Which term refers to the circular canal draining aqueous humor from the anterior chamber into Schlemm's canal?

• A. Uvea
• B. Trephine
• C. Canal of Schlemm
• D. Zonules

Answer: (C)

The main idea here is the outflow pathway of aqueous humor in the eye. After fluid is produced, it travels from the anterior chamber through the trabecular meshwork into a circular channel known as the Canal of Schlemm. This canal collects the aqueous humor and drains it further into the venous system via collector channels and episcleral veins. So, the Canal of Schlemm is the structure that serves as this circular drainage channel from the anterior chamber into Schlemm's canal network.

The other terms don’t describe this drainage channel: the uvea is the eye’s middle layer, not a drainage canal; a trephine is a surgical instrument; and zonules are the ligaments that hold the lens in place.