PORTLAND, Ore. October 9, 2006, /EurekAlert/ -- Traditional assumptions
have held that contact lenses are safer than laser surgery to correct
vision problems. Now, an Oregon Health & Science University Casey
Eye Institute physician, comparing data from several recent studies,
has found that belief may not be true.
William Mathers, M.D., professor of ophthalmology in the OHSU School
of Medicine, reviewed several large, peer-reviewed studies and found
a greater chance of suffering vision loss from contact lenses than
from laser vision correction surgery, also known as "refractive"
surgery. His findings are published in a letter in today's issue
of Archives of Ophthalmology.
"Several times a year, I have patients who lose eyes from complications
because they've been wearing contacts and they've gotten an infection.
By this I mean their eyes have to be physically removed from their
bodies," said Mathers, an eye surgeon with a strong background in
contact lens issues and former president of the Contact Lens Association
of Ophthalmologists. "It's not that contacts aren't good. They're
better than they've ever been. But one cannot assume contacts are
safer."
The risks associated with laser surgery versus contact lenses can
not be compared directly, partly because complications from contact
lenses accumulate over years of use, and complications from surgery
occur soon after the surgery.
Data extrapolated from a study in Lancet shows the lifetime risk
of bacterial keratitis to be 1 in 100 for contact lenses worn daily.
Bacterial keratitis is an infection that causes an inflammation
of the cornea and can lead to vision loss. Wearing contact lenses
overnight or improper care or cleaning further increases the risk
of infection from contacts. The risk of bacterial keratitis has
changed little over the years for contact lens wearers and is the
same worldwide.
Vision loss from laser surgery is easier to calculate. Mathers looked
at a large study of military personnel who had laser surgery and
found results similar to those of the OHSU Casey Vision Correction
Center.
A study of more than 32,000 U.S. Armed Forces members receiving
laser surgery published in the journal Ophthalmology found a loss
of vision of one line on an eye chart was 1 in 1,250. A loss of
two or more lines of vision, which would be more significant, but
less frequent, was not reported. Data from the OHSU Casey Vision
Correction Center showed no cases of vision loss greater than two
lines in 18,000 procedures performed over 10 years.
"Even with perfect care of your contacts, the risks for infection
and vision loss are still there," said Mathers. "Our long-term results
at OHSU confirm the experience of the U.S. military: Laser surgery
is as safe, and probably safer, than long-term use of contact lenses."
The calculated risks of vision loss from contact lenses and laser
surgery are approximate and subject to change. Highly oxygen-permeable
contact lenses and advances in laser surgery should make both even
safer. There are approximately 20 million to 25 million contact
lens wearers in the United States, and approximately 1 million people
in the United States have laser surgery every year.
"Data from these studies strongly suggest our intuition regarding
these risks needs to be reassessed," Mathers said. "I, for one,
look forward to further investigations of these risks."
