New Contact Lenses, Old Infection Risk
Corneal Infections Not More Common With 30-Day Silicone Hydrogel Contact Lenses
Dec. 6, 2005 -- The newest extended-wear contact lenses have a similar risk
of eye infections as older soft lenses worn for fewer nights.
That news is reported in Ophthalmology. It comes from postmarketing
studies funded by CIBA Vision, which makes the silicone hydrogel lenses,
marketed as Night & Day.
The researchers included Oliver Schein, MD, MPH, of Johns Hopkins
University's medical school.
The FDA approved the silicone hydrogel lenses in 2001 for continuous wear
for up to 30 nights.
Older generations of extended-wear contacts had been associated with rare
cases of vision loss and eye infections. That prompted the FDA's 1989 decision
to cut extended wear to seven days.
Years later, silicone hydrogel lenses were developed. Compared with older
lenses, they allow four times as much oxygen to reach the eye. Better oxygen
flow was seen as a way to possibly lower infection risk in the eye's
The FDA ordered postmarketing studies of silicone hydrogel lenses to check
corneal infection rates.
The study included 6,245 people who had been given prescriptions for the
silicone hydrogel lenses. Most (80%) wore their lenses nonstop for at least
During the year-long study, few participants had corneal infections. Two had
corneal infections that led to vision loss. Eight others had corneal infections
that didn't cause vision loss.
Overall, the yearly rate of corneal infections was 18 per 10,000 people, the
That's similar to rates previously reported for conventional, extended-wear
soft lenses worn for fewer consecutive nights, according to the
Researchers' Pecking Order
Schein's team calls contact lenses "very safe" in general, though
they note that contact lenses are associated with some extra risks, compared
They rank the risk of vision loss from eye infection for different types of
- Lowest risk: Rigid, gas-permeable contact lenses for daily wear
- Next-to-lowest risk: Soft contact lenses for daily wear
- Highest risk: Silicone hydrogel contact lenses for extended wear of
However, they're not calling silicone hydrogel lenses dangerous. The odds
appear "reasonable," write the researchers, for people who understand
the risks and want to wear their contacts around the clock.
The study notes that one researcher is a CIBA Vision consultant and one is a
CIBA Vision employee.