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 (greater than or equal to1 D) on the relative risk of developing accommodative esotropia and of developing unsatisfactory control with spectacles once esotropia was present. Results: Anisometropia (greater than or equal to1 D) increased the relative risk of developing accommodative esotropia to 1.68 (P <.05), Anisometropia (<greater than or equal to>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 (greater than or equal to1 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 (greater than or equal to1 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.