People who wear contacts every day may have greater risk of vision loss than people who have laser surgery to correct their vision, a new study at Oregon Health & Science University's Casey Eye Institute concludes. The study has significant implications for the 36 million contact lens wearers in the United States and the more than 1 million people who have laser surgery each year.
"If you wear your lenses daily for more than 15 years, you are better off with laser surgery," said William Mathers, M.D., professor of ophthalmology at Casey Eye Institute. "And if you use extended-wear lenses and leave them in over night, your risk goes up dramatically." People who wear Rigid Gas Permeable contacts, which allow oxygen to reach the eye, are the exception. RGP contacts are worn only by a small percentage of people in the United States.
Mathers and Hall T. McGee, M.D., a physician in Pittsburgh, conducted the research. They compared results from a U.S. Army analysis of laser surgeries on more than 32,000 eyes with several large epidemiological studies of contact wearers who developed infectious keratitis and suffered vision loss. The results of the study were published in the current issue of the Journal of Cataract Refractive Surgery.
The risks of contacts are not generally appreciated, Mathers said. Contact lenses interfere with the flow of tears over the eye, which flushes bacteria away. As a result, the lenses are subject to bacterial contamination that can damage vision.
"Thousands and thousands of people have gotten infections from contact lenses," Mathers said. "This is a major public health issue."
The statistics about contacts have not changed during the last 20 to 30 years. Laser surgery, meanwhile, has improved. This doesn't mean laser surgery always is better. "Laser isn't perfect," Mathers said. "And it is surgery. But it is not correct to say, 'Just wear contacts and you'll be OK.'"