The normal distribution of corneal eccentricity and its determinants in two rural areas of north and south of Iran

Purpose: the aim of this study was to determine the distribution of corneal eccentricity (e-value) in a normal population and to examine related factors. methods: in this cross-sectional study, two villages were selected in iran using multistage cluster sampling. selected persons were invited to have a comprehensive eye examination. examinations in each village were performed at a specific location under standard conditions. after testing for vision and refraction and conducting the slit-lamp exam, e-value was measured with pentacam. results: of the 3851 selected individuals, 3314 participated in the study. after applying the exclusion criteria, data from 2610 subjects was used in the analysis for this report. mean e-value was 0.53 [95% confidence interval (ci): 0.52 to 0.54]. e-value was not significantly different between males and females. mean e-value reduced with age from 0.60 in subjects aged 6–20 years to 0.47 in subjects older than 70 years. the hyperopic group of participants had significantly lower e-value than myopic and emmetropic ones (p < 0.001). the relationship of e-value with age, gender, and other anterior segment variables and spherical equivalent was examined in a multiple linear regression model. in multiple linear regression model, age (coef = −0.003), spherical equivalent refraction (coef = −0.005), pupil diameter (coef = 0.018), anterior chamber volume (coef = −0.001), and anterior chamber angle (coef = 0.003) significantly correlated with e-value. conclusions: the results of this study showed that the cornea in normal populations is prolate, and the degree of prolateness varies by age, such that older age is associated with a less prolate cornea. this study showed that factors such as age and refractive errors and anterior chamber indices influence the e-value.