Amblyopia Treatment Efficacy in Anisometropia

PURPOSE: To compare the treatment efficacy of optical correction and occlusion therapy and/or penalization for different anisometropic refractive errors (hyperopic, myopic, and mixed). METHODS: Medical records of 51 patients with anisometropic amblyopia managed by both optical correction and occlusion therapy and/or penalization were evaluated retrospectively. Patients were categorized into hyperopic, myopic or mixed anisometropia groups. Cycloplegic refraction, spherical anisometropia, baseline visual acuity, baseline interocular difference, final visual acuity and final interocular difference were analyzed to assess association between type of anisometropia with both resolution of anisometropic amblyopia and the time required to achieve it. RESULTS: Baseline visual acuity of the amblyopic was 0.94±0.47 in the hyperopic group; 1.12±0.56, in the myopic group; and 1.08 ±0.39 in the mixed group. Final visual acuity in the amblyopic eye was 0.34±0.30 in the hyperopic group, 0.78±0.59 in the myopic group, and 0.78±0.56 in the mixed group. The difference in final visual acuity in the amblyopic eye between the groups was significant (P=0.014). The amblyopia was improved in 50% of patients in the hyperopic group, 23.8% in the myopic group, and 14.3% in the mixed group (P=0.081). The type of anisometropia was significantly associated with the improvement of visual acuity in the amblyopic eyes (P=0.044). The mean time for amblyopia improvement was 16.50±10.52 months in the hyperopic groups, 15.60±12.44 months in the myopic group, and 21.00±21.21 months in the mixed group (P=0.947). CONCLUSION: Lower amounts of hyperopic anisometropia are as amblyogenic as higher amounts of myopic or mixed anisometropia. Mean improvement in visual acuity of an amblyopic eye with both optical correction, occlusion therapy and/or penalization is higher in patients with hyperopic anisometropia in comparison with myopic or mixed anisometropia. No significant difference was found in the time required to achieve improvement between the study groups.