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Ewa Niechwiej-Szwedo, Herbert C. Goltz, Manokaraananthan Chandrakumar, Agnes M. Wong; Differential Effects Of Residual Stereopsis On Saccade And Reach Initiation During Binocular Viewing In Strabismic Amblyopia. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3896.
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© ARVO (1962-2015); The Authors (2016-present)
Impairment of spatiotemporal visual processing in amblyopia has been studied extensively, but its effects on visuomotor tasks have been examined rarely. Here, we investigate how deficits in visual acuity and stereopsis affect saccade latencies and reach reaction times in patients with strabismic amblyopia.
Fourteen patients with strabismic amblyopia (5 with mild acuity deficits and stereopsis [MILD+], 5 with mild acuity deficits and negative stereopsis [MILD-], and 4 with severe acuity deficits and negative stereopsis [SEVERE-]), and 14 visually-normal subjects executed saccades and reach-to-touch movements to targets presented on a computer monitor during binocular and monocular viewing. Each trial began with a central fixation cross. After a variable delay, a target appeared randomly at 5° or 10° to the left or right of fixation.
A significant interaction between group and viewing condition was found for saccade latency (p< 0.001) and reach reaction time (p=0.008). Control subjects showed a binocular advantage for initiation of saccades (binocular 171± 28 ms vs. monocular 190± 30 ms) and reaching (binocular 328± 91 ms vs. monocular 345± 86 ms). Patients showed no binocular advantage: mean latencies for saccades and reaches during binocular viewing were not shorter that those during monocular fellow eye viewing. During binocular viewing, patients with negative stereopsis had comparable saccade latencies (MILD-: 162± 26 ms; SEVERE-: 165± 41 ms) to control subjects (171± 28 ms). In contrast, patients with residual stereopsis had longer saccade latencies (MILD+ : 202± 48 ms). Residual stereopsis had no effect on reach initiation during binocular viewing. In comparison to control subjects, all patients had longer reaction times during binocular viewing (MILD+ : 365± 92 ms; MILD-: 356± 87 ms; SEVERE-: 389± 66 ms).
Our preliminary data show that residual binocularity impacts saccade latency but not reach initiation during binocular viewing. These data suggest dissociation between the planning of saccades and reaching in patients with amblyopia.
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