Rapid contrast sensitivity assessment in keratoconus.

Contrast sensitivity derangement may accompany keratoconus even in the presence of normal or near normal Snellen visual acuity. This has been demonstrated with computer-driven contrast sensitivity test devices. The purpose of this study was to evaluate the utility and efficacy of rapid screening devices for contrast sensitivity testing. However, such devices are often cumbersome and difficult to use clinically. We tested 12 patients with keratoconus on 2 simple chart systems designed to test contrast sensitivity in a rapid and clinically useful manner: the Vistech chart and the Regan multi-contrast visual acuity charts. Both devices detected the contrast sensitivity abnormalities present in early keratoconus, but some patients [with greater than or equal to 6/12 (20/40) visual acuity] were unable to respond to areas of the charts corresponding to high spatial frequency and/or low contrast tasks. Such simple wall charts may be useful in measuring the visual abnormalities in early keratoconus, in monitoring the progression of the disease, and in evaluating various treatment options.