Long-term comparison of laser in situ keratomileusis versus laser surface ablation in corneas thinner than 470 μm

PURPOSE: To compare long-term refractive and visual outcomes of laser in situ keratomileusis (LASIK) and laser surface ablation in eyes with corneas thinner than 470 μm. SETTING: Private clinics, Spain. DESIGN: Comparative case series. METHODS: The study comprised eyes with myopic error and corneas thinner than 470 μm that had at least 2.9 years of postoperative follow-up between September 2001 and June 2007. The main outcome measures were safety, efficacy, predictability, and complications. RESULTS: The mean central corneal thickness was 462.0 μm (range 440 to 469 μm) in the LASIK group (n = 40) and 458.1 μm (range 420 to 469 μm) in the laser surface ablation group (n = 88). All eyes had normal preoperative topography. In the LASIK group after a mean follow-up of 5.1 years ± 1.5 (SD), the safety index was 1.07, efficacy was 0.99, and predictability (± 1.00 diopter [D]) was 0.93. In the laser surface ablation group after a mean follow-up of 4.8 ± 1.3 years, the safety index was 1.01, efficacy was 0.93, and predictability (± 1.00 D) was 0.92. The mean residual corneal bed thickness in all eyes was 345 ± 25 μm (range 270 to 399 μm). No major complications occurred. The safety index was better in the LASIK group than in the laser surface ablation group. CONCLUSION: Both techniques were effective, safe, and predictable in eyes with corneas thinner than 470 μm, normal preoperative topography, and a residual corneal bed thickness greater than 250 μm.