and
Ocular Motility,
and I consider this recognition as
one of the highlights of my career.
I hope that my input to this edition has not
interfered with the homogeneity of this book and
its original message.
Both Dr. von Noorden and I would appreciate
any input from our readers that may help us to
make future editions even more useful.
I would like to express my gratitude to my
collaborators Drs. Costantino Schiavi and
Costan-The formerly voluminous chapter on sensory
adaptation and stereopsis has been divided into
three smaller chapters for easier access. Because
sensorial anomalies in strabismus are only briefly
dealt with in current texts, or receive at best
spuri-ous coverage in most teaching curricula for
resi-dents, the comprehensive discussion of this
sub-ject in this book appears to be fully justified.
The contributions and teaching of Hermann
Bu-rian remain apparent throughout this text but
espe-cially in Part One. We submit this volume not
only as his legacy but also that of his teacher,
Alfred Bielschowsky, who has influenced
strabis-mology during the first half of the 20th century
like no one else.
My thanks are due to Mrs. Louise Thomas, my
faithful former secretary, for obtaining copies of
articles from the local medical libraries and
illus-trations through the Baylor Department of Medical
Illustrations, and to Mr. Mike Piorunski, librarian
of the Friedenwald Library of the Wilmer Institute,
for locating and verifying older references. Last,
but not least, I thank my dear wife for her
contin-ued support and patience during the work on this
edition.
The authors have no proprietary interest in any
of the commercial products, drugs, or instruments
mentioned in this book.
Gunter K. von Noorden
tino Bellusci, who have helped me in the
prepara-tion of clinical illustraprepara-tions and surgical drawings.
Many thanks also to Stefania Piaggi, C.O., for
having located obscure references and for her help
with the computer search of the literature.
I am grateful to all my collaborators and to
those close to me for their patience during the
preparation of the manuscript and ask their
for-giveness for any lack of attention during this most
stimulating but time-consuming venture.
Preface to the First Edition
He who is theoretic as well as practical is
therefore doubly armed: able not only to prove
the propriety of his design but equally so to
carry it into execution.
VITRUVIUS
T
his volume is the product of the cooperative
efforts of the two authors. Parts I and II were
written by Burian, and Parts III and IV by von
Noorden; however, both authors take full
responsi-bility for the complete text.
In this work, our aim is to provide the
practic-ing ophthalmologist as well as the buddpractic-ing one
with the theoretic knowledge and practical
know-how that will enable him to pursue the field of
neuromuscular anomalies of the eyes in the
man-ner set forth in the precept of Vitruvius.
The sound physiologic tradition of Hering,
Helmholtz, Donders, Tschermak, Hofmann, and
their schools forms the solid ground upon which
was built the clinical work of Javal, Worth,
Bielschowsky, Duane, Lancaster, and, more
re-cently, Harms, Cu¨ppers, Lyle, Bagolini, ourselves,
and many others. Our purpose has been to convey
this physiologic basis as concisely and simply as
possible, always with the practicing
ophthalmolo-gist in mind and wherever possible emphasizing
its immediate clinical application. But much has
happened in our field since the days of the old
masters, and due consideration is given to the
exciting and significant modern studies in the
psy-chophysical and neurophysiologic areas as well as
in the field of clinical management of strabismus.
This volume is not a handbook or a system,
how-ever, and is not intended to be systematically or
historically complete. We, therefore, have omitted
many points that are to be found in reference
works. Neither does this book supplant the
Atlas
of Strabismus
by von Noorden and Maumenee,
which continues to be a useful guide to the
diag-nostic aspects of strabismus.
The theoretic foundation has served us as a
means to make the strictly clinical chapters both
‘‘theoretic and practical,’’ telling the
ophthalmolo-gist not only the ‘‘what and how’’ but also the
‘‘why.’’ We hope that the long hours of labor
expended on this volume may be of real
use-fulness in the study of strabismus, particularly to
the younger generation of ophthalmologists.
Hermann M. Burian
Gunter K. von Noorden
Contents
P A R T O N E
Physiology of the Sensorimotor
Cooperation of the Eyes
1
General Introduction
. . . 3
The Eyes as a Sensorimotor Unit 3 The Tasks of the Motor System 3
Nature and Control of Ocular Movements 3
Voluntary and Involuntary Eye Movements 3 Cybernetic Control of the Eye Movements 4 Apparent Movement of the Environment 5
Empiricism and Nativism 5
2
Binocular Vision and Space
Perception
. . . 7
Fusion, Diplopia, and the Law of Sensory Correspondence 7
Relative Subjective Visual Directions 7 Retinomotor Values 8
Common Relative Subjective Visual Directions 9 Retinal Correspondence 10
Sensory Fusion 10 Motor Fusion 11
Retinal Rivalry 11
Objective (Physical) and Subjective (Visual) Space 12
Discrepancies of Objective and Subjective Metrics 14
Distribution of Corresponding Retinal Elements 15
The Foveae as Corresponding Elements 15 The Horopter 16
Physiologic Diplopia 18
Clinical Significance 18 Suppression 19
Panum’s Area of Single Binocular Vision 20 Fixation Disparity 21
Stereopsis 21
Physiologic Basis of Stereopsis 22 Local vs. Global Stereopsis 23 Stereopsis and Fusion 24 Stereoscopic Acuity 25
xi
Monocular (Nonstereoscopic) Clues to Spatial Orientation 25
Interaction of Stereoscopic and Monocular Clues 27 Clinical Significance of Monocular Clues 27
Experimental Determination of the Longitudinal Horopter and the Criteria of Retinal Correspondence 28
Criterion of Single Vision 28 Apparent Frontal Plane Criterion 28 Criterion of Common Visual Directions 29 Criterion of Highest Stereoscopic Sensitivity 29
Egocentric (Absolute) Localization 29
Egocentric Localization and Convergence 29 Egocentric Localization and Proprioception 30 Clinical Significance of Relative and Egocentric
Localization 31
Theories of Binocular Vision 31
Correspondence and Disparity 31
Neurophysiologic Theory of Binocular Vision and Stereopsis 31
Older Theories of Binocular Vision 33
Advantages of Binocular Vision 35
3
Summary of the Gross Anatomy
of the Extraocular Muscles
. . . 38
Rectus Muscles 39
Muscle Pulleys 41
Oblique Muscles 42 Fascial System 44
Tenon’s Capsule 44
Muscle Sheaths and Their Extensions 45 Ligament of Lockwood 47
Check Ligaments 47
Intracapsular Portion of the Muscle 47 Functional Role of the Fascial System 48
Developmental Anomalies of Extraocular Muscles and the Fascial System 48
Innervation of Extraocular Muscles 49 Blood Supply of Extraocular Muscles 49
4
Physiology of the Ocular
Movements
. . . 52
Basic Kinematics 52
Translatory and Rotary Movements 52 Center of Rotation 52
xii
ContentsDefinitions of Terms and Action of Individual Muscles 52
Further Considerations of Mechanics of Extraocular Muscles 56
The Fundamental Laws of Ocular Motility 59
Donders’ and Listing’s Laws 59
Sherrington’s Law of Reciprocal Innervation 63 Hering’s Law of Equal Innervation 64 Experimental Studies of Integration of Ocular
Movements by Muscle Transposition 67
Survey of Ocular Movements and Their Characteristics 67
Terminology of Ocular Movements 67 Versions 68
Vergences 71
Characteristics of Version and Vergence Movements 76
Fixation and the Field of Fixation 79
Fixation 79 Field of Fixation 79
5
The Near Vision Complex
. . . 85
Accommodation 85
Mechanism of Accommodation 85
Units of Measurement of Accommodation and Definition of the Prism Diopter 86 Sympathetic Innervation 86
Convergence 86
Units of Measurement of Convergence 87 Components of Convergence 88
Pupillary Constriction 99
6
Histology and Physiology of
the Extraocular Muscles
. . . 101
Structure and Function of the Extraocular Muscles 101
General Histologic Characteristics 101 Nerve Supply 102
Physiologic and Pharmacologic Properties 102 Slow and Fast Twitch Fibers 103
Structural and Functional Correlations 107 Muscle Spindles and Palisade Endings in the
Extraocular Muscles 109 Electromyography 109
Sources of Tonus of the Extraocular Muscles 111
7
Visual Acuity, Geometric Optical
Effects of Spectacles, and
Aniseikonia
. . . 114
Visual Acuity 114
Basic Physiologic Concepts 114 Variables Affecting Visual Acuity 115
Geometric Optical Effects of Spectacles 118 Aniseikonia 119
P A R T T W O
Introduction to Neuromuscular
Anomalies of the Eyes
8
Classification of Neuromuscular
Anomalies of the Eyes
. . . 127
Heterophoria and Heterotropia 127 Relative and Absolute Position of Rest 128 Ocular Alignment 129
Direction of Deviation 129 Comitance and Incomitance 131 Constancy of Deviation 131 State of Vergence Systems 132 Type of Fixation 132
Time of Onset of Deviation 132 Paralytic Strabismus 132
Paralysis and Paresis 132 Muscles Affected 133 Duration and Cause 133 Seat of Lesion 133
Mechanical-Restrictive Strabismus 133 Orbital Strabismus 133
9
Etiology of Heterophoria and
Heterotropia
. . . 134
Factors Responsible for the Manifestation of a Deviation 134
Abnormalities of Fusion Mechanism 134 Reflexologic Theories 137
Factors Causing the Underlying Deviation 138
Mechanical (Muscular) Theories 138
Structural Anomalies of Extraocular Muscles 139 Role of Accommodation and Refraction in Comitant
Strabismus 139 Fixation Disparity 140
Other Innervational (Neurologic) Factors in Comitant Strabismus 141
Brain Damage 143 Embryopathy 145
Facial and Orbital Deformities 145
Genetics of Comitant Strabismus 145
Summary 148
Concluding Remarks 148
10
Symptoms in Heterophoria
and Heterotropia and the
Psychological Effects
of Strabismus
. . . 153
Asthenopia and Diplopia 153
Psychological Effects of Strabismus 156
11
Examination of the Patient—I
Preliminaries . . . 158
History 158
Contents
xiii
Estimation of Visual Acuity in Infants 159 Measurement of Visual Acuity in Preschool-Age
Children 162
Measurement of Visual Acuity in School-Age Children and Adults 163
Refraction 163
Changes of Refraction with Age 165
12
Examination of the Patient—II
Motor Signs in Heterophoria and
Heterotropia . . . 168
Inspection of the Eyes and Head Position 168
Inspection of the Lids and Lid Fissures 168 Position of the Globes—Angle Kappa 169
Measurement of Angle Kappa 171 Size of Angle Kappa 172
Clinical Significance of Angle Kappa 172
Observation of Head Position 173
Determination of Presence of a Deviation—Cover and Cover-Uncover Tests 174
Measurement of Deviation 176
Prism and Cover Test 177
Physiologic Basis 177 Performance 178 Limitations 181
Prism and Cover Test in Diagnostic Positions of Gaze 182
Measurement with the Major Amblyoscope 183 Corneal Reflection Tests 185
Photographic Methods 186 Bru¨ckner Test 187 Subjective Tests 187
Diplopia Tests (Red-Glass Test and Others) 187 Haploscopic Tests 190
Measurement of Cyclodeviations 194
Qualitative Diagnosis Based on Position of Double Images 194
Maddox Double Rod Test 194 Bagolini Striated Glasses 195 Major Amblyoscope 196
Ophthalmoscopy and Fundus Photography 196 The New Cyclo Test 198
Scotometry 198
Determination of the Subjective Horizontal or Vertical 198
Measurement of Dissociated Vertical Deviations 198 The Head Tilt Test 198
Examination of the Motor Cooperation of the Eyes 199
Ductions and Versions 199
Elevation or Depression of the Adducted Eye (Upshoot or Downshoot in Adduction) 201
Measurement of Vergences 202
Measurement With Prisms 202
Measurement With a Major Amblyoscope 206 Fusional Movements Elicited by Peripheral Retinal
Stimuli in Strabismus 206
Near Point of Convergence 206
Maintenance of Convergence 207
13
Examination of the Patient—III
Sensory Signs, Symptoms,
and Binocular Adaptations
in Strabismus . . . 211
Confusion and Diplopia 212
Monocular Diplopia 213 Binocular Diplopia 214
Suppression 215
Mechanism and Seat 215 Clinical Features 216 Tests for Suppression 217
Binocular Perimetry and Haploscopy 217 Prisms 218
The Four-Prism Diopter Base-Out Prism Test 218 Monocular Visual Acuity Measured Under
Binocular Conditions 219 The Worth Four-Dot Test 219
Suppressing Versus Ignoring a Double Image 220 Measurement of Depth of Suppression 221
Blind Spot Mechanism 221 Anomalous Correspondence 222
Basic Phenomenon and Mechanism 222 Tests 225
Afterimage Test 225
Striated Glasses Test of Bagolini 227 Testing With the Major Amblyoscope 228 Diplopia Test 230
Testing With Projection Devices 230 Foveo-Foveal Test of Cu¨ppers 230
Evaluation of Tests 231 Neurophysiologic Basis 233
Suppression and Anomalous Correspondence 233 Development and Clinical Picture 234
Development 234 Clinical Picture 235
Quality of Binocular Vision in Anomalous Correspondence 239
Prevalence 239 Theories 240
Review and Summary 241
14
Examination of the Patient—IV
Amblyopia . . . 246
Prevalence, Social and Psychosocial Factors 246 Classification and Terminology 248
Strabismic Amblyopia 249 Anisometropic Amblyopia 250
Visual Deprivation Amblyopia (Amblyopia Ex Anopsia) 252
Idiopathic Amblyopia 253 Organic Amblyopia 253
Amblyopia Secondary to Nystagmus 254
Clinical Features of Strabismic Amblyopia 254
Fixation Preference 254 Visual Acuity 255
Fixation Pattern of the Amblyopic Eye 260 The Sensitive Period 268
Pathogenesis and Pathophysiology of Amblyopia 269
Psychophysical Studies 269 Higher Nervous Center Activities 277
xiv
ContentsEye Movements in Amblyopia 279 Electrophysiologic Studies 279
Amblyopia vs. Suppression 282
Experimental Amblyopia in Animal Models and Histologic Abnormalities in Brains of Human Amblyopes 282
The Essence of Amblyopia 286
15
Examination of the Patient—V
Depth Perception . . . 298
Development of Stereopsis 298 Stereopsis and Strabismus 298 Testing for Stereopsis 299
Major Amblyoscope or Stereoscope 299 Stereogram 299
Titmus Stereo Test 299 Random-Dot Stereograms 301 TNO Test 302
Lang Test 303 Two-Pencil Test 304
P A R T T H R E E
Clinical Characteristics of
Neuromuscular Anomalies of
the Eye
16
Esodeviations
. . . 311
Esophoria and Intermittent Esotropia 311
Etiology 311 Clinical Signs 311 Symptoms 312
Sensorial Adaptation 312 Diagnosis 312
Therapy 313
Accommodative Esotropia 314
Refractive Accommodative Esotropia (Normal AC/A Ratio) 314
Definition 314 Etiology 314
Clinical Characteristics 316 Therapy 316
Nonrefractive Accommodative Esotropia (High AC/A Ratio) 318
Definition 318
Clinical Characteristics 318 Therapy 318
Hypoaccommodative Esotropia 319
Definition 319
Clinical Characteristics 319
Partially Accommodative Esotropia 319
Definition 319
Clinical Characteristics 320 Therapy 320
Nonaccommodative Esotropia 320
Essential Infantile Esotropia 320
Definition 320
Terminology, Prevalence, Etiology 320
Differential Diagnosis 321 Clinical Characteristics 321 Therapy 329
Nonaccommodative Convergence Excess Esotropia (Normal AC/A Ratio) 336
Definition 336
Clinical Characteristics 336 Treatment 336
Acquired or Basic Esotropia 336
Definition 336
Clinical Characteristics 337 Therapy 337
Esotropia in Myopia 338
Acute Acquired Comitant Esotropia 338
Acute Strabismus After Artificial Interruption of Fusion 338
Acute Esotropia Without Preceding Disruption of Fusion (Burian-Franceschetti Type) 339 Acute Esotropia of Neurologic Origin 339
Microtropia 340
Historical Review 340
Current Concepts and Clinical Significance 342 Diagnosis 343
Therapy 344
Recurrent Esotropia 345 Secondary Esotropia 345
Sensory Esotropia 345
Etiology and Clinical Characteristics 345 Therapy 346
Consecutive Esotropia 347
Management of Surgical Overcorrections 347 Esotropia Associated with Vertical Deviations 348
Clinical Characteristics and Diagnosis 348 Therapy 349
17
Exodeviations
. . . 356
Classification and Etiology 356 Primary Exodeviations 358
Clinical Characteristics 358 Therapy 365
Surgical Treatment 367
Dissociated Exodeviations 372 Secondary Exodeviations 372
Sensory Exotropia 372 Consecutive Exotropia 372
18
Cyclovertical Deviations
. . . 377
Comitant Hyperdeviations 377
Etiology and Clinical Characteristics 377 Therapy 378
Dissociated Vertical Deviations 378
Terminology 378
Clinical Characteristics 378 Measurement 380
Etiology 381
Differential Diagnosis 383 Therapy 383
Dissociated Horizontal Deviations 385 Elevation in Adduction (Strabismus
Contents
xv
Clinical Characteristics 385 Etiology 386
Therapy 387
Depression in Adduction (Strabismus Deorsoadductorius) 387
Cyclodeviations 389
Diagnosis 389
Clinical Characteristics 389 Therapy 391
19
A
and
V
Patterns
. . . 396
Etiology 398
Horizontal School 398 Vertical School 399 Oblique School 399 Orbital Factors 399
Craniofacial Anomalies 399 Heterotropia of Muscle Pulleys 400
Anomalies of Muscle Insertions and Cyclotorsion 401
Conclusions 402
Prevalence 404
Clinical Findings and Diagnosis 404 Treatment 406
Indications for Surgery 406 Surgical Methods 407
Surgery on the Horizontal Rectus Muscles 407 Surgery on the Oblique Muscles 407 Transposition of Horizontal or Vertical Rectus
Muscles 409
Slanting of the Horizontal Muscle Insertions 410
Choice of Surgical Procedure 410
20
Paralytic Strabismus
. . . 414
Diagnosis and Clinical Characteristics 414
Ductions and Versions 415 Measurement of the Deviation 415 Head Tilt Test 416
Compensatory Anomalies of Head Position 417 Sensory Anomalies 421
Past-Pointing 421 Electromyography 422
Neurogenic Paralysis vs. Myogenic or Structural Restriction of Eye Movements 422
Forced Duction Test 423
Estimation of Generated Muscle Force 425 Eye Movement Velocity 426
Paralytic vs. Nonparalytic Strabismus 427 Congenital vs. Acquired Paralysis 427 Orbital Imaging Techniques 429 Evaluation of Visual Impairment Caused by
Diplopia 429
Paralysis of Individual Extraocular Muscles 429
Cranial Nerve III Paralysis 430 Cranial Nerve IV Paralysis 434 Cranial Nerve VI Paralysis 439
Skew Deviation 442
Double Elevator Paralysis 442 Double Depressor Paralysis 443
Supranuclear and Internuclear Paralysis 444
Therapy of Paralytic Strabismus 444
Nonsurgical Therapy 445 Surgical Therapy 445 Alternative Methods 451
21
Special Forms of Strabismus
. . . 458
Retraction Syndrome (Duane Syndrome) 458
Laterality and Sex Distribution 458 Etiology 459
Clinical Findings and Diagnosis 461 Therapy 465
Brown Syndrome 466
Incidence, Laterality, and Heredity 466 Associated Anomalies 467
Natural History 467 Etiology 467
Diagnosis and Differential Diagnosis 470 Therapy 470
Adherence Syndrome 471 Strabismus Fixus 471
Clinical Findings and Etiology 471 Therapy 472
Strabismus in High Myopes 473 Fibrosis of the Extraocular Muscles 474 Graves’ Endocrine Ophthalmopathy 476
Etiology 476
Diagnosis and Clinical Findings 476 Therapy 478
Acute Orbital Myositis 480 Cyclic Heterotropia 480
Clinical Findings and Etiology 480 Therapy 482
Acquired Motor Fusion Deficiency 482 Fracture of the Orbital Floor 483
Clinical Findings and Etiology 483 Therapy 484
Fracture of the Medial Orbital Wall 486 Superior Oblique Myokymia 487
Clinical Findings and Etiology 487 Therapy 487
Ocular Myasthenia Gravis 488
Clinical Findings 488 Diagnosis 488 Therapy 489
Chronic Progressive External Ophthalmoplegia (Ocular Myopathy of von Graefe) 489
Clinical Findings and Etiology 489 Therapy 490
22
Anomalies of Convergence and
Divergence
. . . 500
Anomalies of Convergence 502
Convergence Insufficiency 502
Convergence Insufficiency Associated with Accommodative Insufficiency 503 Convergence Paralysis 503 Convergence Spasm 504
Anomalies of Divergence 505
Divergence Insufficiency 505 Divergence Paralysis 505
xvi
Contents23
Nystagmus
. . . 508
Manifest Congenital Nystagmus 508
Sensory and Motor Type 508 Clinical Characteristics 509 Compensatory Mechanisms 511
Latent and Manifest-Latent Congenital Nystagmus 516
Clinical Characteristics 516
Treatment 520
Medical Treatment 521 Surgical Treatment 522
P A R T F O U R
Principles of Therapy
24
Principles of Nonsurgical
Treatment
. . . 537
Optical Treatment 537
Refractive Correction 537 Prisms 540
Pharmacologic Treatment 541
Miotics 541 Atropine 543 Chemodenervation 543
Orthoptics 543
Applications 543
Indications and Contraindications 544 Treatment of Amblyopia 545 Red Filter Treatment 550 Prisms 550
Penalization 550 Drugs 552 Pleoptics 552 CAM Treatment 553 Other Types of Treatment 553 Rationale for Treatment 553
25
Chemodenervation of Extraocular
Muscles—Botulinum Toxin
. . . 559
Mechanisms of Action 559 Injection Technique 560 Indications 561
Botox in Infantile Esotropia 561
Botox in Other Forms of Comitant Strabismus 562 Botox in Paralytic Strabismus 562
Botox in Endocrine Ophthalmopathy and Other Ocular Motility Disturbances 563 Botox in Nystagmus 563
Other Ophthalmologic Indications 563
Alternatives to Botox for Chemodenervation 563
26
Principles of Surgical Treatment
. 566
History and General Comments 566 Choice of Operation 568
Motility Analysis 569
Symmetrical vs. Asymmetrical Operations 570 Amount of Operation 571
Prism Adaptation Test 572
Operations to Weaken the Action of a Muscle 573 Operations to Strengthen the Action of a
Muscle 579
Combined Recession-Resection Operation 580
Single vs. Multiple Procedures 580
Preparation of Patient and Parents for Surgery 581 Anesthesia 581
General Anesthesia 581 Local Anesthesia 582
Instruments, Sutures, Needles 582 Surgical Techniques 583
Preparation of the Eye 583 Fixation of the Globe 584
Conjunctival Incision and Exposure of a Rectus Muscle 584
Recession of a Rectus Muscle 587 Resection of a Rectus Muscle 588 Adjustable Sutures 591
Marginal Myotomy of a Rectus Muscle 597 Myectomy of the Inferior Oblique Muscle 598 Recession of the Inferior Oblique Muscle 600 Tenectomy of the Superior Oblique Muscle 602 Recession of the Superior Oblique Muscle 603 Tucking of the Superior Oblique Muscle 603 Anterior and Lateral Displacement of the Superior
Oblique Tendon for Excyclotropia (Harada-Ito Procedure) 607
Posterior Fixation Suture 609 Muscle Transposition Procedures 612
Recession of Conjunctiva and Tenon’s Capsule 617 Traction Sutures 617
Use of Plastic Materials 618
Complications 618
Surgical Complications 618 Complications of Anesthesia 619 Postoperative Complications 620
Overcorrections 623 Postoperative Care 623
Length of Hospitalization and Postoperative Checkups 623
Dressing 624 Medication 624