Comparison between Small Incision Lenticule Extraction and Wavefront-Guided Femtosecond Laser-Assisted In Situ Keratomileusis in Correction of Myopic Astigmatism

Abstract

Ocular refractive surgeries require precise corneal correction to achieve ideal visual outcomes and visual quality. Femtosecond laser (FL) utilizes ultrafast pulses to create precise ocular tissue ablation, and is commonly used in corneal refractive surgeries to create corneal flaps in femtosecond laser-assisted in situ keratomileusis. Recently, FL has also increasingly been used to create a transparent refractive lenticule in femtosecond lenticule extraction (FLEx) with a lifted corneal flap, and in small-incision lenticule extraction (SMILE) without a lifted flap. SMILE has been considered as an alternative procedure to conventional laser in-situ keratomileusis (LASIK) because of its potential advantages of reduced denervation, faster resolution of post-operative dry eye, improved biomechanics, and no flap related risks. Key procedural differences between SMILE and wavefront-guided femtosecond laser-assisted in situ keratomileusis (WFG FS-LASIK) could contribute to the noted differences in optical qualities following the procedures. SMILE relies on subjective fixation on a target light without eye tracking and iris registration. In contrast, WFG FS-LASIK utilizes iris registration to trace the pupil shift. Pupil shift might affect these two procedures