Biomechanical properties of the rat sclera obtained with inverse finite element modeling.
Biomechanical properties of the rat sclera obtained with inverse finite element modeling.
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DOI：
10.1007/s10237-020-01333-4
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发表时间：
2020-12
影响因子：
3.5
通讯作者：
Ethier CR
中科院分区：
文献类型：
--
作者：
Schwaner SA;Hannon BG;Feola AJ;Ethier CR
生物力学在青光眼的病理生理中起着重要作用，但其机制尚不清楚。大鼠是一种常见的青光眼动物模型，有限元模型的开发为深入了解大鼠后眼的生物力学环境提供了急需的信息。然而，大鼠眼组织（包括巩膜）的材料特性目前尚不清楚。由于巩膜在眼后生物力学中起着重要作用，我们的目标是使用逆有限元建模来提取大鼠巩膜材料的特性。我们首先在全球膨胀测试中使用数字图像相关来测量巩膜表面位移。我们将巩膜建模为嵌入胶原纤维的非线性材料，然后使用差分进化算法将模型位移拟合到实验数据中。构建受试者特异性模型，其中3个参数描述后眼基质和胶原纤维的硬度，16个参数定义8个巩膜亚区内纤维的主要方向和排列。我们成功地提取了8只大鼠眼的巩膜材料特性。模型位移再现了实验位移的一般模式，但并不总是与局部模式匹配。纤维方向和纤维浓度参数变化很大，但平均而言，纤维呈周向排列，乳头周围巩膜比周围巩膜更排列。这里确定的材料特性将用于未来大鼠后眼的有限元模型，目的是阐明生物力学在青光眼病理生理中的作用。
It is widely accepted that biomechanics plays an important role in glaucoma pathophysiology, but the mechanisms involved are largely unknown. Rats are a common animal model of glaucoma, and finite element models are being developed to provide much-needed insight into the biomechanical environment of the posterior rat eye. However, material properties of rat ocular tissues, including the sclera, are currently unknown. Since the sclera plays a major role in posterior ocular biomechanics, our goal was to use inverse finite element modeling to extract rat scleral material properties. We first used digital image correlation to measure scleral surface displacement during whole-globe inflation testing. We modeled the sclera as a nonlinear material with embedded collagen fibers, then fit modeled displacements to experimental data using a differential evolution algorithm. Subject-specific models were constructed in which 3 parameters described the stiffness of the ground substance and collagen fibers in the posterior eye, and 16 parameters defined the primary orientation and alignment of fibers within eight scleral sub-regions. We successfully extracted scleral material properties for eight rat eyes. Model displacements recreated general patterns of the experimental displacements but did not always match local patterns. The fiber directions and fiber concentration parameters were highly variable, but on average, fibers were aligned circumferentially and were more aligned in the peripapillary sclera than in the peripheral sclera. The material properties determined here will be used to inform future finite element models of the rat posterior eye with the goal of elucidating the role of biomechanics in glaucoma pathophysiology.
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