Corneal resistance factor and corneal hysteresis in a 6- to 18-year-old population
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Purpose To determine the distribution and normal range of the corneal resistance factor (CRF) and corneal hysteresis (CH) in the 6- to 18-year age range and their relationship with biometric components. Setting Dezful, Iran. Design Cross-sectional study. Methods This study of Dezful school children used a multistage, stratified, cluster approach sampling. All students had examinations for biometry, noncycloplegic refraction, and corneal biomechanical properties; the examinations were performed in the same order in all cases. Results Of the 864 selected students, 683 participated in the study. The mean CRF and CH was 11.74 mm Hg ± 1.77 (SD) (95% confidence interval [CI], 11.58-11.89) and 11.49 ± 1.91 mm Hg (95% CI, 11.33-11.65), respectively. In a linear multiple regression model, the CRF significantly correlated with female sex (β coefficient = 0.488, P=.013), central corneal thickness (CCT) (β coefficient =.034, P=.001), and keratometry (β-coefficient = 0.157, P=.003) and CH significantly correlated with CCT (β coefficient = 0.025, P < .001), axial length (β coefficient = -0.303, P=.011), and keratometry (β coefficient = 0.11, P=.043). Each year increase in age was associated with a 42-unit decrease in the peak 1 area (P=.003). Conclusions The distribution of CRF and CH in an Iranian population was symmetrical and bell shaped. However, the CRF did not have a normal distribution. The mean CRF and CH were higher than those reported in almost all previous studies. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned. © 2014 ASCRS and ESCRS.