Binocular Therapy for Childhood Amblyopia Improves Vision Without Breaking Interocular Suppression

PURPOSE. Amblyopia is a common developmental visual impairment characterized by a substantial difference in acuity between the two eyes. Current monocular treatments, which promote use of the affected eye by occluding or blurring the fellow eye, improve acuity, but are hindered by poor compliance. Recently developed binocular treatments can produce rapid gains in visual function, thought to be as a result of reduced interocular suppression. We set out to develop an effective home-based binocular treatment system for amblyopia that would engage high levels of compliance but that would also allow us to assess the role of suppression in children's response to binocular treatment. METHODS. Balanced binocular viewing therapy (BBV) involves daily viewing of dichoptic movies (with "visibility'' matched across the two eyes) and gameplay (to monitor compliance and suppression). Twenty-two children (3-11 years) with anisometropic (n = 7; group 1) and strabismic or combined mechanism amblyopia (group 2; n = 6 and 9, respectively) completed the study. Groups 1 and 2 were treated for a maximum of 8 or 24 weeks, respectively. RESULTS. The treatment elicited high levels of compliance (on average, 89.4% +/- 24.2% of daily dose in 68.23% +/- 12.2% of days on treatment) and led to a mean improvement in acuity of 0.27 logMAR (SD 0.22) for the amblyopic eye. Importantly, acuity gains were not correlated with a reduction in suppression. CONCLUSIONS. BBV is a binocular treatment for amblyopia that can be self-administered at home (with remote monitoring), producing rapid and substantial benefits that cannot be solely mediated by a reduction in interocular suppression.