Biomechanical analysis of the keratoconic cornea
Biomechanical analysis of the keratoconic cornea
复制标题
DOI：
10.1016/j.jmbbm.2008.07.002
复制
发表时间：
2009-07-01
影响因子：
3.9
通讯作者：
Mandel, Yossi
中科院分区：
文献类型：
--
作者：
Gefen, Amit;Shalom, Ran;Mandel, Yossi
圆锥角膜是一种非炎症性疾病，其特征是角膜不规则变薄和逐渐隆起，导致角膜表面变形，从而导致视力模糊。我们进行了三维有限元（FE）模拟，以分析生物力学因素有助于扭曲的形状的圆锥角膜。我们假设正交各向异性的线性弹性组织的机械性能，并模拟局部组织变薄（从0.5毫米减少到0.35或0.2毫米）。我们分析了组织变形，应力和理论屈光度地图预测的模型，眼内压（IOP）为10，15 - 20和25毫米汞柱。分析表明，三个因素影响圆锥角膜的形状变形：（i）局部变薄，和（ii）减少组织的子午线弹性模量或（iii）减少垂直于角膜表面的剪切模量，而变薄显示出最主要的效果。最大应力水平发生在凸出区域的中心，在最薄的点。眼压水平对健康角膜的屈光力影响很小，但对圆锥角膜有很大影响。目前的FE研究允许表征圆锥角膜的生物力学相互作用，以了解这种研究不足的疾病的病因。(c)2008爱思唯尔有限公司保留所有权利。
Keratoconus is a non-inflammatory disease characterized by irregular thinning and gradual bulging of the cornea, which results in distortion of the corneal surface that causes blurred vision. We conducted three-dimensional finite element (FE) simulations to analyze the biomechanical factors contributing to the distorted shape of a keratoconic cornea. We assumed orthotropic linear elastic tissue mechanical properties, and simulated localized tissue thinning (reduction from 0.5 mm to 0.35 or 0.2 mm). We analyzed tissue deformations, stresses and theoretical dioptric power maps predicted by the models, for intraocular pressure (IOP) of 10, 15 20 and 25 mmHg. The analyses revealed that three factors affect the shape distortion of keratoconic corneas: (i) localized thinning, and (ii) reduction in the tissue's meridian elastic modulus or (iii) reduction in the shear modulus perpendicular to the corneal surface, whereas thinning showed the most predominant effect. Maximal stress levels occurred at the centers of the bulged regions, at the thinnest points. The IOP levels had little influence on dioptric power in the healthy cornea, but a substantial influence in keratoconic conditions. The present FE studies allowed characterization of the biomechanical interactions in keratoconus, toward understanding the aetiology of this poorly studied malady. (c) 2008 Elsevier Ltd. All rights reserved.