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.