- Contact lens use has become the leading cause of a type of eye infection in people with otherwise healthy eyes.
- A new study has found that people with reusable contact lenses are more likely to develop a rare, but serious eye infection than those who wear daily disposable lenses.
- Different factors can cause it, including wearing them in the shower, and can result in a sight-threatening infection.
People who wear reusable contact lenses are nearly four times more likely to develop a rare, sight-threatening eye infection than those wearing daily disposables, a new study has found.
Multiple factors increase the risk of acanthamoeba keratitis (AK), including reusing lenses or wearing them overnight or in the shower, say the researchers from University College London.
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AK is a condition that results in inflammation of the cornea. The rare but serious eye infection can result in permanent visual impairment or blindness, explains the US Centers for Disease Control and Prevention (CDC). While it is most common in people who wear contact lenses, anyone can develop the infection, it adds.
"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," lead author, professor John Dart from the UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, says in a university news release.
Dart adds: “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."
AK causes the front surface of the eye (cornea) to become painful and inflamed, explain the authors. The most severely affected typically end up with less than 25% of vision or become blind following the disease and face prolonged treatment. Overall, 25% of people affected require corneal transplants to treat the disease or restore sight.
What they found
The team recruited more than 200 patients from Moorfields Eye Hospital. Each patient was asked to complete a survey, including 83 people with AK. This was compared with a control group of 122 participants who came to eye care clinics with other conditions.
People who wore reusable soft contact lenses (such as monthly pairs) had 3.8 times the odds of developing AK compared to those who wore daily disposable lenses.
Here’s what else they found:
- Showering with lenses increased the odds of AK by 3.3 times.
- Wearing lenses overnight increased the odds by 3.9 times.
- Among daily disposable wearers, reusing their lenses increased their infection risk.
- Having had a recent contact lens check with a health professional reduced the risk.
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Previous studies have linked AK to wearing contact lenses in hot tubs, swimming pools or lakes, but the latest research adds showers to that list, and underlines that “exposure to any water when wearing lenses should be avoided,” says study author, associate professor Nicole Carnt.
Dart believes that all contact lens packaging should include basic information on lens safety, even a simple sticker warning stating 'no water' on each case.
That said, here are important safety tips for taking care of your contact lenses the right way.
- Always wash and dry your hands before handling your contact lenses.
- Before putting in your lenses, check that the edges aren’t torn as that could cut into your eye.
- Replace your contact lenses on schedule: If you generally buy the monthly pairs, ensure you change them every month.
- Change to a new contact lens case when you open a new bottle of solution.
- Remove your lenses when showering, as per the current study’s suggestions.
- Remove your lenses when swimming unless you’re wearing well-fitted goggles. This is because the water you swim in may be contaminated.
- Don’t wear your lenses beyond the recommended wear time.
- Avoid sleeping in your lenses unless your lens type is specifically meant to wear to bed.
- Always use a fresh solution when cleaning your lenses, and never rinse them with tap water.
"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,” says Dart.