A  retinal implant has given a brief glimpse of light to a small number of  blind people, and could one day be a common treatment for vision loss  due to injury or disease.

Shawn Kelly, a senior systems scientist at Carnegie Mellon University, has developed a computer chip that translates camera images into electrical pulses that the nerves inside the brain can understand. The result is vision.

The cameras are incredibly small and mounted to a pair of glasses. The digital  information picked up from the camera is sent along a wire to a thin  film surgically implanted in the back of the patient's eye, between the  sclera and the retina. The electrical signals stimulate the nerves in  the retina, and that allows the patient to see. The system is powered  via induction -- not much current is necessary since the electric field  doesn't have to penetrate far into the head.

It's a far cry from the bionic eyes of science fiction, though. The  resolution is only 256 pixels total, because that's how many electrodes  can be made to fit on the back of the film. A typical digital camera has  resolutions measured in millions of pixels and ordinary human vision  involves approximately 1 million nerves, and more than 100 millon rod  and cone cells. But it is something.

"At 256 we start to get some function back to people," Kelly told  Discovery News.  He said people who tested the system reported the  ability to see some shapes and light and dark regions. The tests were  not "field tests" in real-world conditions, but situations where the  implant was used for a few hours and then removed.

There have been other proposals for retinal implants. Recent work in Britain used a self-powered retinal implant that  is powered by light that enters the eye rather than the external  glasses. At the Uniersity of Tubingen in Germany, another project  involves an implant that has a 1,500 pixel resolution that is inserted on the front of the retina. That too, requires a pair of glasses.

Kelly said the difference with his design is that the processor is  sealed well enough that no water vapor gets inside. Ordinarily the  liquids in the eye (and the body generally) are in chemical equilibrium,  but any implanted device with wires has spaces in it that can allow  small amounts of vapor to form, which can reduce the implant's  effectiveness." We have more intelligence in the eye," Kelly said. "Ours  is designed to be stable long term."

One kind of blindness that will be targeted with this device is  retinitis pigmentosa, a hereditary disease that destroys the cells in  the eye that recieve light. Military veterans could also be helped.  (Kelly recently recieved a $1.1 million grant from the Department of Veterans' affairs). Some veterans of World War  II and Korea suffer from age-related macular degeneration. Others had  their eyes damaged by laser rangefinders, Kelly said. The lasers (which  are far more powerful than barcode scanners or CD players) can injure the eyes in a way that causes damage later in life.

This story was provided by Discovery News.