关键词: 近视, 角膜塑形镜, 偏心

Abstract: Objective To investigate the effects of orthokeratology decentration on myopia progression. Design Retrospective case series. Participants 132 children from June 2016 to October 2018 in the Optometry Hospital of Wenzhou Medical University who met the criteria and insisted on wearing orthokeratology lens for 24 months. Methods The axial length before wearing the lens and after wearing the lens for 2 years was compared. A tangential difference map from the tangential map before the orthokeratology and after wearing for 3 months was built. The tangential difference map was imported into Matlab to depict the shaping circle and locate the center of the circle. The distance between the circle center and corneal vertex was decentration distance. The decentration distance was measured and the direction of decentration was analyzed. According to the orthokeratology lens decentration degree (<0.5 mm, 0.5~1.0 mm, >1.0 mm), it could be divided into low-decentration, medium-decentration and high-decentration groups. The relationship between the elongation of axial length and orthokeratology decentration was measured. Main Outcome Measures Baseline age, baseline spherical equivalent refractive power, orthokeratology decentration, and elongation of axial length. Results After wearing the orthokeratology lenses for 2 years, the axial length (25.58±0.74) mm increased compared with baseline axial length (25.19±0.80) mm, (t=-12.72, P<0.001). There were no significant differences of baseline age, baseline spherical equivalent refractive power, baseline axial length, and pupil area in decentration groups. The changes (0.39±0.32) mm of axial length in this 2 years was negative correlated with the baseline age [(11.49±1.96) years, r=-0.352, P<0.001], decentration distance [(0.67±0.32) mm, r=-0.377, P<0.001] and pupil area [(19.78±7.04) mm2, r=-0.180, P=0.039], but positive correlated with the baseline spherical equivalent refractive power [(-3.67±1.26) D, r=0.316, P<0.001]. Conclusion The decentration was inevitable after wearing orthokeratology. The orthokeratology decentration was negatively correlated with the elongation of axial length; it might show an effect on myopia control. （Ophthalmol CHN, 2020, 29: 345-349）

Key words: myopia, orthokeratology, decentration