'It's very important for patients to know the A to Z of the procedures, the pros and cons before they decide to have the surgery and actually go for it,' he said.

The warning came after the Consumer Council checked 14 centres offering Lasik corrective eye surgery and found some gave only brief information on possible complications.

Lasik - laser-assisted in situ keratomileusis - uses laser energy to change the curvature of the cornea to correct short-sightedness, long-sightedness and astigmatism.

The Consumer Council surveyed Lasik surgery services at four private hospitals and 10 eye-surgery clinics.

Of the 14 service providers, some provided materials detailing the potential risks, while others only briefly noted the complications that might arise, the council found.

Dr Lam acknowledged that in most cases, patients could enjoy much better vision without spectacles, but he reminded consumers that they might still not have perfect vision without glasses or contact lenses.

'It's difficult to get zero degree, but if you're starting from, say, 500 degrees and now you're only 50 degrees, then you're spectacle-free 99.9 per cent of the time.

'But sometimes if you want very good vision, you may have [to use] supplementary spectacles; this is the most likely scenario.'

Dr Lam said all surgeries carried risks and limitations and advised consumers to understand thoroughly before making the decision.

'We have to create a cornea flap [in the surgery], and the flap may have a wrinkle. It is a wound, so there can be healing problems, including wound infections,' he said.

Dr Lam cautioned that a number of risks were involved in the procedure. According to experts, the risks and possible side effects of Lasik surgery included irregular flaps, wrinkles or folds, epithelial in-growth, corneal ulcer, infection, cone-shaped cornea, halo, double vision and dry eye.

Dr Lam said less than 1 per cent would have serious complications.

'My view is, this is an option. If you're really interested, you should look at the good side and the bad side and the worst-case scenario,' he said.

He said the majority of patients were suitable for the surgery, but urged consumers to balance the pros and cons before going under the knife.

'You have to consider your own visual demands, whether you really want surgery or not,' he said.

'Although the procedure is already mature to a good extent, this is still a surgery.'

Who can benefit from Lasik surgery

Lasik is not recommended for patients with lupus erythematosus, rheumatoid arthritis, keratitis, dacryocystitis, a cone-shaped cornea, glaucoma or progressive cataracts.

People with serious myopia should be aware that Lasik changes only the shape of the cornea. It does not prevent or stop myopia-associated diseases like retinal degeneration and detachment, cataracts or chronic glaucoma.

Treatment depends on many factors, for example, if the patient has enough corneal tissue for ablation.

Short-sightedness can be treated up to about 1,200 degrees (100 degrees = 1 dioptre); long-sightedness and astigmatism each up to about 600 degrees.

Lasik and other corneal vision-correction procedures will affect any subsequent cataract surgery.