ANISOMETROPIA AND BINOCULARITY

Purpose: To determine the effects of experimentally induced anisometro pia on binocular function in healthy adults as a means of assessing th e potentially detrimental effects of uncorrected anisometropia on bino cular development in childhood. Methods: Nineteen adults with normal b inocularity, ranging in age from 26 to 59 years, were studied. Unilate ral myopia, hyperopia, or astigmatism (at 90 degrees or 45 degrees) wa s induced in each subject using trial lenses. Sensory status then was assessed by measuring stereoacuity, Worth four-dot fusion, and Bagolin i lens response. Results: All subjects showed a decline in binocular f unction with increasing levels of anisometropia. Foveal suppression wa s evident on the Worth four-dot test, and increased in proportion to t he anisometropia. Stereoacuity was similarly degraded by the induced a nisometropia, with some subjects showing significant loss of stereoacu ity with as little as 1 diopter of spherical anisometropia. Bagolini l ens responses were binocular in almost all patients, although occasion al abnormalities were found. Conclusions: Relatively low degrees of an isometropia may cause significant abnormalities in high-grade binocula r visual functions in adults. The potential effects of uncorrected ani sometropia on binocularity in children require further investigation, but should be considered in developing guidelines for the empiric corr ection of refractive errors.