Dichoptic training improves contrast sensitivity in adults with amblyopia

Abstract

Purpose: Dichoptic training is designed to overcome suppression and promote binocular function in patients with amblyopia. Initial studies have found that the training effects transfer to both binocular (stereopsis) and monocular (recognition acuity) visual functions. This suggests that suppression plays an important role in amblyopia and may gate plasticity within the amblyopic visual cortex. Our aim was to assess whether dichoptic training effects also transfer to monocular contrast sensitivity (CS) in adults with amblyopia.

Methods: Amblyopic eye CS data from 30 adults who had taken part in previous dichoptic training studies were analyzed. CS was measured using Gabor patches (0.5, 3 and 10 cpd) before and after 10 days of dichoptic training. Treatment was delivered using a modified video game (Tetris) viewed through video goggles or on an iPod touch equipped with a lenticular overlay screen. Dichoptic training was compared to monocular training in a sub-group of participants (n = 15). Test re-test reliability for the CS measurement technique was assessed in a group of 8 adults with normal or corrected to normal vision.

Results: Dichoptic training significantly improved CS across all spatial frequencies tested (F = 41.35, p < 0.0001), however only the mean improvements for 3cpd and 10cpd were greater than the 95% confidence limits for test re-test reliability in controls. Contrast sensitivity improvements at 10cpd were positively correlated with improvements in visual acuity (r = 0.46, p = 0.01) and dichoptic training resulted in significantly greater CS improvements than monocular training (F = 6.9, p = 0.02, n = 15).

Conclusions: These data suggest that the therapeutic effects of dichoptic training may transfer to CS in adults with amblyopia. This supports the argument that amblyopia treatments targeting binocular vision can also enhance monocular visual function without the need for monocular occlusion.

Keywords: 417 amblyopia • 478 contrast sensitivity • 434 binocular vision/stereopsis