Last Updated: 2002-08-21 16:50:14 -0400 (Reuters Health)
By Anne Harding
BOSTON (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.
The 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.
But 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.
Reid reported the findings here Wednesday at the American Chemical Society’s annual meeting.
After 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.
Reid 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.
The 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.
According 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.