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

Shengyu He; Yiqi Luo; Yiming Ye; Pei Chen; Chang Liu; Lei Lei; Jing Zhuang; Keming Yu

doi:10.21037/atm-22-330

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

Ann Transl Med. 2022 Jul;10(13):730. doi: 10.21037/atm-22-330.

Authors

Shengyu He^#¹, Yiqi Luo^#¹, Yiming Ye¹, Pei Chen¹, Chang Liu¹, Lei Lei¹, Jing Zhuang¹, Keming Yu¹

Affiliation

¹ State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, China.

^# Contributed equally.

Abstract

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.