Bionic Eyes

Using space technology, scientists have developed extraordinary ceramic photocells that could repair malfunctioning human eyes.

Rods and Cones. Millions of them are in the back of every healthy human eye. They are biological solar cells in the retina that convert light to electrical impulses - impulses that travel along the optic nerve to the brain where images are formed.

Without them, we're blind.

Indeed, many people are blind - or going blind - because of malfunctioning rods and cones. Retinitis pigmentosa and macular degeneration are examples of two such disorders. Retinitis pigmentosa tends to be hereditary and may strike at an early age, while macular degeneration mostly affects the elderly. Together, these diseases afflict millions of people; both occur gradually and can result in total blindness.

"If we could only replace those damaged rods and cones with artificial ones," says Dr. Alex Ignatiev, a professor at the University of Houston, "then a person who is retinally-blind might be able to regain some of their sight."

Years ago such thoughts were merely wishful. But no longer. Scientists at the Space Vacuum Epitaxy Centre (SVEC) in Houston are experimenting with thin, photosensitive ceramic films that respond to light much as rods and cones do. Arrays of such films, they believe, could be implanted in human eyes to restore lost vision.

Image courtesy A. Ignatiev. A schematic diagram of the retina - a light-sensitive layer that covers 65% of the interior surface of the eye. SVEC scientists hope to replace damaged rods and cones in the retina with ceramic microdetector arrays.

"There are some diseases where the sensors in the eye, the rods and cones, have deteriorated but all the wiring is still in place," says Ignatiev, who directs the SVEC. In such cases, thin-film ceramic sensors could serve as substitutes for bad rods and cones. The result would be a "bionic eye."

The Space Vacuum Epitaxy Centre is a NASA sponsored Commercial Space Centre (CSC) at the University of Houston. NASA's Space Product Development (SPD) program, located at the Marshall Space Flight Centre, encourages the commercialisation of space by industry through 17 such projects. At the SVEC, researchers apply knowledge gained from experiments done in space to develop better lasers, photocells, and thin films - technologies with both commercial and human promise.