Background To investigate the effect of initial refractive error on the control of myopia by orthokeratology.
Methods Retrospective study. Data were analyzed from 78 patients (156 eyes) who underwent orthokeratology in Beijing Children's Hospital from January 2014 to April 2018. The changes of axial length and diopter after wearing the lenses were measured. Patients were divided into six groups according to refractive error: <-1.00D, -1.00~ -2.00D, -2.00D~ -3.00D, -3.00D~ -4.00D, -4.00D~ -5.00D and -5.00~ -6.00D. A mixed-effect model was used to analyze the relevant data. At the same time, the interaction item between diopter and wearing time was analyzed, and the influence of gender was corrected.
Results Patients averaged 12.9±2.161 years old. Two years after wearing orthokeratology lenses, there was a statistically significant difference with the interaction item between refractive error and wearing time in each group. The estimated values were 0.0631 for the right eye and 0.053 for the left eye. Orthokeratology lenses controlled the progression of myopia well, but the reduction depended on the initial diopters. Binocular axial length examination didn’t show statistically significant difference with the interaction item. Axial length increased with time, and the magnitude of increase did not differ among groups. However, the increase in the axial length of the male more than that of the female.
Conclusion Initial refractive errors have a significant impact on the control of myopia by orthokeratology. The less severe myopia patient demonstrated a more pronounced benefits after wearing orthokeratology lenses. Key words: refractive error; myopia; orthokeratology