Comparison of Postoperative Corneal Higher-Order Aberrations, Asphericity, Densitometry, and Optical Quality Between SMILE Pro and LASIK: A Retrospective Cohort Study.

Abstract

Purpose: To compare postoperative changes in corneal higher-order aberrations (HOAs), densitometry, and optical quality following SMILE Pro and laser in situ keratomileusis (LASIK), and to investigate the relationship between corneal densitometry and postoperative optical quality.

Patients and methods: This retrospective matched cohort study included 60 eyes of 30 patients who underwent SMILE Pro and 60 eyes of 30 age-, sex-, and preoperative spherical equivalent-matched patients who underwent LASIK for myopia at Hanamizuki Eye Clinic between July 2025 and March 2026. Anterior, posterior, and real corneal HOAs, spherical aberration (SA), coma, anterior corneal Q value, and central (0-4 mm) corneal densitometry were evaluated using anterior segment optical coherence tomography (CASIA2). Optical quality was assessed using the modulation transfer function (MTF) Area Ratio (Total and HO) obtained with the OPD-Scan III. Longitudinal comparisons were analyzed using linear mixed-effects models, and correlations were evaluated using Spearman's rank correlation coefficient.

Results: Compared with LASIK, the SMILE Pro group showed significantly lower posterior corneal coma at 1 week, lower anterior and real SA at 1 month, and lower anterior and real SA as well as real corneal coma at 3 months (all P<0.05). Q values were significantly lower at 1 and 3 months. Corneal densitometry was significantly higher in the SMILE Pro group at 1 week, 1 month, and 3 months (all P<0.05), whereas the 3-month MTF Area Ratio Total was significantly lower (P=0.004). Within the SMILE Pro group, corneal densitometry at 1 week, 1 month, and 3 months was significantly negatively correlated with the 3-month MTF Area Ratio HO (all P<0.05), whereas no significant correlations were observed in the LASIK group.

Conclusion: Compared with LASIK, SMILE Pro was associated with fewer postoperative corneal HOAs and better preservation of corneal asphericity. Although higher-order optical quality was comparable between the two procedures, postoperative corneal densitometry was associated with higher-order optical quality only after SMILE Pro. These findings suggest that anterior segment OCT-derived corneal densitometry may provide additional noninvasive information on postoperative stromal interface healing and its relationship with optical quality following SMILE Pro.