Distribution of keratometry and its determinants in a general population of 6-to 12-year-old children

Purpose: To determine the distribution of keratometry and its determinants in Iranian school children. Methods: The present cross-sectional study was conducted in 2015 in Shahroud in the north of Iran. The entire rural population of elementary school children was invited to the study. In urban areas, cluster sampling was conducted. Pentacam HR (Oculus Inc., Lynnwood, WA) was used to measure the flat meridian, the steep meridian, and the mean keratometry. Linear regression was used to determine the associated variables with mean keratometry. Results: Of 5620 participated in the study, 5559 children were analyzed after applying the exclusion criteria. Mean keratometry was 43.56 +/- 1.96 diopters (D) (95% confidence interval = 43.48-43.64) in the total sample, 43.18 +/- 2.23 D (95% confidence interval = 43.09-43.26) in boys, and 44.01 +/- 1.46 D (95% confidence interval = 43.95-44.07) in girls (p < 0.001). The highest and lowest mean keratometry was 43.28 +/- 1.66 D (95% confidence interval = 43.00-43.55) and 42.89 +/- 2.70 D (95% confidence interval = 42.68-43.11) in 6-year-old and 10-year-old children, respectively (p = 0.031). The results of multiple linear regression showed that mean keratometry in girls was 0.82 D higher than in boys (p < 0.001), and in groups older than 9 years, it was significantly decreased. Mean keratometry in myopic children was 0.62 D higher than emmetropic children (p < 0.001). Conclusion: This study provided valuable findings from the status of keratometry in Iranian children. In line with other studies, corneal power was higher in girls than in boys, and the cornea becomes flatter with age in children.