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Preeti Verghese, Saeideh Ghahghaei; Stereo perimetry reveals peripheral loci mediating coarse stereopsis in macular degeneration. Journal of Vision 2018;18(10):996. doi: 10.1167/18.10.996.
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The aim of this study is to explore the potential for binocularity and coarse steropsis in peripheral retina for individuals with central field loss due to age-related macular degeneration (AMD). We hypothesize that for patients with AMD, corresponding locations in the periphery where the retina has residual function can provide coarse stereopsis that is useful for eye-hand coordination. We developed a novel stereo perimetry method to evaluate coarse stereopsis across the visual field. Observers fixated a spot on a large-field stereoscopic display of random dots, and detected a target patch presented in a near depth plane. The target appeared along the cardinal and diagonal axes at an eccentricity from 0 to 25°, and its size was m-scaled for eccentricity. We used large steps (20 to 30 arc mins) to test peripheral locations at eccentricities of 15 to 25 degrees. For individuals with AMD, we performed monocular perimetry in a Scanning Laser Ophthalmoscope to estimate scotoma extent and preferred retinal locus (PRL), and used Optical Coherence Tomography to delineate the non-functioning fovea. This information was combined with a binocular scotoma mapping procedure to estimate intact regions with potential binocular overlap. These observers were tested primarily in their lower visual field. The four control participants showed intact stereopsis at all tested eccentricities. Of the two AMD participants, one had large scotomata with binocular overlap and measurable stereopsis at the PRL, whereas the other participant had smaller patchy scotomata in the two eyes with partial binocular overlap and no measurable stereopsis at the PRL. For stereo perimetry, both AMD participants showed coarse stereopsis at eccentricities greater than 10°, regardless of their ability to perceive depth at the PRL. Thus it appears that a relatively extensive region in the periphery can mediate coarse stereopsis that might be useful for eye-hand coordination.
Meeting abstract presented at VSS 2018
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