Comparison of visual acuity, higher-order aberrations and corneal asphericity after refractive lenticule extraction and wavefront-guided laser-assisted in situ keratomileusis for myopia

Aim To compare postoperative visual acuity, higher-order aberrations (HOAs) and corneal asphericity after femtosecond lenticule extraction (FLEx) and after wavefront-guided laser-assisted in situ keratomileusis (wfg-LASIK) in myopic eyes. Methods We examined 43 eyes of 23 patients undergoing FLEx and 34 eyes of 19 patients undergoing wfg-LASIK to correct myopia. Ocular HOAs were measured by Hartmann-Shack aberrometry and corneal asphericity was measured by a rotating Scheimpflug imaging system before and 3months after surgery. Results There was no statistically significant difference in uncorrected (p=0.66 Mann-Whitney U-test) or corrected distance visual acuity (p=0.14) after two surgical procedures. For a 6-mm pupil, the changes in fourth-order aberrations after FLEx were statistically significantly less than those after wfg-LASIK (p<0.001). On the other hand, there were no statistically significant differences in the changes in third-order aberrations (p=0.24) and total HOAs (p=0.13). Similar results were obtained for a 4-mm pupil. The positive changes in the Q value after FLEx were statistically significantly less than those after wfg-LASIK (p=0.001). Conclusions In myopic eyes, FLEx induces significantly fewer ocular fourth-order aberrations than wfg-LASIK, possibly because it causes less oblation in the corneal shape, but there was no statistically significant difference in visual acuity or in the induction of third-order aberrations and total HOAs. It is suggested that FLEx is essentially equivalent to wfg-LASIK in terms of visual acuity and total HOA induction, although the characteristics of HOA induction are different.