Comparative Change in Anterior Corneal Asphericity After FS-LASIK and SMILE.

Abstract

To evaluate changes in anterior corneal asphericity (ΔQ) by calculating tangential radius (rt) after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE). Sirius corneal topography (Costruzione Strumenti Oftalmici) was used to evaluate 120 right eyes from patients with moderate and high myopia who had previously undergone FS-LASIK and SMILE. The preoperative and postoperative tangential radii obtained in reference to various semi-meridional regions and radii zones were compared. Variation in ΔQ values in semi-meridional regions across 360 degrees of the anterior surface after FS-LASIK and SMILE were compared. The tangential radii in the 1.2- and 1.8-mm radii zones were lower in patients who underwent SMILE compared to those who underwent FS-LASIK. The tangential radii in the 2.4- and 3-mm zones were higher in patients who underwent SMILE compared to those who underwent FS-LASIK. In both the moderate and high myopia groups, postoperative Q-values and ΔQ-values were lower in patients who had undergone SMILE than in patients who had undergone FS-LASIK. Postoperative Q-values and ΔQ-values were lower in the moderate myopia group than in the high myopia group for FS-LASIK and SMILE. The magnitude of variation in ΔQ as a function of semi-meridional region was lower in patients who had undergone SMILE than in patients who had undergone FS-LASIK. FS-LASIK and SMILE alter anterior corneal tangential radius and anterior corneal asphericity in patients with moderate or high myopia. SMILE is more effective than FS-LASIK in preserving normal anterior corneal asphericity. [J Refract Surg. 2021;37(3):158-165.].