Saturday, June 30, 2007

Cat's Eye Implants May Help Humans See

In "Star Trek: The Next Generation," Geordi La Forge is a blind character who can see through the assistance of special implants. While the Star Trek character "lives" in the 24th century, people existing in the 21st century may not have to wait that long for this illuminating technology. Kristina Narfstrom, a University of Missouri, Columbia, veterinary ophthalmologist, has been working with a microchip implant to help blind animals "see." She indicates that the preliminary results are promising.

"About one in 3,500 people worldwide is affected with a hereditary disease, retinitis pigmentosa, that causes the death of retinal cells and, eventually, blindness.

"Our current study is aimed at determining safety issues in regard to the implants and to further develop surgical techniques," Narfstrom explains. "We also are examining the protection the implants might provide to the retinal cells that are dying due to disease progression with the hope that natural sight can be maintained much longer than would be possible in an untreated patient."

Narfstrom is involved primarily with Abyssinian and Persian cats that are affected with hereditary retinal blinding disease. The cat's eye is a good model to use for this type of research because it is very similar to a human eye in size and construction, so surgeons can utilize the same techniques and equipment. Cats also share many of the same eye diseases with humans. The Abyssinian cats that Narfstrom is working with typically start to lose their sight when they are around one or two years old and are completely blind by age four.

During surgery, Narfstrom makes two small cuts in the sclera, the outer wall of the eyeball. After removing the vitreous, which is the gelatinous fluid inside the back part of the eyeball, Narfstrom creates a small blister in the retina and a tiny opening, large enough for the microchip, which is just two millimeters in diameter and 23 micrometers (one-millionth of a meter) thick. The chip includes several thousand microphotodiodes that react to light and produce small electrical impulses in parts of the retina.

"We are really excited about the potential uses for this technology and the potential to create improved vision in some of the millions of people affected worldwide with retinal blindness," Narfstrom relates. "This technology also may be beneficial for pets that have similar diseases because this technology can benefit both animals and humans."

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