Bionic retina may hold hope for the blind

From...

By Jon Surmacz

(IDG) -- On May 8, Dr. Alan Chow, a pediatric ophthalmologist, revealed data from a two-year clinical trial of the Artificial Silicon Retina (ASR) -- a device he and his brother Vincent conceived more than 10 years ago to help victims of retinitis pigmentosa (congenital diseases that affect the light-sensing cells of the retina). The news, picked up by Reuters and Good Morning America among others, was that the implanted retina was able to restore some vision in all six test subjects.

In a healthy eye, the photoreceptor cells transform the light that reaches the retina into an electrochemical signal that is sent to the brain. That signal is interpreted as sight.

To combat the effects of retinitis pigmentosa, the ASR is implanted in the subretinal space of the eye, which is located behind the retina near the optic nerve. The ASR, which is about 2 millimeters in diameter and 25 microns thick, detects light using the 5,000 microphotodiodes on its surface.

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These microscopic solar cells transmit a signal directly to the healthy tissue surrounding it, which in turn sends a chemical signal to the optic nerve. There were concerns that the chip might corrode in the eye, or that the body might reject the implant. Neither appears to have happened in these early trials, says David McComb, spokesperson for Optobionics, the Chicago-based company founded by the Chows to develop the ASR.

"One of the good factors of placing the chip in the subretinal space is it's a place in the body where the chip will maintain its physical characteristics," McComb says. "It's very fortunate that the placement of the chip in a relatively safe position is possible."

The data is the first evidence that shows that the device and procedure is safe and can improve sight in humans. McComb says the company is cautiously optimistic about the data, but he also emphasized that this was the first step in a process that could take several years.

"There was no inflammation, infection or rejection in any of the six patients," says McComb. "Weâre fortunate that in its first shot it seems to be safe and improves visual function."

In January 2000, the Food and Drug Administration approved Dr. Chow to conduct a two-year clinical trail of the ASRs. The first chips were surgically implanted into three patients in June of that year. Three more patients had the procedure done in 2001. McComb said the near-term goal is to find four more patients to complete the trial. There are also plans to publish a paper for review by the scientific and medical communities.

"From a scientific observer's perspective, that will be an important next milestone," McComb says.

Once the research is reviewed and the clinical trial complete, Optobionics will seek pre-market approval from the FDA to market and test the chip for commercial purposes, which is probably still five years down the road. Five years may sound like a long time, but for those who have lost their sight because of this degenerative retinal disease the ASR provides hope. Just a little vision is better than none at all.

"We're not talking about creating 20/20 vision for people who had been barely light receptive," McComb says. "But the ability to navigate a living room is quite a success for someone who has lost that ability."