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I Screening of Children Study: Evaluation of Tests of Suppression Screening of Children Study: Evaluation of Tests of Suppression THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Lauren Janelle Pallet Graduate Program in Vision Science The Ohio State University 2017 Master's Examination Committee: Marjean Taylor Kulp, O.D., M.S., Adviser Andrew Toole, O.D., Ph.D. Catherine McDaniel, O.D., M.S. i Copyright by Lauren Janelle Pallet 2017 i Abstract Background: Suppression is a phenomenon whereby an individual develops the ability to ignore a part of their binocular visual field. This condition is associated with binocular vision conditions such as amblyopia and anisometropia. Current commercial methods of testing suppression measure only foveal or central suppression at one test distance. Purpose: The purpose of our study was to assess a new suppression target on an iPad that provides consistent luminance and assesses foveal and central suppression at one testing distance. Methods: Subjects aged 3 and older that presented for a routine eye examination at The Ohio State College of Optometry were invited to participate in our study. Routine testing including visual acuity, dry and wet refraction/retinoscopy, stereopsis and cover test were performed by the doctor and recorded by the examiner. Each of the suppression tests were then performed by the examiner in a random order, and repeated with the colored filters reversed. The results for each test were recorded. Cross-tabulation and McNemar chi-square analysis was used to compare the suppression testing devices. Results: Fifty subjects were enrolled (mean age = 17.5). Twelve subjects reported suppression and one reported diplopia. Testability was excellent for all tests. There was no significant difference between tests in reported suppression, with all p values equal to .22 or greater. No difference in reported suppression was observed with change ii in orientation of the anaglyphic filters. Six subjects reported foveal suppression alone at near which was not identified with Worth 4 dot. Conclusion: The iPad test of suppression provided high testability and excellent agreement with commonly used tests of suppression. iii Dedication This document is dedicated to my family. iv Acknowledgments I would like to thank Dr. Kulp for her encouragement and support over the last three years. The time and effort she spent teaching me about research, binocular vision and editing the many papers I sent her way has allowed me to complete this project. Her role as my advisor has taught me an incredible amount about research and her guidance has been highly valued. Thank you to Lynn Mitchell for her invaluable help with the statistical analysis. Thank you to my other committee members, Dr. Toole and Dr. McDaniel, for all of their helpful insights during the development of the project and during the defense discussion. Thank you to G-labs and Dr. Simonson for collaborating with us on this project and all the time they spent modifying the suppression target. v Vita 2009................................................................Southwest Senior High 2013................................................................B.S. Biology, University of Florida 2017................................................................Doctor of Optometry, Ohio State Fields of Study Major Field: Vision Science vi TABLE OF CONTENTS Abstract ............................................................................................................................... ii Vita ..................................................................................................................................... vi List of Tables ..................................................................................................................... ix List of Figures ..................................................................................................................... x LITERATURE REVIEW ................................................................................................... 1 Definition and Characteristics ......................................................................................... 1 Binocular Rivalry versus Suppression ............................................................................ 2 Area of Retinal Suppression ............................................................................................ 4 Binocular Vision Conditions Associated with Suppression ............................................ 8 Importance of Treating Suppression ............................................................................. 10 Treatment Options for Suppression............................................................................... 12 Current Methods of Suppression Testing ...................................................................... 13 METHODS ....................................................................................................................... 22 Subjects ......................................................................................................................... 22 Procedures ..................................................................................................................... 22 iPad Suppression Test Design and procedure ............................................................... 24 vii Statistical Analysis ........................................................................................................ 27 RESULTS ......................................................................................................................... 28 Subjects with Suppression ............................................................................................. 28 Agreement between Suppression Tests ......................................................................... 32 Comparing Stereopsis Findings with Suppression ........................................................ 35 Subjects with Amblyopia or Strabismus who did not report Suppression .................... 36 DISCUSSION ................................................................................................................... 37 Strengths and Limitations.............................................................................................. 39 Considerations for Future Testing ................................................................................. 39 CITATIONS ..................................................................................................................... 40 viii List of Tables Table 1: Subjects with Suppression and Diplopia…........……………………..…….……………..30 Table 2: iPad Compared to Combined Worth Tests ......................................................... 33 Table 3: iPad Comapred to Worth Four Dot ..................................................................... 34 Table 4: Worth Four Compared to iPad Central Suppression .......................................... 35 Table 5: Subjects with Amblyopia, Anisometropia and Strabismus who did not report Suppression…………………………………………………………………………………………..……………..36 ix List of Figures Figure 1: Normal Response on Four Prism Base Out Test……………………..…….…………….15 Figure 2: Worth Four Dot 1 .............................................................................................. 17 Figure 3: Polarized four dot 1 ........................................................................................... 18 Figure 4: Worth Test with Letters…………………………………………………………………………..20 Figure 5: iPad Suppression Target……………………………………………….…………………………25 Figure 6: Filter Comparison……………………………………………….……………………………...…. 26 x LITERATURE REVIEW Definition and Characteristics Adler defined suppression as an inability to perceive images in all or a part of the visual field.1 Jampolsky defined suppression as an ability to inhibit the part of the binocular field that is confusing to our visual orientation.2 He described it “as an active internal inhibition and, like other sensory inhibitions, a type of conditioned reflex” that is only present in conditions of binocular vision.2 The need for the mechanism of suppression can arise from problems with binocularity such as strabismus (an eye turn) and interocular differences between the eyes, such as differences in visual acuity and/or refractive error. When the eye turns in or out the macula is now fixating on a different object from that of the other eye which causes two different images to be cast onto corresponding points on the retina. Thus, confusion in our visual field occurs due to the perception of two separate images as superimposed because each macula is viewing a different object.3 Diplopia is when we have double vision, seeing the same image in two locations. This confusion and potential diplopia is difficult for the brain to interpret and eventually the deviated eye’s image is ignored.1 Jampolsky investigated characteristics of suppression in amblyopic subjects in a 1950 paper. Amblyopia is a reduction of vision 1 that is not correctable with refractive means and is not secondary to pathological or structural defects.3 He evaluated the area of the retina being suppressed to determine if the suppressed area was consistently in one area or if it varied with the subject’s position of gaze. He found that amblyopic suppression was always specific to a retinal region and he theorized that this was because it is used to relieve discomfort in a certain area or position of gaze. Jampolsky also identified
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