Pattern electrical stimulation of the human retina

Experiments were conducted to study if electrical stimulation of the retina l surface can elicit visual sensation in individuals blind from end-stage r etinitis pigmentosa (RP) or age-related macular degeneration (AMD). Under l ocal anesthesia, different stimulating electrodes were inserted through the eyewall and positioned over the surface of the retina. Subjects' psychophy sical responses to electrical stimulation were recorded. Subjects perceived simple forms in response to pattern electrical stimulation of the retina. A non-flickering perception was created with stimulating frequencies betwee n 40 and 50 Hz. The stimulation threshold was dependent on the targeted ret inal area (macular versus extramacular). (C) 1999 Published by Elsevier Sci ence Ltd. All rights reserved.