Sunday November 26, 2006
By Miles Erwin
Concern has been raised about the long-term effects of laser eye surgery after a new study has shown that tens of thousands of Kiwis are likely to suffer defective vision from the surgery in their later years. Studies from Otago and Oxford Universities have shown that laser surgery for short-sightedness could cause haze, glare and blurred vision as people reach their 60s and 70s. Given that around 25,000 New Zealanders have had the surgery, Otago University head of ophthalmology Anthony Molteno said there could be significant legal class actions in the future, an issue that is causing major concern among eye surgeons.
In the procedure the central cornea is flattened. That provides better eyesight, but research shows that it seriously affects the movement of corneal cells, which affect sight. In a normal eye, the cells start at each end of the eye and migrate towards the centre. The top cells move quicker and meet the lower cells below the pupil. Where they meet, called the Hudson-Stahli Line, they create pigment, scattering light and causing glare, haze and blur.
As people age, that area increases and moderately affects eyesight but isn't a real problem, as the line is below the pupil.
"But after the surgery, the top cells move slowly down the flattened cornea, meeting the lower cells in front of the pupil. That causes haziness immediately, and most people who have the surgery see as though they're "looking through hazy spectacles", according to Molteno.
The new findings show the new location of the Hudson-Stahli Line will cause haze and glare in front of the pupil as people age. "The question is, is this permanent, and is it going to increase in the normal manner with age? If so, a lot are going to have a hazy, soft, fuzzy view of society as they get older. This is a long-term effect, and we are following these people. If this turns out to be a major effect, I presume it will one day see a major class action suit."
Molteno said the problems could be serious, with people unlikely to be able to drive. "Anybody who's had their cornea planed would be eaten by a lion at the water hole... If there was serious break-down of law and order, they would probably get shot before the others because they couldn't see so well."
At present, the process cannot be fixed. "The issue is really this: if you pay the private sector to do this, they do it at a profit and pay taxes. The question is how much of those taxes come to the public sector, and how much is it going to cost to clean up the mess? We don't know."