Long-term evaluation of eyes with central corneal thickness <400 μm following laser in situ keratomileusis

PURPOSE: To study long-term refractive and visual outcomes of laser in situ keratomileusis (LASIK) in eyes with a postoperative thin central cornea. METHODS: In this retrospective observational case series, we studied 282 myopic eyes with a normal preoperative topographic pattern and postoperative thin corneas (<400 μm) that had at least 3 years of follow-up after LASIK in three private clinics. The main outcome measures were safety, efficacy, predictability, percent tissue altered, and complications. RESULTS: The mean postoperative central corneal thickness was 392.05 μm (range: 363.00–399.00 μm). After a mean follow-up of 6.89±2.35 years (standard deviation), the safety index was 1.17, the efficacy index was 0.94, and predictability (±1.00 diopter [D]) was 73.49. The mean residual stromal bed thickness was 317.34±13.75 μm (range: 275–356 μm), the mean flap thickness was 74.76±13.57 μm (range: 55–124 μm), and the mean percent tissue altered was 37.12%±3.62% (range: 27.25%–49.26%). No major complications were recorded. CONCLUSION: LASIK with a resultant central cornea thickness <400 μm seems to be effective, safe, and predictable provided that preoperative topography is normal and the residual stromal bed thickness is >275 μm.