people who use contact lenses reusable are almost four times more likely to develop Acanthamoeba keratitisa rare sight-threatening eye infection, than those who wear daily disposable lenses, according to a study led by researchers at University College London and Moorfields Eye Hospital.
The case-control study, published in Ophthalmology, identifies several factors that increase the risk of this pathology, a type of microbial keratitis that causes inflammation of the cornea (the transparent protective outer layer of the eye) and requires intensive treatment and even a cornea transplant, leaving serious sequelae in vision. Among the habits that can increase the chances of suffering from it are lens reuse or its use during night or in the shower.
“In recent years, we have seen a increased keratitis by Acanthamoeba in the UK and Europe, and although infection is still rare, it is preventable and in need of a public health response,” said lead author Professor John Dart, from the UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS. Foundation Trust.
“Contact lenses are generally very safe, but they are associated with a small risk of microbial keratitis, usually caused by bacteria, which is the only sight-threatening complication of contact lens wear. With approximately 300 million people worldwide wearing contact lenses, it’s important for people to know how to minimize the risks of developing keratitis,” adds Dart.
Vision loss from microbial keratitis is uncommon, but Acanthamoeba, although a rare cause, is one of the most serious, accounting for about half of contact lens wearers who develop vision loss after keratitis. 90% of cases are associated with avoidable risks, although the infection remains rare, affecting fewer than 1 in 20,000 contact lens wearers a year in the UK.
Acanthamoeba keratitis causes the front surface of the eye, the cornea, to be sore and inflamed due to infection with Acanthamoeba, a cyst-forming microorganism. The most severely affected patients (a quarter of the total) end up with less than 25% vision or go blind after the disease and face prolonged treatment. Overall, one in four affected people require corneal transplants to treat the disease or restore vision.
For the study, the researchers recruited more than 200 Moorfields Eye Hospital patients who completed a survey, including 83 people with this condition, and compared them with 122 participants who attended eye care clinics with other conditions, acting as a group of control.
People who wore reusable soft contact lenses (such as monthly ones) were 3.8 times more likely to develop Acanthamoeba keratitis, compared to people who wore daily disposable lenses. Showering with contact lenses increased the odds by 3.3 times, while wearing contact lenses at night increased the odds by 3.9 times. Among daily disposable contact lens wearers, reuse increased the risk of infection. In contrast, having had a recent lens check-up by a health professional lowered the risk.
A recent study led by Professor Dart found that this type of keratitis is increasing in prevalence in the UK. Reviewing incidence data from Moorfields Eye Hospital from 1985 to 2016, he and his team found an increase from 2000-2003, when it went from eight to 10 cases per year to between 36 and 65 cases per year at the end. of the study period.
“Previous studies have linked Acanthamoeba keratitis to contact lens wear in Jacuzzis, pools or lakes, and here we’ve added showers to that list, stressing that exposure to water should be avoided when wearing lenses. Public swimming pools and coastal authorities could help reduce this risk by advising against swimming with contact lenses,” explains Associate Professor Nicole Carnt, from the UCL Institute of Ophthalmology and Moorfields Eye Hospital, and first author of the study.
In Dart’s opinion, “the contact lens box should include information on risk prevention, even something as simple as contact lens stickers. ‘no water’ in each case, considering that many people buy their lenses online without talking to a health professional«. In addition, the main author of the study reminds that taking the basic hygiene measures when wearing contact lenses can go a long way in preventing infections, “such as wash and dry hands thoroughly before putting on the contact lenses.