Binocular benefits of optical treatment in anisometropic amblyopia

In this study, we investigated the effect of optical treatment on sensory eye balance in anisometropic amblyopia. Fourteen individuals (age: 13.7 ± 8.4 years old) with previously untreated anisometropic amblyopia were enrolled in the study. The average magnitude of their anisometropia (spherical equivalent) was 4.02 ± 1.19 DS. Their best corrected monocular visual acuity and sensory eye balance were measured before and after a 2-month period of full refractive correction (i.e., our optical treatment). Spectacle-corrected distance visual acuity (at 5 m) was measured monocularly using the Tumbling E Chart. Sensory eye balance was quantitatively assessed using a binocular phase-combination paradigm to determine the interocular contrast ratio at which the two eyes were balanced in binocular sensory combination (i.e., the balance point). We found that both interocular contrast ratio at the balance point (p = 0.006) and visual acuity of the amblyopic eye (p < 0.001) were significantly improved after 2 months of optical treatment, often referred to as refractive adaptation. We conclude that sustained optical treatment improves interocular sensory balance in anisometropic amblyopia as well as monocular acuity. Optical treatment is a passive form of binocular therapy and a necessary first step in treating the binocular dysfunction that characterizes amblyopia.