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首页> 外文期刊>Journal of Biomechanics >Viscoelastic shear properties of the corneal stroma
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Viscoelastic shear properties of the corneal stroma

机译：角膜基质的粘弹性剪切特性

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摘要

The cornea is a highly specialized transparent tissue which covers the front of the eye. It is a tough tissue responsible for refracting the light and protecting the sensitive internal contents of the eye. The biomechanical properties of the cornea are primarily derived from its extracellular matrix, the stroma. The majority of previous studies have used strip tensile and pressure inflation testing methods to determine material parameters of the corneal stroma. Since these techniques do not allow measurements of the shear properties, there is little information available on transverse shear modulus of the cornea. The primary objectives of the present study were to determine the viscoelastic behavior of the corneal stroma in shear and to investigate the effects of the compressive strain. A thorough knowledge of the shear properties is required for developing better material models for corneal biomechanics. In the present study, torsional shear experiments were conducted at different levels of compressive strain (0-30%) on porcine corneal buttons. First, the range of linear viscoelasticity was determined from strain sweep experiments. Then, frequency sweep experiments with a shear strain amplitude of 0.2% (which was within the region of linear viscoelasticity) were performed. The corneal stroma exhibited viscoelastic properties in shear. The shear storage modulus, G', and shear loss modulus, G″, were reported as a function of tissue compression. It was found that although both of these parameters were dependent on frequency, shear strain amplitude, and compressive strain, the average shear storage and loss moduli varied from 2 to 8. kPa, and 0.3 to 1.2. kPa, respectively. Therefore, it can be concluded that the transverse shear modulus is of the same order of magnitude as the out-of-plane Young's modulus and is about three orders of magnitude lower than the in-plane Young's modulus.
机译：角膜是一种高度专业的透明组织，覆盖了眼睛的前部。它是一种坚韧的组织，负责折射光线并保护眼睛的敏感内部内容。角膜的生物力学特性主要来自其细胞外基质，基质。先前的大多数研究已使用剥离拉伸和压力膨胀测试方法来确定角膜基质的材料参数。由于这些技术不允许测量剪切性能，因此关于角膜横向剪切模量的信息很少。本研究的主要目的是确定剪切状态下角膜基质的粘弹性行为并研究压缩应变的影响。为了开发更好的角膜生物力学材料模型，需要对剪切特性有透彻的了解。在本研究中，在猪角膜纽扣上以不同水平的压缩应变（0-30％）进行了扭剪实验。首先，从应变扫描实验确定线性粘弹性的范围。然后，进行了剪切应变幅度为0.2％（在线性粘弹性区域内）的扫频实验。角膜基质在剪切中表现出粘弹性。剪切储能模量G'和剪切损耗模量G''被报告为组织压缩的函数。发现虽然这两个参数都取决于频率，剪切应变振幅和压缩应变，但是平均剪切存储和损耗模量在2至8 kPa和0.3至1.2之间变化。千帕。因此，可以得出结论，横向剪切模量与平面外杨氏模量处于相同数量级，并且比平面内杨氏模量低大约三个数量级。

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