Comparative Change In Anterior Corneal Asphericity After Fs-Lasik And Smile

PURPOSE: To evaluate changes in anterior corneal asphericity (Delta Q) by calculating tangential radius (r(t)) after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE).METHODS: 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 Delta Q values in semi-meridional regions across 360 degrees of the anterior surface after FS-LASIK and SMILE were compared.RESULTS: 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 Delta Q-values were lower in patients who had undergone SMILE than in patients who had undergone FS-LASIK. Postoperative Q-values and Delta Q-values were lower in the moderate myopia group than in the high myopia group for FS-LASIK and SMILE. The magnitude of variation in Delta Q as a function of semi-meridional region was lower in patients who had undergone SMILE than in patients who had undergone FS-LASIK.CONCLUSIONS: 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.