Effects of Induced Anisometropia by Refractive Surgery on Binocular Vision

Abstract

Purpose: To evaluate the effects of induced anisometropia by refractive surgery on binocular vision and to determine the usefulness of screening tools. Case summary: Anisometropia was induced in 7 patients by photorefractive keratectomy (PRK). Binocular vision was determined with the Titmus stereo test, Worth 4-dot test, 4 prism diopter base-out test and Bagolini striated lens test. Each test was performed before surgery, after PRK of one eye and after PRK of both eyes. After PRK of one eye, mean stereopsis by the Titmus stereo test was 1877.14 seconds of arc and after surgery of both eyes, 40 seconds of arc. After surgery of one eye, 6 patients (86.7%) showed suppression with the Worth 4 dot test at distance fixation and one patient (14.3%) at near fixation. After surgery of both eyes, all patients showed fusion with the Worth 4 dot test. After surgery of one eye, 3 patients (42.9%) showed suppression with the 4 prism diopter base-out test and after surgery of both eyes, 2 of the patients showed fusion. All patients showed fusion with the Bagolini striated lens test after surgery of one or both eyes. Conclusions: Most cases showed decreased binocular vision by the Titmus stereo test at near fixation and the Worth 4 dot test at distance fixation. The changes of binocular vision determined by each tool were variable. Therefore, improved results in evaluating binocular vision will be obtained with a combination of various tools including the Bagolini striated lens test and 4 prism base-out test.