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Fatema Firoz Ghasia, Aasef Shaikh; Fixational eye movements in Strabismus. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2454.
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© ARVO (1962-2015); The Authors (2016-present)
Microsaccades are miniature eye movements that constantly change the gaze during attempted visual fixation. Saccades and microsaccades represent an oculomotor continuum and are produced by common neural machinery. Strabismic patients have impaired binocular horizontal saccades<span style="font-size:11px; line-height:17px">.</span> We examined the fixational eye movements (microsaccades and ocular drifts) in strabismic patients and correlated the severity of their disconjugacy with strabismus angle and binocular vision.
Eye movements were recorded with infrared video-oculography in 13 strabismic patients (stereopsis present=5;stereopsis absent=8) and 17 controls while they performed a visual fixation task.
The microsaccades in strabismic subjects were disconjugate. Binocular disconjugacy was larger in patients with no binocular vision (strabismic stereopsis absent=0.53°±1.7°;strabismic stereopsis present=0.41° ±1.2°;controls = 0.14° ±0.19° one-way ANOVA p<0.0001) or when they had larger angle strabismus (controls: 0.14±0.19°; small-angle(<15PD, n=4):0.20±0.29°;medium-angle(15-30PD, n=4):0.45±1.3°;large-angle (>30 PD, n=5):0.69±2.1,one-way ANOVA p<0.0001). The strabismics also had a mild disconjugacy in the drift velocity (strabismic=1.05°/sec±1.8°/sec; controls=0.89°/sec ±1.0°/sec, ttest p = 0.004).
Microsaccades are disconjugate in strabismics and exceed the capabilities of the sensory system to fuse the normal fixation disparity of 0.05-0.35°<span style="font-size:11px; line-height:17px">.</span> The disconjugacy is more pronounced in patients with large angle strabismus and absent binocularity. The increased disconjugacy of fixational eye movements in strabismus patients suggests that the fine-tuning of the motor and visual systems responsible for achieving binocular fusion is impaired with deficient oculomotor adaptive capabilities.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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