Chip That Would Restore Sight
Implanted in People
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.
by Debra Sherman
http://dailynews.yahoo.com/h/nm/20000630/sc/health_vision_dc_1.html