Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Nankai University Affiliated Eye Hospital, No 4. Gansu Road, He-ping District, Tianjin, 300020, China.
Department of Health Statistics, College of Public Health, Tianjin Medical University, Tianjin, China.
Adv Ther. 2021 Dec;38(12):5763-5776. doi: 10.1007/s12325-021-01922-4. Epub 2021 Oct 10.
To evaluate normal reference ranges for corneal morphological parameters and investigate age-related changes in these parameters in Asian subjects with healthy eyes in order to provide reference data for preoperative evaluation of corneal refractive surgery and the early differential diagnosis of subclinical and asymptomatic keratoconus.
This cross-sectional, multicenter, observational study was conducted in five provinces of China, from January 2014 through October 2019. It is a retrospective analysis. Examiner-blinded clinical measurements were performed after stratification of the subjects into the following age groups: < 18, 18-30, 31-40, 41-50. We evaluated 30,618 healthy eyes of Chinese subjects who exhibited a normal corneal morphology, had no history of eye surgery or trauma, stopped wearing soft contact lenses for at least 2 weeks (rigid contact lenses for at least 4 weeks), and underwent topographic studies for both eyes on the same day.
While the anterior and posterior corneal curvatures (K1 and K2) increased with age, corneal astigmatism of the anterior and posterior surfaces (ΔK) and central, minimum, and overall corneal thicknesses decreased with age. Age-related decrease of the overall corneal thickness was more obvious toward the periphery. The anterior and posterior corneal surface heights exhibited a decrease and an increase, respectively. Both index of height asymmetry (IHA) and index of vertical asymmetry (IVA) exhibited an increase with age.
The cornea exhibits overall thinning with age and gradually changes from a flat ellipse to an elongated ellipse in Asian individuals with healthy eyes. However, the anterior and posterior surfaces become smoother with age. Owing to the very large number of cases, these small differences are statistically significant. The results obtained are consistent with the hypothesis that a normal cornea seems to withstand quite well the effect of IOP, external pressures, and the natural cross-linking.
为了评估亚洲健康人眼角膜形态学参数的正常参考范围，并研究这些参数随年龄的变化，为角膜屈光手术术前评估和亚临床及无症状圆锥角膜的早期鉴别诊断提供参考数据。
本横断面、多中心、观察性研究于 2014 年 1 月至 2019 年 10 月在中国五个省份进行，是一项回顾性分析。将受检者分为以下年龄组：<18 岁、18-30 岁、31-40 岁、41-50 岁，进行分层，然后进行检查者盲法临床测量。我们评估了 30618 只来自中国的表现出正常角膜形态、无眼部手术或外伤史、软性隐形眼镜至少停戴 2 周（硬性隐形眼镜至少停戴 4 周）、并且在同一天对双眼进行了地形图研究的健康人眼角膜。
随着年龄的增长，前、后角膜曲率（K1 和 K2）增加，而前、后表面角膜散光（ΔK）以及中央、最小和总角膜厚度则随年龄减少。角膜总厚度随年龄的减少在周边更明显。前、后角膜表面高度分别下降和增加。高度不对称指数（IHA）和垂直不对称指数（IVA）均随年龄增加而增加。
在亚洲健康人眼中，角膜整体随年龄变薄，从前到后逐渐从扁椭圆变成长椭圆。然而，前、后表面会随年龄变得更光滑。由于病例数量非常多，这些小差异在统计学上具有显著性。结果与假说一致，即正常角膜似乎能够很好地抵抗眼压、外部压力和自然交联的影响。
