A new treatment for myopia, available privately to patients in Britain, is unlicensed in the US.
Between 8 million and 10 million people suffer short-sightedness, or myopia, in the UK, a condition detested by many of them. Theidea that they can quickly and simply "cure" the problem is attractive.

In the past five years, advertisements have appeared on radio and in the press suggesting that a simple solution is at hand - laser treatment called photorefractive keratectomy (PRK).

While its success is acknowledged for those with mild myopia, questions are being raised about a minority of patients who suffer "side-effects". This week in the British Medical Journal, David Gartry, fellow in corneal surgery at Moorfields Eye Hospital, London, says that complications "must be taken into account".

He says that 15 per cent of patients who have undergone PRK lose some visual acuity, and "a further 10 per cent experience halos around lights at night, which may make night driving difficult".

William Jory, consultant ophthalmologist at the London Centre for Refractive Surgery, a private clinic, is concerned at the lack of collated data on the estimated 15,000 PRK operations conducted in Britain.

The procedures to treat myopia are designed to alter the shape of the cornea. In PRK, the laser removes a small circle of tissue at the centre of the cornea (ablation) to flatten it. PRK has joined micro-surgery - a safer US development of the old Russian operation, in which microscopic incisions are made in the peripheral cornea, which also flattens the centre.

Even three years ago, it was known that PRK was not an entirely successful procedure. In 1992, Joseph Colin, of Brest in France, reported the results of the French Corneal Graft Survey to the 1992 Congress of the Ophthalmological Society of Europe in Brussels. This showed that of nine patients who had required corneal grafts following PRK, seven were because of corneal scarring and two because of the "decentration of ablation" (the ablation zone is the width of the cornea treated by the laser).

Such is the popularity of PRK in this country, however, that patients can check in to a private clinic and, following counselling, pay anything up to £1,400 per eye in order, hopefully, to walk away with their eyesight restored to normal.

This scenario contrasts with that in the US, where the Food and Drug Administration (FDA) maintains a constant watch and collates the results of experimental treatments. Before the microsurgical procedure for treating myopia was sanctioned in the US, for example, the National Eye Institute conducted a safety programme at nine university hospitals.

The FDA has yet to license PRK and is still conducting safety trials. In Britain, there is no comparable official body to judge new techniques. Private clinics are checked once a year by the local health authority and asked to demonstrate that lasers used for PRK are safe.

PRK is not available on the NHS, so it is extremely difficult to compare results of some 40 private clinics and three research centres.

Mr Jory practises both microsurgery and PRK in the correction of myopia. "I use both methods, for the simple reason that I would not be in a position to make a valid comparison between the two if I were to limit myself to one or the other. With PRK, we need to do ongoing research into the effects on the cornea from this treatment, and the Government should ensure that all laser surgeries operate to a strict professional code of conduct.

"Figures are emerging that approximately 10 per cent of patients lose a significant amount of vision and some will not be able to pass their driving test. The long-term effects are not known yet, but we do know that the excimer laser causes thinning of the cornea and that the shock wave from it can cause damage to the back layer of the cornea."

Mr Gartry was the first surgeon to carry out the procedure in this country while he was at St Thomas's Hospital, London. He has written 10 papers on the subject. "I believe a reporting body would definitely be helpful," he says. "I also feel that patients should receive full counselling before any procedure is carried out, and that the patients should be selected with great care.

"Vision is measured in dioptres, with minus one being the mildest form of short-sightedness, ranging up through minus seven to minus 10 and even minus 15 dioptres.

"It is important to realise that the best results are achieved where the patient has minus one to minus three. We have found that with patients who have up to minus seven, 85 per cent are pleased with the procedure. About 7 per cent have an indifferent result and a further 7 per cent find that their sight returns to where it was before."

Mr Gartry believes the US licence will be limited. "In fact, the indications are that although they may well permit the licensing of private clinics in America in about six months, it will be only for short sight below six dioptres."

Dr Charles Cory is an ophthalmologist and clinical director of Optimax, one of the largest private organisations in Britain offering PRK. He says: "Of the 10,000 patients we have treated in the past three years, 60 per cent reported that the results were excellent, 31 per cent stated that the results were good, 6 per cent felt that the results were worthwhile and 3 per cent were disappointed.

"At Optimax, we use trained counsellors before the procedure, and patients must sign a 16-point consent form. We ensure that they are aware of what happens during and after the laser treatment."

A Which? report published in February says that the eye can take weeks or even months to stabilise after excimer laser treatment. Which? stated: "Lasers may be completely programmable and automated, but what experts call your `natural healing response' is less so."

Which? also pointed out that PRK is inadvisable for a number of groups: pregnant women, those taking immuno-suppressant drugs; people under 21, as short sight may not stabilise before then, people with vision only in one eye, and those with the herpes simplex virus, very dry eyes, diabetes, or any condition that affects the immune system or connective tissue (including rheumatoid arthritis and systemic lupus erythematosus).

Emanuel Rosen, editor of the European Journal of Implant and Refractive Surgery, wrote: "The irreversibility of PRK is one of its greatest weaknesses. Couple this with doubtful predictability of outcome for any correction other than the lower degrees of myopia, and an unsatisfactory scenario evolves."

Despite the care that is taken by the various organisations using PRK, Mr Jory remains concerned by the lack of control in this field. "We should have a limited number of operations by approved clinics with independent assessment of results," he says.

"I remain unconvinced that sufficient research into the long-term effects of photoreactive keratectomy has been done. I'm not anti-PRK, but please, please let's go slowly, collate and examine the results and then judge the results."

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