Survival analysis of myopic regression after small incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis for low to moderate myopia

Abstract

Background To report the predictive factors of myopic regression in patients who had undergone small incision lenticular extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileuses (FS-LASIK) after 3–12 months of follow-up. Methods This retrospective case series study recruited patients with a subjective sphere of − 1.00 to − 6.00 D myopia. SMILE was performed in 1629 eyes of 1629 patients with a subjective refraction spherical equivalent (SEQ) of − 4.57 ± 1.20 D and 1414 eyes of 1414 patients with a subjective SEQ of − 4.53 ± 1.26 D in FS-LASIK. Refractive outcomes were recorded at 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. Predictors affecting myopic regression and other covariates were estimated with a Cox proportional hazard (Cox PH) model for the two surgical methods. Results At 12 months, no significant difference was evident in the efficacy (P = 0.934), predictability (P = 0.733), or stability (P = 0.66) between FS-LASIK and SMILE. The survival rates were 83.7% in the FS-LASIK group and 88.1% in the SMILE group. Multivariate analysis by the Cox PH model revealed a similar probability of postoperative myopic regression with SMILE or FS-LASIK (P = 0.630). Predictors of myopic regression included preoperative higher-order aberration root mean square with 3 mm pupil diameter (pre-HOA-RMS3) (P = 0.004), anterior chamber depth (ACD) (P = 0.015), pre-subjective sphere (P = 0.016), corneal diameter (P = 0.016), optical zone (OZ) (P = 0.02), and predicted depth of ablation (DA) (P = 0.003). Conclusion SMILE and FS-LASIK had a similar risk of myopic regression for low to moderate myopia. Pre-HOA-RMS3, ACD, pre-subjective sphere, corneal diameter, OZ, and predicted DA were predictors of myopic regression.

Refraction and topographic risk factors for early myopic regression after small-incision lenticule extraction surgery

“…We speculate that a greater flat corneal curvature indicates a greater baseline corneal curvature that may be prone to extension after SMILE surgery. Additionally, a study including more than 1000 participants revealed a correlation between preoperative SA and myopic regression in SMILE patients 12 , and the current study corresponds to this publication. HOA and CD were significantly associated with myopic regression in that study 12 , contrary to the results of the present study.…”

“…Additionally, a study including more than 1000 participants revealed a correlation between preoperative SA and myopic regression in SMILE patients 12 , and the current study corresponds to this publication. HOA and CD were significantly associated with myopic regression in that study 12 , contrary to the results of the present study. Nevertheless, the aORs of total HOA and CD in the current study presented a marginally positive correlation with myopic regression, and these findings may become statistically significant if more participants are included.…”

“…Accordingly, the predictability of the SMILE in our institution could be guaranteed. The survival rate of myopic regression in the current study was 96.67% after 6 months, which is also not inferior to that reported in previous studies 12 .…”

“…In previous studies discussing the risk factors for myopic regression after LASIK, the degree of myopia, greater postoperative central corneal thickness, aspherical ablation and large transitional zone of laser ablation were correlated with a greater risk of myopic regression 11 , 18 . Another study also demonstrated the association between the pre-subjective sphere and the risk of myopic regression in the LASIK and SMILE procedures 12 . However, few studies have evaluated ocular factors for early myopic regression after SMILE surgery.…”

Femtosecond laser-assisted in situ keratomileusis versus small-incision lenticule extraction: current approach based on evidence

“…Studies also suggest that SMILE and FS-LASIK have similar myopic regression rates at postoperative year 1 [12], and up to 5 years [13]. Although one study suggested that SMILE may provide more refractive stability than FS-LASIK [12], this difference was no longer statistically significant after adjusting for covariates [12]. However, SMILE may have other advantages of lower induced spherical aberration [8,14], and better dry eye symptoms [15,16] compared to FS-LASIK.…”