Visual parameter status as a predictive factor for the outcomes of occlusion therapy in anisometropic amblyopia

Purpose: The purpose is to compare visual parameters between normal and amblyopic eyes in anisometropic amblyopia and to find predictive factors for occlusion therapy.

Methods: Sixty patients with anisometropic amblyopia between the ages of 5 and 25 years were enrolled in the prospective, longitudinal, and interventional study. Patients were selected based on no improvement with spectacle correction alone after 1 month of follow-up. Baseline parameters such as LogMAR visual acuity, LEA contrast sensitivity, TNO stereopsis test, online Farnsworth D-15 test for color vision, accommodation with RAF ruler, +2.00/-2.00 flipper test, and dynamic retinoscopy were recorded. All patients were treated with occlusion therapy depending on their grades of amblyopia. After 6 months of follow-up, improvement in visual acuity was recorded with a LogMAR chart and correlated with initial visual parameters. Paired "t" test, Chi-square test, independent "t" test, analysis of variance test were used as statistical analysis.

Results: Visual functions such as contrast sensitivity, accommodative facility, near point of accommodation, and accommodative amplitude showed a statistically significant difference between normal and amblyopic eyes of anisometropic amblyopia patients, whereas color vision did not differ significantly between normal and amblyopic eyes. Sixty-seven percentage of patients had poor stereopsis. Eighty percentage of patients who were younger had improvement in final best-corrected visual acuity and these patients had better stereopsis, contrast sensitivity, and mild-to-moderate amblyopia on initial testing.

Conclusion: The age of the patient, degree of anisometropia, spherical equivalent in amblyopic eyes, stereopsis, contrast sensitivity values at initial presentation, and compliance to occlusion therapy were found to be positive predictive factors of occlusion therapy.