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Kevin Thomas Willeford, Kenneth J Ciuffreda, George A Zikos; Objective Assessment of Eye Dominance. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):552.
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© ARVO (1962-2015); The Authors (2016-present)
The electrophysiological correlates of monocular defocus during binocular viewing have yet to be explored with respect to eye-dominance using the visual-evoked potential (VEP). Following determination of both sensory and motor eye-dominance with subjective clinical tests, a counterbalanced experimental design was used to test the hypothesis that monocularly defocused dominant eyes differentially affect the objective, pattern-VEP waveform as compared to non-dominant eyes. Thus, the goal was to determine whether one or both subjective tests of eye-dominance could predict the binocular VEP waveform with a range of monocular defocus, with application to monovision refractive correction.
The DiopsysTM NOVA-TR system was used to record the pattern-VEP waveforms of 10 visually-normal, presbyopic, adult subjects aged 50-70 yrs (x̄ = 60). VEP amplitude and latency were used as the outcome measures. First, eye dominance was assessed in two ways: a sensory-based “sensitivity to blur task” and a motor-based “sighting task”. Next, while monocularly defocused, subjects binocularly viewed a black-and-white checkerboard (20 min arc check size, 74 cd/m2), pattern-reversal stimulus under 7 different test conditions: baseline (full refractive correction), dominant (DE) eye defocused +1 D, non-dominant (NDE) eye defocused +1 D, DE +2 D, NDE +2 D, DE +3 D, and NDE +3 D. Data were analyzed in two-ways: first, each eye was classified as either “sensory dominant” or “non-sensory dominant”, and second as either “motor dominant” or “non-motor dominant”. Two one-way, repeated-measures ANOVAs were used to investigate the effect of increasing monocular defocus with both classifications.
Under nearly all conditions (22/24=92%), the amplitude and latency significantly decreased and increased, respectively, from baseline with any amount of monocular defocus (p < 0.05). Conversely, there was no difference in amplitude or latency between the monocular defocus conditions themselves (p > 0.05). Moreover, there were no significant differences revealed when comparing defocused dominant vs. non-dominant eyes (p > 0.05): this was true for both sensory and motor eye-dominance classifications.
Neither eye-dominance status (i.e., DE or NDE) nor type (i.e., sensory or motor) provided a differential effect with respect to the VEP findings. Thus, the VEP technique does not show promise as an objective adjunct in the determination of eye-dominance.
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