As part of the second round of clinical trials authorized by the Food and Drug Administration, surgeons have implanted microscopic chips in the eyes of three patients suffering from retinal disease. Optobionics Corp. of Wheaton, Ill., manufacturer of the Artificial Silicon Retina, installed the first device in a human June 28, 2000. To date, six patients have received the implants. The chips, which feature 3500 microphotodiodes, stimulate the remaining healthy cells of the retina. They are suitable for patients who have retinal pigmentosa or age-related macular degeneration. Up to 10 patients may receive the implants under the current study.