UIC investigates eye infections tied to contact lens use

The use of a particular contact lens solution has a strong association with Acanthamoeba keratitis, a rare severe eye infection, report researchers at the University of Illinois at Chicago in a study published online this week by the American Journal of Ophthalmology.

AK is an often severe, painful infection of the cornea that commonly causes corneal scarring and sometimes blindness.

"We began to look for possible contact lens-related causes for the sharp increase in cases, all in contact lens wearers, in this previously rare infection," said Charlotte Joslin, assistant professor of ophthalmology and visual sciences at UIC and principle investigator in the study. "In the last three and half years we have seen 63 cases of the infections, compared to the two or three cases a year we would normally expect to see."

In their study, the researchers compared 38 AK patients with 100 controls, all of whom were UIC clinic patients between 2003 and 2006. All participants were asked to fill out a survey.

Survey questions focused on the six-month period prior to symptoms and targeted three areas: water exposure; contact lens hygiene, including solutions and lens types; and other habits associated with contact lens use. Participants were provided with color images of the contact lens solution bottles to help them recall what type they had used.

Among soft contact lens wearers, participants with AK were significantly more likely to report having exclusively used AMO Complete MoisturePlus than the control group (55.2 percent vs. 10.5 percent).

"The results correlated with previously published laboratory studies that showed that Acanthamoeba is largely resistant to contact lens solutions in general and to Complete MoisturePlus in particular," said Dr. Elmer Tu, associate professor of clinical ophthalmology, who is also involved with the study.

In their voluntary recall, the company emphasized that there is no evidence to suggest that today’s voluntary recall is related to a product contamination issue.

The researchers also found a statistically weak association between three other contact lens use factors and infection: reusing solution, rubbing the lenses when cleaning them, and showering with lenses on.

"Showering can scatter water-borne microbes into a mist and increase exposure to the microbe that causes the infection," said Joslin. Reusing solutions and not rubbing lens when cleaning and storing them could also result in more exposure to the microbe.

Because these factors are associated with an increased likelihood of infection and this is the second very recent outbreak of an extremely rare eye infection, the researchers emphasize that it is important to look for additional causes behind the outbreak of this infection and to evaluate whether changes in the water supply may be contributing to this increase in disease.

For instance, Joslin said, recent Environmental Protection Agency regulations that decrease the levels of disinfectant in the water supply may have led to an increase in the microbial load that contact lens solutions must kill in order to prevent disease.

"Our results demonstrate that the use of AMO Complete MoisturePlus Multi-Purpose Solution is strongly associated with AK disease -- but it was not a factor in nearly 40 percent of cases," Joslin said.

The UIC researchers alerted the Illinois Department of Public Health to the outbreak in 2006, which in turn informed the U.S. Centers for Disease Control and Prevention.

Source: University of Illinois at Chicago

Related stories:

'Deadly dozen' reports diseases worsened by climate change
Health experts from the Wildlife Conservation Society today released a report that lists 12 pathogens that could spread into new regions as a result of climate change, with potential impacts to both human and wildlife health and global economies. Called The Deadly Dozen: Wildlife Diseases in the Age of Climate Change, the new report provides examples of diseases that could spread as a result of changes in temperatures and precipitation levels. The best defense, according to the report's authors, is a good offense in the form of wildlife monitoring to detect how these diseases are moving so health professionals can learn and prepare to mitigate their impact.
Study: Lasik safer than contact lenses
Portland, Ore., researchers have said contact lens users are more likely than Lasik surgery patients to develop complications leading to further vision loss.
'Crabby' compound that skewers bacteria could prevent medical implant infections
A chemical compound found in crabs and shrimp that has long been known to have certain medicinal value also can act like a "bed of nails," fending off microbes seeking to colonize wound dressings, catheters and other implantable medical devices, according to Montana State University researchers. Using the compound to coat these medical devices, they say, could help prevent thousands of bacterial and yeast infections annually.
Lens solution blamed for eye infection
A U.S. agency and eye doctors reportedly agree the ReNu With Moisture Loc contact lens solution alone was responsible for an eye infection outbreak this year.
Moistureloc removed from worldwide market
MoistureLoc contact lens solution was permanently removed from worldwide markets, effective immediately, Bausch & Lomb announced Monday.
Eye infection cases reported in Europe
Bausch & Lomb, based in Rochester, N.Y., reportedly has confirmed "a handful" of cases of eye infection in Europe among its ReNu contact lens solution users.
Controlling light with sound: new liquid camera lens as simple as water and vibration
New miniature image-capturing technology powered by water, sound, and surface tension could lead to smarter and lighter cameras in everything from cell phones and automobiles to autonomous robots and miniature spy planes.
Keeping an eye on intruders
Electronic fingerprinting, iris scans, and signature recognition software are all becoming commonplace biometrics for user authentication and security. However, they all suffer from one major drawback - they can be spoofed by a sufficiently sophisticated intruder. Writing in the International Journal of Biometrics, Japanese researchers describe a new approach based on a person's reflexes that could never be copied, forged, or spoofed.

News discussion:

Medicine & Health news