飞秒激光小切口角膜基质透镜取出术联合快速角膜交联矫正中高度近视术后角膜形态学和生物力学变化OA

Objective To investigate the changes in corneal morphology and biomechanics after small incision lenti-cule extraction(SMILE)combined with accelerated corneal crosslinking(ACXL)for the correction of moderate-to-high myopia.Methods In this retrospective case-control study,67 myopic patients(67 eyes)who underwent SMILE surgery at our hospital from January 2021 to October 2024 were enrolled and divided into the SMILE group(36 patients)and the SMILE Xtra group(31 patients).Visual acuity,refractive power,corneal morphological parameters,and corneal biomechani-cal parameters were assessed preoperatively and at 1,3,and 6 months postoperatively.Generalized linear mixed models were used to analyze the variation trends of the observed indicators before and after surgery and differences between groups,with multiple comparisons adjusted using Bonferroni correction.Results Six months postoperatively,there were no statistically significant differences in uncorrected visual acuity or spherical equivalent between the two groups(both P＞0.05).Intergroup comparisons showed that at each time point,there were no statistically significant differences in the 2-mm maximum deformation amplitude ratio(DA Ratio 2 mm),stress-strain index(SSI),or integrated radius(IR)between the two groups(all P＞0.05).At 1 and 3 months postoperatively,the corneal stiffness parameter at the first applanation(SP-A1)in the SMILE Xtra group was lower than that in the SMILE group(both P＜0.05).The ΔDA Ratio 2 mm and ΔIR in the SMILE Xtra group were lower than those in the SMILE group(both P＜0.05),while there were no statistically significant differences in ΔSP-A1 or ΔSSI between the two groups(both P＞0.05).The index of surface variance(ISV)and index of vertical asymmetry(IVA)at each postoperative time point,the index of height asymmetry(IHA)at 1 month postoperative-ly,and the index of height decentration(IHD)at 1 and 3 months postoperatively in the SMILE Xtra group were higher than those in the SMILE group(all P＜0.05).Intragroup comparisons showed that there were no statistically significant differ-ences in SSI at any time point in either group(all P＞0.05).Compared with preoperative values,DA Ratio 2 mm,IR,ISV,IVA,and IHD in both groups increased at each time point postoperatively,while SP-A1 decreased postoperatively(all P＜0.05),with no statistically significant differences between 1 and 3 months postoperatively(all P＞0.05).In the SMILE Xtra group,SP-A1 at 6 months postoperatively was higher than that at 1 and 3 months postoperatively(both P＜0.05).IHA in the SMILE Xtra group showed increases at all postoperative time points compared with preoperative values,while IHA in the SMILE group showed increases at 3 and 6 months postoperatively compared with preoperative values(all P＜0.05).Con-clusion Within the follow-up period of this study,SMILE Xtra demonstrates good safety and efficacy for the correction of moderate-to-high myopia.SMILE Xtra achieves postoperative biomechanical stability,with a small magnitude of surgically induced biomechanical loss.