Corneal curvature, asphericity, and aberrations after transepithelial photorefractive keratectomy and femtosecond laser-assisted in situ keratomileusis for myopia: A prospective comparative study

PURPOSE: We aimed to compare transepithelial photorefractive keratectomy (TPRK) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for myopia treatment by analyzing corneal curvature, asphericity (Q-value), and corneal aberration. METHODS: Corneal topography was measured before and 6 months after the TPRK or FS-LASIK surgery. We measured and compared corneal curvature (sagittal curvature in the 1- to 7-mm zones), change in keratometric measurements (Kmpost – Kmpre, ΔK), Q-values (from the vertex of the 6-, 7-, 8-, and 9-mm zones), higher-order aberration (HOA), vertical and horizontal trefoil (Z3(-3) and Z3(3)), vertical and horizontal coma (Z3(-1) and Z3(1)), and spherical aberration (Z4(0)) between the two surgery groups. RESULTS: The sagittal curvature Δ K in the 1-mm zone after TPRK was significantly higher than after FS-LASIK. The Δ K/ΔSE (ΔSE [spherical equivalent] = SEpre – SEpost) ratio in the 1- to 4-mm diameter zones was significantly higher after TPRK than after FS-LASIK. The preoperative Q-values of the 6- and 7-mm zones did not differ between the treatment groups, but postoperative values were significantly higher following FS-LASIK than following TPRK. HOA, Z4(0), and Z3(-1) were all significantly higher after surgery in both groups. Postoperative Z3(-3) was significantly higher following TPRK but not following FS-LASIK. There were no postoperative differences in aberrations in either group; however, the change in HOA and Z3(-1) was significantly greater following FS-LASIK. CONCLUSION: TPRK changes the corneal curvature to a greater extent and the visual quality (Q-value, aberrations) to a lesser extent than FS-LASIK.