Contact lens wear safe, despite rise in infections, physician says

CHICAGO — Contact lens wear remains relatively safe, even as cases of infectious keratitis continue to rise, according to a speaker here.

"Although Acanthamoeba is on the rise, it still represents a small percentage of cases of infectious keratitis with contact lenses," Elmer Tu, MD, said at the American Society of Cataract and Refractive Surgery meeting. "They were considered safe before, and they should still fit that definition now."

Dr. Tu said that cases of infection have risen despite the global recall of Complete MoisturePlus Multi-Purpose Solution (Advanced Medical Optics), which was suspected of causing several keratitis outbreaks.

After that recall, there was a drop in keratitis cases, but a subsequent outbreak in Chicago made researchers question whether other modifiable risk factors might also play a role in further outbreaks.

"Interestingly, at the same time there was an EPA rule change concerning water disinfection implemented first here in Chicago," Dr. Tu said. "We hypothesized that this may be related."

There is a wide variation in keratitis incidence estimates, with the original being two per million contact lens users per year, Dr. Tu reported. Some studies indicate that number may be as high as 100 per million. In Chicago, it was around 20 per million in 2007 and expected to be around 30 per million this year, Dr. Tu said.

"There are changing risk factors for microbial keratitis in contact lens wear that exists in a complex and changing landscape," Dr. Tu said. "There are external factors including hygiene, habits and environment. Contact lens materials are changing, as well as tear systems. The changes are not always for the better."