Purpose: We assessed repeatability and intercorrelations of five standard v
ision tests in subjects with normal vision. Methods: Seventy-eight subjects
(aged 21 to 68 years) completed five measurements each of high- and low-co
ntrast visual acuity, near visual acuity and contrast sensitivity (Pelli-Ro
bson chart). Results: Except for correlations between high- and low-contras
t Visual acuity (r = 0.78), intercorrelations between tests were low to mod
erate (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 avera
ge, 1 to 2 lines can be expected to be lost over the normal lifespan on eac
h test. Variability in responses did not increase significantly with age fo
r 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.