Chip That Restores Sight Implanted in People
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CHIP THAT WOULD RESTORE SIGHT IMPLANTED IN PEOPLE
By Debra Sherman
June 30, 2000
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
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
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
"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
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
"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.
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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