Long-Term Data on LASIK Vesrus PRK: Long-Term Data Show Both PRK and LASIK to be Safe, Effective

PRK and LASIK outcomes were safe, stable, and predictable in a large series of low, intermediate, and high myopic eyes, according to 10-year follow-up data published in 2008 by Jorge L. Alió, MD, PhD, and colleagues.^1-4

The study included approximately 500 PRK-treated eyes and 300 LASIK-treated eyes. Mean preoperative spherical equivalent (SE) was -6.50 D in the PRK group and -11.80 D in the LASIK group. All procedures were performed with the VISX 20/20 excimer laser (Abbott Medical Optics Inc., Santa Ana, California), and patients were followed at 3 months and 1, 2, 5, and 10 years. No retreatments were performed until at least 6 months after surgery.

PRK OUTCOMES

Of 225 PRK-treated eyes with a preoperative SE of less than -6.00 D, 169 were within ±1.00 D and 207 were within ±2.00 D of the targeted refraction at 10 years. Retreatments were performed in 95 eyes due to over-correction, regression, or both. The mean SE decreased slightly over 10 years, with a mean magnitude of -0.10 ±1.08 D (myopic regression, -0.01 ±0.11 D per year). An increase in BCVA from preoperative levels was seen in 41 of 225 eyes after 10 years; one eye lost 8 lines due to cataract, and two eyes lost vision due to posterior segment-related complications. The mean corneal haze score gradually decreased from 0.22 ±0.39 at 3 months to 0.01 ±0.09 at 10 years.

In 267 eyes with more than -6.00 D of myopia, 156 were within ±1.00 D and 209 were within ±2.00 D of the targeted refraction at 10 years. Retreatments were performed in 124 eyes due to over-correction, regression, or both. The mean SE decreased in eyes that did not undergo retreatment, with a mean magnitude of -1.33 ±2.00 D over 10 years (myopic regression, -1.13 ±0.20 D per year). BCVA improved from preoperative levels in 121 eyes, and eight eyes lost lines of BCVA due to cataract and posterior segment-related complications. The mean corneal haze score decreased gradually from 0.48 ±0.69 at 3 months to 0.09 ±0.33 at 10 years.

LASIK OUTCOMES

At 10 years, of 97 eyes undergoing LASIK for myopia of up to -10.00 D, 71 were within ±1.00 D, and 89 were within ±2.00 D of the targeted refraction. Retreatments were performed in 20 eyes due to over- or under-correction, regression, or both. The mean SE decreased slightly over 10 years, with a mean myopic regression of -0.12 ±0.16 D per year. BCVA improved in 54 eyes. Corneal ectasia was not observed in any of the eyes, and three eyes lost more than 2 lines of BCVA due to complications that were not attributable to the LASIK procedure.

At 10 years, of 196 eyes undergoing LASIK for myopia of more than -10.00 D, 82 were within ±1.00 D and 119 were within ±2.00 D of the targeted refraction. Retreatments were performed in 54 eyes due to over-correction, undercorrection, regression, or both. Myopic regression occurred over time in eyes that did not undergo retreatment at a mean rate of -0.25 ±0.18 D per year. Eleven eyes lost more than 2 lines of BCVA, and 78 eyes had postoperative UCVA of 20/40 or better.

Complications after PRK included 10 cases of central islands, four cases of corneal leukoma, and two corneal ulcers. Complications after LASIK included 13 cases of corneal epithelial problems, eight cases of moderate corneal melting, six cases with symptomatic ocular surface syndrome, four cases of severe corneal striae, and two cases of corneal scarring at the interface. Corneal ectasia developed in two eyes in the LASIK group with more than 15.00 D of myopic correction. The authors noted that myopic regression slowed over time in eyes that underwent LASIK.

LOOKING AHEAD

In an e-mail to CRST Europe, Dr. Alió said that he and colleagues are now collecting 15- to 20-year follow-up data. “Since our initial study in 1998, outcomes have improved due to better patient selection and technology,” he said. “The future of these patients is excellent, as predictability has improved twofold compared with what we originally reported. We are now performing LASIK in myopia up to -13.00 D with excellent safety and predictability.” These results, Dr. Alió said, will soon be published in the American Journal of Ophthalmology.

1. Alió JL,Muftuoglu O,Ortiz D,et al.Ten-year follow-up of photorefractive keratectomy for myopia of less than -6 diopters.Am J Ophthalmol.2008;145(1):29-36.
2. Alió JL,Muftuoglu O,Ortiz D,et al.Ten-year follow-up of photorefractive keratectomy for myopia of more than -6 diopters.Am J Ophthalmol.2008;145(1):37-45
3. Alió JL,Muftuoglu O,Ortiz D,et al.Ten-year follow-up of laser in situ keratomileusis for myopia of up to -10 diopters.Am J Ophthalmol. 2008;145(1):46-54.
4. Alió JL,Muftuoglu O,Ortiz D,et al.Ten-year follow-up of laser in situ keratomileusis for high myopia.Am J Ophthalmol.2008;145(1):55-64.