The role of anisometropia in the development of accommodative esotropia.

PURPOSE: To determine whether anisometropia increases the risk for the development of accommodative esotropia with hypermetropia. METHODS: Records of all new patients with a refractive error of +2.00 D or more (mean spherical equivalent of both eyes) over a 42-month period were reviewed. Three hundred forty-five patients were thus analyzed to determine the effect of anisometropia (>or=1 D) on the relative risk of developing accommodative esotropia and of developing unsatisfactory control with spectacles once esotropia was present. RESULTS: Anisometropia (>or=1 D) increased the relative risk of developing accommodative esotropia to 1.68 (P < .05). Anisometropia (>or=1 D) increased the relative risk for esotropia to 7.8 (P < .05) in patients with a mean spherical equivalent less than +3.00 D and increased it to 1.49 (P < .05) in patients with a mean spherical equivalent of +3.00 D or more (P = .016). In patients with esotropia and anisometropia (>or=1 D), the relative risk for a deviation that was unsatisfactorily controlled with spectacles was 1.72 (P < .05) compared with patients with esotropia but without anisometropia. Unsatisfactorily controlled esotropia was present in 33% of patients with anisometropia versus 0% of patients without anisometropia, with a mean hypermetropic spherical equivalent of less than +3.00 D (P = .003); however, anisometropia did not significantly increase the relative risk of unsatisfactory control of esotropia with spectacles in patients with a hypermetropic spherical equivalent of +3.00 D or more. Although amblyopia and anisometropia were closely associated, anisometropia increased the relative risk for esotropia to 2.14 (P < .05), even in the absence of amblyopia. CONCLUSIONS: Anisometropia (>or=1 D) is a significant risk factor for the development of accommodative esotropia, especially in patients with lower overall hypermetropia (>+3.00 D). Anisometropia also increases the risk that an accommodative esotropia will not be satisfactorily aligned with spectacles.