ABSTRACT
The conventional outflow pathway is pressure-dependent and represents 85-90% of the total outflow in adults. Moving from the anterior chamber outward, the aqueous travels through the trabecular meshwork and into Schlemm’s canal (Figure 1.4). From Schlemm’s canal, the aqueous enters the collector channels and flows through aqueous veins to the episcleral or conjunc-
Figure 1.5 Three layers of the trabecular meshwork. Aqueous humor first passes through the inner layer of the uveal meshwork. This layer is a forward extension of the ciliary muscle. It consists of flattened sheets, which branch and interconnect in multiple planes that do not offer any significant resistance to aqueous drainage. The middle layer, or the corneoscleral meshwork, includes several perforated sheets of connective tissue extending between the scleral spur and Schwalbe’s line. The sheets are connected to each other by tissue strands and endothelial cells. The openings are very small, providing resistance to the flow of aqueous. The outer layer, or the juxtacanalicular meshwork, lies adjacent to the inner wall of Schlemm’s canal. It contains collagen, glycosaminoglycans and glycoproteins, fibroblasts, and endotheliallike juxtacanalicular cells. It also contains elastic fibers that may provide support for the inner wall of Schlemm’s canal. This meshwork contains very narrow, irregular openings providing high resistance to fluid drainage. Reproduced with permission from Toris CB,Yablonski ME, Tamesis R. Aqueous humor dynamics. In: Choplin NT, Lundy DC, eds. Atlas of Glaucoma. London; Martin Dunitz, 1998.
