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Wednesday, 26 April, 2000, 23:05 GMT 00:05 UK
Blind 'to see' with artificial eye

It is hoped the artificial eye could restore some sight
An "artificial eye" which would allow blind people to see is due to be implanted in a patient within the next few months.

The device taps directly into the optic nerve and could restore some measure of sight to people whose retinas have been damaged or destroyed.

Visual sensations beamed from a video camera are created in the brain by the artificial eye, developed by a team at the Catholic University of Louvain, in Belgium, directly stimulating different parts of the optic nerve.

Other implants being developed stimulate the ganglia cells on the retina or the visual cortex of the brain itself.

But the Louvain team, led by Claude Veraart, says these other techniques require large number of electrodes to create images which are recognisable.

His device uses a coil to wrap round the optic nerve with only four points of electrical contact.


A video camera, positioned externally, transmits via a radio transmitter and microchip to an implant behind the ear. This is connected to the electrodes on the optic nerve.

Different parts of the optic nerve are stimulated by altering the signals, similar to the way in which the electron guns in TVs are aimed at different parts of the screen.

Veraart and his colleagues have spent the past two years experimenting with a volunteer who has the electrode implanted, with wires leading out of her body to the signal processor.

By asking her to point in response to various stimuli, Veraart and his colleague Charles Trullemans have been able to map camera pixels onto the corresponding parts of her visual field.

This was possible, said Veraart in New Scientist magazine, because the subject was once sighted and knows what it means to "look at" something.

The researchers hope the device will at least allow blind people to avoid obstacles, though more tests are necessary before the device is implanted.

Most critical is the time it takes to realise they are approaching an object.

"If it takes her 30 seconds to recognise an obstacle it will be of little use," said Veraart. But if the reaction time is fast, the team plan to implant at least three more patients, starting in August.

Rebecca Griffith, health promotion officer for the Royal National Institute for the Blind, in the UK, welcomed the advance but sounded a word of caution.

"It is four months to the testing phase, not four months to public availability," she said.

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