Reusable contact lenses more than triple risk of rare eye infections that threaten vision, study finds | UK News


Wearers of reusable contact lenses are almost four times more likely to contract a rare, vision-threatening eye infection than those who wear daily disposables, according to a new study.

Acanthamoeba keratitis (AK) is a type of corneal infection and condition that leads to inflammation of the cornea — the eye’s clear outer protective layer.

The study, led by the UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, identified several factors that increase AK risk, including reusing lenses or wearing them overnight or in the shower.

More than 200 patients at the hospital completed a survey, including 83 people with AK and 122 who attended eye clinics with other conditions.

Researchers found that people who wore reusable soft contact lenses — like monthly disposables — were 3.8 times more likely to develop AK compared to people who wore daily disposables.

Showering with lenses increased the odds of AK by 3.3 times, while wearing lenses overnight increased the odds by 3.9 times.

Researchers estimate that 30-62% of cases of the condition in the UK, and possibly many other countries, could be prevented if people switched from reusable to daily lenses.

They suggested that people should not wear their contact lenses while swimming or showering, and that the packaging should include “no water” stickers.

While vision loss from infection is uncommon, Acanthamoeba, although a rare cause, is one of the most serious and is responsible for about half of contact lens wearers who develop vision loss after keratitis.

Around 90% of AK cases are associated with preventable risk, although the infection remains rare, affecting less than 1 in 20,000 contact lens wearers per year in the UK.

The most affected patients – a quarter of the total – end up with less than 25% of their vision or become blind.

Overall, 25% of those affected require corneal transplants to treat the disease or restore vision, the study found.

Lead author Professor John Dart said: “In recent years we have seen an increase in Acanthamoeba keratitis in the UK and Europe and while the infection is still rare it is preventable and requires a public health response.

“Contact lenses are generally very safe but carry a low risk of microbial keratitis, most commonly caused by bacteria and the only sight-threatening complication of their use.

“With an estimated 300 million people wearing contact lenses around the world, it’s important that people know how to minimize their risk of developing keratitis.”

The study, published in Ophthalmology, was funded by Fight for Sight, the NIHR Moorfields Biomedical Research Center and the Moorfields Eye Charity.

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