AIM: To investigate the risk factors of refractive regression after correction of moderate and high myopia by femtosecond laser assisted in situ keratomileusis(FS-LASIK)for 1 a, and construct prediction model.

METHODS: A retrospective analysis was performed on the clinical data of 400 patients(800 eyes)with moderate and high myopia undergoing FS-LASIK correction in Xi'an Gaoxin Hospital from June 2017 to November 2018, and the patients were randomly divided into modeling group(n=300)and verification group(n=100)according to a ratio of 3:1. The modeling group was divided into regression group and non-regression group according to the occurrence of refractive regression at 1 a after surgery. The changes of corneal curvature and corneal thickness were observed. Logistic regression analysis was used to screen the risk factors of refractive regression in patients with moderate and high myopia at 1 a after FS-LASIK correction, and the prediction model was built based on the regression coefficient. Receiver operating curve(ROC)was used to evaluate model differentiation.

RESULTS:Refractive regression occurred in 44 eyes of the modeling group and 15 eyes of the verification group at 1 a after surgery. The anterior corneal surface curvature in the modeling group was lower than that in the regression group at 6 and 12 mo after surgery(all P<0.05). The degree of corneal hyperplasia in the regression group was greater than that in the non-regression group at 1, 3, 6 and 12 mo after surgery(all P<0.05). The regression equation of the probability value of refractive regression in patients with moderate and high myopia corrected by FS-LASIK at 1 a after surgery is as follows:P=1/\〖1+e^{-(-5.989+0.127×age+2.019×preoperative diopter-0.022×preoperative central corneal}

^{thickness+0.043×depth of cutting-1.569×diameter of cutting optical region)}\〗, Hosmer-Lemeshow detected the goodness of fit of the regression equation(P=0.818). Internal verification using the modeling group data showed that the area under ROC curve was 0.890(95%CI: 0.843-0.937), the sensitivity was 81.82%, and the specificity was 84.71%. The area under ROC curve was 0.838(95%CI: 0.717-0.959), the sensitivity was 80.00%, and the specificity was 87.57%.

CONCLUSIONS:The established risk model has good discriminating validity and can be used to identify the high-risk group of refractive regression at 1 a after FS-LASIK in patients with moderate and high myopia.