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Artificial Retina May Enable the Blind to See - 2002-11-27


Medical researchers say the blind may one day see with electronic implants. Two patients are now using the experimental devices, which scientists say could help many more in the future. They are called microelectronic retinal implants, and they now provide a limited form of vision, the ability to distinguish light and dark and detect movement.

But the research is promising, says U.S. Secretary of Energy Spencer Abraham. His department is funding a laboratory devoted to the research at the University of Southern California's (USC) Doheny Eye Institute. "We're going to be teaming up with this outstanding Doheny team to create a device much more powerful than the initial prototype that has shown such success," he says. "Our immediate aim is a more robust device that can ultimately transmit not just light but images, and all of this in a very tiny silicon chip sitting directly on a patient's eye."

The department is contributing $9 million for the project, which is based in California and North Carolina. The federal agency is also offering scientific expertise at its national laboratories, which conduct research on subjects ranging from nuclear energy to the human genome.

Doctor Mark Humayun heads the implant project at USC. He says the current device is basic. It uses a tiny camera attached to the patient's glasses. The camera transmits a picture to a receiver implanted behind the patient's ear. The signal is then sent to an implant, four millimeters by five millimeters, attached to the back of the eye.

The system offers this blind patient limited vision. Dr. Humayun says the implant uses just 16 electrodes. His goal is a device with much greater definition. "We call it jokingly the thousand points of light because it's a thousand electrodes, but microelectronics will certainly get us there," he says. "I think with the Department of Energy labs and their know-how, we'll get there. But the key there is really how to interface them with the biology, where the electronics meet the tissue, and that's the part where we really have to work hard and figure out the science."

The science is indeed difficult, says Doctor Robert Greenberg, whose California company, Second Sight, developed the retinal implant. "The retina is like wet tissue paper, and so it's very difficult to make these high resolution devices compatible with that tissue," says Mr. Greenberg. "And the amount of stimulation or electrical excitation of the natural tissue that's been required to date is also a significant challenge, and so those are areas that we're working on."

Doctor Mark Humayun says, in spite of the challenges, the researchers have an optimistic timetable. He notes that the first implant was made in February, and the second in late July. "Now, with our first two implants, we believe that a low resolution device could be available for patients in two to three years, and then the high-resolution, the one that allows people to read and recognize, is going to be a little bit further off," says Dr. Humayun. "I think we'll probably have a prototype, a beginning working model, in five to six years, but maybe a bit longer before patients can benefit from it."

The experimental procedure holds out hope for those who once had sight but have lost it to degenerative conditions, caused by disease or aging. Those who were blind from birth present greater challenges, but the researchers say new technology may one day offer sight for them as well.

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