About two dozen vision-aiding electronic devices are under development worldwide. In addition to microchips, they include video cameras mounted on eyeglasses or even implanted in the eye. Narfstrom's surgical skills had been sought by a number of the groups competing to develop bionic visual devices before she agreed to collaborate with Optobionics of Naperville, Ill.
"I considered the others' methods too invasive," she says. "Some required wires that came out of the eyes."
The Optobionics chips are tiny, just two millimeters in diameter and 37 microns thick, or about one third the thickness of a human hair. Narfstrom hopes that eventually the chips can be implanted routinely in the eyes of people with retinal diseases such as retinitis pigmentosa.
RP is a hereditary disorder that affects about one in every 4,000 people. It causes the progressive deterioration of the retina's photoreceptor cells, called rods and cones, which turn light into electrical current. As their retinal cells die, people with RP first lose peripheral and night vision, then lose their sight entirely.
Many of Narfstrom's Abyssinians have a genetic trait that leads to a condition similar to retinitis pigmentosa, making them ideal test subjects for the microchips.
The chips contain thousands of miniature solar cells that turn light into electrical current. These receptors may be able to serve as stand-ins for lost rods and cones. But early studies show that they may have even further benefits for people with RP. They seem to actually slow progression of the disease.
"It appears that there is a neuroprotective effect," Narfstrom says. "The theory is that the electrical current can stimulate growth factors in the retina so that the cells live longer."
So far, an early version of the chip has been implanted in 30 people. Published results on the first six are promising. Some of these patients found they could read more lines on an eye chart. Most could perceive colors for the first time since their vision had gone into decline; they could see the vivid green of a lawn or the bright red and white checks on a tablecloth.
The chips have continued to evolve, and that's where Narfstrom and her cats come into play. Each new generation of the chip has to be tested first on animals. Surgical techniques have to be perfected.
Narfstrom's brood of Abyssinians has been an important part of her career for the past 30 years. They have been used across the world in research projects on the structure and electrophysiology of the retina. Cinnamon, one of her Abyssinians, became a celebrity two years ago when she was selected by the National Human Genome Research Institute to be the genetic model representing house cats worldwide. Narfstrom expects the genome data assayed from the small blood and tissue samples that Cinnamon donated to be published soon.
Published by the Office of Research.
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