Cataract, pattern stimulation and visually evoked potentials.

Visually evoked potentials on pattern stimulation are lowered by cataracts via scatter, absorption and defocusing. These effects have to be known before pattern stimulation can be fruitfully applied in patients when a lowered vision cannot or can hardly be explained by the cataract. It was remarkable that pattern responses were relatively good as compared to visual acuity. With a pattern of 80' check size and 80% contrast all patients with a visual acuity of more than 0.1 had recognizable responses; this holds also true with 40' check size and 40% contrast in all patients with a visual acuity of more than 0.3. Reversely, with 10' check size and 10% contrast only half of the normal subjects had detectable responses.