Retinal Implant Restores Limited Sight to Blind

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Usually striking early in life, the condition most commonly results in the uncorrectable loss of peripheral vision and color perception.

By contrast, macular degeneration (MD) involves damage to the center of the retina and the loss of central vision, rendering the patient unable to focus clearly on objects straight ahead. Over time, reading, driving, and face recognition are all severely impaired by this incurable disease, which has no known cause and is most common among the elderly. By some estimates, more than 10 million Americans are currently afflicted with the illness.

Both the original and current versions of the retinal implants, each manufactured by study co-sponsor Second Sight Medical Products, are designed to communicate with an external camera and computer.

The implant patient is outfitted with a pair of glasses rigged with a video camera. The camera records incoming visuals and transmits the sights by wire to a customized computer for processing. The data is, in turn, sent wirelessly directly to the implant, whose electrodes decode the message into an electrical impulse that can be directed to the brain for visual interpretation.

The second-generation study will focus on patients over the age of 50 who once had healthy vision before contracting either RP or MD.

The researchers expressed enthusiasm about the new device's prospects, noting that this suped-up version will bring also faster implant and recovery times, because it is just one-quarter the size of the original model.

However, Dr. John Loewenstein, an associate chief of ophthalmology with the Massachusetts Eye and Ear Infirmary in Boston, cautioned that even these cutting-edge technologies cannot promise anything like complete eyesight.

"This is by no means a slam-dunk, in the sense that it will provide true vision in the way we usually think about it," said Loewenstein, who is also an associate professor at Harvard Medical School and involved in similar work.

"I don't want to denigrate the work, and this is a beginning," he said. "But the retina's electrical transmission process is very sophisticated, and we simply don't yet understand the language well enough to simulate it."