Dichoptic movie viewing treats childhood amblyopia

Abstract

Background: Contrast-balanced dichoptic experience with perceptual-learning tasks or simple games has been shown to improve visual acuity significantly in amblyopia. However, these tasks are intensive and repetitive, and up to 40% of unsupervised patients are noncompliant. We investigated the efficacy of a potentially more engaging movie method to provide contrast-balanced binocular experience via complementary dichoptic stimulation.

Methods: Eight amblyopic children 4-10 years of age were enrolled in a prospective cohort study to watch 3 dichoptic movies per week for 2 weeks on a passive 3D display. Dichoptic versions of 18 popular animated feature films were created. A patterned image mask of irregularly shaped blobs was multiplied with the movie images seen by the amblyopic eye and an inverse mask was multiplied with the images seen by the fellow eye. Fellow-eye contrast was initially set at a reduced level that allowed binocular vision and was then incremented by 10% at each visit. Best-corrected visual acuity, random dot stereoacuity, and interocular suppression were measured at baseline and 2 weeks.

Results: Mean amblyopic eye visual acuity (with standard error of the mean) improved from a logarithm of minimum angle of resolution of 0.72 ± 0.08 at baseline to 0.52 ± 0.09 (P = 0.003); that is, 2.0 lines of improvement at the 2-week outcome visit. No significant change in interocular suppression or stereoacuity was found.

Conclusions: Passive viewing of dichoptic feature films is feasible and could be a promising new treatment for childhood amblyopia. The maximum improvement that may be achieved by watching dichoptic movies remains to be determined. No known side effects are associated with this new treatment.

FIG 1

A screenshot from one of the dichoptic movies. The two eyes’ views are shown side by side for the sake of clarity but were displayed superimposed on a 3D monitor in the study. The high-contrast image (left) was presented to the amblyopic eye and low-contrast image (right) to the fellow eye. A patterned image mask composed of irregularly shaped blobs was multiplied with the images seen by the amblyopic eye, and the inverse patterned mask was multiplied with the images seen by the fellow eye. The shape and location of the blobs were varied dynamically every 10 seconds.

FIG 2

Amblyopic eye BCVA at baseline and 2-week outcome visits. Data points that would otherwise be superimposed have been jittered slightly for clarity. All eight children had improved amblyopic eye BCVA.