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

## TL;DR

This study compares the long-term effects of two eye surgeries, SMILE and LASEK, on corneal shape and vision quality six years after treatment for mild-to-moderate nearsightedness.

## Contribution

The study provides a six-year comparative analysis of SMILE and LASEK on corneal irregularity and visual quality, focusing on long-term outcomes.

## Key findings

- Both SMILE and LASEK showed comparable safety and efficacy indices after six years.
- LASEK caused more flattening of the anterior cornea and reduced regular astigmatism more effectively than SMILE.
- SMILE induced less horizontal coma compared to LASEK six years post-surgery.

## Abstract

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.

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.

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).

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