Modeling individual-specific human optic nerve head biomechanics. Part I: IOP-induced deformations and influence of geometry
Modeling individual-specific human optic nerve head biomechanics. Part I: IOP-induced deformations and influence of geometry
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DOI：
10.1007/s10237-008-0120-7
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发表时间：
2009-04-01
影响因子：
3.5
通讯作者：
Ethier, C. Ross
中科院分区：
文献类型：
--
作者：
Sigal, Ian A.;Flanagan, John G.;Ethier, C. Ross
青光眼是一种以视网膜神经节细胞（RGC）轴突的进行性丧失为特征的眼部疾病，是世界范围内第二大常见的致盲原因。生物力学因素被认为在RGC损失中起核心作用，但这种疾病的具体机制仍然未知。我们的目标是表征生物力学环境中的视神经乳头（ONH）-该地区的RGC损伤发生在人眼。对死后人眼进行成像，在5或50 mmHg压力下固定，并进行组织学处理，以通过ONH获得连续切片。从这些切片重建ONH区域的三维模型，并将其嵌入通用巩膜壳中以创建整个眼睛的模型。我们使用有限元模拟来量化眼内压从5到50 mmHg的急性变化对ONH生物力学环境的影响。计算的应变在ONH内变化很大，其中前板神经组织和筛板显示出最大的应变。具有最大幅度的应变模式是第三主应变（压缩），在筛板和前板神经组织中均达到12-15%。剪切应变也很大。所有ONH组织中的菌株分布在眼睛之间非常相似。ONH几何结构（解剖结构）的个体间差异对ONH生物力学只有适度的影响，可能无法解释个体间对眼内压升高的易感性。与先前使用通用ONH模型的结果一致，玻璃体-视网膜界面和筛板前表面的位移可以显著不同，这表明目前可用的光学成像方法不能提供ONH组织内急性变形的信息。ONH组织内的预测应变具有潜在的生物学意义，并支持生物力学因素有助于导致青光眼中RGC损失的初始损伤的假设。
Glaucoma, the second most common cause of blindness worldwide, is an ocular disease characterized by progressive loss of retinal ganglion cell (RGC) axons. Biomechanical factors are thought to play a central role in RGC loss, but the specific mechanism underlying this disease remains unknown. Our goal was to characterize the biomechanical environment in the optic nerve head (ONH)-the region where RGC damage occurs-in human eyes. Post mortem human eyes were imaged, fixed at either 5 or 50 mmHg pressure and processed histologically to acquire serial sections through the ONH. Three-dimensional models of the ONH region were reconstructed from these sections and embedded in a generic scleral shell to create a model of an entire eye. We used finite element simulations to quantify the effects of an acute change in intraocular pressure from 5 to 50 mmHg on the ONH biomechanical environment. Computed strains varied substantially within the ONH, with the pre-laminar neural tissue and the lamina cribrosa showing the greatest strains. The mode of strain having the largest magnitude was third principal strain (compression), reaching 12-15% in both the lamina cribrosa and the pre-laminar neural tissue. Shear strains were also substantial. The distribution of strains in all ONH tissues was remarkably similar between eyes. Inter-individual variations in ONH geometry (anatomy) have only modest effects on ONH biomechanics, and may not explain inter-individual susceptibility to elevated intraocular pressure. Consistent with previous results using generic ONH models, the displacements of the vitreo-retinal interface and the anterior surface of the lamina cribrosa can differ substantially, suggesting that currently available optical imaging methods do not provide information of the acute deformations within ONH tissues. Predicted strains within ONH tissues are potentially biologically significant and support the hypothesis that biomechanical factors contribute to the initial insult that leads to RGC loss in glaucoma.