A ten year follow up study carried out by researchers in Spain and Turkey on patients who had laser surgery to treat high myopia (short or near sightedness) found the treatment was safe and effective in the long term, with a retreatment rate of under 30 per cent.
The study is published in the January 2008 issue of the American Journal of Ophthalmology and is the work of researchers from Miguel Hernandez University, Medical School, Alicante, Spain, and from Ankara University School of Medicine, Ankara, Turkey.
Laser surgery for eye problems has been around since the early 1990s. There are two main types for correcting myopia: PRK, Photorefractive Keratotomy, for low to moderate myopia; and LASIK, laser in situ keratomileusis, for high myopia.
In that time there have been over 18 million LASIK operations worldwide, with controversial evidence about the maximum correction possible and the long term effects of the technique.
This new study found that in the long term, LASIK was a safe and effective procedure for patients with preoperative myopia of over -10 D.
The researchers evaluated 196 eyes of 118 patients that needed at least 10 diopter (10 D) corrections to achieve 20/20 vision before receiving laser surgery. The extent of the preoperative myopia was a mean of -13.95 plus or minus 2.79 D.
The patients all received LASIK surgery at the Instituto Oftalmologico de Alicante, in Spain, between April 1992 and December 1995. They came back for check ups after 3 months, 1, 2, 5 and 10 years.
The results showed that:
- After 10 years, 42 per cent of eyes were within plus or minus 1.00 D.
- 61 per cent of eyes were within plus or minus 2.00 D.
- 27.5 per cent of eyes were retreated because of under correction or regression, or both.
- Myopic regression in eyes that were not retreated occurred at a mean rate of -0.25 plus or minus 0.18 D per year.
- 5 per cent of eyes lost more than 2 lines of best spectacle corrected visual acuity (BSCVA).
- 40 per cent of eyes showed a postoperatively uncorrected visual acuity of 20/40 or better.
- 1 per cent of eyes with more than 15 D myopic correction developed corneal ectasia (bulging).
- The retreatment rate was 27 per cent.
The researchers concluded that:
“LASIK for myopia over -10 D is a safe procedure with myopic regression that slows down with time and a high rate of BSCVA increase in the long term.”
Lead investigator, Jorge L. Alio, said that:
“These results are extremely encouraging considering that this refractive correction implies the maximum limit of application of this technique.”
“This study has allowed us to demonstrate that, in spite of the prejudices about the limits of LASIK technique, the results regarding predictability, efficacy and safety for high myopic patients are very good in the long term,” he added.
He stressed that the optimum limit of predicatability for this type of surgery appears to be around 10 D of myopia.
In an editorial in the same issue of the journal, Dr George O Waring, of Emory University and Inview in Atlanta, generally supported the findings, and said that LASIK and other vision correction procedures have improved significantly in the last ten years, with some recent studies on LASIK reporting correction to plus or minus 0.5 D in more than 90 per cent of eyes.
“Ten-year Follow-up of Laser In Situ Keratomileusis for High Myopia.”
Jorge L. Alio, Orkun Muftuoglu , Dolores Ortiz , Juan Jose Perez-Santonja , Alberto Artola , Maria Jose Ayala , Maria Jose Garcia , Gracia Castro de Luna.
American Journal of Ophthalmology, 2008 January, Vol. 145, Issue 1, Pages 55-64.e1.
Written by: Catharine Paddock