Factors affecting the total occlusion time in eyes with hyperopic anisometropic amblyopia

Abstract

Purpose To investigate the factors that affected the total occlusion time (TOT) in eyes with hyperopic anisometropic amblyopia. Methods Subjects were 58 patients (26 boys and 32 girls; age range, 3.6-9.2, average, 5.8 ± 1.3 years) with hyperopic anisometropic amblyopia. All the subjects had initially visited and completed occlusion therapy with improved visual acuity (VA) of 1.0 (0.0 logMAR equivalent) or better in the amblyopic eye at Kindai University Hospital between January 2007 and March 2017. Using the subjects’ medical records, five factors for the TOT were evaluated retrospectively: the age at treatment, the initial VA of the amblyopic eye, refraction of the amblyopic eye, anisometropic disparity, and the presence of microstrabismus. Results The initial VA of the amblyopic eye ranged from 0.1 to 0.9 (median, 0.4). The TOT ranged from 140 to 1795 (median, 598) hours with an average daily occlusion time of 7 hours. The initial VA of the amblyopic eye and presence of microstrabismus were the influential factors for the TOT (p< 0.01). To achieve VA of 1.0 or better, patients with initial VA of ≤ 0.3 in the amblyopic eye required a longer TOT. Moreover, patients with concomitant microstrabismus required a 1.7-fold longer TOT compared to those without microstrabismus. Conclusion Patient’s initial VA and the presence of microstrabismus are the significant factors that affect the TOT.