Health:- Light-powered bioniceye invented to help restore sight

A retinal implant - or bionic eye - which is powered by light has been
invented by scientists at Stanford University in California.

Implants currently used in patients need to be powered by a battery.
The new device, described in the journal Nature Photonics , uses a
special pair of glasses to beam near infrared light into the eye.
This powers the implant and sends the information which could help a
patient see.
Diseases such as age-related macular degeneration and retinal
pigmentosa result in the death of cells which can detect light in the
eye.
Eventually this leads to blindness.
Wiring eliminated
Retinal implants stimulate the nerves in the back of the eye, which
has helped some patients to see.
Early results of a trial in theUK mean two men have gone from being
totally blind to being able to perceive light and even some shapes.
However, as well as a fitting a chip behind the retina, a battery
needs to be fitted behind the ear and a cable needs to join the two
together.
Prof Robert MacLaren from Oxford Eye Hospital explains how a bionic
eye implant works
The Stanford researchers say their method could be a step forward
by"eliminating the need for complex electronics and wiring".
A retinal implant, which works in a similar way to a solar panel, is
fitted in the back of the eye.
A pair of glasses fitted witha video camera records what is happening
before apatient's eyes and fires beams of near infrared light on to
the retinal chip.
This creates an electrical signal which is passed on to nerves.
Natural light is 1,000 timestoo weak to power the implant.
The researchers said:"Because the photovoltaic implant is thin and
wireless, the surgical procedure is much simpler than in other retinal
prosthetic approaches.
"Such a fully integrated wireless implant promises the restoration of
useful vision to patients blinded by degenerative retinal diseases."
The implant has not been tested in people, but has been shown to work in rats.
Dr Keith Mathieson, now at the Institute of Photonics at the
University of Strathclyde, was one of thelead researchers on the
project. He said: "Age-related macular degeneration is a huge medical
challenge and, with an aging population, is continuing to grow.
"This means that innovative, practical solutions are essential if
sight is to be restored to people around the world with the condition.
"The implant is thin and wireless and so is easier to implant. Since
it receives information on the visual scene through an infra-red beam
projected through the eye, the device can take advantage of natural
eye movements that play acrucial role in visual processing."

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