Washing your face while wearing contact lenses could increase your chances of getting a potentially blinding eye infection. And the risk is greatest in the UK, according to a leading eye specialist.
The culprit in question is a free-living, water-borne amoeba called Acanthamoeba, which can cause severe ulcerations of the cornea – a condition called Acanthamoeba keratitis. The disease is rare but extremely painful and can lead to blindness.
“It’s a ghastly disease,” says John Dart, an ophthalmologist at Moorfields Eye Hospital in London. “It’s very resistant to treatment and difficult to eradicate.”
Contact lens wearers are most susceptible. Only around one in 30,000 contact lens users in the UK contracts the disease. But this rate is 15 times as high as in the US, and seven times as high as it is in the Netherlands.
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Unique plumbing
Dart wondered if the UK’s unique plumbing was to blame for the unusually high rate. Until recently, regulations required all homes to have a cold-water storage tank. Dart suspected that because the water in these tanks is stagnant, the tanks could be a breeding ground for Acanthamoeba.
To test the link, Dart and his colleagues analysed the mitochondrial DNA of Acanthamoeba found in eight patients and in their water supplies. In six of these cases the organisms were identical, indicating that the water supply was the source of the infection.
Although some patients admitted to occasionally storing lenses in tap water or contaminating their contact lens cases with it, Dart believes the greatest risk comes from washing while wearing lenses or handling lenses with wet hands.
He recommends that people keep tap water away from their eyes when they are wearing contact lenses.
Journal reference: Investigative Ophthalmology & Visual Science (vol 45, p 165)
