Artificial Silicon Retina


Chip That Would Restore Sight Implanted in People
by Debra Sherman

Source: Reuters

June 30 5:26 PM ET

CHICAGO (Reuters) - Illinois scientists on Friday said they have successfully implanted silicon microchips beneath human retinas for the first time, a procedure that holds promise for millions of people with failing eyesight.

Earlier this week, three patients who lost almost all of their vision from retinitis pigmentosa -- a hereditary condition in which the retina gradually degenerates -- became the first people to have an Artificial Silicon Retina implanted.

Doctors said they will not know for weeks whether the chip has restored vision because the incisions made to implant the device must first heal.

The patients are wearing shields over their eyes to protect from light and debris.

The 2-1/2-hour operations, performed at the University of Illinois at Chicago Medical Center and at Central DuPage Hospital in Winfield, Illinois, were part of a Food and Drug Administration-approved study to determine whether the chip can be tolerated.

Doctors said initial signs suggest the chip -- smaller than the head of a pin and about half the thickness of a piece of paper -- had not been rejected.

Cautious Optimism

``We'll have to wait three or four weeks to see how it's functioning,'' Dr. Alan Chow, the ophthalmologist who invented the device with his brother, Vincent Chow, an electrical engineer. ``We're cautiously optimistic.''

The chip contains about 3,500 microscopic solar cells that convert light into electrical impulses. It works by replacing damaged photoreceptors, the so-called light-sensing cells of the eye. Those cells normally convert light into electrical signals within the retina.

Loss of photoreceptors cells occurs in people with retinitis pigmentosa and other retinal diseases including macular degeneration, a condition in which the central area of the retina degenerates.

Macular degeneration and retinitis pigmentosa, the two most common causes of untreatable blindness in developed countries, affect at least 30 million people in the world.

The chip will not help people with blindness caused by severe glaucoma or diabetes.

The implants require no batteries or wires. They are completely self-contained since they are powered by light that enters the eye.

Doctors hope the implants will stimulate the retina so patients develop some vision.

``We still don't know how much vision can be restored. It's still very early,'' said Alan Chow, president and chief executive of Wheaton, Ill.-based Optobionics Corp., which developed the chip.

He said he ``tossed and turned'' for six hours the night before the first surgery worrying about what might go wrong.

``The thing that surprised us most was how smoothly it went,'' he said.

Surgery Detailed

The microsurgery starts with three tiny incisions no larger than the diameter of a needle in the white part of the eye. Through the incisions, surgeons introduce a vacuuming device that removes the gel in the middle of the eye and replaces it with saline solution.

Surgeons then make a pinpoint opening in the retina to inject fluid in order to lift up a portion of the retina from the back of the eye, creating a pocket to accommodate the chip.

The retina is resealed over the chip. Doctors then inject air into the middle of the eye to force the retina back over the device and close the incisions. The air bubble is reabsorbed and replaced by fluids created within the eye within a day or two.

``If the implant is tolerated well and is able to successfully stimulate the retina, it may open up new opportunities for restoring sight in patients with the end stages of retinitis pigmentosa,'' said Dr. Gholam Peyman at the Tulane University Medical Center's ophthalmology department.

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