New Delhi, July 23 -- SAN FRANCISCO - A French woman with advanced age-related macular degeneration had been told the words would never come back. The condition, the leading cause of blindness in adults over fifty, had hollowed the center of her visual field until text on a page became unreadable. After surgeons implanted a small chip at the back of her eye, she read a 300-page novel.

That patient was among those enrolled in the European clinical trials for PRIMA, a retinal brain-computer interface developed by Science Corporation. On Tuesday, European medical device regulators granted PRIMA approval for commercial sale, the first such clearance for any implantable device designed to restore central vision by stimulating retinal neurons ...