Laser surgery: a short-sighted view on glasses?

THE new Hong Kong Eye Hospital has just announced plans to research controversial laser surgery for myopia, but despite doubts about treatment overseas at least eight people a week are now applying for the operation at one of the territory's three privatehospitals already supplying the service. Public hospitals in Hong Kong have not introduced the operation because of the lack of research data, and fears that it could cause a stampede among the 3.5-million Hong Kong people who are short-sighted. In America, where laser treatments for re-sculpting the eye are offered by approved institutions under close supervision, only a few hundred people have asked for the procedure. But in Hong Kong 400 people have put their names down for the HK$12,000 treatment at one private hospital since the technique - which shaves off their cornea - was introduced last October. Many seem attracted by the fact that the surgery offers an alternative to contact lenses or heavy and unsightly glasses. But some specialists have warned that patients are taking on an unknown quantity and risk worsening their reading vision long-term. They may also experience short-term pain, disturbances in night vision and see halos round bright objects for as long as six months. The Professor of Ophthalmology at the Chinese University of Hong Kong, Patrick Ho Chi-ping, warned that the latest treatment was not always the best, particularly without a full understanding of the problem and its causes. The technology is still under extensive clinical evaluation. Ophthalmologists agree the deficiency of widely-acclaimed research results is the main concern in introducing lasers to the public. They do not eliminate the possibility of long-term damage to vision by the surgery either. ''Nobody found any complication with breast implants 20 years ago. For this reason, we cannot say if there are long-term effects from the lasers now. But as a public hospital, we have to ensure safety before recommending it to the public,'' Professor Ho said. ''Myopia is an especially widespread problem in Hong Kong. We have to be careful not to spark anything that could turn out to be less desirable later.'' In America, people who have undergone the treatment have gained excellent long-distance vision, but some also have experienced worse reading vision. That means patients may be able to throw away their distance glasses but still have to use reading glasses for close work. To overcome the drawback, a new laser surgery called monovision is being tested. The procedure has been devised to overcome an important drawback of laser surgery for the middle-aged or elderly, many of whom wear bifocal spectacles because they need one type of lens to provide good distance vision and another for reading. If they undergo the new laser surgery (known as photorefractive keratectomy, or PRK), the surgeons can provide them with excellent long-distance vision by shaving off a microscopic layer of tissue at the front of the cornea - but that can worsen reading vision. Patients have one eye fully corrected by the lasers and another eye deliberately under-corrected. When people provided with monovision are driving or watching the cinema, their brain picks up the picture from the normally-sighted eye; and when reading or doing other close work, their brain uses the picture from the short-sighted one. British consultant ophthalmologist Paul Cherry said that monovision did not suit everyone but that it was ideal for a particular group. ''If patients are over 45, I discuss the possibility with them,'' he said. ''Some people come thinking that their vision is going to be perfect with laser surgery. I have to warn them that if I give them good distance vision, they will still have to wear glasses for reading. ''Some are perfectly happy with that and say that they do not read much anyway. But others say that their primary motivation in having surgery is not to wear glasses at all. I then tell them about the concept of monovision.'' If patients are interested, he gives them a trial after he has operated on their first eye. He provides them with a contact lens for the second eye, which shows them what the effect would be if the second one was not fully corrected. ''Some people cannot get used to the effect,'' Mr Cherry said. ''It is very disconcerting. You have to let one eye do this work for you and suppress the message from the other one. Some people cannot do that. Others find it easy, however, and are very satisfied with the results.'' Some ophthalmic surgeons are sceptical about producing monovision by laser surgery but Dr Steven Bailey, consultant ophthalmologist at a laser eye clinic in London, said he thought that best results were likely to be achieved when only one eye was corrected, and the other was suitable for reading anyway. One problem was the need for a very high degree of accuracy in outcome, of which laser surgery was not always capable, Dr Bailey said. Meanwhile, Hong Kong professionals like Professor Ho are not convinced the surgery should be offered in public hospitals at this stage. An ophthalmologist in Lo Ka Chow Ophthalmological Centre also said safety had not been proved through research. She warned that patients who had the cornea tissue ''polished'' away could not change their mind and have it stitched back together again. She said the treatment was evolving with experience but public hospitals, funded by taxpayers, should observe and wait for the most refined model. The lasers for shaving off a microscopic layer of tissue at the front of the cornea cost $4 million to $5 million, but could be superseded with new developments. Unlike America, where lasers for myopia are only used as research tools at present, private eye clinics in Hong Kong are already offering the surgery to the public. There is no legislation to supervise the practice of surgical lasers and the fees. Though the term ''monovision'' is not used, a private ophthalmologist said people could choose whether to have both short-sighted eyes operated on or not. He said the laser could produce some haziness of the cornea directly under the treated area which, in turn, causes pain for one to three days after the surgery. Some people might need three to six months to get used to their new vision. Sometimes people had to undergo the procedure twice if the effect of the first surgery was not satisfactory. The private ophthalmologist said he would only recommend lasers to people who did not want glasses and had problems with their contact lenses. Patients should also be over 21 years old because vision is always changing during adolescence. However, when Professor Ho of the Chinese University was asked to compare the effect of different ways of improving short-sighted vision, he laughed. ''You'll notice most ophthalmologists are wearing glasses.''