A comparative and prospective study of corneal biomechanics after SMILE and FS-LASIK performed on the contralateral eyes of high myopia patients.

BACKGROUND

To compare the corneal biomechanical changes after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) with the same programmed optical zone (POZ) and similar refractive correction in patients with high myopia.

METHODS

In this prospective comparative study of the contralateral eye, 50 patients with high myopia with the same POZ and similar refractive correction who underwent SMILE in one eye and FS-LASIK in the other eye. Corneal biomechanical parameters and central corneal thickness (CCT) were measured using a Corvis ST II. All the patients were evaluated during follow-up visits beyond one year. Additionally, the corneal volume (CV) of the 10-mm diameter region was measured using a Pentacam.

RESULTS

Ambrosio relational thickness to the horizontal profile (ARTh) and stiffness parameter A1 (SP-A1) decreased significantly after SMILE and FS-LASIK, whereas deformation amplitude ratio 2.0 mm (DA ratio 2.0 mm) and integrated radius (IR) increased significantly in both groups. The ARTh and SP-A1 were greater after SMILE than those after FS-LASIK at all the follow-up visits. In addition, there were greater amounts of CCT and CV after SMILE compared with that after FS-LASIK. Moreover, a positive correlation was found between ARTh and SP-A1 and postoperative CCT, while a negative correlation was found between IR and DA ratio 2.0 mm and postoperative CCT. A moderate correlation was observed between SP-A1 and CV after both SMILE and FS-LASIK, whereas there were no relationships between CV and ARTh, IR, or DA ratio 2.0 mm.

CONCLUSIONS

SMILE had greater CCT, CV, ARTh, and SP-A1 than FS-LASIK in high myopia with the same POZ and similar refractive correction. Our results demonstrated that SMILE had lesser effect on corneal biomechanics than FS-LASIK in high myopia.

KEYWORDS

Corneal biomechanics; Corvis ST II; small incision lenticule extraction (SMILE); femtosecond laser-assisted in situ keratomileusis (FS-LASIK); high myopia.