Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: A prospective fellow eye study

Abstract

Purpose: To compare corneal hysteresis (CH) and corneal resistance factor (CRF) between eyes treated with small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK). Setting: Beyoglu Eye Training and Research Hospital. Design: Prospective comparative case series. Methods: Sixty eyes from 30 patients with bilateral myopia or myopic astigmatism were studied. Inclusion criteria were spherical equivalent of subjective manifest refraction (SE) <10 diopters (D) and a difference <= 0.50 D between the SEs of both eyes. One eye of each patient was treated with SMILE, and the fellow eye underwent femto-LASIK. Randomization was performed using a sealed envelope system. The main outcome measures were CH and CRF measured preoperatively and postoperatively (1 and 6 months). Results: Preoperative SE was similar in both groups (p = 0.852). CH and CRF values were reduced postoperatively in both groups compared to their corresponding preoperative values (p < 0.001). At the 6-month follow-up visit, the mean CH values in the SMILE and femto-LASIK groups were 8.95 +/- 1.47 and 9.02 +/- 1.27, respectively (p = 0.852), and the mean CRF values were 7.77 +/- 1.37 and 8.07 +/- 1.26, respectively (p = 0.380). Conclusion: CH and CRF decreased after SMILE. There were no differences between SMILE and femto-LASIK treatments in postoperative CH or CRF values. Crown Copyright (C) 2013 Published by Elsevier Ltd on behalf of British Contact Lens Association. All rights reserved.