Repeatability and Intercorrelations of Standard Vision Tests as a Function of Age

PURPOSE: We assessed repeatability and intercorrelations of five standard vision tests in subjects with normal vision. METHODS: Seventy-eight subjects (aged 21 to 68 years) completed five measurements each of high- and low-contrast visual acuity, near visual acuity and contrast sensitivity (Pelli-Robson chart). RESULTS: Except for correlations between high- and low-contrast visual acuity (r = 0.78), intercorrelations between tests were low to moderate (r < 0.5). For each measure, variability for the group was about one line on the chart (one triplet for the Pelli-Robson chart) and the minimum variability for an individual subject was about one third of this. On average, 1 to 2 lines can be expected to be lost over the normal lifespan on each test. Variability in responses did not increase significantly with age for any test. CONCLUSIONS: The criterion for judging change on commonly used clinical vision tests is about one line for subjects over a wide age range.