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The Evoked Cortical Potential in Macular Degeneration *

ABSTRACT: Macular degeneration causes a profound loss of visual acuity due to inadequate blood circulation in the capillaries of the choroid plexus and pigment epithelium of the important pattern‐recognizing area of the retina. This disease is the cause of half the blindness in people over the age of 65 and of nearly one‐third of all blindness. In this study an important new technique was added to six tests already in use to assess retinal disease. Data on 10 patients were collected by the following methods: 1) optic disc photography; 2) fluorescein angiography; 3) visual acuity testing; 4) visual fields; 5) foveal sensitivity; 6) electroretinography with automatic analysis of the record by use of an electronic sampling filter and a specially built computer to measure the total electrochemical energy released by the retina; and 7) the evoked cortical response (as indicated in the electroencephalogram) to the stimulus of an alternating chess‐board pattern. This new technique tests the total system for visual pattern recognition. The results indicate that the evoked cortical response is the best objective test of visual acuity.