Predictability comparison of central corneal thickness reduction in myopic eyes with or without astigmatism undergoing FS-LASIK with two profiles of MEL 90

To compare the predictability of central corneal thickness (CCT) reduction in myopic patients undergoing femtosecond laser-assisted in situ keratomileusis (FS-LASIK) using the aberration-optimized (Triple-A) and topography-guided (TG) profiles on the MEL 90 platform. This study involved 82 patients, treating one eye with the Triple-A profile and the other with the TG profile on the MEL 90, with an average spherical equivalent of - 5.76 ± 2.02 D (Triple-A) and - 5.79 ± 1.90 D (TG). Refractive assessments were done preoperatively and at 1 day, 1 week, 1 month, and 3 months postoperatively. Achieved CCT reduction (via Pentacam) = CCT_pre-op-CCT_post-op. The MEL 90 platform provided the predicted CCT reduction, and comparative statistical methods and linear regression analyses were conducted. The 3-month CCT reduction was underestimated by 5.18 ± 7.41 μm in the Triple-A group (P < 0.0001) and by 14.44 ± 10.10 μm in the TG group (P < 0.0001). The planned CCT reduction in the TG group was much smaller than that in the Triple-A group (P < 0.0001), yet the achieved reduction was greater (P = 0.034), mainly in moderate myopia (P = 0.012). Moreover, subgroup analyses indicated that these differences were present exclusively in moderate to high myopia. As the corrected refraction increased, the planned-achieved difference (PAD) also increased. For patients with moderate and high myopia, both Triple-A and TG profiles of FS-LASIK on the MEL 90 laser platform may underestimate the CCT reduction. TG LASIK does not save corneal tissue but even consumes more of it in moderate myopia.