The BrightFocus Foundation states that aqueous humor drains from the eye through a spongy tissue at the front of the eye called the trabecular meshwork. Beginning in the ciliary body where it is produced, the aqueous humor flows into the anterior chamber of the eye and finally exits through the trabecular meshwork and into a drainage canal.
The majority of the aqueous humor in the eye flows out of the trabecular meshwork; this process is called the conventional outflow method, according to the International Glaucoma Association. A smaller amount of aqueous humor leaves the eye through the ciliary body; this process is called the uveo-scleral or non-conventional outflow pathway.
The BrightFocus Foundation elaborates by saying that the aqueous humor, the fluid produced in the eye, allows vision to remain normal when it is flowing freely. However, when the aqueous humor is blocked, this can produce interocular pressure that, over time, can cause damage to the optic nerve and result in vision loss. Many types of glaucoma are characterized by high interocular pressure resulting from the decreased flow of the aqueous humor in the eye; for example, open-angle glaucoma is characterized by the failure of fluid to flow through the trabecular meshwork.