We investigated adult age differences in four measures of visual function: distance acuity, near acuity, stereopsis, and contrast sensitivity. Twenty-four young adults (mean age 19.5 years) and 24 older adults (mean age 68.4 years) participated. Age differences were present in each of the four measures. A stepwise discriminant analysis performed on the four measures revealed that, when the correlations among the measures were taken into account, only contrast sensitivity significantly discriminated young and older adults' performance. The strength of the correlations among the four measures was greater for older adults than for young adults. The results indicated that contrast sensitivity is a useful measure for detecting age-related changes in visual function and that a common mechanism may underlie age differences on various visual tests.