Hassan Hashemi1, Ebrahim Jafarzadehpur1, Shiva Mehravaran1, Abbasali Yekta1, Hadi Ostadimoghaddam1, Reza Norouzirad1, Mehdi Khabazkhoob2. 1. From the Noor Ophthalmology Research Center (Hashemi, Jafarzadehpur, Mehravaran), Noor Eye Hospital, and the Department of Optometry (Jafarzadehpur), Iran University of Medical Sciences, the Department of Epidemiology (Khabazkhoob) Faculty of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, the Refractive Errors Research Center (Yekta, Ostadimoghaddam) and the Department of Optometry (Yekta, Ostadimoghaddam), School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, and the Dezful University of Medical Sciences (Norouzirad), Dezful, Iran. 2. From the Noor Ophthalmology Research Center (Hashemi, Jafarzadehpur, Mehravaran), Noor Eye Hospital, and the Department of Optometry (Jafarzadehpur), Iran University of Medical Sciences, the Department of Epidemiology (Khabazkhoob) Faculty of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, the Refractive Errors Research Center (Yekta, Ostadimoghaddam) and the Department of Optometry (Yekta, Ostadimoghaddam), School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, and the Dezful University of Medical Sciences (Norouzirad), Dezful, Iran. Electronic address: khabazkhoob@yahoo.com.
Abstract
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.
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.
Authors: Samira Heydarian; Sara Sardari; Zahra Heidari; Abbas Ali Yekta; Hadi Ostadimoghaddam; Mehdi Khabazkhoob Journal: J Curr Ophthalmol Date: 2020-12-12