Comparison of laser in situ keratomileusis and automated lamellar keratoplasty for the treatment of myopia.

BACKGROUND

Automated lamellar keratoplasty (ALK) and laser in situ keratomileusis (LASIK) are surgical procedures used to correct high myopia, although their differences in effectiveness and long-term stability have not been sufficiently documented. Little information exists about the results of the two procedures in the hands of the same surgeon.

METHODS

To assess long-term stability of refractive results of ALK and LASIK, a retrospective study of 260 eyes that received ALK and 308 eyes that received LASIK was undertaken. The mean follow-up was 1.8 years for ALK and 1.4 years for LASIK.

RESULTS

The mean baseline spherical equivalent refraction in ALK eyes was -14.30 +/- 2.05 D (range -5 to -25 D) and in LASIK eyes was -8.50 +/- 1.75 D (range -3 to -26 D). At 3 months after surgery, 65 ALK eyes (25%) were within +/- 1.00 D of intended correction compared with 269 LASIK eyes (87.5%). At 1 year, only 31 ALK eyes (16%) were within +/- 1.00 D of intended correction, compared with 224 eyes (82%) in the LASIK group. At 3 months after surgery, the mean spherical equivalent refraction was -2.64 D in ALK eyes; at 1 year it was -4.60 D, and at 2 years it increased to -5.50 D. In contrast, the mean spherical equivalent refraction in the LASIK eyes at 3 months after surgery was -0.22 D and remained nearly stable until 1.5 years after surgery, when it was -0.50 D. More regression occurred when a large amount of corneal stromal tissue was removed. One out of four eyes that had more than 25% of its corneal tissue removed lost correction after 6 months for both ALK and LASIK. No ALK or LASIK eyes with a remaining corneal thickness of 310 microns or more had regression of the refractive result after 6 months.

CONCLUSIONS

Both ALK and LASIK can reduce moderate and high myopia. The safety and long-term stability of LASIK is better than that for ALK. Although both procedures take advantage of lamellar keratoplasty techniques, the LASIK technique minimizes the depth of ablation while maximizing optical zone size which results in more accurate correction and better long-term stability, the latter depending primarily on the amount of corneal stromal tissue removed.