目的：以不同年龄段分组评估前角膜散光(ACA)和后角膜散光(PCA)。同时分析各年龄段ACA、PCA之间散光程度、散光轴的相关性。

方法：横断面研究，包括381眼。将临床测得的散光数值转换为向量记法，以分析ACA和PCA。在整体人群和四个不同年龄段(5～19， 20～39， 40～59， 和≥60)中评估ACA和PCA之间散光程度、散光轴的关系。使用随机效应线性回归模型评估ACA、PCA散光程度之间的关系。

结果：在5～9岁儿童中，ACA平均散光度最高为3.59D，PCA为0.50D。总体上来说，ACA在1～10.0D，PCA在0～3.5D。在较年轻的分组中(5～19岁)，ACA和PCA显著相关(r=0.85， P<0.001)。在60岁以上组中，ACA每增加1D，PCA增加0.04D(95%CI： 0.005， 0.07； P=0.03)，增加程度相比其余组最少。

结论：在60岁以上人群中，相比仅仅依靠经验公式，通过ACA数据计算IOL度数，更为谨慎的方法是同时测定后角膜散光度和散光轴。

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.