Eye doctors are urging consumers to be scrupulous about cleaning and caring for their contact lenses following reports that a Taiwanese student lost her sight after microscopic bugs ate through her eyeballs.

The story, which went viral on social media this week, described how Lian Kao, 23, reportedly did not remove her limited-wear, disposable contact lenses for six months straight and even wore them while swimming.

As a result, amoeba got under her lenses and tunnelled through her corneas, causing permanent damage that led to blindness in both eyes. The single-cell bug, called Acanthamoeba, can survive in tap water, swimming pools and hot tubs.

"While an amoeba burrowing into one's cornea is certainly an extreme case, we want people to realize the importance of using contact lenses as prescribed," said Dr. Tim Hillson, chair of the Eye Physicians and Surgeons of Ontario. "Because they are worn directly on the eye, contacts create an environment that could lead to infections, corneal ulcers and, in rare cases, blindness."

Opportunity to penetrate

Hillson said contact lenses decrease the amount of oxygen available to the corneas, which causes excess blood vessels to grow — the body's way of supplying oxygen and nutrients to the eyes. Wearing lenses overnight severely compounds the problem.

"Those cells, when they don't get enough oxygen, they are not as healthy as they usually are and they're more susceptible to infection," the ophthalmologist said Tuesday from Orillia, Ont., where he practises. "So there's some bacteria clinging onto the contact lens and they have an opportunity to penetrate the cornea."

Although having amoeba infect the eyes is a rare occurrence — Hillson said he saw a similar case years ago while a resident in training — it underscores the importance of using contact lenses as prescribed and keeping them clean.

"Most people don't get Acanthamoeba. It's usually common bacteria like staphylococcus aureus or other skin organisms. So they're not usually weird and wonderful things like this, but they're common and can still hurt the corneas."

"To lose the eye altogether, that's rare, but you could have a scar on the cornea that affects your vision and you don't correct to 20/20 anymore."

Disinfect nightly

If the eyes look red, feel sore or have a gooey discharge, those could be signs of infection requiring medical attention, he said.

Hillson said it's critical to disinfect lenses nightly, preferably using one of the commercially prepared cleaning solutions, which contain chemicals that destroy micro-organisms.

"They've got to come out every night and the catchphrase we use is: 'If in doubt, take it out,"' he said, advising that contact lens users get a pair of glasses they feel good wearing to give their eyes a breather.

"Generally, people who don't like taking their contacts out, it's usually a vanity thing. Just not liking their glasses. But a big, red, drippy eye is not exactly attractive either. So that's worth remembering."