PDF(Pubmed)
Abstract：
OBJECTIVE: The conventional aqueous outflow pathway, which includes the trabecular meshwork (TM), juxtacanalicular tissue (JCT), and the inner wall endothelium of Schlemm\'s canal (SC), regulates intraocular pressure (IOP) by controlling the aqueous humor outflow resistance. Despite its importance, our understanding of the biomechanics and hydrodynamics within this region remains limited. Fluid-structure interaction (FSI) offers a way to estimate the biomechanical properties of the JCT and SC under various loading and boundary conditions, providing valuable insights that are beyond the reach of current imaging techniques.
METHODS: In this study, a normal human eye was fixed at a pressure of 7 mm Hg, and two radial wedges of the TM tissues, which included the SC inner wall basement membrane and JCT, were dissected, processed, and imaged using 3D serial block-face scanning electron microscopy (SBF-SEM). Four different sets of images were used to create 3D finite element (FE) models of the JCT and inner wall endothelial cells of SC with their basement membrane. The outer JCT portion was carefully removed as the outflow resistance is not in that region, leaving only the SCE inner wall and a few µm of the tissue, which does contain the resistance. An inverse iterative FE algorithm was then utilized to calculate the unloaded geometry of the JCT/SC complex at an aqueous humor pressure of 0 mm Hg. Then in the model, the intertrabecular spaces, pores, and giant vacuole contents were replaced by aqueous humor, and FSI was employed to pressurize the JCT/SC complex from 0 to 15 mm Hg.
RESULTS: In the JCT/SC complex, the shear stress of the aqueous humor is not evenly distributed. Areas proximal to the inner wall of SC experience larger stresses, reaching up to 10 Pa, while those closer to the JCT undergo lower stresses, approximately 4 Pa. Within this complex, giant vacuoles with or without I-pore behave differently. Those without I-pores experience a more significant strain, around 14%, compared to those with I-pores, where the strain is roughly 9%.
CONCLUSIONS: The distribution of aqueous humor wall shear stress is not uniform within the JCT/SC complex, which may contribute to our understanding of the underlying selective mechanisms in the pathway.
METHODS: In this study, a normal human eye was fixed at a pressure of 7 mm Hg, and two radial wedges of the TM tissues, which included the SC inner wall basement membrane and JCT, were dissected, processed, and imaged using 3D serial block-face scanning electron microscopy (SBF-SEM). Four different sets of images were used to create 3D finite element (FE) models of the JCT and inner wall endothelial cells of SC with their basement membrane. The outer JCT portion was carefully removed as the outflow resistance is not in that region, leaving only the SCE inner wall and a few µm of the tissue, which does contain the resistance. An inverse iterative FE algorithm was then utilized to calculate the unloaded geometry of the JCT/SC complex at an aqueous humor pressure of 0 mm Hg. Then in the model, the intertrabecular spaces, pores, and giant vacuole contents were replaced by aqueous humor, and FSI was employed to pressurize the JCT/SC complex from 0 to 15 mm Hg.
RESULTS: In the JCT/SC complex, the shear stress of the aqueous humor is not evenly distributed. Areas proximal to the inner wall of SC experience larger stresses, reaching up to 10 Pa, while those closer to the JCT undergo lower stresses, approximately 4 Pa. Within this complex, giant vacuoles with or without I-pore behave differently. Those without I-pores experience a more significant strain, around 14%, compared to those with I-pores, where the strain is roughly 9%.
CONCLUSIONS: The distribution of aqueous humor wall shear stress is not uniform within the JCT/SC complex, which may contribute to our understanding of the underlying selective mechanisms in the pathway.
摘要：
目的：常规的房水流出途径，其中包括小梁网(TM)，耳旁组织（JCT），和Schlemm管（SC）的内壁内皮，通过控制房水流出阻力来调节眼内压（IOP）。尽管它很重要,我们对该区域的生物力学和流体动力学的理解仍然有限。流体-结构相互作用（FSI）提供了一种在各种载荷和边界条件下估计JCT和SC的生物力学特性的方法。提供当前成像技术无法触及的有价值的见解。
方法：在本研究中，正常的人眼被固定在7mmHg的压力下，和两个TM组织的径向楔形，其中包括SC内壁基底膜和JCT，被解剖,已处理,并使用3D串行块面扫描电子显微镜(SBF-SEM)成像。使用四组不同的图像来创建JCT和SC的内壁内皮细胞及其基底膜的3D有限元（FE）模型。由于流出阻力不在该区域，因此小心地移除了外部JCT部分。只留下SCE内壁和几微米的组织，其中确实包含了抵抗。然后利用逆迭代FE算法来计算在0mmHg的房水压力下JCT/SC复合物的卸载几何形状。然后在模型中，骨小梁间的空间，毛孔,巨大的液泡内容物被房水取代，和FSI用于将JCT/SC复合物从0加压至15mmHg。
结果：在JCT/SC复合体中，房水的剪切应力分布不均匀。靠近SC内壁的区域承受较大的应力，达到10帕，而那些更接近JCT的人承受较低的应力，大约4帕。在这个建筑群中，有或没有I孔的巨大空泡的行为不同。那些没有I孔的人经历了更明显的压力，14%左右,与那些有I-毛孔的相比,其中应变大约是9%。
结论：在JCT/SC复合体内，房水壁切应力的分布不均匀，这可能有助于我们理解该途径中潜在的选择机制。
方法：在本研究中，正常的人眼被固定在7mmHg的压力下，和两个TM组织的径向楔形，其中包括SC内壁基底膜和JCT，被解剖,已处理,并使用3D串行块面扫描电子显微镜(SBF-SEM)成像。使用四组不同的图像来创建JCT和SC的内壁内皮细胞及其基底膜的3D有限元（FE）模型。由于流出阻力不在该区域，因此小心地移除了外部JCT部分。只留下SCE内壁和几微米的组织，其中确实包含了抵抗。然后利用逆迭代FE算法来计算在0mmHg的房水压力下JCT/SC复合物的卸载几何形状。然后在模型中，骨小梁间的空间，毛孔,巨大的液泡内容物被房水取代，和FSI用于将JCT/SC复合物从0加压至15mmHg。
结果：在JCT/SC复合体中，房水的剪切应力分布不均匀。靠近SC内壁的区域承受较大的应力，达到10帕，而那些更接近JCT的人承受较低的应力，大约4帕。在这个建筑群中，有或没有I孔的巨大空泡的行为不同。那些没有I孔的人经历了更明显的压力，14%左右,与那些有I-毛孔的相比,其中应变大约是9%。
结论：在JCT/SC复合体内，房水壁切应力的分布不均匀，这可能有助于我们理解该途径中潜在的选择机制。
