Evaluation of Corneal Irregular Astigmatism and Visual Quality Following Bilateral Sequential SMILE and LASEK: A Six-Year Comparative Study.

PURPOSE: To compare the corneal spherical component (SC), regular astigmatism (RA), irregular astigmatism (IA, including asymmetry and irregularity), and visual quality 6 years after small incision lenticule extraction (SMILE) and laser subepithelial keratomileusis (LASEK) for mild-to-moderate myopia.

METHODS

This retrospective, comparative study comprised the SMILE group (35 eyes) and LASEK group (36 eyes). Visual acuity, corneal topography utilizing swept-source anterior segment OCT, and wavefront aberrations were recorded preoperatively and 6 years postoperatively. Fourier analysis of keratometric-derived parameters of the anterior, posterior, and total cornea at 6 mm zone was evaluated.

RESULTS

Six years postoperatively, the safety and efficacy indices were comparable between both groups. Fourier analysis revealed significant changes in SC decrease and asymmetry increase of the anterior and total cornea (p < 0.001), with LASEK exhibiting a more pronounced flattening effect of the anterior cornea (p = 0.001). Interestingly, RA of the anterior and total cornea decreased significantly after LASEK (p = 0.016,  0.002, respectively). Further linear correlation analysis showed that changes in SC (Δ SC) of anterior cornea and total cornea were correlated with the preoperative spherical power, mean refractive spherical equivalent (MRSE), lenticule thickness/ablation depth, ΔK1, and ΔK2 (all |r| > 0.85, p < 0.001). Compared with LASEK, SMILE induced less horizontal coma at 6 years postoperatively (p = 0.008).

CONCLUSIONS

Both SMILE and LASEK are safe and effective procedures for correction of mild-to-moderate myopia. LASEK demonstrates an advantage in flattening the anterior cornea and reducing regular astigmatism, while SMILE exhibits superior performance in inducing less horizontal coma Trial Registration: ClinicalTrials.gov identifier: NCT06673992.