Grasping Deficits and Adaptations in Adults with Stereo Vision Losses.

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Grasping Deficits and Adaptations in Adults with Stereo Vision Losses. Invest Ophthalmol Vis Sci. 2009 Apr 1; Authors: Melmoth D, Finlay AL, Morgan M, Grant S PURPOSE: To examine the effects of permanent versus brief reductions in binocular stereo vision on reaching and grasping (prehension) skills. METHODS: The first experiment compared prehension proficiency in 20 normal and 20 long-term stereo-deficient adults (10 with coarse, 10 with undetectable disparity sensitivities) when using binocular vision or just their dominant or non-dominant eye. The second experiment examined effects of temporarily mimicking similar stereoacuity losses in normal adults, by placing de-focusing low or high plus lenses over one eye, compared to their control (neutral lens) binocular performance. Kinematic and error measures of prehension planning and execution were quantified from movements of the subjects' preferred hand recorded while they reached, precision-grasped and lifted cylindrical objects (two sizes, four locations) on 40-48 trials under each viewing condition. RESULTS: Performance was faster and more accurate with normal compared to reduced binocular vision and least accomplished under monocular conditions. Movement durations were extended (up to ~100 ms) whenever normal stereo vision was permanently (ANOVA p