04 May 2012, 05:41
Two blind British men have electronic retinas fitted
LONDON. May 4. KAZINFORM Two British men who have been totally blind for many years have had part of their vision restored after surgery to fit pioneering eye implants.
They are able to perceive light and even some shapes from the devices which were fitted behind the retina.
The men are part of a clinical trial carried out at the Oxford University Eye Hospital and King's College Hospital in London.
Professor Robert MacLaren and Mr Tim Jackson are leading the trial.
The two patients, Chris James and Robin Millar, lost their vision due to a condition known as retinitis pigmentosa, where the photoreceptor cells at the back of the eye gradually cease to function.
The wafer-thin, 3mm square microelectronic chip has 1,500 light-sensitive pixels which take over the function of the photoreceptor rods and cones.
The surgery involves placing it behind the retina from where a fine cable runs to a control unit under the skin behind the ear.
When light enters the eye and reaches the chip it stimulates the pixels which sends electronic signals to the optic nerve and from there to the brain.
The chip can have its sensitivity altered via an external power unit which connects to the chip via a magnetic disc on the scalp.
Chris James from Wroughton in Wiltshire said there was a "magic moment" when the implant was switched on for the first time and he saw flashing lights - showing that the device was functional.
"I am able to make out a curve or a straight line close-up but I find things at distance more difficult. It is still early days as I have to learn to interpret the signals being sent to my brain from the chip."
Mr James, a motor-racing enthusiast, says his ambition is to be able to make out the silhouettes of different cars on the race-track.
Prof MacLaren, who fitted the first implant in the UK at the Oxford Eye Hospital, said:
For full version http://www.bbc.co.uk/news/health-17936302
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