Contrast sensitivity versus visual acuity in retinal disease.

A large group of individuals with retinal disease were tested prospectively for contrast sensitivity by means of Arden gratings. A subgroup of 19 were also tested with the Nicolet automated television system. Individuals with macular or peripheral dystrophy showed a general reduction in contrast sensitivity as visual acuity decreased. The loss of contrast sensitivity was more prominent for high spatial frequencies (6.4 cycles per degree) than for low ones (0.2 cycles per degree). Similar results were obtained for patients with achromatopsia and congenital stationary night blindness. Patients with functional complaints, but no organic basis for decreased acuity, showed greater scatter in their test scores. The Nicolet results showed somewhat smoother curves, but were no more specific in separating normality from abnormality. Contrast sensitivity testing was not specific for the retinal disease entities considered, but may be useful in recording a degree of retinal damage and a degree of functional visual disability. Contrast sensitivity appeared to be reduced whenever acuity was reduced, so that a distinction could be made between patients having a loss of contrast beyond the expectations for their level of acuity and those in whom a loss of contrast simply corroborates the reduction of acuity.