Newer Contact Lenses Don't Cut Infections
Daily Disposables, Newer Materials Have Not Reduced Infection; Overnight Wear Increases Risk Most, Studies Show
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Contact Lenses & Infection Risk: The U.K. Study continued...
''Gas-permeable lenses are safer than any other type of lenses,'' Dart says,
although he adds that they are not a popular choice among contact lens wearers,
who tend to find them uncomfortable.
Even though the daily disposable wearers had more risk of infection than
those who wore reusable soft lenses, vision loss from the infection was less
likely to occur in the daily disposable lens wearers. None of the daily
disposable lens wearers lost vision beyond 20/40, he says.
"It's safer to use a daily disposable [than a reusable]," Dart says,
"because the type of bugs you get are less nasty." Reusable lenses must
be disinfected and stored, and "lens cases harbor nasty bacteria in some
patients," he says.
Some brands were associated with more infections than others, Dart found,
but he says most of the contact lenses he studied have probably been redesigned
since the study was done.
Contact Lenses & Infection Risk: The Australian Study
In the second study, a team led by Fiona Stapleton, PhD, of the University
of New South Wales, interviewed 285 contact lens wearers who had microbial
keratitis and 1,798 lens wearers without the infection.
After looking at the type of lenses worn, wearing patterns, and other
factors, they estimated the annual incidence for the infection.
They also found that new lens materials haven't reduced infection. Overnight
use was the strongest risk factor for infection, just as in the U.K. study.
For instance, they estimate that microbial keratitis occurred in 1.2 per
10,000 of those who wore daily-wear rigid gas-permeable lenses but in 25.4 per
10,000 of those who wore silicone hydrogel lenses overnight.
Other factors that increased the risk of infection included smoking, buying
lenses over the Internet, wearing lenses beyond the recommended time spans, and
improper hand cleaning before handling lenses.