Salk Researcher Seeks a Cure for Blindness
Monday, May 11, 2009
Technological advances have helped many disabled people perform normal functions again. Helping blind people to see is beyond today's technology. But tomorrow's technology may be able to do it. A researcher at San Diego's Salk Institute is trying to create a prosthetic device that can restore sight. KPBS health reporter Tom Fudge explains.
SAN DIEGO Technological advances have helped many disabled people perform normal functions again. Helping blind people to see is beyond today's technology. But tomorrow's technology may be able to do it. A research at San Diego's Salk Institute is trying to create a prosthetic device that can restore sight.
KPBS health reporter Tom Fudge explains.
Giving sight to the blind. It's a hope that sounds miraculous. Even biblical. But medical science is discovering ways to reconnect the nerves of the eye to the brain, where visual images are made. E.J. Chichilnisky is a professor at the Salk Institute who studies the retina. He says a disease called macular degeneration destroys the photoreceptor cells in the retina, causing blindness. He says he can't cure the disease. But…
"The question is whether we can intervene, using technology, to replace the function of those cells with an artificial device," he says.
Chichilnisky's research focuses on macular degeneration and retinitis pigmentosa. Both of those diseases destroy photoreceptor cells. Those are the cells receive light and stimulate other nerve cells in the retina. Those cells, in turn, send impulses to the brain.
When Chichilnisky talks about intervening with an artificial device, he's talking about creating a prosthesis that would be placed in the retina. Actually, he says cameras and computer technology already provide some of the part that are needed to make such a device.
"We know how to build cameras," says Chichilnisky. "No problem. We know how to build microchips that process information in whatever way we want to. No problem. Tricky point is when those microchips interface to the nerve cells. You have to cause the nerve cells to send electrical impulses down to the brain. How do you do that?"
One answer to that question has been found in the effort to deal with another disability. Deafness. Cochlear implants replace that part of the inner ear that sends electrical signals to the brain. These implants have already shown tremendous potential to help deaf people. Chickilnisky remembers being in grad school, about fifteen years ago, when he first saw the demonstration of a cochlear implant.
"And I saw this clinician speak to this person who was previously deaf," he says. "And he spoke to him from behind so there was no possibility of lip reading. And the man who had been deaf for such a long time was able to understand and respond to the speech."
Some companies are already making implants for the blind. Second Sight Medical Products is the name of a company in Sylmar, California. They've received FDA approval to fit twenty patients with an implant that might, one day, replace photoreceptor cells in the eye.
Matt McMahon is the senior principal scientist at Second Sight. He says the company's implant has 60 electrons that deliver current to retinal nerve cells. And these implant have allowed people, who are totally blind, to see the light.
"They can now sense light when light are on and lights are off. But also it allows them to look around in the world to see kind of crude shapes and crude forms."
He says the advance of the technology could go much further.
"All the way down the road to kind of the holy grail which would be restoring their ability to read or their ability to see faces."
But there's a long way to go before that holy grail is in hand. Keep in mind that while the Second Sight implant has 60 electrons, there are 1.25 million optic nerve fibers in a healthy retina.
Chichilnisky says one other approach to curing blindness is the use of stem cells, which can theoretically become any cell in the body. He says, theoretically, stem cells could be trained to become and replace damaged photoreceptor cells.
"That, in a certain deep sense, is probably preferable to replace biological tissue with biological tissue rather than to have to deal with all the complications of an electronic interface."
But E.J. Chichilnisky says for now, implants show the most promise of providing sight of the blind. Tom Fudge, KPBS News.
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