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Sonisha Neupane, Clara Mestre, T Rowan Candy; Ability of the peripheral visual field to maintain motor alignment. Journal of Vision 2021;21(9):2679. doi: https://doi.org/10.1167/jov.21.9.2679.
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© ARVO (1962-2015); The Authors (2016-present)
Objective: Some patients are believed to use peripheral vision to achieve motor eye alignment. The objective of this study was to test the ability of peripheral field to drive vergence. Method: 8 adults (15 to 51 years) participated. Naturalistic images (SYNS dataset) were presented dichoptically (80x60deg) with a monocular fixation target and binocular mean luminance simulated central scotoma (radii 0,5,10,15,20, or 25 deg). The scotoma had a smooth transition to the image and antiphase serration in the periphery in two eyes. In each trial, the subjects performed a nonius task to confirm alignment before the image stepped to a disparity (0,0.5,1,2,4, or 8 deg) for 1.5 secs while responses were recorded with an Eyelink1000 (SR-Research). Six repetitions were performed in random order. Results: Disparity tuning with no scotoma was similar to the previous literature, peaking at 1° disparity for divergent & 2° for convergent stimuli. Mean open loop vergence amplitude at the second latency point for 0°, 5°, 10°, 15°, 20° & 25° scotoma were 0.41+/-0.23, 0.42+/-0.18, 0.62+/-0.14, 0.42+/-0.13, 0.21+/-0.11, 0.21+/-0.45 deg when averaged across 2° convergent and divergent disparities. At 0° scotoma, subjects were able to respond to the smallest disparity, but as scotoma size increased (at 20°& 25°), there was minimal response to disparity < 2°. Conclusion: Peripheral visual field (to 40° eccentricity) is able to initiate vergence responses to the removal of a 25° radius central scotoma, with reduction in response amplitude that varies across individuals. The highest amplitude was at 2-deg of disparity for all scotoma sizes. This has implications for understanding how patients with central scotomas resulting from suppression or retinal pathology may be able to maintain eye alignment.
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