Retinal Implant Restores Limited Sight to Blind

But second-generation device is still a far cry from full vision, experts say.

By Alan Mozes
HealthDay Reporter
Saturday, February 17, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

FRIDAY, Feb. 16 (HealthDay News) -- U.S. researchers say a new high-tech implant is restoring at least some sight to people blinded by eye disease.

The device -- known as the Argus II Retinal Prosthesis System -- is an updated and more powerful version of an electronic retinal implant that has been the subject of ongoing clinical trials since 2002.

Speaking in San Francisco on Thursday at the annual meeting of the American Association for the Advancement of Science, the device's developers announced that the U.S. Food and Drug Administration had recently granted approval for a new clinical trial of the technology.

The prototype artificial retina used an array of 16 electrodes surgically inserted into a diseased eye to function as light-sensitive surrogates for damaged retinal photoreceptor cells.

Implants of this original configuration were able to give six blind patients the limited ability to distinguish light, perceive motion, and identify general shapes and objects.

The second generation retinal prosthesis will be fitted with 60 electrodes -- an increase that the researchers say will offer the blind the opportunity to acquire higher-resolution sight.

"Our work to date with our retinal prosthesis has exceeded all expectations we had, and we are very excited and look forward to the results from our 60-channel implant," said lead researcher Dr. Mark Humayun, an ophthalmology professor at the Doheny Eye Institute of the University of Southern California's Keck School of Medicine in Los Angeles.

He said that clinical trials of the newest generation of retinal prosthesis will begin later this year.

The technology is being targeted at both young and elderly patients blinded by either retinitis pigmentosa or macular degeneration. Approximately 25 million people, six million in the United States alone, have lost most or all of their vision to such diseases, a figure Humayun said researchers expect will double by 2020.

The term "retinitis pigmentosa" (RP) refers to a number of hereditary eye diseases characterized by the slow deterioration of retinal receptor cells, known as rods and cones. Such cells are key in capturing and translating light into an electrical pulse, which the brain then interprets as an image.