People who wear reusable contact lenses are about four times more likely to get the sight-threatening eye infection acanthamoeba keratitis (AK) than people who wear daily disposable lenses, says a study published in the journal Ophthalmology.
Researchers say contact lens wearers can easily reduce their risk by not wearing their lenses while swimming or in the shower. They also advise that stickers saying “No Water” be placed on contact lens packages.
Health authorities have seen a rise in AK cases in the United Kingdom and Europe in recent years, the lead author for the study, John Dart of the UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, said in a news release. The infection is rare but still deserves a public health response, he said.
“Contact lenses are generally very safe but are associated with a small risk of microbial keratitis, most commonly caused by bacteria, and which is the only sight threatening complication of their use,” he said. “Given that an estimated 300 million people across the globe wear contact lenses, it is important that people know how to minimize their risks for developing keratitis.”
AK causes the cornea to become inflamed because of infection by acanthamoeba, a cyst-forming microorganism, the news release said. About a quarter of severely affected patients end up with less than 25% of their vision or become blind. About 25% of people require corneal transplants to treat the disease or restore vision.
More than 200 patients from Moorfields Eye Hospital completed a survey, including 83 with AK. They were compared to a control group of 122 people who came to eye care clinics with other conditions.
People wearing reusable soft contact lenses were found to have 3.8 times the chances of developing AK, when compared to people who wore daily disposable lenses, the study said. Showering with lenses increased the odds of AK by 3.3 times, while wearing lenses overnight increased the odds by 3.9 times.
Researchers said 30% to 62% of cases in the U.K. could be prevented if people switched from reusable to daily disposable lenses.
“Basic contact lens hygiene measures can go a long way in avoiding infections, such as by thoroughly washing and drying your hands before putting in your lenses,” Dart said.