Understanding Lasik's side effects

Although relatively safe, the eye operation does come with risks and complications


FOUR months after she had gone for her Lasik operation, teacher Audrey Cheong is still waiting to throw her spectacles away.

While she no longer wears her glasses during the day, she has to put them on at night when she is driving.

One reason is that her eyesight is not fully corrected. She had myopia of 800 degrees in her left eye and 100 in her right. After the surgery, her left eye has perfect vision, but her right eye still has myopia of 50 degrees.

The other is that she sees halos in both eyes at night.

Putting on glasses helps Ms Cheong, 26, cope with both problems when she drives at night.

'Since I had perfect eyesight with glasses last time, I wish I could have perfect eyesight without them as well,' she says.

Like all Lasik patients here, she was briefed about its side effects before she signed her consent form and went for her operation, which was performed at a public-sector hospital.

Doctors say that while Lasik is generally a safe procedure with high success rates - a Ministry of Health study released last year puts the figure at above 98 per cent - it also has risks and side effects, just like any other surgery.

Complications from Lasik surgery came under the spotlight recently when the Singapore National Eye Centre (SNEC) stopped all Lasik procedures more than two weeks ago.

This was triggered by a spike in the number of eye inflammation cases among patients who had undergone the operation at the centre.

The condition affected 17 patients in two days. In comparison, the centre saw 25 cases in the first two months of this year and at times in the past, had gone for months without a single case.

The centre is currently investigating the spate of inflammation cases and is inspecting its equipment, sponges, cleaning fluids and air-conditioning system.

It says the 17 patients are responding well to treatment and will continue to be monitored.

This marks the first time that SNEC has suspended its Lasik procedure since it began offering it in 1996. Procedures will be suspended until at least the end of the month.

SNEC is the main centre for Lasik, handling about two-thirds of more than 10,000 surgeries performed here in 2005. The cost of Lasik varies between $2,500 and $7,000, depending on the type of procedure and where it is performed.

Besides eye inflammation, Lasik could also lead to other side effects and complications, such as dry eyes, seeing glares and halos in dark conditions and corneal flap problems (see other story).

Reaction to foreign particles

THE eye inflammation in question is known as diffuse lamellar keratitis (DLK) and has been documented since Lasik was pioneered by Dr Jose Barraquer of Colombia more than 10 years ago. It usually manifests one to six days after surgery.

Patients may experience pain or blurred vision, or they may not experience any symptoms at all.

It occurs when the eyes' immune system reacts excessively to foreign particles that are introduced during the operation. When viewed under a microscope, the clusters of white blood cells resemble wave-like patterns on a sand dune - hence DLK's nickname, 'Sands of Sahara'.

However, it is not known exactly what kind of foreign particles cause this reaction.

Studies have suggested that triggers could range from oil secreted from the eyelid to debris from the microkeratome blade which creates the corneal flap, or even dead bacteria found in sterilisation tools.

If DLK is discovered early - and it usually is because the patient goes back for a follow-up the day after surgery and again within the week - it can be easily treated, says Dr Julian Theng, a consultant ophthalmologist and medical director of the Eagle Eye Centre at Mount Alvernia Hospital.

Simple cases are treated with steroid eye drops, which reduce the inflammation.

For serious cases, however, the patient may need to go back to the operating room, says Dr Ronald Yeoh, a consultant ophthalmologist at Gleneagles Medical Centre.

There, the corneal flap has to be lifted again, and the debris flushed out using a salt solution. The procedure takes about five minutes and has no permanent effect on one's eyesight.

DLK is one of the more common complications of Lasik and it usually affects just 1 to 5 per cent of Lasik patients. However, worldwide occurrence varies and incidence rates of up to 30 per cent have been reported, says Dr Theng.

He adds that although it often occurs sporadically, it has also occurred in clusters as well, according to international reports. The reason for these patterns is unclear.

Still, doctors hope that the public won't be unduly alarmed by this incident.

They say that the worst-case scenario of Lasik - loss of vision from infection - is very rare, although there has been at least one documented case of this here.

It occurred at SNEC two years ago when a 42-year-old woman went temporarily blind in one eye after being infected by a rare and virulent strain of bacteria after surgery.

However, she was treated with antibiotic eye drops and has since regained her sight, says an SNEC spokesman. She also doesn't need glasses anymore.

Dr Theng says that it is highly unlikely that someone will go permanently blind because of Lasik surgery. He says he has not heard of such a case anywhere worldwide.

Low incidence aside - only one in 10,000 people suffers from infections after Lasik - the infection has to be very serious for the person to lose his vision.

'In the worst-case scenario, even if the person's cornea is badly scarred, they can still have a cornea transplant, which means that they can regain their sight,' he says.

As for Ms Cheong, she is hopeful that the night-time halos and glares will go away with time - as they often do - before she finally does away with her spectacles.

She has also learnt that 50 degrees is actually within the acceptable range of success, as it is slightly better than 6/12 vision - where one does not need glasses.

'Don't get me wrong. Even without achieving perfect eyesight, I don't regret doing Lasik,' she says.

'It's easier to play sports and I don't have to spend time putting on contact lenses anymore.'