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Deborah Giaschi, Sathyasri Narasimhan, Ryan Lo, Christopher Lyons, Jane Gardiner, Maryam Aroichane, Laurie Wilcox; Sparing of coarse stereopsis in children with amblyopia. Journal of Vision 2012;12(9):1364. doi: 10.1167/12.9.1364.
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© ARVO (1962-2015); The Authors (2016-present)
It is widely recognized that stereoscopic depth percepts result from small retinal disparities within Panum’s fusional area (fine stereopsis). Less recognized is the fact that reliable depth information is also provided by large disparities that cannot be fused (coarse stereopsis). The role of coarse stereopsis in vision is not well understood, but we hypothesize that it develops early in life and is used to guide vergence eye movements that are necessary for the development of fine stereopsis. This is supported by our recent finding that coarse stereopsis is mature by age 4 when fine stereopsis is still developing. Here we test the possibility that the early development of coarse stereopsis makes it resilient to the factors that cause amblyopia. We compared performance in children with strabismic or anisometropic amblyopia and age-matched control children (5-12 years) on computerized tests of fine and coarse stereopsis. Stereoscopic stimuli were presented using liquid crystal shutter glasses. The observer’s task was to indicate whether a cartoon character was nearer or farther away than a zero-disparity fixation marker. We assessed perceived depth for a set of fine (0.02, 0.08, 0.17, 0.33, 0.67, 1.0 degrees) and a set of coarse (2.0, 2.5, 3.0, 3.5 degrees) crossed and uncrossed disparities. Accuracy increased with disparity in the fine range for both groups. Children with amblyopia performed significantly worse than control children at fine disparities, as predicted by their performance on the Randot Preschool Stereoacuity Test (>200 arc sec). Accuracy was constant at approximately 65% across all disparities in the coarse range for both groups. These findings suggest that coarse stereopsis may be spared when fine stereopsis is disrupted by early visual deprivation. This residual binocular function has important clinical implications, given the movement towards treating amblyopia as a disorder of binocular processing.
Meeting abstract presented at VSS 2012
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