Contact lens wearers everywhere need to be on the lookout for a rare, but potentially blinding, eye infection, British researchers warn.
In southeast England, cases of the infection, called Acanthamoeba keratitis, have tripled since 2011, a new study found.
The illness is typically tied to poor contact lens hygiene use.
The infection combines a tiny single-cell amoeba with the bacteria keratitis. Once the eye is infected, it causes the the cornea to become painful and inflamed due to this cyst-forming microorganism.
For one in every four of people infected, the disease results in a loss of most of their vision or blindness and they face prolonged treatment, the research team said.
While rare, outbreaks have also occurred in the United States, one ophthalmologist said.
"There have been a few outbreaks in the U.S., most notably from improper disinfection of contact lenses," said Dr. Jules Winokur, who practices at Lenox Hill Hospital in New York City. He wasn't involved in the new study.
"In clinical practice, we see cases of acanthamoeba on a regular basis, " he said. "Most often, these cases present in patients wearing contact lenses who have been exposed to contaminated water, which could be from swimming pools, water parks or even showers at home."
"The treatment of acanthamoeba can be prolonged and difficult," Winokur explained. "Toxic medications and even corneal transplantation may be necessary treatments."
The British study was led by Dr. John Dart, from University College London's Institute of Ophthalmology. His team collected data on patients seen from 1985 to 2016 at Moorfields Eye Hospital.
They found an increase in cases of the disease from the eight to 10 a year seen in 2000 -2003, to 36 to 65 cases per year more recently.
Overall, 25 percent of those affected required corneal transplants to treat the disease or restore vision, the researchers said.
Dart's team also conducted a second study, this time in people who wore reusable contact lenses daily. The study compared those 63 diagnosed with Acanthamoeba keratitis with 213 people who went to the eye hospital for any other reason.
Dart's group found that the risk of developing the disease was more than three times greater among people with poor contact lens hygiene. This means people who didn't always wash and dry their hands before handling their lenses, or those who used a now discontinued disinfectant product containing Oxipol.
In addition, people who wore their contacts in swimming pools or hot tubs were also at risk, as were those who showered or washed their face while wearing their lenses, the study found.
"People who wear reusable contact lenses need to make sure they thoroughly wash and dry their hands before handling contact lenses, and avoid wearing them while swimming, face washing or bathing," Dart said.
"Daily disposable lenses, which eliminate the need for contact lens cases or solutions, may be safer and we are currently analyzing our data to establish the risk factors for these," he added in a university news release.
Dart stressed that "this infection is still quite rare, usually affecting fewer than 3 in 100,000 contact lens users per year in South East England, but it's largely preventable."
"This increase in cases highlights the need for contact lens users to be aware of the risks," he added.
Dr. Matthew Gorski is an ophthalmologist at Northwell Health in Great Neck, N.Y. He agreed that proper contact lens hygiene could prevent most cases of Acanthamoeba.
According to Gorski, that includes:
  • Washing your hands with soap and water before handling contacts.
  • Properly disinfecting, cleaning and storing your contacts, including never using tap water to clean contacts.
  • Removing contacts from your eyes before water exposures such as swimming, showering or bathing.
  • Removing contacts immediately and seeing your eye doctor if you have any eye pain, sensitivity to light, red eye or change in vision.