Comparison of the HOTV and Lea symbols visual acuity tests in patients with amblyopia

Purpose: To determine whether the Lea symbols visual acuity test, compared with the HOTV visual acuity test, overestimates visual acuity in patients with amblyopia. Patients and Methods: Fifty-nine patients with amblyopia or a history of amblyopia treatment had visual acuity measurements in both eyes with the HOTV and Lea symbols tests. Crowding bars, separated by a width of 1 optotype, and the original pilot-testing protocol in the Amblyopia Treatment Study were used to quantify visual acuity. Results: The patients' ages ranged from 4 to 35 years (mean age, 10.1 years). Visual acuity in the amblyopic eyes ranged from 20120 to 20/250. The mean visual acuity difference (HOTV scores vs Lea symbols scores) was -0.056 logMAR units (P < .001), slightly more than half of a line. The negative value indicates that patients performed better on the HOTV test. In nonamblyopic eyes, the mean difference was -0.05 logMAR units (P < .001). Patients with strabismic amblyopia had a mean difference of -0.05 logMAR units (P = .08); those with anisometropic amblyopia had a mean difference of -0.07 logMAR units (P = .002). Patients 8 years and younger had a mean difference of -0.04 logMAR units (P = .05); those older than 8 years had a mean difference of -0.06 logMAR units (P = .002). Conclusions: In both amblyopic and nonamblyopic eyes, visual acuity measurements were better on HOTV testing compared with Lea symbols testing. The differences persisted regardless of patient age and the cause and severity of amblyopia. Overestimation of visual acuity by the Lea symbols test was not found.