Factors influencing optic nerve head biomechanics
Factors influencing optic nerve head biomechanics
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DOI：
10.1167/iovs.05-0541
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发表时间：
2005-11-01
影响因子：
4.4
通讯作者：
Ethier, CR
中科院分区：
文献类型：
--
作者：
Sigal, IA;Flanagan, JG;Ethier, CR
目的。视神经头(ONH)内的生物力学环境可能在青光眼视神经病变的视网膜神经节细胞丢失中起作用。这是一项系统的分析，使用有限元方法来确定哪些解剖学和生物力学因素对眼球急性变化的生物力学响应影响最大。方法基于先前描述的眼的计算模型，21个代表相关眼组织生物力学特性的输入因素、眼压和14个几何因素各自独立地变化。ONH组织的生物力学响应通过一组29个结果指标来量化，包括每个组织内的峰值和平均应力和应变，以及ONH组织中几何变化的指标。结果：在所有结果测量中，影响最大的5个输入因素依次为：巩膜硬度、眼半径、筛板硬度、眼压和巩膜壳厚度。影响最小的五个因素依次为：视网膜厚度、视盘周围高度、视杯深度、杯盘比和软膜厚度。不同结果测量组和因子范围的因子等级相似。结论：该模型预测ONH生物力学特性强烈依赖于巩膜生物力学特性。ONH组织的急性变形以及随之而来的高水平的神经组织应变，与其说是依赖于IOP对ONH内表面的直接作用，不如说是依赖于IOP对巩膜的间接影响。这表明巩膜特性的个体间差异可能是青光眼发生的危险因素。眼球大小和筛板生物力学特性也对ONH生物力学有很大影响。
PURPOSE. The biomechanical environment within the optic nerve head (ONH) may play a role in retinal ganglion cell loss in glaucomatous optic neuropathy. This was a systematic analysis in which finite element methods were used to determine which anatomic and biomechanical factors most influenced the biomechanical response of the ONH to acute changes in IOP.METHODS. Based on a previously described computational model of the eye, each of 21 input factors, representing the biomechanical properties of relevant ocular tissues, the IOP, and 14 geometric factors were independently varied. The biomechanical response of the ONH tissues was quantified through a set of 29 outcome measures, including peak and mean stress and strain within each tissue, and measures of geometric changes in ONH tissues. Input factors were ranked according to their aggregated influence on groups of outcome measures.RESULTS. The five input factors that had the largest influence across all outcome measures were, in ranked order: stiffness of the sclera, radius of the eye, stiffness of the lamina cribrosa, IOP, and thickness of the scleral shell. The five least influential factors were, in reverse ranked order: retinal thickness, peripapillary rim height, cup depth, cup-to-disc ratio, and pial thickness. Factor ranks were similar for various outcome measure groups and factor ranges.CONCLUSIONS. The model predicts that ONH biomechanics are strongly dependent on scleral biomechanical properties. Acute deformations of ONH tissues, and the consequent high levels of neural tissue strain, were less strongly dependent on the action of IOP directly on the internal surface of the ONH than on the indirect effects of IOP on the sclera. This suggests that interindividual variations in scleral properties could be a risk factor for the development of glaucoma. Eye size and lamina cribrosa biomechanical properties also have a strong influence on ONH biomechanics.