Regional elastic performance of the human cornea
Regional elastic performance of the human cornea
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DOI：
10.1016/0021-9290(95)00152-2
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发表时间：
1996-07-01
影响因子：
2.4
通讯作者：
Hjortdal, JO
中科院分区：
文献类型：
--
作者：
Hjortdal, JO
通过18只完整人眼的压力负荷实验，研究了角膜和角膜缘的局部力学性能。在角膜中央、准中心、周边和角膜缘处测量了压力引起的(2~100 mm Hg)角膜上、内皮侧的经向和周向切向机械应变。应变是通过数字测量固定在角膜表面的微小水银液滴标记之间的距离来计算的。通过测量区域子午线和周向的曲率半径以及测量四个区域的角膜厚度来计算相应的面内薄膜应力。假设角膜基质的弹性行为为正交各向异性，计算了每个区域在子午线和圆周方向的杨氏弹性模数。采用幂函数对非线性弹性应力应变关系进行拟合。压力引起的子午线应变在角膜旁中心和周边最小，在角膜缘最大。周向应变在不同区域之间差异较小，而副中心应变最大。在子午线方向上，角膜中央和中央附近的杨氏弹性模数最高，而角膜缘的周向弹性模数最高。这项研究支持人角膜缘组织中的周向强化结构的记法。与圆周方向相比，人角膜的副中央区域在子午线方向上更硬，这表明人类角膜的副中央部分在子午线方向上得到了强化。这些发现可能对角膜屈光手术的机械建模有重要意义。版权所有(C)1996爱思唯尔科学有限公司。
The regional mechanical performance of the cornea and limbus was studied in vitro by pressure loading of 18 intact human eyes. The pressure-induced (2-100 mmHg) meridional and circumferential tangential mechanical strains of the epi- and endothelial side of the cornea were measured at the centre, the para-centre, the periphery and the limbus. Strains were computed from digital measures of distances between tiny mercury droplet markers fixed on the corneal surfaces. Corresponding in-plane membrane stresses were calculated from measurements of the regional meridional and circumferential radius of curvature and from measurements of the corneal thickness of the four regions. Young's moduli of elasticity were computed for each region in the meridional and circumferential direction assuming orthotropic elastic behaviour of the corneal stroma. A power function was used to fit the non-linear elastic stress-strain relationships. The pressure-induced meridional strains were smallest at the corneal paracentre and periphery, and largest at the limbus. The circumferential strains varied less between regions with the para-centre straining most. In the meridional direction, Young's modulus of elasticity was highest at the central and para-central corneal regions, whereas the highest circumferential elastic modulus was found at the limbus. This study supports the notation of circumferentially orientated reinforcing structures in human limbal tissue. The para-central region of the human cornea was found stiffer in the meridional direction compared with the circumferential direction, suggesting a meridionally orientated reinforcement of the para-central parts of the human cornea. These findings may have important implications for mechanical modelling of keratorefractive procedures. Copyright (C) 1996 Elsevier Science Ltd.