ARTIFICIAL SIGHT RESEARCH

 

Development in retinal cell transplants


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Mon May 12, 1:10 PM ET

From Yahoo News

By Deena Beasley

LOS ANGELES (Reuters) – A bionic retina can restore some eyesight in people blinded by degenerative eye diseases and may some day bring vision to children born blind, according to new research.

 

 

Three patients have so far been implanted with the device, a sliver of silicone and platinum studded with 16 electrodes — one-third the size of a contact lens — that sits atop the retina. It works by electrically stimulating remaining healthy retinal cells, which pass on the visual information to the brain through the optic nerve. The device "can be used by the patients to detect light or even to distinguish between objects such as a cup or plate," Dr. Mark Humayun, professor of ophthalmology at the University of Southern California in Los Angeles, said on Friday.

The trial results were announced at a meeting on Thursday of the Association for Research in Vision and Ophthalmology in Fort Lauderdale, Florida. The bionic implant is designed to stand in for damaged retinal cells in people suffering from blinding diseases like retinitis pigmentosa and macular degeneration, the leading cause of blindness in the elderly. The first trial patient was implanted with the microelectronic device in February 2002, another received the implant in July of last year and the third eye surgery was conducted in March.

The implanted retina, made by Sylmar, California-based Second Sight LLC, does not process light directly. Patients are fitted with a pair of glasses mounted with a video camera, which transmits images to a wireless (news web sites) receiver. The receiver relays the signal to the bionic chip, where the pattern of the original image is recreated by lighting up appropriate electrodes.

"The camera is very tiny. There are a lot of advantages to using it — there are zoom features, you can adjust colors," Humayun said. With just 16 electrodes, the chip cannot achieve the sharpness of normal vision. Eventually, a version with up to 1,000 electrodes will be used to produce sharper images and a wider field of vision, he said. "The eye has millions of light-sensing cells. Our results are a testament to the brain’s ability to use crude information and make sense of it," he said.

Eventually, the bionic retina might be used the way the cochlear implant is now used to restore hearing in children who are born deaf, Humayun said. These implants contain electrodes positioned in the inner ear, or cochlea. The devices have to be implanted in early childhood, before the brain is hard-wired for nonhearing, Humayun noted. "I envision the same kind of thing with this condition."

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