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Laser eye surgery

MagazineFebruary 1994 (Vol. 4 Issue 11)Laser eye surgery

Q:I would be interested to see some discussion in WDDTY on the pros and cons of laser operations to correct vision defects

Q:I would be interested to see some discussion in WDDTY on the pros and cons of laser operations to correct vision defects. H H, Reading, Berks.......

A:Laser eye operations or photo refractive keratectomy (PKP) to correct short sightedness is the new darling of the operating room. It was first introduced in the US in 1987 and in the UK two years later to replace surgical correction (radial keratotomy), which entailed making several surgical cuts into the eye.

In myopia, the eyeball is too long to focus perfectly. In PRK, an ultraviolet laser corrects this by removing the epithelium, or outer tissue, of the eye. The laser then shaves the cornea with a few second's exposure, evaporating tissue no thicker than a human hair. By changing the shape of the cornea, it allows the eye to focus correctly.

In the operation, which is performed under a local anesthetic, a computer fed with details of the patient's glasses prescription calculates the amount of corneal tissue to be excised. It then activates the Excimer argon fluorine laser, which can vaporize tissue supposedly without damaging the surface below.

An outpatient procedure, the operation last 15 minutes and costs lb2000.

Since its launch, more than 5000 British patients have undergone laser eye surgery most to satisfy vanity or get rid of the bother of glasses.

In Britain, ophthalmologists investing in lb300,000 laser machines were given an unexpected fillip in April 1992 when researchers studying 79 patients at The Corneal Laser Centre in Merseyside, UK, announced that 78 per cent had regained normal vision with a "noticeable" lack of side effects. And since the introduction of laser surgery, the media has since mainly reported uncritically on the success stories about this supposed miracle new procedure and its advantages over the surgical correction of vision.

The biggest problem with this technique is that it has been launched on the public without a single study examining its short or long term safety and effectiveness. It's worth remembering that, unlike drugs companies, surgeons in Britain and America operate without any regulatory body to subject their practices to review prior to being used on patients. Although there are professional bodies to deal with cases of outright malpractice, there is nothing to stop a surgeon from carrying out any treatment he or she wishes including essentially an experimental one.

Indeed, all surgical techniques are experimental since they are rarely tested before being used on patients. (One obvious reason; it is virtually impossible to conduct a double blind study in which some patients in a group don't have the surgery but don't know it.)

In the case of laser eye surgery, the College of Ophthalmologists in the UK still labels the procedure experimental and expects the results of all cases to be reported and monitored.

Those studies that have been done don't show as high a success rate as the general perception fostered by press coverage. Although an American study (Arch Ophthalmol (1991; 109: 1525-30) argued that the procedure was promising, only two thirds of patients had any significant improvement and a little more than half achieved a change within one diopter of attempted correction. (Vision is measured in diopters, with normal vision zero and moderate myopia classified as anything up to six diopters).

A more recent study has been even more cautionary. A report from Moorfield Eye Hospital in London published in the medical journal Eye (1993; 7: 617-24) said that laser surgery gives its best results in patients with mild myopia.

"Longer follow up will be required to establish when refractive outcome can be expected to stabilize and whether there are late consequences," it concluded.

If we don't have any idea about long term effects, we do know what laser surgery does in the short term. For one thing, it can take several months for the eye to heal, and many patients experience agonizing pain during the first 48 hours after the operation and, in some cases, for far longer than that.

Professor John Marshall of St Thomas's Hospital in London, who pioneered the procedure in Britain, has gone on record as warning that some patients have disturbances in night vision, seeing haloes or radiating lines from sources of light such as lamps. "Most [people with short sight] would have that problem anyway but surgery can make it worse," he says.

If the laser cut is even a little off the mark, patients can have problems with double vision and may have to be operated on again at a later date. Still others are left with a loss of transparency in the cornea, causing an opaque vision again requiring a second operation to put it right.

And of course this procedure will not halt the normal ophthalmic aging process; as the lens loses its ability to change shape and focus, people get far sighted. This may mean that by your mid forties or fifties, you're back to wearing glasses this time to improve your short sight.

Our panelist ophthalmologist Stanley Evans is strictly opposed to the new laser techniques. "Any surgery on the eye I'm very much against because I see so much damage," he says. "I disagree with the practice of cutting the cornea, the most delicate part of the eye. It is the same problem as surgery for squint. Eye surgeons cannot assess the outcome. They try it to see what happens. "

In Evans' view, since eye problems like glaucoma or myopia are caused by nutritional deficiencies (see WDDTY vol 2 no 3 and vol 3 no 5), the best treatment is nutritional correction at the first diagnosis of a problem, especially if the patient is a child.

"If you get a child early , before he is given glasses, you can arrest myopia," says Evans. Glasses are the worst possible treatment, he says, because in a number of cases it arrests the development of the eye; the release of hormones which control the growth of the eye is dependent on the use of the organ; glasses make the eye work less hard. And with insufficient hormone released, short sightedness gets progressively worse.

The Evans approach and that of a few mavericks like Gary Price Todd and Stuart Kemeny in the States is to correct what may be a person's exceptional need for vitamin A and other nutrients. In one case, Evans talked a patient of his with myopia out of the laser surgery. After using his combination diet, supplement programme with special eye exercises, she was able to read three more lines down the standard vision chart.

For more information about the Evans approach, he has available a book called Help for Progressive Myopes. (You can get hold of a copy by sending lb4.99 to Sanctuary House, Oulton Road, Oulton, Lowestoft, Suffolk NR32 4QZ.)


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