London: A retinal implant could one day be used for restoring vision lost through injury or disease, after it gave a brief glimpse of light to a group of patients.
The device, which is the creation of Shawn Kelly from Carnegie Mellon University in Pittsburgh and the result of a decade’s worth of research, is made up of two tiny cameras attached to a pair of glasses which send images to a computer chip attached to the patient’s eye.
The chip turns the images into an electrical current sent along a wire to a film inserted behind the retina.
“From this thin plastic film, the width of an eyelash, flexible electrodes send stimulating current signals to retinal nerves, helping to restore vision,” the Daily Mail quoted Kelly as saying.
“My device is very much like a camera, replacing the function of the rods and cones in the human eye,” he said.
In basic terms the eye operates on the same principle as a camera. The eye, however, takes two simultaneous pictures, one in black and white, and the other in colour.
Cells in the retina, called rods, register black and white only; they are so sensitive that they can detect light as faint as 100-trillionth of a watt. Other retinal cells, the cones, are affected by colour and are most abundant at the fovea, the place where the image falls when the eye focuses.
The blind spot, lacking both rods and cones, is where the optic nerve leaves the retina, carrying the pictures for the brain to see.
So far the device has been successfully tested on a small group of blind patients, who reported seeing patches of light and dark and some shapes.
“My tools are designed to help individuals struggling with blindness, and to ultimately help injured veterans with head and eye wounds recover some peripheral vision,” he said.
The device can only create an image with a resolution of 256 pixels because that’s how many electrodes can currently fit onto the back of the film.
However, Kelly said that the device was extremely stable and wouldn’t deteriorate because no water vapour can get into the well-sealed processor.
A similar device is being trialled by patients in the UK although this powered by light entering the eye directly rather than images sent from cameras.
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