Stereopsis in small-angle strabismus

Our purpose was to evaluate the presence of stereopsis in a number of small-angle strabismic patients, using several stereotests, and to attempt to associate the presence of stereopsis with certain clinical characteristics of the strabismus--the magnitude of the deviation, the severity of the amblyopia, the depth of the anomalous correspondence, and the etiological category. The evaluation of stereopsis was performed using the Titmus, Randot, Random-dot E, TNO, and Frisby stereotests. Thirty-two percent of the small-angle strabismic patients examined demonstrated no stereopsis on any of the stereotests. Patients having strabismic deviations exceeding 5 delta, showing anomalous correspondence on multiple tests, and having had extraocular muscle surgery were the least likely to demonstrate stereopsis. The test that most often indicated the presence of stereopsis was the Titmus stereo test, and the tests that least often indicated the presence of stereopsis were the Random-dot E and the TNO stereotests. Our results indicate that careful consideration should be given to the clinical characteristics of the strabismus and the selection of the stereotest when evaluating small-angle strabismic patients for the presence of stereopsis.