Which structure drains aqueous humor from the anterior chamber?

• A. Iris
• B. Vitreous humor
• C. Optic nerve
• D. Canal of Schlemm

Answer: (D)

Understanding how aqueous humor exits the eye helps explain why Schlemm’s canal is the right pick. Aqueous humor is produced by the ciliary body, flows from the posterior chamber through the pupil into the anterior chamber, and then drains mainly through the trabecular meshwork into Schlemm’s canal. Schlemm’s canal sits at the angle between the cornea and iris and channels the fluid into the episcleral veins, providing the primary conventional outflow for the anterior chamber. The iris itself governs pupil size but does not function as a drainage pathway. The vitreous humor lives in the posterior segment, not involved in anterior chamber drainage. The optic nerve is the conduit for neural signals from the retina, not a drainage structure. (There is a secondary, less prominent uveoscleral outflow pathway, but Schlemm’s canal is the principal route for drainage from the anterior chamber.)