Schlemm's canal is primarily involved in which function?

• A. Used to drain excess aqueous fluid
• B. Drains vitreous humor
• C. Produces aqueous humor
• D. Maintains tear film

Answer: (A)

The main concept is the aqueous humor outflow pathway and Schlemm's canal’s role in draining excess fluid to help regulate eye pressure. Schlemm's canal is a circular channel located at the drainage angle of the anterior chamber. Aqueous humor flows from the posterior to the anterior chamber, passes through the trabecular meshwork, and enters Schlemm's canal. From there, it drains into collector channels and ultimately into the episcleral veins, completing the conventional outflow route. By providing this drainage path, Schlemm's canal helps keep intraocular pressure balanced as fluid is continually produced by the ciliary body.

It doesn’t drain vitreous humor, which fills the posterior segment and has separate pathways. It doesn’t produce aqueous humor itself—the production is done by the ciliary processes. It also isn’t involved in tear film maintenance, which is related to the lacrimal system and tear production on the ocular surface.

Understanding this pathway helps explain why blockages or increased resistance in the conventional outflow can raise intraocular pressure and contribute to glaucoma.