May 25, 2000 — A simple vaccine given in the form of nose drops may prevent a serious type of eye infection in people who wear contact lenses, researchers say.
Researchers have developed a vaccination against a bacterium known as Pseudomonas aeruginosa, which is particularly troublesome in contact lens wearers, especially those who use extended-wear and disposable contacts. The bacterium is the most common cause of ulcerative or corneal keratitis, a dangerous infection of the front of the eye.
The experimental vaccine was given to mice in the form of nose drops, say the researchers, who discussed their work at a recent meeting of the American Society for Microbiology. These mice, along with another group that didn’t get the vaccine, were then exposed to the bacterium. The mice who got the vaccine were less prone to developing eye infections caused by P. aeruginosa, the researchers found.
“The development of safe vaccines that are easy to administer, such as nose drops, for potentially destructive conditions such as ulcerative keratitis is what our research may represent,” says one of the researchers, Gerald B. Pier, PhD. “The [most serious] consequence of this infection is the loss of eyesight, which is pretty devastating.” Pier is a professor of medicine in the department of microbiology and molecular genetics at Harvard Medical School and a microbiologist in the department of medicine at Brigham and Women’s Hospital in Boston.
The overall risk of contracting an infection caused by this bacteria is low, occurring in less than 0.2% of contact lens wearers. But because contact lenses are worn by so many people, this translates into 20,000 to 50,000 cases of keratitis annually, Pier says.
William Ehlers, MD, who is in private practice in Torrington, Conn., notes that ulcerative keratitis is the most worrisome complication faced by users of extended-wear lenses.
“In infectious keratitis, the eyes are severely inflamed, with … discharge, and large lesions develop, mainly in the central cornea,” he says. Although the condition is fairly rare, and has been found in people who wear all types of contact lenses, several studies have shown that wearing lenses overnight is a major risk factor, he tells WebMD. “In fact, the condition’s incidence has been reported to be roughly four to 20 times higher with extended-wear lenses.”
Although progress is being made with this vaccine, nothing takes the place of proper handling of contact lenses. For those who want to use extended-wear lenses, experts say, rigorously following the recommendations about wearing, cleaning, and replacing lenses will reduce the chances of infection. Most infections and complications in people who use extended-wear lenses are related to improper and irregular cleaning and disinfection of the lenses.