SCIENTISTS from NASA have built a bionic eye that could restore sight to the blind.An artificial retina has been developed which uses implanted arrays of 100,000 tiny solar cells, each only 1/20 the thickness of a hair, in an attempt to replace damaged rod and cone cells in human retinas. The first bionic eyes will be given to volunteers next year.
In healthy eyes, the retina’s rods and cones convert light into electrical impulses that travel along the optic nerve to the brain, where images are formed.
But, Dr Alex Ignatiev, a professor at the University of Houston, said: "There are some diseases where the sensors in the eye have deteriorated but all the wiring is still in place.
"If only we could replace those damaged rods and cones with artificial ones, a person who is retinally blind might be able to regain some of their sight."
Diseases like retinitis pigmentosa, which tends to be hereditary and can strike at any age, and macular degeneration - which mostly affects the elderly - results in millions of people losing their sight. Ceramic-thin film microdetectors, built atom-by-atom and layer-by-layer using a technique called epitaxy, which was developed aboard the space shuttle, offer new hope to the victims of these diseases.
The arrays are stacked in a hexagonal structure mimicking the arrangement of the rods and cones they are designed to replace.
At five microns, individual ceramic detectors are exactly the same size as human cone cells, and will allow nutrients to flow freely around them.
Earlier attempts to build artificial rods and cones failed because the photodetectors were both too large to allow for normal irrigation, and were made of silicon, a toxin that reacts unfavourably with fluids in the eye.
This new generation of cells gets round both problems - but they are so small that surgeons can’t safely handle them. Each 100,000-cell array has to be attached to a millimetre-square polymer film, which will dissolve away within a fortnight or so, leaving the detectors in place.
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