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. 2022 Jul;10(13):730.
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

Shengyu He #  1 , Yiqi Luo #  1 , Yiming Ye  1 , Pei Chen  1 , Chang Liu  1 , Lei Lei  1 , Jing Zhuang  1 , Keming Yu  1
Affiliations

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

Shengyu He et al. Ann Transl Med. 2022 Jul.

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.

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Conflict of interest statement

Conflicts of Interest:All authors have completed the ICMJE uniform disclosure form (available at https://atm.amegroups.com/article/view/10.21037/atm-22-330/coif). All authors report that this study was supported by the National Natural Science Foundation of China (Grant Nos. 81900850 and 82101134), the Science and Technology Planning Projects of Guangzhou city (Nos. 201803010091 and 201804010076), and the Science and Technology Project of Guangzhou (No. 2018A030313573). The authors have no other conflicts of interest to declare.

Figures

Figure 1
Figure 1
Changes in corneal biomechanical parameters after SMILE and FS-LASIK. **P<0.01, statistically significant; *P<0.05, statistically significant; ***P<0.001, statistically significant. ARTh, Ambrosio relational thickness to the horizontal profile; Pre-op, preoperative; mo, month; SMILE, small incision lenticule extraction; FS-LASIK, femtosecond laser-assisted in situ keratomileusis; SP-A1, stiffness parameter A1; DA, deformation amplitude; IR, integrated radius.
Figure 2
Figure 2
Changes in CCT and CV after SMILE and FS-LASIK. ***P<0.001, statistically significant. Pre-op, preoperative; mo, month; CCT, central corneal thickness; CV, corneal volume; SMILE, small incision lenticule extraction; FL-LASIK, femtosecond laser-assisted in situ keratomileusis.
Figure 3
Figure 3
Scatterplots and simple linear regression analysis between corneal biomechanical parameters and CCT and CV postoperatively. ARTh, Ambrosio relational thickness to the horizontal profile; CCT, central corneal thickness; SMILE, small incision lenticule extraction; FS-LASIK, femtosecond laser-assisted in situ keratomileusis; SP-A1, stiffness parameter A1; IR, integrated radius; DA, deformation amplitude; CV, corneal volume.
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