Hydration Dependent Viscoelastic Tensile Behavior of Cornea
Hydration Dependent Viscoelastic Tensile Behavior of Cornea
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DOI：
10.1007/s10439-014-0996-6
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发表时间：
2014-08-01
影响因子：
3.8
通讯作者：
Hatami-Marbini, Hamed
中科院分区：
文献类型：
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作者：
Hatami-Marbini, Hamed
角膜是一种保护性透明结缔组织，覆盖在眼睛的前部。标准单轴拉伸实验是研究角膜生物力学特性最流行的技术之一。本实验方法表征了浸在浴液中的角膜条的应力应变反应。在本研究中，研究了角膜水化对拉伸粘弹性的重要作用。以厚度为水化指标，分别对1100亩（4.87 mg水/mg干组织）、900亩（4.13 mg水/mg干组织）、700亩（3.20 mg水/mg干组织）、500亩（1.95 mg水/mg干组织）4种不同平均厚度（水化）的牛角膜样品进行单轴拉伸实验。为了防止样品在实验过程中膨胀，将样品浸泡在矿物油中。采用准线性粘弹性（QLV）模型对实验数据进行分析，确定粘弹性材料常数。随着组织厚度（水化）的减小，最大应力和平衡应力（松弛应力）均呈指数增长。此外，QLV模型成功捕获了角膜粘弹性响应，平均R(2)值大于0.99。在OBSS中进行了额外的实验，以确认这些粘弹性特性的显著变化是由于角膜水化而不是沐浴液。本研究结果表明，在解释早期单轴拉伸试验结果及其与角膜生物力学特性的对应关系时，必须格外小心。
The cornea is a protective transparent connective tissue covering the front of the eye. The standard uniaxial tensile experiments are among the most popular techniques for investigating biomechanical properties of the cornea. This experimental method characterizes the stress-strain response of corneal strips immersed in a bathing solution. In the present study, the important roles of corneal hydration on tensile viscoelastic properties were investigated. The thickness was used as a surrogate for hydration and uniaxial tensile experiments were performed on bovine corneal samples with four different average thickness (hydration), i.e., 1100 mu m (4.87 mg water/mg dry tissue), 900 mu m (4.13 mg water/mg dry tissue), 700 mu m (3.20 mg water/mg dry tissue), and 500 mu m (1.95 mg water/mg dry tissue). The samples were immersed in mineral oil in order to prevent their swelling during the experiments. A quasilinear viscoelastic (QLV) model was used to analyze the experimental measurements and determine viscoelastic material constants. It was observed that both maximum and equilibrium (relaxed) stresses were exponentially increased with decreasing tissue thickness (hydration). Furthermore, the QLV model successfully captured the corneal viscoelastic response with an average R (2) value greater than 0.99. Additional experiments were conducted in OBSS in order to confirm that these significant changes in viscoelastic properties were because of corneal hydration and not the bathing solution. The findings of this study suggest that extra care must be taken in interpreting the results of earlier uniaxial tensile testings and their correspondence to the corneal biomechanical properties.