Full-field deformation of bovine cornea under constrained inflation conditions
Full-field deformation of bovine cornea under constrained inflation conditions
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DOI：
10.1016/j.biomaterials.2008.06.011
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发表时间：
2008-10-01
期刊：
影响因子：
14
通讯作者：
Nguyen, Thao D.
中科院分区：
文献类型：
--
作者：
Boyce, Brad L.;Grazier, J. Mark;Nguyen, Thao D.
采用体外膨胀(Bulge)实验和数字图像相关的空间分辨形变映射相结合的方法来表征牛角膜的粘弹性响应。一种符合角膜缘环的复杂固定器被开发出来，以保持附着的巩膜坚硬，同时只允许角膜变形。在3.6-8千帕(27-60毫米汞柱)的压力范围内进行了一组统计实验，代表了标称牛眼内压(IOP)到急性青光眼条件。还考察了0-32kPa(0-240 mm Hg)更宽的压力范围，以表征组织的非线性有限变形行为。结果显示，在眼压附近和以上的压力下，大部分变形局限在角膜缘和周边区域，这使得中央角膜基本上没有变形。这一观察结果与已知的在中央角膜外的胶原纤维的首选周向排列是一致的。一般而言，充气实验观察到了粘弹性行为，表现为角膜顶端压力-变形响应的速率依赖滞后，恒定充气压力下的尖端变形蠕变，以及恒定充气体积下的压力响应松弛。在3.6-8kPa(27-60 mm Hg)的压力范围内，角膜产生了较小的粘弹性变形和近乎线性的压力-变形响应，这表明在生理压力范围内，角膜可以近似为线性粘弹性或线性伪弹性材料。(C)爱思唯尔有限公司出版。
The viscoelastic response of bovine corneas was characterized using in vitro inflation (bulge) experiments combined with spatially-resolved deformation mapping via digital image correlation. A complex fixture conforming to the limbal annulus was developed to hold the attached sclera rigid while allowing deformation only in the cornea. A statistical set of experiments was performed for a pressure range of 3.6-8 kPa (27-60 mmHg), representing nominal bovine intraocular pressure (IOP) to acute glaucoma conditions. A broader pressure range of 0-32 kPa (0-240 mmHg) was also examined to characterize the nonlinear finite deformation behavior of the tissue. Results showed that for pressures near and above IOP, the majority of the deformation was localized in the limbus and peripheral regions, which left the central cornea largely undeformed. This observation was consistent with the known preferred circumferential alignment of collagen fibrils outside of the central cornea. In general, the inflation experiments observed viscoelastic behavior in the form of rate-dependent hysteresis in the pressure-deformation response of the apex of the cornea, creep in the apex deformation at a constant inflation pressure, and relaxation in the pressure response at a constant inflation volume. The 3.6-8 kPa (27-60 mmHg) pressure range produced small viscoelastic deformations and a nearly linear pressure-deformation response, which suggests that for physiological pressure ranges, the cornea can be approximated as a linear viscoelastic or linear pseudo-elastic material. (c) Published by Elsevier Ltd.