Retinal prosthesis restores partial vision

October 23, 2009--A new artificial retina--an array of electrodes implanted on the back of the eye and fed by a small camera--has been found to restore partial vision to totally blind people.

October 23, 2009--A new artificial retina--an array of electrodes implanted on the back of the eye and fed by a small camera--has been found to restore partial vision to totally blind people. In a study focused on 15 blind participants who had the implant for at least three months, 10 of the patients subsequently tested were able to identify the direction of moving objects. The research was presented at Neuroscience 2009 (October 17 to 21; Chicago, IL), the annual meeting of the Society for Neuroscience.

"These results give new hope to the many people with degenerative retinal diseases," said Jessy Dorn of Second Sight Medical Products (Sylmar, CA) and lead author of the study. More than two million Americans suffer from eye diseases such as retinitis pigmentosa and age-related macular degeneration, slowly losing their vision as the nerve cells that detect light are destroyed, due to either age or illness. There is no known cure.

Bionic motion detection
In this case, the researchers worked around the destroyed cells. Each participant was given a pair of glasses with a small video camera mounted on it, and a belt with a miniature computer attached. The computer processed video images from the camera and transmitted the data to the implanted electrodes on the retina. When the users "looked" at a monitor with a white bar sweeping across a black screen, the electrodes that corresponded with the moving bar stimulated cells in the eye, creating spots of light in their fields of vision.

"We found that most of the study participants were better able to determine the direction of the bar when using the prosthesis system than without it, or with a scrambled video input," Dorn said. "In other words, this new system gave most blind people the ability to identify an object's direction of motion--something they could not do without it."

An international clinical trial is now testing the prosthesis system. To date, 32 blind people have received the implant.

The research was supported by the National Eye Institute.
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--posted by John Wallace, johnw@pennwell.com

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