Wearing contact lenses while showering or swimming – or sleeping with them – may seem like an innocent time-saver.
But these common habits increase the risk of painful eye problems and even blindness, experts warn.
The main problem is a microscopic parasite often found in water, including tap water, called acanthamoeba keratitis.
The bug is normally harmless, but wearing contact lenses can cause microscopic tears in the front part of the cornea, allowing acanthamoeba to enter.
They then multiply and cause eye pain, redness, blurred vision, light sensitivity and watery eyes. In the worst case, this can lead to blindness.
Acanthamoeba can get into the eyes while bathing or showering, and if contact lenses are worn during these activities, the chance of infection increases dramatically.
Even leaving contacts overnight can increase the risk.
This is because small numbers of acanthamoeba can be transferred to the eyes when someone washes their hands and then touches their face.
Nina Wang, 30, from London, fell victim to the parasite in July 2019 while on holiday in Bali
At first, Ms. Wang felt only irritation and stickiness, but her symptoms progressed to aches, pains and unbearable sensitivity to light. Two days later, on July 16, 2019, she went to the hospital
Wearing contact lenses during sleep creates the perfect environment for acanthamoeba to thrive.
Lens manufacturers and opticians make these risks clear, but according to the College of Optometrists, hundreds of Britons suffer from the infection every year.
Meanwhile, an estimated 1,500 Americans get it every year, according to The Cleveland Clinic.
Nina Wang, 30, from London, fell victim to the parasite while on holiday in Bali in July 2019.
The businesswoman, who has worn contact lenses since she was 11, initially stared with a feeling of irritation in her right eye, but assumed her symptoms were just mild conjunctivitis and would go away on their own.
“I’ve had a lot of irritations that are normally minor, but the next day it got worse,” she told MailOnline.
She admitted to occasionally falling asleep with her contact lenses in, alternating between monthly and daily types to limit the number she had to take with her on her six-week trip.
At first, Ms. Wang felt only irritation and stickiness, but her symptoms progressed to aches, pains and unbearable sensitivity to light.
The photo (left) shows the scar blocking the pupil and vision, and the photo on the right shows how specialist treatment removed the scar area in the pupil while significantly reducing myopia (nearsightedness)
Two days later, on July 16, 2019, she went to the hospital.
When her symptoms escalated, she sought medical attention at a local hospital in Bali, where she was diagnosed with microbial keratitis.
She was given antibiotics and the medical staff advised her to travel to Jakarta for more specialized treatment, but she decided to stay in Bali.
Ms. Wang followed the hospital’s initial instructions, which included wearing an eye patch, avoiding sunlight and using prescribed drops.
When Ms Wang returned to Britain three weeks later on August 4, she sought further care at Moorfields Eye Hospital, where specialists recognized the infection.
Over time, the infection caused a scar that blocked vision in her right eye, but she continued to wear her lenses for eighteen months.
Finally, in November 2020, she went to see Professor Dan Reinstein, a specialist eye surgeon at the London Vision Clinic.
She underwent laser eye surgery, which gave her 90 percent of her vision back.
McCasland had to stop work at the cafe due to the infection. The pain, which had lasted for a month and a half, made it difficult to work, as did the loss of vision in her left eye, which caused changes in depth perception.
McCasland has lost the sight in her right eye and is awaiting an expensive transplant that has only a slim chance of restoring her sight
Ms Wang said: ‘This has been a multi-year process with a lot of time and money spent correcting the scar, and Dan has done a fantastic job.’
She added that her vision is now “completely manageable.”
But not everyone is as lucky as Ms. Wang; some are permanently blind due to the infection.
Brooklyn McCasland, 23, from Texas, US, lost all sight in her right eye after contracting the parasites – which also live in fresh and salt water – while swimming with her contact in it.
The barista was initially told by the doctors that she simply had sand in her eye. Later they blamed it on a common infection and gave her eye drops and antibiotics.
But the pain continued and the outer layer of her eye began to cloud, with what her doctor assumed was damage from an infection.
Ms McCasland is now blind in her right eye and awaiting an expensive corneal transplant that has only a slim chance of restoring her sight.
In May 2019, Emily Kelleher, a high school English teacher in Massachusetts, felt as if her left eye was being stabbed by a “knife or an ice pick” – she was also infected with the parasite.
Mrs. Kelleher’s eye under the microscope (pictured here) in her doctor’s office revealed the presence of acanthamoeba parasites
Her doctors told her she probably got it when the parasites got into her eye while taking contact showers, something she did every day.
Last year, Rachel Prochnow, a lifestyle writer from Austin, Texas, went blind in her right eye after showering with her lenses in.
She had always been careful about taking care of her eyes and had worn contact lenses since she was 12.
Ms. Prochnow claims that she always took them out at night, cleaned them thoroughly and threw away her contact lens cases regularly so that everything was sterile.
But she admits she didn’t realize that showering, swimming or getting in a hot tub with her contact lenses in could make her vulnerable to infections.
If acanthamoeba keratitis is caught early, doctors can easily treat it with eye drops.
Tina Patel, contact lens optician at Feel Good Contacts, emphasized that the best way to prevent infection is to maintain a good lens care routine.
She told MailOnline: ‘If you wear two weekly or monthly lenses, make sure your lenses are removed, cleaned and stored properly every night before you go to sleep.
Mrs. Prochnow first noticed something was wrong when her eye felt a little ticklish and sensitive to light. Soon she was in excruciating pain and could no longer see anything other than slight movements and hand movements
‘Contact lenses should also never be worn in swimming pools, hot tubs and showers.’
She warns that even residual water left on the hands before inserting the lenses can be enough to cause acanthamoeba keratitis.
Professor Reinstein told MailOnline: ‘Soft contact lenses are most susceptible to acanthamoeba keratitis, due to the higher water content that can attract and harbor microorganisms.
‘In addition, extended wear lenses, which are often worn at night, restrict oxygen flow to the cornea and can trap contaminants against the eye for extended periods, increasing the risk of infection.’