The role of anisometropia in the development of accommodative esotropia.

PURPOSE: To determine if anisometropia increases the risk for the development of accommodative esotropia in hypermetropia.
METHODS: Records of all new patients with a refractive error of > or = +2.00 (mean spherical equivalent [SE] of both eyes) over a 42-month period were reviewed. Three hundred forty-five (345) patients were thus analyzed to determine the effect of anisometropia (> or = 1 diopter [D]) on the relative risk of developing esodeviation and of requiring surgical correction once esodeviation was present (uncontrolled deviation).
RESULTS: Anisometropia (> or = 1 D) increased the relative risk of developing accommodative esodeviation to 1.68 (P < .05). Anisometropia (> or = 1 D) increased the relative risk for esodeviation to 7.8 (P < .05) in patients with a mean SE of < 3 D and to 1.49 (P < .05) in patients with SE of > or = 3 D. This difference was significant (P = .016). In patients with esotropia and anisometropia (> or = 1 D), the relative risk for an uncontrolled deviation was 1.72 (P < .05) compared with nonanisometropic esotropic patients. Uncontrolled esodeviation was present in 33% of anisometropic patients versus 0% of nonanisometropic patients with a mean hypermetropic SE of < 3 D (P = .003); however, anisometropia did not increase the relative risk of uncontrolled esotropia in patients with SE of > or = 3 D. Although amblyopia and anisometropia were closely associated, anisometropia increased the relative risk of esodeviation to 2.14 (P < .05) even in the absence of amblyopia.
CONCLUSIONS: Anisometropia (> 1 D) is a significant risk factor for the development of accommodative esodeviation, especially in patients with lower overall hypermetropia (< 3 D). Anisometropia also increases the risk that an accommodative esodeviation will not be fully eliminated with hypermetropic correction.