Abstract：
Aqueous humor (AQH) is a transparent fluid with characteristics similar to those of the interstitial fluid, which fills the eyeball posterior and anterior chambers and circulates in them from the sites of production to those of drainage. The AQH volume and pressure homeostasis is essential for the trophism of the ocular avascular tissues and their normal structure and function. Different AQH outflow pathways exist, including a main pathway, quite well defined anatomically and referred to as the conventional pathway, and some accessory pathways, more recently described and still not fully morphofunctionally understood, generically referred to as unconventional pathways. The conventional pathway is based on the existence of a series of conduits starting with the trabecular meshwork and Schlemm\'s Canal and continuing with a system of intrascleral and episcleral venules, which are tributaries to veins of the anterior segment of the eyeball. The unconventional pathways are mainly represented by the uveoscleral pathway, in which AQH flows through clefts, interstitial conduits located in the ciliary body and sclera, and then merges into the aforementioned intrascleral and episcleral venules. A further unconventional pathway, the lymphatic pathway, has been supported by the demonstration of lymphatic microvessels in the limbal sclera and, possibly, in the uvea (ciliary body, choroid) as well as by the ocular glymphatic channels, present in the neural retina and optic nerve. It follows that AQH may be drained from the eyeball through blood vessels (TM-SC pathway, US pathway) or lymphatic vessels (lymphatic pathway), and the different pathways may integrate or compensate for each other, optimizing the AQH drainage. The present review aims to define the state-of-the-art concerning the structural organization and the functional anatomy of all the AQH outflow pathways. Particular attention is paid to examining the regulatory mechanisms active in each of them. The new data on the anatomy and physiology of AQH outflow pathways is the key to understanding the pathophysiology of AQH outflow disorders and could open the way for novel approaches to their treatment.
摘要：
房水（AQH）是一种透明液体，具有与间质液相似的特征，填充眼球前后房，并在其中从生产部位循环到引流部位。AQH容量和压力稳态对于眼无血管组织的滋养及其正常结构和功能至关重要。存在不同的AQH流出途径，包括一条主要途径，在解剖学上定义得很好，被称为传统路径，和一些附属途径，最近描述，但仍未完全理解形态功能，通常被称为非常规途径。常规途径是基于一系列导管的存在，从小梁网和施莱姆管开始，并继续巩膜内和巩膜上小静脉系统，它们是眼球前段静脉的支流。非常规途径主要表现为葡萄膜巩膜途径,AQH流经裂缝，位于睫状体和巩膜的间质导管,然后合并入上述巩膜内和巩膜上静脉。另一种非常规途径，淋巴通路,已经得到了巩膜角膜缘淋巴微血管的证明，可能,在葡萄膜(睫状体，脉络膜）以及眼部淋巴通道，存在于神经视网膜和视神经中。由此可见，AQH可能通过血管从眼球排出(TM-SC通路，US途径）或淋巴管（淋巴途径），不同的途径可以相互整合或相互补偿，优化AQH排水。本综述旨在定义有关所有AQH流出途径的结构组织和功能解剖的最新技术。特别注意检查每个机构中活跃的监管机制。有关AQH流出途径的解剖学和生理学的新数据是了解AQH流出障碍的病理生理学的关键，并可能为其治疗的新方法开辟道路。
