Like a lot of people who don’t want to wear glasses, Charlotte Clarkson, 24, thought corrective lenses, which reshape the front of the eye while you sleep so you can see better by day, were the perfect way to improve her short-sightedness.
But one evening she put them in with slightly damp hands and it left her blind in one eye, after a minuscule waterborne parasite called acanthamoeba burrowed into her right cornea, the clear front part of the eye.
Alarmingly, acanthamoeba keratitis, the condition that left her blind, is on the rise.
Acanthamoeba is common in soil and water, including tap water. It can get into the eye through gardening, but the main cause is poor contact lens hygiene.
Charlotte Clarkson, 24, a nanny from Edinburgh, was left blind in one eye after a minuscule waterborne parasite called acanthamoeba burrowed into her right cornea, the clear front part of the eye
When droplets of water containing the microscopic parasite get trapped between the cornea and the contact lens, which sits on the cornea, the bug is able to bore into the eye. It literally eats into the cornea, causing severe pain, extreme sensitivity to light and, in at least a quarter of cases, blindness.
The latest figures from University College London and Moorfields Eye Hospital show that the number of cases in England has risen from an average of 18 cases a year in 2011 to 50. Worldwide, up to three million people develop the condition each year.
Around 95 per cent of infections are in contact lens wearers, according to research from the charity Fight For Sight.
The risk is highest for those with nightly or reusable contacts, simply because people are more likely to clean their lenses in water (the risk is much lower for those who wear daily disposables, but is still an issue).
While many opticians warn patients not to shower or swim while wearing their lenses, or to clean them with tap water, in case they become contaminated with the bug, manufacturers are not obliged to carry warnings on their packaging.
But the message is falling on deaf ears, it seems, with a recent poll from Fight For Sight revealing that 54 per cent of those surveyed had showered or gone swimming with lenses in, while only a quarter knew that washing lenses in water put them at any sort of risk.
Ms Clarkson was working in a children’s holiday camp while on a trip of a lifetime to Canada two years ago when the parasite got into her right eye
Users may also be unaware that exposure to just tiny amounts of water can be enough to cause harm, as in Charlotte’s case.
‘I knew it was dangerous to shower or swim with any kind of contact lenses in, but I had no idea that even the most minimal contact with water could have such devastating effects,’ says Charlotte, who spent three months in a darkened bedroom because of the overwhelming pain whenever her eye was exposed to light.
Charlotte, a nanny from Edinburgh, was working in a children’s holiday camp while on a trip of a lifetime to Canada two years ago when the parasite got into her right eye.
One night she put in the corrective lenses — which she’d worn since she was 13 — as usual before going to bed, only to wake up the next morning with what felt like a piece of grit in her eye.
When her eye became increasingly sore, red and inflamed over the next few days, a doctor diagnosed a particularly aggressive stye — a small, infected lump on the eyelid, which would clear up by itself.
Still in pain a fortnight later, Charlotte got a second opinion from an optician, who confirmed she had a stye and prescribed a course of antibiotic drops.
But her eye continued to deteriorate over the next few weeks, becoming increasingly painful and sensitive to light, and Charlotte’s boss insisted on taking her to an ophthalmologist, a specialist eye doctor.
‘He looked at my eye under a microscope and literally shuddered: ‘Oh my goodness,’ and I knew then that I wasn’t dealing with a stye,’ she recalls.
Charlotte was diagnosed with HSV keratitis — an infection caused by the cold sore virus — but the steroid drops she was given didn’t help and her eye become even more painful.
In fact, it became so inflamed and sensitive to light over the next month that she was admitted to hospital for tests and prescribed a week in a darkened room at the home of a Canadian friend’s parents.
By then, the right side of Charlotte’s face was badly swollen and her vision was blurred, too.
It was only then, eight weeks after her eye first became sore, that a specialist at the hospital where she was being treated asked Charlotte if she wore contact lenses — and if there was any way they could have been exposed to water.
‘I remembered that in order to avoid using a shared towel at the camp I would often shake my hands dry before getting ready for bed and putting my lenses in,’ says Charlotte.
‘I just had no idea that handling lenses with even slightly damp hands could cause such a problem.’
A corneal scrape test — in which anaesthetic is applied to the surface of the eye before a small sample of cells is taken from it and examined in the lab — came back negative for the acanthamoeba parasite twice.
So, while Charlotte’s symptoms fitted the condition, she still did not have a much-needed diagnosis.
Cases like Charlotte’s are frequently misdiagnosed, says Professor John Dart, a consultant ophthalmologist at University College London’s Institute of Ophthalmology, because the corneal scrape test picks up only half of infections.
‘Even if acanthamoeba keratitis is suspected, the corneal scrape has a low sensitivity, which means we can identify only 50 per cent of true positives,’ he says.
Patients have a good chance of complete recovery if they get the right treatment within a month, he adds. Otherwise, a quarter of all patients run the risk of blindness in one eye and one in ten becomes blind in both.
After Charlotte’s eye worsened to the point where she couldn’t read the top line of a sight chart, the Canadian specialist advised her to return home for treatment.
Bad, good, best: How to get the most of our food choices
This week: Mushrooms
Bad: In stroganoff
Creamy stroganoff is a sure way to turn mushrooms into a high-calorie dish. Made with crème fraiche or sour cream, the dish has 540 calories, or 755 with a small portion of rice.
It’s the saturated fat content of the cream that’s unhealthy — a typical serving supplies up to 14g or 70 per cent of your recommended daily limit, which can raise heart disease risk.
A healthy way to serve mushrooms, even though it increases calories to about 85 per 80g portion (compared with six calories in 100g raw). Frying helps concentrate nutrients such as potassium.
Fry in sunflower oil for added vitamin E, which works with selenium in the mushrooms to protect cells from damage linked to conditions such as cancer.
Best: Baked and stuffed
For the biggest health benefits, stuff open-cap mushrooms with cooked lentils and mozzarella.
Two mushrooms will then count as one of your five a day for just 250 calories, plus 15g of protein from the lentils and cheese. Placing the mushrooms gill side up next to a sunny, open window for an hour boosts their vitamin D.
‘I’d been having the time of my life in Canada,’ she says. ‘But I was in intense pain and my eyesight was fading.’
Back in Scotland, another course of steroids failed to help, and it wasn’t until winter — six months after her eye problems began — that a corneal scrape came back positive and she was diagnosed with acanthamoeba keratitis.
By then, she was in such agony that she was admitted to hospital for four days, during which she had antiseptic eye drops applied every hour day and night. The eye was so intolerant of any light that she was forced to spend the next three months at home with her parents.
‘I was stuck in the house and bedridden. I couldn’t even watch a movie or read as the world was literally too bright for me.’
When she was finally able to venture out, it was months before she could ditch the eye patch, sunglasses and hat that she’d worn, even inside, to shield her eye from the light.
The only hope of restoring the sight in her right eye is through a corneal transplant, in which the damaged cornea is replaced by a donor one. However, in patients with Charlotte’s condition there is a high risk of failure.
Fortunately, 18 months on, Charlotte’s life is returning to normal and, with the vision in her left eye unaffected, she is back working as a nanny.
She has to put in eye drops once a day, and she’s acutely aware she must continue using them, as it’s possible that the medication didn’t kill the parasite but put it into ‘hibernation’ — meaning it could become active again if she stops taking them.
Professor Dart believes the majority of the UK’s 4.2 million contact lens wearers simply have no idea about the dangers of mixing contacts with water.
He says: ‘It is a scandal that contact lens companies don’t have to put ‘how to use’ information in with their packaging or ‘no water’ stickers on the boxes.
People also need to be aware that they need to avoid all contamination with water. They can do this by cleaning and drying their hands before insertion and removal.’
Adds Charlotte: ‘I just hope anyone reading this will take extra care when it comes to contact lens hygiene. I’ve gone through so much so needlessly.’