CORNEAL BIOMECHANICAL STABILITY AFTER SMILE AND FS-LASIK: A SYSTEMATIC REVIEW AND META-ANALYSIS

Published 2026 - 30th ESCRS Winter Meeting

Reference: FP06.11 | Type: Free Paper | DOI: 10.82333/6nn7-pa39

Authors: Nuno Rodrigues Alves* ¹ , Catarina Barão ¹ , Matheus Pedrotti Chavez ² , Joana Ferreira ¹ , Lívio Costa ¹ , Diogo Hipólito ¹ , Nuno Filipe Alves ¹ , Vítor Maduro ¹

¹Ophthalmology,Unidade Local de Saúde de São José,Lisbon,Portugal, ²Ophthalmology,Universidade Federal de Santa Catarina,Florianopolis,Brazil

Purpose

To compare postoperative corneal biomechanical properties following Small-incision lenticule extraction (SMILE) and femtosecond laser–assisted in situ keratomileusis (FS-LASIK) in adults with myopia or myopic astigmatism.

Setting

Department of Ophthalmology, Unidade Local de Saúde de São José, Lisbon, Portugal

Methods

Following PRISMA 2020 guidelines (PROSPERO CRD420251036404), PubMed, Embase, and the Cochrane Library were searched for randomized controlled trials and prospective cohorts. Primary outcomes were corneal hysteresis (CH) and stiffness parameter at first applanation (SP-A1). Secondary outcomes included other biomechanical indices (CRF, DA 2 mm, A1/A2 metrics, IR, ARTh, SSI, CBI). Data were pooled using random-effects models, and heterogeneity was assessed with I². Subgroup analyses were conducted by myopia degree (≥ –6.00 D vs. < –6.00 D) and study design. Meta-regression evaluated baseline spherical equivalent (SE) as a predictor of CH and SP-A1.

Results

Eighteen studies (six RCTs) involving 2,031 eyes (SMILE: 1,087; FS-LASIK: 944) from 1,497 patients were included. SMILE was associated with higher CH at last follow-up (MD = 0.32 mmHg; 95% CI: 0.07 to 0.58; p = 0.01; I² = 80%), with a greater effect in the high myopia subgroup (MD = 0.91 mmHg; 95% CI: 0.84 to 0.98; p < 0.00001; I² = 0%). SP-A1 differences were not significant overall but favored SMILE in high myopia (MD = 4.66 mmHg/mm; 95% CI: 1.22 to 8.10; p = 0.008; I² = 0%). Meta-regression showed that baseline SE towards higher myopia was associated with a significant advantage for SMILE in CH and SP-A1 (p = 0.0035; p = 0.045, respectively). SMILE also improved CRF, A1 metrics, ART and IR (p < 0.05), while other indices were similar between groups.

Conclusion

SMILE provides superior preservation of corneal biomechanical properties compared to FS-LASIK, especially in high myopia. Baseline refractive error should guide surgical technique to optimize corneal stability. Well-powered, long-term RCTs are warranted to determine whether these advantages translate into reduced postoperative ectasia risk.