Every year, the Singapore National Eye Centre (SNEC) sees 20 to 30 patients who have to be hospitalised for severe and potentially blinding contact lens-related corneal ulcers.

If that doesn't frighten you, consider Miss Chen Huiwen's case. She thought she was doing everything right. She said she did not wear contact lenses often - and cleaned them thoroughly when she did. Yet she developed corneal ulcer in June this year and ended up partially blind in her left eye.

Ninety per cent of corneal ulcers are due to contact lens wear, according to an eye specialist. Neither Miss Chen nor the doctors know the exact reasons behind her corneal ulcer. But the 19-year-old polytechnic student believes it's because she was a contact lens user. She washed her lens es thoroughly and used monthly
disposable lenses which are considered safer than permanent lenses. But she forgot one thing.

Miss Chen asked: 'Must we change the case regularly? I didn't even know.' She had not changed her contacts lens case for a year. It's not enough to just clean the lenses and take no care of the case.

As Dr Nguyen of 20/20 Eyecare said: 'It is like rinsing your mouth with water in a cup full of slime.'

Describing her frightening experience, Miss Chen said: 'On that day (when her eye became infected), I wore lenses the whole day. At night, when I was at a hawker centre, some smoke got into my eyes and my eyes started feeling very uncomfortable. When I took the lenses out, my eye was very red, sore and painful.'

She visited a doctor and was told she had an eye infection. However, her condition worsened within the next 24 hours.

She said: 'My eye hurt so badly I could not sleep. I kept tearing . There was pus at the side of my eyeball. My mum tried to use cotton bud and tissue to remove it, but the pus could not be wiped away.'

She went back to her doctor, who told her to go to a hospital immediately. She spent two weeks in hospital and was given another two weeks of medical leave.

Miss Linda Teo, an optician at Sintat Optical Centre, said her customers often need reminders before they change their lens cases.

Dr Jerry Tan, a consultant eye surgeon in private practice, explained how the cases get dirty: 'You put your lenses in the case and whatever oil, protein is on the lenses will transfer to the case. The case will develop this layer of slime which protects the bacteria from the chemicals in the solution.

'Bacteria then grows. Meanwhile, the surface quality of the lenses becomes less smooth with time and the bacteria gets easily attached to the lenses.'

Dr Tony Ho, an ophthalmologist in private practice, added that the lens cases may look new on the outside but the inner surface may have scratches, breeding germs.


Dr Tan said the correct way to clean lens cases is to scrub it thoroughly with a small toothbrush (used solely for cleaning the cases) and contact lens cleaner.

He said: 'Then rinse the case under running tap water and dry it for the whole day. Do that once a week.'

He added that lens cases should be replaced regularly, especially if there are cracks or scratches in them. Not all contact lens wearers forget about their cases, though.

Miss Ong Kai Ching, 21, a student, said: 'I change my case regularly because I am scared the dirt will accumulate and cause eye irritations.'

For Miss Chen, however, it is too late for regrets. She has accepted that she can't wear lenses any more and her poor vision does not allow her to get a driving licence although she has passed her theory tests.

She said: 'I will not ask people not to wear lenses, but just be really careful, take care of your lenses and case properly.'

CORNEAL ulcers occur when the cornea is infected, usually by germs or parasites, explained Dr Tony Ho, an ophthalmologist in private practice.

He said: 'The cornea is a transparent window to the eyes. Corneal ulcers can cause blindness because of corneal scarring where the cornea is covered by an opaque white scar.

Vision will be affected especially if the scar is in the middle of the cornea.

He added: 'In severe cases, the germs spread to the deeper tissues of the eye and literally cause the eyeball to become pus.'

He said he sees about three patients with corneal ulcers each week.

In 2002, 31 patients the Singapore National Eye Centre (SNEC) saw for contact lens related corneal ulcers were hospitalised.

Ni nety per cent of corneal ulcers are due to contact lens wear, Dr Ho said.

Dr Lim Li, consultant, corneal service, SNEC, cited several reasons for corneal ulcers: Lack of lens hygiene, overnight wear of lenses and dusty environments.

She added: 'The wrong use of solutions is another reason. Some patients use saline, instead of an appropriate solution, to soak their lenses.

'The lens material plays another part. Chances of corneal infection are higher when the lens have low oxygen permeability.'

She said a corneal ulcer is marked by a red eye, worsening pain, photophobia (intolerance to light) and there may be a white spot in the cornea. One should immediately stop wearing contact lenses and consult an eye-care practitioner.

Dr Ho said patients would be given frequent antibiotics in the form of eyedrops or injections.

In severe cases, a cornea transplant may be carried out.

After the ulcer has healed, patients are adv ised not to wear lenses again.

He had a word of advice: 'The rule is not to wear your lenses when you don't feel comfortable. Let your eyes rest for a day. The next day, if you put them on and it still feels uncomfortable, see an optometrist.'

EIGHT out of 12 contact lens wearers The New Paper spoke to said they do not change or clean their lens cases regularly.

Said Miss Janice Hong, 21, an administrative staff: 'I don't change my lens case unless it really becomes dirty or yellow.'

Miss Elaine Soh, 22, an undergraduate, said she is too lazy to change her lens case.

She said: 'I really don't bother. What is the point of changing the case regularly?'