Corneal Power, Anterior Segment Length and Lens Power in 14-year-old Chinese Children: the Anyang Childhood Eye Study.

Shi-Ming Li,Rafael Iribarren,Jos J Rozema,Ningli Wang,Si-Yuan Li,Yun-Yun Sun,Meng-Tian Kang,Luo-Ru Liu,He Li,Bo Meng,Si-Yan Zhan

doi:10.1038/srep20243

Abstract

To analyze the components of young Chinese eyes with special attention to differences in corneal power, anterior segment length and lens power. Cycloplegic refractions and ocular biometry with LENSTAR were used to calculate lens power with Bennett’s method. Mean refraction and mean values for the ocular components of five different refractive groups were studied with ANOVA and post-hoc Scheffé tests. There were 1889 subjects included with full data of refraction and ocular components. As expected, mean axial length was significantly longer in myopic eyes compared to emmetropes. Girls had steeper corneas, more powerful lenses and shorter eyes than boys. Lens power was lower in boys and also lower in myopic eyes. Lens thickness was the same for both genders but was lower in myopic eyes. Although cornea was steeper in myopic eyes in the whole sample, this was a gender effect (more girls in the myopic group) as this difference disappeared when the analysis was split by gender. Anterior segment length was longer in myopic eyes. In conclusion, myopic eyes have lower lens power and longer anterior segment length, that partially compensate their longer axial length. When analyzed by gender, the corneal power is not greater in low and moderate myopic eyes.

Highlights

During the first years of ocular growth in humans, the cornea and the lens lose power while the axial length grows, increasing the anterior segment and the vitreous chamber lengths
Since most of the data in the literature focused on changes at the posterior pole, instead this paper looks at the anterior ocular components in myopic eyes, with special attention to differences in corneal power, anterior segment length and lens power between different refractive groups
This study analyzed a representative sample of children from mainland China with high prevalence of myopia by age 14

Summary

Introduction

During the first years of ocular growth in humans, the cornea and the lens lose power while the axial length grows, increasing the anterior segment and the vitreous chamber lengths. During this period refraction remains stable and becomes clustered in a leptokurtic low hyperopic distribution because more hyperopic eyes tend to grow faster in axial length[1]. Previous prospective studies on the changes of the ocular components during myopia development[4,5,6,7,8,9] have shown that the principal change seen is an increased rate of axial elongation in myopic cases.

Methods

Results

Conclusion