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Peter Lewis, Victoria Holm, Karthikeyan Baskaran, Jorgen Gustafsson; Dynamic stimulus presentation facilitates peripheral resolution acuity. Invest. Ophthalmol. Vis. Sci. 2013;54(15):574.
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Peripheral high-contrast resolution is sampling limited; the center to center spacing between ganglion cells ultimately limiting visual performance (Thibos et al., 1987). Although retinal image motion in the fovea has a detrimental effect on visual acuity, previous studies have suggested that retinal image motion may be advantageous in the peripheral visual field (Bex et al., 2003; Brown, 1972; Macedo et al., 2010). The aim of this study was to evaluate the effect of drift motion on peripheral resolution acuity.
Peripheral high-contrast resolution acuity in a group of 26 subjects (age 23.5 ± 3.2 years) was initially determined using a 2-alternative forced-choice Bayesian algorithm; the threshold value defined as the spatial frequency resulting in a 75% correct response rate. The stimuli used to measure static visual acuity were stationary Gabor-patches with a visible diameter of 2° and were presented at 20° in the nasal visual field. We determined the percentage correct response rate for varying velocities using drifting Gabor patches of the same spatial frequency as determined during measurement of static visual acuity. The sine-wave gratings drifted within the Gaussian envelope at one of 10 angular velocities, varying from 0.2 to 2.0 degrees/second in 0.2 degrees/second steps.
Results showed an overall improvement in the subjects’ performance for all velocities. There was a significant difference in the percentage of correct responses between static stimulus presentation and for velocities of between 0.4 to 1.2 degrees/second (p < 0.05, One-way repeated measures ANOVA with Bonferroni post hoc tests). The average “correct response” for static stimulus presentation was 76 ± 2 %, improving to at least 85 % for velocities between 0.4 to 1.2 degrees/second. At velocities greater than 1.2 degrees/second performance was still better than for static stimulus presentation, but showed a gradual decline with increasing speed.
In line with previous studies stimulus motion has a positive effect on peripheral high-contrast resolution acuity. Presenting moving stimuli may benefit patients who rely on peripheral visual function, such as those with central visual field loss subsequent to AMD.
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