• Twenty-eight patients were given the Titmus stereoacuity test (TST). Seven-teen patients had documented optic nerve disease, and 11 had no known optic nerve disease. Thirteen of 17 patients (76%) with known optic nerve disease failed to achieve their expected TST scores, while only three of 11 (27%) of the patients without optic nerve disease fell into this category. Patients with reduced visual acuity secondary to optic nerve disease showed a disproportionately greater reduction in their TST scores than would be expected, based on Snellen's visual acuities.