Abstract
Purpose: :
Amblyopia is marked by low and high-level visual function deficits, and suppression during binocular viewing. Training studies using action video games that involve precise motor control for visually guided aiming have reported enhanced post-training vision, in both normally sighted subjects and amblyopic patients. The purpose of this project is to develop a treatment tool that combines conventional anti-suppression therapy principles for amblyopia with benefits rendered by action video games in order to harness visual recovery and binocularity in amblyopia.
Methods: :
We modified the popular PC action video game, Unreal Tournament 2004. Our custom game features (a) stereoscopic viewing of split screen images, (b) independent control of image contrast to each eye, (c) suppression checks, (d) easier game levels that facilitate learning of gameplay, and (e) an embedded Gabor orientation-discrimination task targeting only the amblyopic eye. The Gabor task both increases the "workload" of the amblyopic eye, and serves as a suppression check during binocular game play. The custom game was piloted on two adult strabismic unilateral amblyopes, with presenting visual acuities 20/160-1 & 20/80-1. Subjects were trained for 1-2 hours/day for a total of 40 hours. Image contrast to the fellow eye was adjusted to place the amblyopic eye at a competitive advantage. Pelli-Robson contrast sensitivity, Randot stereotest, and reading acuity and speed (MNRead test) were measured before and after training as were psychophysical crowding acuity, contrast sensitivity function, low spatial frequency stereoacuity, and position sensitivity.
Results: :
Visual acuity (VA) recovered in both subjects. Post-treatment VA was 20/80-2 & 20/50-1, equivalent to 0.28 & 0.2 logMAR improvements, respectively. Stereopsis was nil before and after treatment. However, both subjects reported a dramatic reduction in switching between eyes with training, and were able to use both eyes simultaneously. This is evidenced by an increased tolerance to a high contrast image in the fellow eye. Near visual acuity and reading speed recovered as well. Other functions will be reported. One of the two subjects returned for a two-month, follow-up post-test, and VA remained stable at 20/50-1.
Conclusions: :
We conclude that our new custom game platform has promising potential for amblyopia treatment. A preclinical study is currently underway for assessing game efficacy.
Keywords: amblyopia • vision and action • learning