Anisometropia in bilateral hyperopic refractive amblyopia requires eye patching

The anisometropic eye of patients with bilateral hyperopic refractive amblyopia is presumed to have worse prognosis for visual acuity than the fellow eye. We sought to investigate the effect of anisometropia on visual prognosis in patients with bilateral hyperopic refractive amblyopia in order to estimate the necessity and timing of patching. We retrospectively analyzed the medical records of 71 patients with bilateral hyperopic refractive amblyopia aged ≤ 5 years at the initial visit. Hyperopia was defined as spherical equivalent (SE) power of ≥2.0 diopters (D) in both eyes. Hyperopic anisometropia was defined as SE power ≥1.0 D. Age before the start of treatment and at the last observation; gender; cycloplegic refractive values before the start of treatment and at the last observation; visual acuity (converted to logMAR) before the start of treatment, 1 year after the start of treatment, and at the last observation; prevalence of strabismus; eye patching rate during the year after the initial visit; and stereoacuity at the last observation were analyzed. Patients with bilateral hyperopic refractive amblyopia were divided into groups with or without anisometropia. The group with anisometropia was subdivided into groups with greater or smaller hyperopia. Of 71 patients with hyperopic refractive amblyopia, 20 patients had anisometropia. Mean age ± standard deviation before the start of treatment was 35.1 ± 12.7 months in the group with anisometropia and 34.2 ± 12.7 months in the group without anisometropia (P = 0.798). SE values before the start of treatment were 7.08 ± 2.12 D in the group with greater hyperopia, 5.33 ± 1.91 D in the group with smaller hyperopia, and 6.44 ± 2.95 D in the group without anisometropia (P = 0.098). LogMAR before the start of treatment was 0.86 ± 0.25 in the group with greater hyperopia, 0.68 ± 0.29 in the group with smaller hyperopia, and 0.87 ± 0.30 in the group without anisometropia. LogMAR before the start of treatment was statistically significantly better in the group with smaller hyperopia than in the group without anisometropia (P = 0.028). LogMAR at 1 year after the start of treatment was 0.45 ± 0.30 in the group with greater hyperopia, 0.25 ± 0.31 in the group with smaller hyperopia, and 0.28 ± 0.27 in the group without anisometropia (P = 0.057). The eye patching rate during the year after the initial visit was higher in the group with anisometropia than in the group without anisometropia (55.0% vs. 13.7%, P = 0.001). The presence of anisometropia in bilateral hyperopic refractive amblyopia might favor visual development in the eye with smaller hyperopia. Early spectacle use and eye patching might be important for the visual development of the eye with greater hyperopia.