Clinical Meaning of Half Success Duration in Successful Occlusion Treatment of Amblyopia

Abstract

Purpose To evaluate the factors affecting total occlusion duration and to determine whether half success duration (the time to reach an intermediate visual acuity between the initial visual acuity and 1.0) affects the total duration of treatment in amblyopia patients when the best-corrected visual acuity (BCVA) improves to that of the fellow eye after occlusion. Methods Fifty-three pediatric patients with amblyopia who achieved the same BCVA as that of the fellow eye after occlusion were selected. The total duration and half success duration were compared according to sex, initial visual acuity, age, spherical equivalent, cause of amblyopia (anisometropia, strabismus, or combined), as well as other factors. Results The mean age of the initial amblyopic patients was 4.6 years, and the mean duration of total occlusion treatment was 23.15 months. The mean half success duration was 9.98 months. The duration of total occlusion treatment was longer in children whose spherical equivalent of the amblyopic eye was over +3.0 diopters. The half success duration was longer in amblyopic patients with esotropia whose angle of deviation exceeded 20 prism diopters. However, there were no significant differences according to other factors. The total occlusion duration was shorter in patients whose half success duration was less than 12 months. Conclusions The treatment duration that was needed to achieve a BCVA close to that of the fellow eye was shortened when the spherical equivalent of the amblyopic eye was below +3.0 diopters. The half success duration was shortened when the angle of deviation was well below 20 prism diopters in patients with esotropia. Additionally, patients with a short half success duration had a shorter total occlusion duration. These factors can be used to predict the duration of occlusion treatment. Keywords: Amblyopia; Half success duration; Occlusion; Total occlusion duration