Spatial contrast sensitivity in Alzheimer's disease: a comparison of two methods.

The present study was designed to compare the contrast sensitivity functions (CSF) obtained with the Nicolet CS2000 and the Vistech VCTS6500 for a sample (N = 25) of patients diagnosed with probable Alzheimer's disease (AD) and a sample (N = 25) of healthy elderly adults. With the Nicolet, CSF were determined for gratings presented under static and rapidly counterphased (7.5 Hz) conditions. All research participants were able to complete the Vistech test. However, 13.7 and 7.4% of the original samples of Alzheimer patients and healthy adults, respectively, did not yield usable data. Both test instruments showed uniformly low contrast sensitivities for the AD group. The results support the proposition that AD involves a primary visual disturbance and suggest that the Vistech chart can be used with a broader range of patients for initial screening.