Visual acuity and contrast sensitivity in patients with cerebral lesions.

Spatial contrast sensitivity as a function of spatial frequency was measured in patients with cerebral lesions. In most of these patients visual acuity, as measured by the Snellen chart, was 20/30 or better, yet marked departures from normal contrast sensitivity were found. The greatest loss in contrast sensitivity occurred at high frequencies, but in one patient the loss was greatest in the midfrequency range. This finding lends support to the channel hypothesis of spatial contrast discrimination.