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- AFTER 10 years of complete
blindness, Harry Churchey saw the shape of words again. Scientists had
implanted a sophisticated electronic chip into one of his eyes in an experiment
to see if it is possible to restore lost vision.
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- "When they put this thing into my eye, I could see
the letter H in all its glory," Churchey said last week. "It
may not sound much, but I can tell you that after 10 or so years that was
an amazing sight."
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- Churchey is one of several blind people undergoing experimental
treatment that has succeeded in giving them enough vision to make out shapes
and lights. Scientists have used silicon chips planted inside their eyes
to bypass their damaged retinas and send electrical signals directly to
the brain.
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- The technique, like the development of cochlea implants
used to restore useful hearing to deaf people, is under test at several
centres in America and Germany, including Johns Hopkins University in Baltimore.
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- Dr Gerald Chader, chief scientific officer of the Foundation
Fighting Blindness, which funds the work at Johns Hopkins, said: "Some
patients have now seen images, including a letter, and that is a big breakthrough.
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- "The initial target is to create crude images. A
person will be able to see the shapes of large objects, such as a door,
a piece of furniture, a window, cars and trucks and so on. The fine vision
is in the future and we think it will come very quickly."
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- In a healthy eye the surface of the retina is covered
with tiny rods and cones that act as photo-electric cells, converting light
into electrical signals. The signals, which vary according to the intensity
and colour of the light focused on the retina, are relayed to ganglion
cells and then to the optic nerve, which delivers them to the brain. The
brain reassembles the signals into our images of reality.
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- One of the biggest causes of blindness is degeneration
of the photo-electric cells and nerve tissue in the retina, caused by several
diseases with age-related macular degeneration at the top of the list.
Blindness can strike when the brain no longer gets sufficient electrical
signals to process into an image.
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- To counter the problem, doctors at Johns Hopkins inserted
chips into patients' eyes which bypassed the retina and delivered electric
signals that stimulated the ganglion cells directly.
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- So far the chips have only been put in for a short time
because further work is needed to find the best way to install them on
such a delicate surface as the retina. However, they did succeed in getting
image signals through to some patients' brains.
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- Dr Tim Schoen, of the Foundation Fighting Blindness,
said: "Johns Hopkins is one of very few laboratories that is testing
this technology on blind people. They bring somebody in, open the eye,
put the chip on the surface of the retina and stimulate it using different
voltages and frequencies.
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- "They have transmitted images like boxes, circles
and simple letters and they have achieved simple form vision.
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- "There is an array with 64 points on a chip of two
square millimetres. You stimulate the points you need to form a shape using
an electric current carried along a wire."
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- The eventual aim is to implant chips permanently. The
subjects would wear special spectacles that would convert the image of
what is in front of them into an electrical code. This code would be sent
by a tiny laser to the retina chip, in much the same way that a television
picture travels along a cable.
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- The electrical signals would then go to the ganglion
cells and, like a television receiver, the brain would convert the signal
into a picture.
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- Teams of researchers at Harvard University, Massachusetts
Institute of Technology (MIT), Utah University and at Bonn and Tübingen
in Germany, are working on similar projects. Harvard has tried its technique
on three people. One woman reported seeing a four-dot design that mimicked
the electronic signal pattern.
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- "The long-term goal is ambitious and we cannot provide
an accurate timetable for its completion," said Professor John Wyatt,
who leads the work at MIT.
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- Johns Hopkins has tried its technology on many more patients
than the other institutions and intends to press ahead with development
in as short a time as possible.
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- "At Johns Hopkins we are looking at clinical trials
in two years. They could take three or four years, and after that the speed
of development will depend on how well the trials go," said Chader.
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- Last week Churchey, a 72-year-old from Baltimore, was
waiting to go back for a fourth time to help with the research.
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- "When I was there last, a five-year-old boy was
a bit worried about what was happening to him," he said. "If
I can help with this work and give hope to kids like that, I'm a happy
man."
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