Objective::To investigate the ef?cacy and safety of orthokeratology for the control of myopia in patients with flat keratometry (Kf<41.00 D).Methods:This was a prospective controlled study. A total of 80 patients (120 eyes) with orthokeratology lenses were enrolled in the study group and 76 patients (120 eyes) with glasses were enrolled in the control group. The two groups were divided into low (-3.00-0 D) and medium (-6.00--3.25 D) arrays based on spherical equivalent (SE). The myopia increment,axial increment, endothelial cell number, corneal thickness and corneal dot were analyzed in each group.In the data, an independent samplest-test was used for the increase in myopia and axial length, and a paired samplest-test was used for the number of endothelial cells and corneal thickness.Results:Myopia increased when wearing either orthokeratology lenses or glasses for 6 array: 6 months:t=3.204,P=0.002; 1 year:t=4.613,P<0.001; 1.5 years:t=5.160,P<0.001) and axial growth (low degree array: 6 months:t=-2.103,P=0.038; 1 year:t=-2.129,P=0.037; 1.5 years:t=-2.398,P=0.020; medium array: 6 months:t=-2.094,P=0.039; 1 year:t=-2.402,P=0.019; 1.5 years:t=-2.464,P=0.018). The orthokeratology lens group had significantly lower values than the frame glasses group.1.5 years after wearing orthokeratology lenses, corneal endothelial cell density, average cellular area,coef?cient of variation, percentage of hexagonal cells, and corneal thickness had no signi?cant changes compared to values before wearing the lenses. No serious ocular complications occurred while wearing orthokeratology lenses.Conclusions:Orthokeratology lenses can control the growth of the ocular axis significantly and myopia increases more slowly compared with glasses in patients with relatively flat corneal curvature. months, 1 year and 1.5 years (low degree array: 6 months:t=2.314,P=0.023; 1 year:t=3.215,P=0.002; 1.5 years:t=4.159,P<0.001; medium