Abstract
Purpose :
Dichoptic training gained intense interest in recent amblyopia practice but evidence from latest clinical trials failed to endorse this idea. We hypothesized that the setting of previous dichoptic perceptual learning, which aimed at increasing the maximal tolerable noise (Strategy 1) in the fellow eye of amblyope, may intrinsically impeded the construction of normal binocular interaction since the fellow eye always received high contrast in daily life vision. Here we report the effect of an alternative training strategy (Strategy 2), whereby the amblyopic eye always received constant and high interocular inhibition from the fellow eye in two groups of participants with amblyopia.
Methods :
Two groups of participants (n=14) with matched visual acuities and CSFs were included. Group 1 (n=7) were trained with strategy 2 for 7-9 days. Group 2 (n=7) were firstly trained with strategy 1 aiming at increasing the maximal tolerable noise contrast in the fellow eye (Liu et al, Vis Res, 2017) in the first phase and crossed over to the Strategy 2 in the second phase. Visual acuities, CSF with and without noise mask in the contralateral eye, stereo acuities were obtained before and after training. Dichoptic gain, defined as contrast threshold elevation under dichoptic viewing condition was used as an index of interocular inhibition.
Results :
Strategy 2 induced significant change of dichoptic gain averaged across three low spatial frequencies (0.5, 1 and 2 cpd) from 30.66±4.43 dB to 24.22±3.58 dB in Group 1 (P=0.026). In Group 2, Strategy 1 showed weak effect in changing dichoptic gain from 33.21±4.01 dB to 30.96±4.92 dB (P=0.05), while Strategy 2 further strengthened interocular cooperation by changing dichoptic gain to 25.44±6.38 during the second phase (P=0.02). Importantly, the strengthened dichoptic gain was accompanied with an improvement of monocular unmasked AULCSF in the amblyopic eye. Neither masked nor unmasked AULCSF in the fellow eye improved after perceptual learning.
Conclusions :
We conclude that the enhancement of the amblyopic eye under natural environment may play a key role in dichoptic perceptual learning, and future design should not solely increase the tolerable noise in the fellow eye.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.