Reusable contact lenses linked to three-fold risk of acanthamoeba keratitis

New research published in Ophthalmology has identified several factors that can increase an individual’s risk of developing acanthamoeba keratitis (AK).

AK is an extremely rare condition that affects fewer than one in 20,000 contact lens wearers per year in the UK. Nine in ten cases are associated with avoidable risks.

Scientists from UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust highlighted that reusable contact lens wearers had a 3.8 times greater risk of developing AK when compared to daily disposable contact lens wearers.

Among daily disposable contact lens wearers, the researchers identified behaviours that elevated an individual’s risk of AK.

Showering in contact lenses was associated with a three-fold greater risk of infection compared with a daily disposable contact lens wearer who does not shower in their lenses.

Reusing daily disposable contact lenses was linked to a five-fold increase in risk while wearing daily disposable lenses overnight was connected with a close to four-fold (3.93) increase in risk.

The most significant modifiable risk factor among daily disposable contact lens wearers was the frequency of professional follow up visits – with less frequent visits associated with a 10-fold increase in the risk of contracting AK.

The study authors estimated that between 30% and 62% of AK cases could be prevented by switching from reusable contact lenses to daily disposable contact lenses.

The research involved recruiting more than 200 patients from Moorfields Eye Hospital to complete a questionnaire, including 83 people with AK. A group of 122 patients who came to eye care clinics with other conditions acted as a control group.

Lead author, Professor John Dart, highlighted that while AK is a rare condition, there has been an increase in the number of infections in recent years within the UK and Europe.

“Given that an estimated 300 million people across the globe wear contact lenses, it is important that people know how to minimise their risks for developing keratitis,” he said.