WHEN 37-YEAR-old Polly Lau decided to have laser eye surgery to correct her shortsightedness, the results were dramatic. 'The morning after the surgery, I opened my eyes and the first thing I saw was the wedding photo I'd hung on the wall opposite my bed,' Lau says. 'For years, it had been a blur. I had to put on my glasses before I could even see it. It was a fantastic feeling'. Lau's reaction is typical of those who have had laser eye surgery, a technique that's been available for more than 10 years. Laser eye surgery, also known as refractive surgery, reshapes the cornea (clear, front part of the eye) and changes its focusing power. 'The aim of the procedure is to replace spectacles or contact lenses, and most patients can achieve 20/20 vision after the operation,' says Arthur Cheng, a professor at the Chinese University of Hong Kong. 'But it really doesn't do any more than that. If a patient is short sighted it doesn't remove the risk of, for example, retinal detachment or glaucoma; it simply makes the patient less dependent on spectacles or lenses'. Patients must be at least 18 years old and have no corneal disease or infection. Cheng says the surgery is suitable for short- and long-sightedness. However, the level of corneal refraction needs to be within a certain range to get the best results and this varies, depending on the thickness of the cornea. There are three types of laser eye surgery, with the most popular being Lasik (Laser-Assisted in Situ Keratomileusis). 'With Lasik, we use special equipment - either a laser or oscillating blade - to cut through the cornea to create a flap,' says Cheng. A hinge is left at one end of the flap, which is then folded back to reveal the middle section of the cornea. Pulses from a computer-controlled laser vaporise the stroma (the thickest layer of tissue in the cornea), and the flap is then replaced. Because the area is protected by the flap, there's minimal pain and recovery is rapid. Lau had her Lasik procedure done at the Sanatorium hospital in Happy Valley. 'It's always scary to have an operation on your eyes, but I needed to have my problems fixed,' she says. 'You're totally conscious and aware of what's going on during the procedure, and this is the most frightening part because you can see the tool coming towards the surface of your eye. 'It was a bit uncomfortable, but it wasn't really painful. There was a sensation of pressure or stinging, but it was bearable.' The other laser eye surgery options are PRK (photorefractive keratectomy) and Lasek. Instead of creating a flap, PRK entails removing the surface layer of the cornea by gently scraping away the cells. 'Laser refractive surgery started with PRK. The surgeon removes the most superficial layer of the cornea and then uses the laser on the surface. Because you've removed the surface cells, there's a large defect on the surface which takes a week or so to heal,' says Cheng. 'One of the problems with PRK is that, because of the defect, patients feel lots of pain afterwards until the cells are healed. As a result it wasn't very popular'. Lasek lies somewhere between the two. 'Like PRK, it also involves removing the surface cells,' Cheng says. 'But there are techniques to preserve these, so that after the procedure, we can put them back into the cornea.' Cheng says the benefit of Lasek is that the cells don't need to be put back in exactly the same position, because they'll be replaced by new cells coming up. Family doctor Kath Reynolds says people shouldn't go into this kind of surgery lightly. 'I don't think there are many doctors who don't agree with the procedure, but it's not for everyone,' she says. It doesn't suit all ages and depends on the level of refraction. You may also think twice, depending on your occupation. For example, you may not want to have it done if you're trying to get work with an airline, in case of complications. Despite the cost (about HK$25,000), Lasik is growing in popularity in Hong Kong, and Cheng says there are now more than a dozen clinics where the procedure is carried out by qualified ophthalmologists. However, surgery is never without risks. Cheng says that, with Lasik, these can include a hole in the flap, which then affects vision. 'The surgeon has to lift up the flap and replace it. It depends on the surgeon's skill, but the risk of damaging the flap during the procedure is less than 1 per cent.' With PRK and Lasek, there's a greater risk of scarring because the surface cells are being removed. 'Whether you do Lasik or Lasek, after the procedure there's a wound, and wherever there's a wound there's more chance of getting an infection. But the chance of infection is low - about one in 1,000.' One of the real issues surrounding laser eye surgery is that you might not come away with the perfect eyesight you envisaged. Lisa Swanson had Lasik four months ago, and although she says it has been successful, her vision isn't as good as she expected. 'I've been wearing glasses and lenses since I was 10 and the pollution in Hong Kong made my eyes sore and irritable,' she says. 'I had to change my lenses twice a day, and my eyes were bloodshot and dry. 'The day after the procedure I could drive home, and I thought that was amazing - previously I couldn't have even found my way to the car.' Nonetheless, she says she's only about 80-90 per cent of the way there. 'My progress is slow. Even so, I'd still recommend it.'