coat shoos bugs away from contact lenses
Updated: 2002-08-21 16:50:14 -0400 (Reuters Health)
(Reuters Health) - An inexpensive coating made from the mineral
selenium can keep contact lenses virtually bacteria-free without
irritating the eyes or interfering with the lenses' corrective powers,
a Texas researcher reported here Wednesday.
last big problem for contact lenses, says Dr. Ted Reid of Texas
Tech University Health Sciences Center in Lubbock, is the adhesion
of bacteria to the lens surface. "This is still a very serious
problem," he said. Bacteria can form stubborn coatings called
biofilms on the lenses, and infection can damage the cornea and
even lead to blindness.
Reid has found--in research involving rabbits and his own eyes--that
selenium coating on contact lenses almost completely prevented bacteria
from attaching to the lens surface. This coating kills bacteria,
Reid noted, but doesn't damage eye tissue. After two months of constant
lens wear, the rabbits showed no sign of eye irritation. Because
the coating is only one molecule thick, Reid said, it shouldn't
interfere with vision.
reported the findings here Wednesday at the American Chemical Society's
completing the tests in rabbits, Reid popped a control contact lens
in his own eye and a selenium-coated lens in the other. He kept
the lenses in for a week, then removed them and placed them in a
lab dish. After four days, he reported, the non-coated lens was
covered in a thick film of bacteria, while the coated lens had only
three bacteria on its surface.
points out that the coating--which is applied by dipping the object
into the selenium material--could be used on other medical materials
to prevent bacterial infection. Reid, who holds six patents on the
coating, said he is in discussions with two contact lens companies,
as well as makers of heart valves.
coating, he added, would not be expensive. He said he expects contact
lens manufacturers would use it as a marketing advantage rather
than charging extra for it.
to Reid, the lenses could be used for three months straight and
perhaps longer. So far the material is long-lived; he said it has
survived in his lab for two years.
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