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Abstract：
The aqueous humor actively interacts with the trabecular meshwork (TM), juxtacanalicular tissue (JCT), and Schlemm\'s canal (SC) through a dynamic fluid-structure interaction (FSI) coupling. Despite the fact that intraocular pressure (IOP) undergoes significant fluctuations, our understanding of the hyperviscoelastic biomechanical properties of the aqueous outflow tissues is limited. In this study, a quadrant of the anterior segment from a normal human donor eye was dynamically pressurized in the SC lumen, and imaged using a customized optical coherence tomography (OCT). The TM/JCT/SC complex finite element (FE) with embedded collagen fibrils was reconstructed based on the segmented boundary nodes in the OCT images. The hyperviscoelastic mechanical properties of the outflow tissues\' extracellular matrix with embedded viscoelastic collagen fibrils were calculated using an inverse FE-optimization method. Thereafter, the 3D microstructural FE model of the TM, with adjacent JCT and SC inner wall, from the same donor eye was constructed using optical coherence microscopy and subjected to a flow load-boundary from the SC lumen. The resultant deformation/strain in the outflow tissues was calculated using the FSI method, and compared to the digital volume correlation (DVC) data. TM showed larger shear modulus (0.92 MPa) compared to the JCT (0.47 MPa) and SC inner wall (0.85 MPa). Shear modulus (viscoelastic) was larger in the SC inner wall (97.65 MPa) compared to the TM (84.38 MPa) and JCT (56.30 MPa). The conventional aqueous outflow pathway is subjected to a rate-dependent IOP load-boundary with large fluctuations. This necessitates addressing the biomechanics of the outflow tissues using hyperviscoelastic material-model. STATEMENT OF SIGNIFICANCE: While the human conventional aqueous outflow pathway is subjected to a large-deformation and time-dependent IOP load-boundary, we are not aware of any studies that have calculated the hyperviscoelastic mechanical properties of the outflow tissues with embedded viscoelastic collagen fibrils. A quadrant of the anterior segment of a normal humor donor eye was dynamically pressurized from the SC lumen with relatively large fluctuations. The TM/JCT/SC complex were OCT imaged and the mechanical properties of the tissues with embedded collagen fibrils were calculated using the inverse FE-optimization algorithm. The resultant displacement/strain in the FSI outflow model was validated versus the DVC data. The proposed experimental-computational workflow may significantly contribute to understanding of the effects of different drugs on the biomechanics of the conventional aqueous outflow pathway.
摘要：
房水与小梁网（TM）积极相互作用，耳旁组织（JCT），和施莱姆运河(SC)通过动态流体-结构相互作用(FSI)耦合。尽管眼内压（IOP）经历了显著的波动，我们对水性流出组织的超粘弹性生物力学特性的理解是有限的。在这项研究中,来自正常人供体眼的前部象限在SC腔中动态加压，并使用定制的光学相干断层扫描（OCT）成像。基于OCT图像中分割的边界节点，重建了具有嵌入胶原纤维的TM/JCT/SC复合有限元（FE）。使用逆FE优化方法计算了具有嵌入粘弹性胶原纤维的流出组织\'细胞外基质的超粘弹性力学特性。此后,TM的三维微结构有限元模型，与相邻的JCT和SC内壁，使用光学相干显微镜从同一供体眼构建，并经受来自SC腔的流量负荷边界。使用FSI方法计算流出组织中的最终变形/应变，并与数字量相关(DVC)数据进行比较。与JCT(0.47MPa)和SC内壁(0.85MPa)相比,TM显示出更大的剪切模量(0.92MPa)。与TM(84.38MPa)和JCT(56.30MPa)相比,SC内壁(97.65MPa)中的剪切模量(粘弹性)更大。常规的房水流出路径经受具有大波动的速率依赖性IOP负荷边界。这需要使用超粘弹性材料模型来解决流出组织的生物力学问题。重要声明：虽然人类传统的房水流出途径受到大变形和时间依赖性眼压负荷边界，我们不知道有任何研究已经计算出超粘弹性力学性质的流出组织与嵌入粘弹性胶原纤维。正常幽默供体眼睛的前部象限从SC腔动态加压，波动较大。对TM/JCT/SC复合物进行OCT成像，并使用逆FE优化算法计算具有嵌入胶原纤维的组织的机械性能。相对于DVC数据验证了FSI流出模型中的所得位移/应变。所提出的实验计算工作流程可能大大有助于理解不同药物对常规水性流出途径的生物力学的影响。
