Purchase this article with an account.
ding han, Hua Bi, Xiaorong Li, Ruihua Wei, Jia Zhou, Bin Zhang; The effect of practice on sensitivity to global motion in subjects with and without visual discomfort. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4228.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Visual discomfort (VD) refers to the perceptual difficulties experienced by individuals when exposed to bright light and the repetitive striped patterns. People with VD have been reported having reduced sensitivity to global motion. However, other studies suggested that the difference only existed at baseline test and disappeared when a second estimate was obtained. The aim of the present study is to investigate the effect of practice on sensitivity to global motion in adults with and without VD.
A total of 103 subjects participated in the study. The degree of VD was determined with the Wilkins &Evans Pattern Glare Test. Subjects looked at square waves patterns with spatial frequencies of 0.5, 3, or 12 cpd for 5 seconds and reported distortions perceived. A subject with a score of >3 on the 3 cpd pattern or a score of >1 on the 3-12 cpd difference was considered as having visual discomfort. The threshold of detecting the global motion was measured with random dot kinematogram. In each trial, the subjects needed to decide if the direction of the perceived global motion was up or down. The coherence of the moving dots was adjusted according to a 3-down-1-up staircase, and threshold was estimated from the mean of the last 6 reversals with an average of 80 trials per test. The test was repeated for 5 times and the improvement rate (IR) was calculated as the log ratio of threshold obtained from the initial to the last test. The comparison between subjects with and without VD was done with Wilcoxon test. Logistic regression was applied to estimate the risk of a subject having VD based on the value of IR.
Based on the pattern glare test, 32 subjects were classified as having VD and 71 subjects were not. The initial threshold to detect global motion was significantly higher in subjects with VD (0.755 vs. 0.636, p=0.022). Although both group showed improvement, the threshold at the last test was still significantly higher in the subject with VD (0.465 vs. 0.277, p<0.001). The IR was significantly lower in subject with VD (1.92 vs 2.91 db, p=0.045). High IR significantly lowered the probability for a subject to have VD (OR=0.8254, p=0.0446).
Although the sensitivity to global motion could be improved through practice, the improvement is much smaller in the subject with VD than those without.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
This PDF is available to Subscribers Only