What question did this study set out to answer?

To compare corneal biomechanical changes and refractive outcomes after SMILE and LASEK in myopia patients with thin corneas.

February 28, 2026Open Access

Comparison of corneal biomechanics after SMILE versus LASEK in moderate to high myopia with relatively thin corneas: a retrospective comparative study

Key Points

To compare corneal biomechanical changes and refractive outcomes after SMILE and LASEK in myopia patients with thin corneas.
Retrospective comparative study design
Including 47 eyes from moderate to high myopia patients
Assessment of corneal biomechanical parameters and refractive outcomes preoperatively and postoperatively
Using biomechanical measuring devices like Corvis ST II
Statistical analysis of safety and efficacy indices alongside biomechanical changes
LASEK showed a higher efficacy index than SMILE (1.09 vs. 0.98; P = 0.02)
LASEK resulted in smaller reductions in corneal stiffness (ΔSP-A1) than SMILE (-11.31 vs. -28.99; P = 0.01)
Postoperative central corneal thickness correlated positively with corneal stiffness parameters
Both procedures demonstrated excellent safety profiles, achieving near-ideal outcomes

Abstract

This study aimed to compare the 2-year refractive outcomes and corneal biomechanical changes after Small Incision Lenticule Extraction (SMILE) versus Laser-Assisted Subepithelial Keratectomy (LASEK) in patients with moderate to high myopia (spherical equivalent SE: -2.00 to -6.75 D) and relatively thin corneas (central corneal thickness CCT ≤ 530 μm). In this retrospective, comparative, non-randomized study, 47 patients (47 eyes) were included, assigned to either SMILE (n = 24) or LASEK (n = 23). Corneal biomechanical parameters (Corvis ST II CST: biomechanically corrected intraocular pressure bIOP, stiffness parameter at first applanation SP-A1, integrated inverse radius IntInv-Rad, deformation amplitude ratio at 2.0 mm DAR 2.0 mm, Ambrosio relational thickness horizontal ARTh) and refractive outcomes (safety and efficacy indices) were evaluated preoperatively and 2 years postoperatively. Intergroup comparisons of changes (Δ) in these parameters and correlation analyses with potential predictors were analyzed. The safety indices were comparable between the two groups (SMILE: 0.90 ± 0.11 vs. LASEK: 0.87 ± 0.09; P = 0.24), but the efficacy index was statistically higher in the LASEK group (1.09 ± 0.18 vs. 0.98 ± 0.13; P = 0.02), although the clinical relevance of this difference is likely limited as both values are close to the ideal of 1.0. Preoperatively, the LASEK group had thinner CCT (492.78 ± 18.92 vs. 509.71 ± 9.47 μm; P < 0.01), lower cylinder (-0.80 ± 0.86 vs. -1.28 ± 0.78 D; P = 0.05), and lower SE (-3.73 ± 1.39 vs. -4.71 ± 1.13 D; P = 0.01). At 2 years, compared with SMILE, LASEK resulted in a significantly smaller reduction in ΔSP-A1 (-11.31 ± 23.72 vs. -28.99 ± 21.37; P = 0.01) and smaller increases in ΔIntInv-Rad (+ 0.98 ± 1.48 vs. +1.75 ± 0.89; P = 0.03) than SMILE. Postoperative CCT was positively correlated with ΔSP-A1 (SMILE: r = 0.50, P = 0.01; LASEK: r = 0.60, P < 0.01) and negatively with ΔIntInv-Rad (SMILE: r=-0.51, P = 0.01; LASEK: r=-0.45, P = 0.03). This study suggests that in patients with moderate to high myopia and relatively thin corneas, LASEK was associated with smaller alterations in certain corneal biomechanical parameters at 2 years postoperatively compared to SMILE, as indicated by better preservation of corneal stiffness (SP-A1) and less change in overall biomechanical response (IntInv-Rad). Postoperative CCT is a significant predictor of these biomechanical alterations. Both procedures demonstrated excellent and comparable safety profiles, with all patients achieving the primary clinical goal of refractive surgery.

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Cite This Study

Zhang et al. (Wed,) studied this question.

synapsesocial.com/papers/69a285da0a974eb0d3c00ba1 https://doi.org/https://doi.org/10.1186/s12886-026-04682-3

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