Retinal prosthesis improved vision in three retinitis pigmentosa patients

An epiretinal prosthesis improved vision in three patients with retinitis pigmentosa, allowing them to perform simple visual tasks, according to a study by California researchers.

Douglas Yanai, MD, and colleagues at the Doheny Eye Institute, Los Angeles, implanted a prototype retinal prosthesis in one eye of each patient under a U.S. Food and Drug Administration investigational device exemption. The device features a four-by-four array of platinum electrodes tacked to the epiretinal surface and is wirelessly controlled by computer or head-mounted video camera, according to the study.

"The subjects performed significantly better than chance in 83% of the tests," the study authors said. Specifically, patients scored from 77% to 100% for locating and counting objects, 63% to 73% for differentiating three objects, 50% to 77% for determining the orientation of a capital L and 40% to 90% for differentiating four directions of a moving object, the authors reported.

A subset of tests found that multipixel settings slightly improved accuracy and reaction time vs. single-pixel settings, the authors noted.

The study is published in the May issue of American Journal of Ophthalmology.