Saturday, May 5, 2012

‘Bionic eye’ restores sight in the blind

Three weeks ago, Chris James, who has been blind for 25 years, saw a sudden pulsating light in his left eye, like a camera bulb or a lighting flash. Doctors had just switched on a wafer-thin, 3mm microchip implanted at the back of his eye. At first all he could see was light. Now he can distinguish shapes and might, in time, even be able to recognize faces.

James's experimental 'bionic eye' reacts to light, sending an electronic signal that is picked up by the optic nerve and processed by the brain into an image. The treatmentcould partially restore the sight of thousands of sufferers of a condition called retinitis pigmentosa, which causes the photoreceptor cells at the back of the eye to deteriorate.

"As soon as I had this flash in my eye, it confirmed that my optic nerves are functioning properly," he said. "It was like someone taking a photo with a flashbulb - a pulsating light."

In March James, a 54-year-old from Wroughton, Wiltshire, underwent an eight-hour operation at the John Radcliffe Hospital in Oxford to have the chip implanted.

A second patient, Robin Millar, 60, a music producer, had the surgery at Kingis College Hospital in London, as part of the first UK clinical trial of the microchip, which has been developed by the German company Retina Implant AG.

The surgery involves inserting a cable through the layers of the eyeball to place thechip on an area of the retina the size of a pinhead. The chip is connected to a power source implanted under the skin behind the ear.

"What makes this unique is that all functions of the retina are integrated into the chip," said professor Robert MacL aren, who carried out the first operation at Kingis College Hospital in London. "It has 1,500 light-sensing diodes and small electrodes that stimulate the nerves to create a pixillated image."

The patients only have a small range of black and white vision : a rectangle about the size of a CD case held at arm's length. At present James can only make outshapes andlinescloseup and it could takes weeks for the brain to begin to accurately interpret the signals received from the microchip.

No comments: