Increased VEP amplitude following optical treatment in adults with amblyopia

Abstract

Purpose : Recent studies suggest that optical treatment can improve visual acuity and stereopsis in adults with amblyopia. We measured monocular visually evoked potentials (VEPs) before and after 12 weeks of optical treatment to assess whether optical treatment alters the cortical response to visual input from the amblyopic eye.

Methods : Five adults with amblyopia (age: 27 ± 3.3; F/M: 2/3; anisometropia/strabismus: 3/2) were provided with full refractive correction in spectacles following PEDIG definitions. Participants were asked to wear their spectacles full-time (i.e., more than 50% of waking hours, > 5 hours/day) for the entirety of 12 weeks. Monocular VEPs were measured using the standard ISCEV pattern reversal VEP protocol at baseline and after 12 weeks of optical treatment. Monocular best corrected visual acuity (BCVA) was measured in logMAR units using an E-ETDRS testing protocol. A moving window bootstrap analysis (5000 iterations, 5 ms moving window, 1 ms steps) was used to analyze changes in VEP amplitude. For all analyses, 5000-iteration bootstraps (resampling with replacement across subjects) were conducted to obtain distributions of the difference between conditions and their 95% confidence intervals.

Results : VEP amplitude differed significantly between the amblyopic and fellow eyes at baseline (amblyopic eye: 10.04 ± 0.9 μV, 12-week: 13.69 ± 2.3 μV; bootstrap p < 0.001). Optical treatment increased VEP amplitude for both eyes (amblyopic eye significant time-window: 79-105 ms, fellow eye significant time-window: 74-114 ms) but the amplitude difference between the eyes did not change (no significant time by eye interaction). Optical treatment induced a small but statistically significant improvement in BCVA for the amblyopic, but not the fellow eye (amblyopic eye baseline: 0.56 ± 0.27, 12-week: 0.48 ± 0.24; bootstrap p = 0.0358, fellow eye baseline -0.10 ± 0.14, 12-week: -0.15 ± 0.07; bootstrap p = 0.105).

Conclusions : VEP amplitude in adults with amblyopia increased following 12 weeks of optical treatment, but there was no change in the interocular amplitude difference.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1. Grand-average pattern reversal VEP waveforms for each eye pre- and post- treatment

 

Figure 2. Group means and individual result of BCVA in each condition