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Saeideh Ghahghaei, Preeti Verghese; Mapping stereopsis in individuals with central field loss. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4326.
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© ARVO (1962-2015); The Authors (2016-present)
Central field loss (CFL) affects stereopsis in individuals with macular degeneration (MD). This is specifically true for fine stereopsis. Nevertheless, peripheral vision is usually preserved and can support coarse stereopsis, which is helpful for tasks of daily living. Awareness of which parts of the visual field support stereopsis in CFL can help with individualized rehabilitation techniques to improve eye-hand coordination or navigation.
Participants with monocular (N=2) or binocular (N=5) CFL and age-matched controls (N=5) with healthy vision participated in the study. Fixation stability and perimetry data for each eye were collected via the Optos OCT/SLO. We also used the OCT to locate the foveal pit. To find the areas that have intact vision in both eyes and can support stereopsis, we used a novel technique to generate a binocular map by overlapping monocular scotoma maps aligned on the respective foveae. We then ran participants in a stereo-perimetry experiment. Targets (with or without depth information) were presented on a random dot background across the visual field (up to 25° eccentricity). The depth targets had true binocular disparity, whereas the non-depth targets were defined by monocular cues such as contrast and dot density. The target was a 1° square region at the fovea and was m-scaled with eccentricity. The depth target had 20’ crossed disparity. In each trial, the participant was asked to maintain fixation during target presentation . During the response interval, participants (i) reported the location of the target by pointing, and (ii) indicated whether it was in depth or flat. Each location was probed at least 6 times. At each location we calculated the sensitivity to depth and then combined the data across locations to generate a stereopsis map.
Controls had high sensitivity to the depth target across the visual field. For individuals with macular degeneration, sensitivity was at chance in the central field but some peripheral locations showed great sensitivity to stereopsis, in line with the predictions of their binocular scotoma map.
Stereo perimetry reveals which areas in the visual field provide coarse stereopsis. This lays the foundation for rehabilitation techniques for tasks that benefit from stereopsis in individuals with CFL.
This is a 2020 ARVO Annual Meeting abstract.
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