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Objectives: To investigate changes in axial length in children undergoing orthokeratology (OK) and evaluate short-term axial change in predicting post-OK myopia progression. Methods: In this retrospective study, the subjects included 70 myopic children aged 8 to 15 years wearing OK contact lenses for more than 3 years. Axial length changes at 0.5, 1, 2, and 3 years relative to the baseline were measured. Patients were evaluated for age, spherical equivalent refraction (SER), pupil size, and half-year axial change using repeated analysis of variance and multivariate linear regression analysis to predict half to 3 year-axial elongation (AE, seventh–36th month post-OK). Results: The axial length grew significantly during the 3 years; the mean annual axial growth was 0.20±0.12 mm. The half-year axial change was 0.04±0.12 mm. The univariate linear analyses showed that half to 3-year AE was correlated with baseline age (r=−0.393, P<0.001) and half-year axial change (r=0.379, P=0.001), but not pupil diameter (P=0.692) or SER (P=0.673). In a multiple linear regression model, the half to 3-year AE was related with the baseline age (standardized β=−0.312, P=0.007) and half-year axial change (standardized β=0.293, P=0.01). The model was fair (adjusted R 2=0.21) and statistically significant (F=10.24, P<0.001). Conclusions: It is practical to predict long-term AE with half-year axial change for children with OK correction. Therefore, this may aid in fast and timely measures in children who are predicted to have rapid myopia progression.

To compare the myopia control efficacy and safety of decentered versus centered positioning of orthokeratology. Methods: This is a retrospective intrasubject study, including 46 children with myopia (25 boys, 21 girls; age 11.1260.33 years) treated for 1 year with OK decentration in one eye (group D) and central location in the other (Group C). Axial length was measured before and at 6 months and 12 months after the initial lens wear, respectively. Corneal topography was measured at baseline and at 1-month after lens wear. The corneal topography obtained from the 1-month visit was used to quantify treatment zone decentration (TZD) for each subject. Cycloplegic refraction was required for all children before fitting the orthokeratology lenses. Results: No differences were found between the groups in the biological ocular parameters (P$0.05 for all). The axial elongation in group D and group C differed after 6 and 12 months (P,0.001 for all). Similar corneal staining rates (P¼0.06) were noted during follow-up in groups D (n¼20; 7.24%) and C (n¼10; 3.62%), all of grade I. The uncorrected visual acuity (UCVA) in group D and C differed after 1, 6, and 12 months (P¼0.002, 0.010, 0.044), except 3 months (P¼0.146). Group D (n¼32; 17.39%) was more likely to have glare or ghosting (chi-squared test, P,0.001) than group C (n¼12; 6.52%) during follow-up visits. Axial elongation was significantly associated with baseline spherical equivalent (SE) in group C (P¼0.019). In group D, axial elongation was significantly associated with SE and TZD (P,0.05 for all). Conclusions: This intrasubject study showed that when the UCVA was acceptable and there were no apparent complications, orthokeratology decentration may be beneficial in controlling the progression of myopia. Axial elongation became slower in children with a higher SE and a larger TZD, because TZD ranged from 0.5 mm to 1.5 mm.

Background Patient non-compliance, that is, failure to perform standard wear and care orthokeratology (ortho-k) lenses procedures, has been shown to be a major risk factor for contact lens-associated complications. Therefore, this study aimed to investigate the compliance with wear and care behaviors of ortho-k patients and analyze its influencing factors. Methods Patients who were successfully prescribed ortho-k lenses at the Eye Center of the Second Affiliated Hospital of Zhejiang University School of Medicine (ECSAHZU) were enrolled in the study. Patient compliance with wear and care behaviors was examined through a questionnaire. Results This study assessed 238 subjects. The subjects’ ages ranged from 7 to 25 (mean ± SD, 11.3 ± 2.5) years. The compliance with wear and care behaviors was 19.7%, and the subjects’ self-assessment compliance was 96.6%. The compliance rate of subjects wearing lenses for less than 1 year was higher than that of subjects wearing lenses for more than 1 year (p < 0.001). In the first year, the compliance rates of wearing experiences for less than 1 month, 1 month, 3 months, 6 months, and more than 6 months were 45, 29, 21.6, 20, and 27.6%, respectively, and there were no statistically significant differences in compliance among these periods (p = 0.314). No correlation was identified between compliance and age (r = − 0.061, p = 0.527) or sex (r = 0.114, p = 0. 751). There was no correlation between compliance and lens care operator (r = − 0.626, p = 0.151). Conclusions The compliance of ortho-k patients was poor. After wearing ortho-k lenses for more than 1 year, compliance with wear and care behaviors declined. In clinical practice, measures should be taken to solve these problems and improve the safety of wearing ortho-k lenses.