Management of Strabismus and Amblyopia.

Management of Strabismus and Amblyopia. John A. Pratt-Johnson and Geraldine Tillson. New York: Thieme, 2000. 2nd ed. Pages: 336. Price: $89.00. ISBN 0-86577-992-9. Robert P. Rutstein, School of Optometry and Vision Science , University of Alabama at Birmingham , Birmingham, Alabama This book is written for eye care practitioners who specialize in binocular vision disorders, especially strabismus and amblyopia. The 22 chapters are clearly written and well organized. There is a glossary that defines the major terms used throughout the text as well as a complete index. The authors in the opening chapter make the point that good visual acuity, stereopsis, and fusion are probably developed as early as 4 months of age but do not become firmly established until about 8 years of age. They differentiate bifoveal fusion from peripheral fusion and emphasize that in many childhood strabismic deviations, the best level of fusion, if any can be achieved, may only be the latter. The authors’ original articles are well referenced and reinforced throughout the text. For example, their concept that strabismic suppression occurs as a “trigger” mechanism and not as a hemiretinal suppression scotoma is emphasized. The authors warn the reader of central fusion disruption. This sometimes develops in adults with previously normal binocular vision who either suffer trauma or prolonged visual deprivation from a unilateral cataract. These patients develop strabismus and diplopia and can only momentarily superimpose the image because of deficient motor fusion. The differential diagnosis of central fusion disruption and bilateral superior oblique palsy with a large excyclodeviation that also precludes fusion is emphasized. I was surprised by the authors’ recommendation of the Titmus stereotest for routine clinical use. With all its monocular clues, its use is contraindicated in determining the fusion ability for a patient with an ocular deviation. There are much better commercially available stereotests. There is only one chapter on heterophoria and none on accommodative dysfunction. According to the authors, alcohol seems to undermine esophoria, and many of these patients may experience diplopia after drinking a glass of wine at dinner. The authors do acknowledge that many patients with convergence insufficiency exodeviations also have defective accommodation and recognize that poor accommodation can cause the exodeviation. In the chapter on amblyopia, it is emphatically stated that the best visual acuity obtained with treatment by 8 years of age is recoverable if the amblyopia recurs later in life. Although I tend to agree, I know of no studies that have followed these patients beyond 10 years after treatment. The authors warn of an increased risk of amblyopia in postsurgical infantile esotropes. Because many of these children alternately fixate presurgically and monocularly fixate postsurgically, this is the probable cause. In the chapter on accommodative esotropia, the imminent question by the parents, “will my child always have to wear glasses?” is addressed. According to the authors, if the amount of hyperopia is ≤3.50 diopters by age 9 years, the child’s glasses can be eliminated. Unfortunately, recent studies, including my own, have found this not always to be the case. The chapters on exotropia, A and V patterns, vertical strabismus, paretic strabismus, mechanically restrictive strabismus, and nystagmus are very informative. The concern of a consecutive esotropia persisting and becoming amblyopiagenic in a surgically treated young intermittent exotrope is emphasized. The authors advise against extraocular muscle surgery with intermittent exotropia unless the deviation exceeds 20 prism diopters. Other forms of therapy including orthoptics/vision therapy should be attempted. I was pleased to see the chapter on vertical strabismus emphasize that any vertical strabismus should be considered to be caused by a superior oblique palsy until proven otherwise. Also, the statement that an acquired isolated weakness of either the medial rectus or vertical rectus muscles without a history of trauma should make the clinician consider ocular myasthenia or multiple sclerosis agrees with my own clinical experience. The chapters I found most informative dealt with strabismus in the adult, diplopia, and mistakes in strabismus management. I agree that some of the most challenging cases involve adults with childhood strabismus who develop binocular vision symptoms. Pratt-Johnson and Tillson correctly emphasize that care must be taken not to disrupt these patients’ sensory status. An example is the adult who starts to fixate with the deviating eye and experiences diplopia. According to the authors, this usually develops secondary to a refractive error change, i.e., a myopic shift in the fixating eye, which forces the patient to now fixate with the deviating eye. There are obvious shortcomings in the book. First, there is limited information on heterophoria, vergence dysfunctions, and accommodative disorders. Second, the references listed at the end of each chapter do not contain references from the optometric literature. Surely there are significant papers on binocular vision disorders from optometric authors. Third, despite giving extensive coverage on the various types of strabismic deviations, there are no figures of patients manifesting these deviations. The authors rely on artist’s drawings for all illustrations. Fourth, there are minimal case examples presented. More of the latter would help the reader better comprehend the information. Accordingly, I do not recommend this book as a primary text for optometric practitioners providing binocular vision care. It can be used only as a supplementary text to add to the practitioner’s library.FIGUREFigure