Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA.
Biological Sciences, Minnesota State University, Mankato, MN, USA.
Exp Eye Res. 2022 Aug;221:109132. doi: 10.1016/j.exer.2022.109132. Epub 2022 May 27.
The distal outflow pathway of the human eye consists of the outer wall of Schlemm's canal, collector channels, and the deep-scleral, mid-scleral and episcleral vessels. It is the last region of transit for aqueous humor before returning to the venous system. While the trabecular meshwork, scleral spur, and inner wall of Schlemm's canal have been extensively analyzed to define their contributions to aqueous outflow, the role of the distal outflow pathway is not completely understood. Collector channels, emanating from Schlemm's canal were previously thought to be passive conduits for aqueous humor. However, recent studies have shown many collector channels contain flap-like appendages which move with changes in pressure. These findings, along with studies demonstrating innervation of episcleral vessels, have led to questions regarding whether other structures in the distal outflow pathway are under neural regulation and how this may influence aqueous humor outflow. This study evaluates the innervation of the outer wall of Schlemm's canal and collector channels, along with the deep-scleral, mid-scleral and episcleral vasculature with microcomputed tomography and 3-dimensional reconstruction, correlative light microscopy, immunohistochemistry, and transmission electron microscopy. Peripheral, autonomic, and sensory nerve fibers were found to be present adjacent to Schlemm's canal outer wall endothelium, collector channel endothelium, and in the different regions of the distal outflow vasculature. Nerves were more commonly identified in regions that contained collector channels when compared to regions without collector channels. These findings regarding the neural anatomy suggest an active neural regulation of aqueous humor outflow throughout the proximal and distal regions of the conventional outflow pathway.
人眼球的远流出道由施莱姆氏管外壁、收集管和深巩膜、中巩膜和表层巩膜血管组成。它是房水返回静脉系统前的最后一段通道。尽管小梁网、巩膜突和施莱姆氏管内壁已经被广泛分析以确定它们对房水流出的贡献，但远流出道的作用尚未完全被理解。先前认为从施莱姆氏管发出的收集管是房水的被动通道。然而，最近的研究表明，许多收集管内含有随压力变化而移动的瓣状附属物。这些发现，以及证明表层巩膜血管有神经支配的研究，引发了关于远流出道的其他结构是否受神经调节以及这可能如何影响房水流出的问题。本研究通过微计算机断层扫描和三维重建、相关光镜、免疫组织化学和透射电子显微镜评估了施莱姆氏管外壁和收集管以及深层巩膜、中巩膜和表层巩膜血管的神经支配。在外壁内皮细胞、收集管内皮细胞以及远流出血管的不同区域周围发现了周围、自主和感觉神经纤维。与没有收集管的区域相比，在包含收集管的区域中更常发现神经。这些关于神经解剖的发现表明，在传统流出途径的近端和远端区域，房水流出受到主动的神经调节。
