Development of Corneal Astigmatism (CA) according to Axial Length/Corneal Radius (AL/CR) Ratio in a One-Year Follow-Up of Children in Beijing, China.

Fenglei Wang,Xuxia Meng,Ling Wang,Dabo Wang,Lin Xiao

doi:10.1155/2018/4209236

Abstract

Purpose The correlations between the axial length-to-corneal radius (AL/CR) ratio and corneal astigmatism (CA) were studied by prospectively analyzing and comparing survey data from school children in the Beijing urban area from 2014 to 2015. Methods In this longitudinal study, a total of 2,970 students were enrolled in 2014, and 2,179 students were enrolled in 2015. The students were in grades 1 and 4 of primary schools located in the Yangfangdian district of Beijing. The students were examined using the standard logarithmic visual acuity chart for uncorrected visual acuity (UCVA) and IOLMaster for ocular components. Results From 2014 to 2015, the students from grades 1 and 4 had significantly worse UCVA results, longer axial lengths (AL), and greater AL/CRs (p < 0.001). The boys had a longer AL and corneal radius (CR) than the girls (p < 0.001). A significantly higher rate of increased CA was observed for the students with increased AL/CR than for those with decreased or unchanged ratios (AL/CR for grade 1, X2 = 12.304, p=0.001; for grade 4, X2 = 29.044, p < 0.001). In addition, with increased AL/CR over one year, the CA value of the students in grades 1 and 4 became significantly larger (grade 1, p=0.001; grade 4, p < 0.001); moreover, the UCVA became worse (p < 0.001). Conclusions We found that UCVA and AL growth were affected by aging. An increase in the AL/CR ratio is a risk factor for the progression of corneal astigmatism for school children.

Highlights

Astigmatism is a common refractive anomaly that is described clinically as a bivariate quantity consisting of an astigmatic modulus and an axis
Longitudinal studies have shown that the early cylindrical error is greatly reduced or eliminated during the first two years of life [7,8,9], followed by slower changes occurring between ages 2 and 6 years [10] and stability between the ages of 6 and 12 years [11]. e positive compensatory changes in corneal and internal astigmatisms accompany a fast reduction in refractive astigmatism in infancy and early childhood [12]
Changes in astigmatism must be associated with the development of ocular biometry and structure. us, the determination of a target for estimating the tendency of astigmatism is quite critical in the prediction of myopic progression

Summary

Introduction

Astigmatism is a common refractive anomaly that is described clinically as a bivariate quantity consisting of an astigmatic modulus and an axis. Chi-square statistics were used to test whether the increases in CA were the same for the grade 1 and 4 students who had increased or decreased AL/CR over the two-year study period.

Results

Conclusion