In order to assess vision in Alzheimer's disease (AD) and related disorders, gerontologists must use tests that make minimal cognitive demands on the subject. Using such tests, we have found a pattern of deficits in color discrimination, stereoacuity, contrast sensitivity, and backward masking that differs from that seen in healthy elderly individuals. Impaired vision predicts deficient performance of subjects with AD on numerous tests of cognition, underscoring the importance of understanding visual changes in this population.