The study involved rabbits. The coating: an extremely thin layer of selenium, a naturally occurring element found in soil, some plants and many foods we eat.
The rabbits showed no ill effects after two consecutive months of wearing the coated lenses, according to Ted Reid, Ph.D., of Texas Tech University Health Sciences Center in Lubbock, Texas, who presented the findings at the 224th national meeting of the American Chemical Society, the world's largest scientific society.
Selenium, which is essential to our diet and immune system, kills bacteria by forming something called superoxide radicals. "It's a natural mechanism we use in our body to kill bacteria," Reid emphasized. "That's why we've had these contact lenses on rabbit eyes for two months and seen no affect whatsoever on the eye."
"I'm ready to put them in my eyes right now," Reid declared.
Nearly all extended wear contact lenses require the wearer to remove them at least weekly for cleaning and disinfection. The U.S. Food and Drug Administration (FDA) so far has approved only two brands that can be left in for up to 30 days. The selenium coating would let people keep their contacts in for at least two months, according to Reid.
The selenium coating is only one molecule thick and does not interfere with the ability of the contact lens to let in oxygen, or its prescription, Reid said. Nor is there any leaching of the selenium, he added. Even if it did, it's not a problem, according to Reid.
"Let's suppose all the selenium came off. The amount of selenium that's on this device is probably .01 percent of what you had for lunch. We're talking miniscule amounts."
Coating the lens is simple, Reid noted. "You just dip the contact lens into
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21-Aug-2002