An evaluation of the agreement betwwn contour-based circles and random dot-based near stereoacuity tests

Introduction: Monocular cues are present in the contour-based Titmus and Randot circles stereoacuity tests frequently giving rise to false-positive results in patients with abnormal stereoacuity. Stereoacuity derived using these 2 test types was compared to evaluate whether discrepancies between these tests were limited to the coarse/nil end of the stereoacuity spectrum or whether they were apparent across a wider range of possible stereoacuity scores, including levels of stereopsis equated with macular fusion. Methods: Fifty-four normal volunteers and 91 patients with a history of anomalous binocular vision by a variety of conditions (eg, strabismus, monovision, or unilateral eye disease) participated. In each participant, stereoacuity was measured using the Titmus (c) circles, the Randot (c) (version 2) circles, and the Preschool Randot (c) Stereoacuity test. Results: In patients with a history of anomalous binocular vision, better stereoacuity scores were acquired using the circles tests than the random dot-based Preschool Randot Stereoacuity test (Friedman repeated-measures analysis of variance on ranks, Chi-square = 99.3, P < 0.001; Student-Newman-Keuls Method, P < 0.05). Among patients with known binocular vision anomalies, stereoacuity score disagreement was evident across the entire range of measurable stereoacuity. Conclusions: Stereoacuity score discrepancies between the circles tests and the random dot based tests frequently cross categories (eg, fine vs. moderate or coarse stereopsis). Disagreement between the test types may reflect different underlying mechanisms by the different types of tests or confounding nonstereoscopic binocular cues in the Titmus and Randot circles test.