DOCSLIB.ORG

Relating Binocular and Monocular Vision in Strabismic and Anisometropic Amblyopia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Relating Binocular and Monocular Vision in Strabismic and Anisometropic Amblyopia CLINICAL SCIENCES Relating Binocular and Monocular Vision in Strabismic and Anisometropic Amblyopia Ritwick Agrawal, MS, MD; Ian P. Conner, PhD; J. V. Odom, PhD; Terry L. Schwartz, MD; Janine D. Mendola, PhD Objectives: To examine deficits in monocular and bin- ing greater deficits in Vernier acuity. Both amblyopic ocular vision in adults with amblyopia and to test the fol- groups were then characterized according to the degree lowing 2 hypotheses: (1) Regardless of clinical subtype, of residual stereoacuity and binocular motion integra- the degree of impairment in binocular integration pre- tion ability, and 67% of subjects with strabismus com- dicts the pattern of monocular acuity deficits. (2) Sub- pared with 29% of subjects with anisometropia were clas- jects who lack binocular integration exhibit the most se- sified as having “nonbinocular” vision according to our vere interocular suppression. criterion. For this nonbinocular group, Vernier acuity is most impaired. In addition, the nonbinocular group Methods: Seven subjects with anisometropia, 6 sub- showed the most dichoptic contrast masking of the am- jects with strabismus, and 7 control subjects were tested. blyopic eye and the least dichoptic contrast masking of Monocular tests included Snellen acuity, grating acuity, the fellow eye. Vernier acuity, and contrast sensitivity. Binocular tests included Titmus stereo test, binocular motion integra- Conclusion: The degree of residual binocularity and in- tion, and dichoptic contrast masking. terocular suppression predicts monocular acuity and may be a significant etiological mechanism of vision loss. Results: As expected, both groups showed deficits in monocular acuity, with subjects with strabismus show- Arch Ophthalmol. 2006;124:844-850 MBLYOPIA IS A DEVELOP- universally reduced and is often absent in mental visual disorder both types of amblyopia. In subjects with characterized by abnor- anisometropia, central vision stereoacu- mal form vision and bin- ity is normal at low spatial frequencies, ocular functions. Past re- subnormal at intermediate spatial frequen- search has differentiated the performance cies, and unmeasurable at higher spatial A 10 of subjects with strabismic and anisome- frequencies. In subjects with strabis- tropic subtypes of amblyopia.1-6 Often the mus, this loss is more profound at all spa- motivation is to better understand the tial frequencies (probably as a result of a pathogenesis of amblyopia. An impor- history of diplopia early in life that is tant source of evidence is monocular po- avoided through competitive suppres- sition acuity tasks. For example, Vernier sion of the visual inputs from one eye). Bin- acuity loss is more severe in subjects with ocular motion integration is another bin- strabismus compared with that in sub- ocular function. Arguments have been jects with anisometropia. In subjects with made that the motion pathway is rela- strabismus, the deficit is larger than that tively spared in amblyopia,11-13 so that re- predicted by linearly scaling their grating sidual binocular integration ability may ex- acuity,5 indicating that additional defi- ist when tested via motion sensitivity, at cits are involved. Different models at- least in the anisometropic subtype.14 Fi- tribute this acuity loss according to the size, nally, interocular inhibition can be mea- shape, or density of receptive fields in the sured via the dichoptic contrast masking Author Affiliations: visual cortex, or to spatial disarray in their that occurs when a suprathreshold stimu- Departments of Neurobiology topographical location.2,7-9 In general, these lus is presented to one eye, because the (in- and Anatomy (Drs Agrawal, models suggest that abnormal “noise” crement) contrast threshold is elevated for Conner, and Mendola), arises in the visual cortex, probably in areas the other eye.15 In subjects with ambly- Ophthalmology (Drs Odom, beyond the primary visual cortex. opia, masking is usually present, al- Schwartz, and Mendola), and Another source of evidence is deficits though it may be abnormal in strength.16-18 Radiology (Dr Mendola) and 14 Center for Advanced Imaging in binocular vision. Binocular integra- Investigators in a recent large study of (Dr Mendola), School of tion of the image formed in each eye re- 427 subjects with amblyopia and 68 con- Medicine, West Virginia sults in several distinct visual abilities. trol subjects came to a provocative conclu- University, Morgantown. Depth perception via stereopsis is almost sion regarding the relationship between (REPRINTED) ARCH OPHTHALMOL / VOL 124, JUNE 2006 WWW.ARCHOPHTHALMOL.COM 844 ©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 Table 1. Characteristics of Clinical Groups Interocular Difference Snellen Acuity Deviation Refraction* in Spherical Age at Age at Eye Patching Subject in Prism Equivalent of Diagnosis, Correction Treatment, Binocular Stereoacuity, No. OS ODDiopter OS OD Refractive Error y Surgery, y mo Vision arc seconds Control 1 20/20 20/20 −0.25 ϩ 0.50 00 0.50 40 ϫ154° 2 20/16 20/20 −2.25 ϩ 0.50 −3.75 ϩ 0.75 1.25 40 ϫ179° ϫ178° 3 20/20 20/20 00 00 0 40 4 20/16 20/16 −0.25 ϩ 0.25 00 0.25 40 ϫ39° 5 20/16 20/20 00 00 0 40 6 20/20 20/16 0.50 0.50 0 40 7 20/20 20/25 −1.75 ϩ 1.75 −1.50 ϩ 1.25 1.0 80 ϫ166° ϫ 175° Anisometropia 1 20/63 20/20 −0.75 ϩ 0.50 1.75 ϩ 2.50 3.5 9 2 Yes 800 ϫ32° ϫ145° 2 20/16 20/32 3.50 ϩ 0.50 −1.00 ϩ 0.25 2.7 9 1 Yes 100 ϫ116° ϫ109° 3 20/63 20/16 0.00 ϩ 0.25 2.00 ϩ 0.75 2.25 8 1 Yes 800 ϫ37° ϫ101° 4 20/32 20/20 −0.25 ϩ 0.25 2.00 ϩ 0.75 2.0 5 24 Yes 800 ϫ71° ϫ101° 5 20/25 20/50 2.75 ϩ 0.50 1.00 ϩ 0.50 1.75 5 12 Yes 400 ϫ11° ϫ64° 6 20/25 20/20 3.25 ϩ 1.00 2.00 ϩ 0.75 1.5 10 2 No 800 ϫ27° ϫ124° 7 20/40 20/160 −12.00 ϩ 2.0 −11.75 ϩ 1.5 0.5 9 12 No 7000† ϫ132° ϫ032° Strabismus‡ 1 20/40 20/20 4 2.25 ϩ 1.25 2.50 ϩ 3.50 1.5 2 2 60 No 800 ϫ88° ϫ95° 2 20/160 20/20 12 1.00 ϩ 0.50 1.75 ϩ 1.00 1.0 4 6 24 No 3500 ϫ118° ϫ71° 3 20/16 20/32 6 2.50 ϩ 0.50 2.50 ϩ 3.50 0.75 3 0.5, 10, 18 24 No 7000† ϫ44° ϫ98° 4 20/25 20/16 6 00 00 0 0.5 ? No 7000† 5 20/25 20/50 8 0.25 ϩ 0.50 0.25 ϩ 0.50 0 10 0 Yes 200 ϫ162° ϫ2° 6 20/25 20/25 0 −1.00 ϩ 1.00 −100 ϩ 0.50 0.25 5 9, 19 1 Yes 200 ϫ171° ϫ15° *00 Indicates no refractive error. †A score of 7000 arc seconds was assigned to subjects who scored incorrect on every trial. ‡All esotropic except for exotropic strabismus in subject 6. monocular and binocular deficits. In this study, McKee and visual resolution. In addition, we introduced a test not in- colleagues proposed that the severity of binocularity loss cluded before, dichoptic contrast masking, so that the de- may sometimes better predict the nature of the physiologi- gree of interocular inhibition could be directly assessed. cal changes in amblyopia than the clinical etiology. In other words, the degree of binocularity may at least partially pre- METHODS dict abnormality on monocular tasks. They compared the Vernier acuity of a binocular group with that of a matched “nonbinocular” group and found a significant difference SUBJECTS (PϽ.001) between them. Similar ideas have been pro- posed in animal models of induced amblyopia.19 This study examined 20 subjects, including 7 control sub- The present study attempts to replicate the conclu- jects, 7 subjects with anisometropia, and 6 subjects with stra- 14 bismus (Table 1); subject groups were matched for mean age sions of the study by McKee et al in a hypothesis-driven (25.1, 28.0, and 26.3 years, respectively) and mean years of edu- manner. We determined whether the results of their study cation (13.7, 14.9, and 13.5 years, respectively). Subjects pro- could be replicated using a more typical moderate num- vided informed consent conforming to the Declaration of Hel- ber of subjects, for whom it is not possible to match sub- sinki (West Virginia University Institutional Review Board jects with binocular and nonbinocular vision according to Protocol 14788). Any subject with known or suspected neu- (REPRINTED) ARCH OPHTHALMOL / VOL 124, JUNE 2006 WWW.ARCHOPHTHALMOL.COM 845 ©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 rological conditions was excluded from the study. All subjects MONOCULAR TESTS completed an ophthalmologic examination to confirm diagno- sis. For control subjects, dominant and nondominant assign- Snellen Acuity ments were given to the eyes based on acuity measures. Most subjects with amblyopia had a history of patch treatment dur- This test was performed at the West Virginia University Eye ing childhood (ie, a patch was worn to cover the dominant [fel- Center as part of a clinical examination. A standard chart (Lom- low] eye). One subject with exotropic strabismus showed equal bart Instrument, Norfolk, Va) was used. visual acuity in both eyes at the time of testing. Diagnosis of anisometropic amblyopia was made on the ba- Grating Acuity sis of (1) an interocular refractive difference of hyperopia of at least 1.00 diopter (D), astigmatism of at least 1.00 D, or myopia For each trial, the subject saw 2 temporally sequenced screens; of at least –2.50 D or (2) a history of anisometropia but no stra- 1 contained a vertical sinusoidal grating (80% contrast, sub- bismus by clinical alternate cover testing and no history of stra- tending 8° of visual angle).
Load more

Recommended publications
  • Seven Myths on Crowding1
    Myths on Crowding_39.doc Seven myths on crowding1 Hans Strasburger, Ludwig-Maximilians-Universität, München, Germany For submission to i-Perception Abstract Crowding has become a hot topic in vision research and some fundamentals are now widely agreed upon. For the classical crowding task one would likely agree with the following statements. (1) Bouma’s law can be succinctly stated as saying that critical distance for crowding is about half the target’s eccentricity. (2) Crowding is predominantly a peripheral phenomenon. (3) Peripheral vision extends to at most 90° eccentricity. (4) Crowding increases strongly and linearly with eccentricity (as does the minimal angle of resolution, MAR). (5) Crowding is asymmetric as Bouma (1970) has shown. For that inner-outer asymmetry, the peripheral flanker has more effect. (6) Critical crowding distance corresponds to a constant cortical distance in primary visual areas like V1. (7) Except for Bouma’s (1970) paper, crowding research mostly started in the 2000s. I propose the answer is ‘not really’ to these assertions. So should we care? I think we should, before we write the textbooks for the next generation. Keywords: Crowding, Psychophysics, Perception, Reading, Visual acuity, Peripheral vision, Fovea, Asymmetries, Sensory systems, Cortical map, Vision science, Visual field. Introduction In 1962, the ophthalmologists James Stuart and Hermann Burian published a study on amblyopia where they adopted a nice and clear term, crowding, to describe why standard acuity test charts are mostly unsuitable for amblyopic subjects: On most standard charts, as ophthalmologists and optometrists knew, optotypes on a line are too closely spaced for valid assessment of acuity in all cases, such that in particular amblyopic subjects (and young children) may receive too low an acuity score.
    [Show full text]
  • Binocular Vision and Ocular Motility SIXTH EDITION
    Binocular Vision and Ocular Motility 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 Mosby A Harcourt Health Sciences Company St. Louis London Philadelphia Sydney Toronto Mosby A Harcourt Health Sciences Company Editor-in-Chief: Richard Lampert Acquisitions Editor: Kimberley Cox Developmental Editor: Danielle Burke Project Manager: Agnes Byrne Production Manager: Peter Faber Illustration Specialist: Lisa Lambert Book Designer: Ellen Zanolle Copyright ᭧ 2002, 1996, 1990, 1985, 1980, 1974 by Mosby, Inc. All rights reserved. No part of this publication may be reproduced or transmit- ted in any form or by any means, electronic or mechanical, including photo- copy, recording, or any information storage and retrieval system, without per- mission in writing from the publisher. NOTICE Ophthalmology is an ever-changing field. Standard safety precautions must be followed, but as new research and clinical experience broaden our knowledge, changes in treatment and drug therapy may become necessary or appropriate. Readers are advised to check the most current product information provided by the manufacturer of each drug to be administered to verify the recommended dose, the method and duration of administration, and contraindications. It is the responsibility of the treating physician, relying on experience and knowledge of the patient, to determine dosages and the best treatment for each individual pa- tient.
    [Show full text]
  • Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: a Narrative Review
    Journal of Clinical Medicine Review Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: A Narrative Review Carlos J. Hernández-Rodríguez 1,2 , David P. Piñero 1,2,* , Ainhoa Molina-Martín 1 , León Morales-Quezada 3, Dolores de Fez 1, Luis Leal-Vega 4 , Juan F. Arenillas 4,5 and María Begoña Coco-Martín 4 1 Group of Optics and Visual Perception, Department of Optics, Pharmacology and Anatomy, University of Alicante, San Vicente del Raspeig, 03016 Alicante, Spain; [email protected] (C.J.H.-R.); [email protected] (A.M.-M.); [email protected] (D.d.F.) 2 Clinical Optometry Unit, Department of Ophthalmology, Vithas Medimar International Hospital, 03016 Alicante, Spain 3 Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA 02215, USA; [email protected] 4 Group of Applied Clinical Neurosciences and Advanced Data Analysis, Neurology Department, Faculty of Medicine, University of Valladolid, 47005 Valladolid, Spain; [email protected] (L.L.-V.); [email protected] (J.F.A.); [email protected] (M.B.C.-M.) 5 Stroke Unit and Stroke Program, Department of Neurology, Universitary Hospital, University of Valladolid, 47003 Valladolid, Spain * Correspondence: [email protected]; Tel.: +34-965-90-34-00 Received: 16 October 2020; Accepted: 7 December 2020; Published: 9 December 2020 Abstract: Active vision therapy using perceptual learning and/or dichoptic or binocular environments has shown its potential effectiveness in amblyopia, but some doubts remain about the type of stimuli and the mode and sequence of presentation that should be used. A search was performed in PubMed, obtaining 143 articles with information related to the stimuli used in amblyopia rehabilitation, as well as to the neural mechanisms implied in such therapeutic process.
    [Show full text]
  • Seven Myths on Crowding and Peripheral Vision
    Review i-Perception 2020, Vol. 11(3), 1–46 Seven Myths on Crowding ! The Author(s) 2020 DOI: 10.1177/2041669520913052 and Peripheral Vision journals.sagepub.com/home/ipe Hans Strasburger Georg-August-Universit€at, Gottingen,€ Germany Ludwig-Maximilians-Universit€at, Mu¨nchen, Germany Abstract Crowding has become a hot topic in vision research, and some fundamentals are now widely agreed upon. For the classical crowding task, one would likely agree with the following statements. (1) Bouma’s law can be stated, succinctly and unequivocally, as saying that critical distance for crowding is about half the target’s eccentricity. (2) Crowding is predominantly a peripheral phe- nomenon. (3) Peripheral vision extends to at most 90 eccentricity. (4) Resolution threshold (the minimal angle of resolution) increases strongly and linearly with eccentricity. Crowding increases at an even steeper rate. (5) Crowding is asymmetric as Bouma has shown. For that inner-outer asymmetry, the peripheral flanker has more effect. (6) Critical crowding distance corresponds to a constant cortical distance in primary visual areas like V1. (7) Except for Bouma’s seminal article in 1970, crowding research mostly became prominent starting in the 2000s. I propose the answer is “not really” or “not quite” to these assertions. So should we care? I think we should, before we write the textbook chapters for the next generation. Keywords crowding, psychophysics, perception, reading, visual acuity, peripheral vision, fovea, asymmetries, sensory systems, cortical map, vision science, visual field Date received: 28 February 2019; accepted: 13 February 2020 In 1962, the ophthalmologists James Stuart and Hermann Burian published a study on amblyopia where they adopted a nice and clear term when they spoke of the crowding phe- nomenon1,2 to describe why standard acuity test charts are mostly unsuitable for amblyopic Corresponding author: Hans Strasburger, Georg-August-Universit€at, Gottingen,€ Germany; Ludwig-Maximilians-Universit€at, Mu¨nchen, Germany.
    [Show full text]
  • Improvement in Vernier Acuity in Adults with Amblyopia Practice Makes Better
    Improvement in Vernier Acuity in Adults With Amblyopia Practice Makes Better Dennis M. Levi* Uri Polat,^ and Ying-Sheng Hu* Purpose. To determine the nature and limits of visual improvement through repetitive practice in human adults with naturally occurring amblyopia. Methods. A key measure the authors used was a psychophysical estimate of Vernier acuity; persons with amblyopia have marked deficits in Vernier acuity that are highly correlated with their loss of Snellen acuity. The experiment consisted of three phases: pretraining measure- ments of Vernier acuity and a second task (either line-detection thresholds or Snellen acuity) in each eye with the lines at two orientations; a training phase in which observers repetitively trained on the Vernier task at a specific line orientation until each had completed 4000 to 5000 trials; and posttrainingmeasurements (identical to those in the first phase). Two groups of amblyopic observers were tested: novice observers (n = 6), who had no experience in making psychophysical judgments with their amblyopic eyes, and experienced observers (n = 5), who had previous experience in making Vernier judgments with their amblyopic eyes (with the lines at a different orientation) using the signal-detection methodology. Results. The authors found that strong and significant improvement in Vernier acuity occurs in the trained orientation in all observers. Learning was generally strongest at the trained orientation but may partially have been transferred to other orientations (n = 4). Significant learning was transferred partially to the other eye (at the trained orientation) in two observers with anisometropic amblyopia. Improvement in Vernier acuity did not transfer to an untrained detection task.
    [Show full text]
  • Seven Myths on Crowding and Peripheral Vision1
    Myths on Crowding_40b.doc Final reading Seven myths on crowding and peripheral vision1 Hans Strasburger, Ludwig-Maximilians-Universität, München, Germany For submission to i-Perception Abstract Crowding has become a hot topic in vision research and some fundamentals are now widely agreed upon. For the classical crowding task, one would likely agree with the following statements. (1) Bouma’s law can, succinctly and unequivocally, be stated as saying that critical distance for crowding is about half the target’s eccentricity. (2) Crowding is predominantly a peripheral phenomenon. (3) Peripheral vision extends to at most 90° eccentricity. (4) Resolution threshold (the minimal angle of resolution, MAR) increases strongly and linearly with eccentricity. Crowding increases at an even steeper rate. (5) Crowding is asymmetric as Bouma has shown. For that inner-outer asymmetry, the peripheral flanker has more effect. (6) Critical crowding distance corresponds to a constant cortical distance in primary visual areas like V1. (7) Except for Bouma’s seminal paper in 1970, crowding research mostly became prominent starting in the 2000s. I propose the answer is ‘not really’ or ‘not quite’ to these assertions. So should we care? I think we should, before we write the textbook chapters for the next generation. Keywords: Crowding, Psychophysics, Perception, Reading, Visual acuity, Peripheral vision, Fovea, Asymmetries, Sensory systems, Cortical map, Vision science, Visual field. Introduction In 1962, the ophthalmologists James Stuart and Hermann Burian published a study on amblyopia where they adopted a nice and clear term when they spoke of the crowding phenomenon2 to describe why standard acuity test charts are mostly unsuitable for amblyopic subjects: On most standard charts, as ophthalmologists and optometrists knew, optotypes on a line are too closely spaced for valid assessment of acuity in all cases, such that in particular amblyopic subjects (and young children) may receive too low an acuity score.
    [Show full text]