This prospective study showed that 3-month visual and safety outcomes were similar between femtosecond-LASIK (FS-LASIK), wave front-guided femtosecond LASIK (WF-LASIK) and femtosecond lenticule extraction (FLEx) for patients undergoing correction of myopia and myopic astigmatism. However, WF-LASIK produced better mesopic contrast sensitivity (CS) and a lower induction rate of higher order aberrations (HOAs) compared with the other two procedures.
Study design and outcomes
In this nonrandomized study, 332 right eyes of 332 patients that were treated showed excellent visual acuity, with 96.1% of the FS-LASIK group, 98.9% of the WF-LASIK group and 96.4% of the FLEx group at 20/20 or better.
Significant increases in HOAs were seen in all 3 groups, but WF-LASIK eyes had significantly better HOA induction rates than FS-LASIK and FLEx (P<0.01). Additionally, a better mesopic CS with and without glare was observed in the WF-LASIK group.
While FS-LASIK, WF-LASIK and FLEx share some similarities, few studies have compared visual outcomes, decentration, CS and HOAs between the 3 procedures.
In theory, FLEx has the advantage of shorter cutting time due to the use of a single femtosecond laser. The very low vacuum suction with FLEx can help patients to stare at the fixation light and improve the accuracy for the optical zone center. Despite these advantages, however, the WF-LASIK can induce less coma and spherical aberrations, and as a result the WF-LASIK group demonstrated less decentration and better corneal regularity than the FLEx cohort. FLEx did induce a lower rate of spherical aberrations than FS-LASIK, as the procedure involves no decrease of energy effect on the peripheral cornea.
The study compared very different platforms and introduced multiple variables in its analysis. Despite that, all 3 procedures show excellent efficacy, safety, stability, and predictability for the correction of myopia and myopic astigmatism. More research is still necessary to confirm the potential superiority of one technique over any other.