The effects of glasses for anisometropia on stereopsis

To assess the effects of glasses for anisometropia on stereopsis and to determine the factors that affect the level of stereopsis.

Retrospective observational case series.

One hundred six nonamblyopic patients who were wearing glasses for anisometropia and 56 who were wearing glasses for isoametropia were enrolled. The levels of stereopsis in the anisometropic patients were divided into normal (≤40 seconds of arc), equivocal (40 < - ≤ 100), and subnormal (100 < - ≤ 400) and compared with those in the isoametropic patients. It was evaluated whether the amount of interocular difference in the lens power of the glasses, the type of anisometropia, a history of amblyopia, and the age at the time of the prescription of the first glasses were related to the stereopsis.

In the anisometropia, the mean stereopsis (seconds of arc) was 77.52 (40-200) in the Titmus-fly test and 52.78 (40-100) in the Randot stereotest. The rate of normal and equivocal stereopsis was 87.7% in the Titmus-fly test and 96.9% in the Randot stereotest. The isoametropic patients demonstrated better stereopsis (52.86 and 39.20 in either test) than did the anisometropic patients (P < .05). The stereopsis was worse in the spherical hyperopic type of anisometropia than in the spherical myopic type (P < .05). The level of stereopsis was not related to the other factors that were investigated.

The level of stereopsis with the wearing of anisometropic glasses was clinically near normal and the glasses did not seriously affect the binocular vision regardless of the severity of the anisometropia.