AIM:To assess the anterior corneal astigmatism (ACA)and posterior corneal astigmatism (PCA) patterns across various age groups.We also evaluated the association between magnitudes and axes of the ACA and PCA across these age groups.METHODS:The present study was a cross-sectional analysis of clinical data of 381 eyes.We converted the clinical astigmatic notation to vector notation for analysis of ACA and PCA.We estimated the correlation between magnitude and axes of the ACA and PCA in the whole population and in four age groups (5-19,20-39,40-59,and ≥ 60y).We used random effects linear regression models for estimating the association between the magnitudes of ACA and PCA.RESULTS:The mean of the magnitude of the ACA (3.59D) and the PCA (0.50D) was highest in children (5 to 9y).Overall,the magnitude of the ACA ranged from 0D to 10.0 Diopters (D) and the magnitude of the PCA ranged from 0 to 3.5 D.There was a significant correlation between the ACA and the PCA in the younger age group (r=0.85,P＜0.001).In those 60y or older,the PCA increased by 0.04 units (95％ confidence intervals:0.005,0.07;P=0.03) with each unit increase in the ACA,the increase was the smallest in this age group.CONCLUSION:It will be prudent to measure the both the magnitude and axis of the PCA,particularly in those above 60y rather than rely on rule-of-thumb calculations based on ACA parameters for IOL power calculation.