Abstract
Purpose :
Amblyopia is a condition in which vision and visuomotor functions are impaired. A recent study has shown that short-term monocular deprivation reduces the visual processing speed of the patched eye. This study aims to look at plasticity in the oculomotor system due to short-term monocular deprivation.
Methods :
Participants over 18yrs, normal or corrected to 20/20 with positive stereoacuity, were included in the study. Ocular dominance was tested with +2.00D lens. The most disturbance to the lens indicated the dominant eye. Baseline oculomotor (fixation stability, vergence stability, saccadic duration, saccadic peak velocity) data, contrast threshold (monocular/binocular), and stereopsis, were measured. The dominate eye was occluded first for two hours. The oculomotor, contrast, and stereopsis matrix were measured after 10 mins and 40 mins of occlusion. Repeated procedure to the non-dominant eye during the second session. Eyelink 1000plus at 2000Hz was used to record eye movements. Nine-point calibration was done for each eye before measuring oculomotor function. Fixation stability was measured using bivariate contour ellipse area (68% confidence interval). Random-dot stereogram was used to measure stereopsis. Contrast sensitivity was measured with the FrACT3.10.5. All statistical tests were performed using sigma plot 2.0 and a custom Matlab script.
Results :
Total of 12 normal subjects were enrolled in the study. Kruskal-Wallis one-way analysis of variance on ranks between fixation stability of dominant eye before and after 10mins and after 40 mins of 2 hours patching was not statistically significant (H=2.7, df=2, p=0.2). Vergence stability decreases significantly after dominant eye patching and worsens after removing the patch (F(2,45)=6.58, p=0.003). Saccadic peak velocity (H=6.13, df=2, p=0.04) and saccadic duration (H=10.25, df=2, p=0.006) of the non-dominant eye were significantly different before and after short-term deprivation. This effect was not seen after 40 mins of occlusion. There was no difference in stereoacuity due to short-term deprivation (H=0, df=2, p=1.0). No significant changes were noticed in monocularly and binocularly contrast sensitivity due to short-term deprivation.
Conclusions :
There was a transient effect of short-term deprivation on vergence stability and saccadic parameters of non-dominant eyes. Largely oculomotor system is not affected by short-term deprivation.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.