Implant may help blind to see

The chip will be implanted into volunteers

By Dr David Whitehouse BBC News Online science editor

US scientists are developing a light-sensitive chip that will be implanted into the eyes of blind people to restore some of their vision.

The goal is to allow people suffering from certain forms of blindness, such as age-related macular degeneration and retinitis pigmentosa, to see 1,000 points of light through 1,000 tiny electrodes positioned on their retinas.

People who are blind will see

Kurt Wessendorf, Sandia Labs

These diseases damage the rod and cone cells that convert light into electrical impulses, but leave intact the neural paths to the brain that relay those signals.

By stimulating those cells, scientists hope that patients will be able to perceive some light and have some useful vision.

"Our aim is to bring a blind person to the point where he or she can read, move around objects in the house, and do basic household chores," said project leader Kurt Wessendorf, of the Sandia National Laboratories in the US.

"They won't be able to drive cars, at least in the near future, because instead of millions of pixels like normally sighted people, they'll see approximately a thousand. The images will come a little slowly and appear yellow. But people who are blind will see."

Conjunction of materials

The idea is to use a tiny camera and radio-frequency transmitter in the frame of a pair of spectacles to transmit information and power to chips placed within the eyeball. The chips will be linked to retinal nerves that will send electrical impulses to the brain for processing.

Dean Cole of the US Department of Energy's Office of Biological and Environmental Research in Washington, DC, said: "We felt that blindness is a devastating problem and that the modern conjunction of materials science with micro- and nanotechnologies in our multidisciplinary national labs offers possibilities for advances where before people had hit brick walls."

The electronic chip will be attached to the retina and will be able to stimulate nerve endings that will produce images good enough to read large print and to distinguish between objects in a room.

"Compared to the elegance of the original biological design, what we're doing is extremely crude," said Wessendorf.

"We'll use a crude, shotgun approach that fires groups of nerves. In the long run, of course, we'd like to stimulate each individual nerve," said Sandia researcher Mike Daily.

A 10-by-10 electrode array is currently being developed; a 33-by-33 array will be constructed next year.

"Integrating microdevices into the human eye is incredibly challenging because of the need for high-reliability operation over decades in a saline environment," said Mike Daily.

Over a five-year period, said Dean Cole, the project would begin with goggles and move in the direction of corneal implants, aiming if all goes well to prepare five patients for the procedure before the project's end.