What produces the aqueous humor?

• A. Ciliary body
• B. Iris
• C. Cornea
• D. Lens

Answer: (A)

Aqueous humor is produced by the ciliary body, specifically the ciliary processes. The ciliary epithelium within these processes secretes fluid from plasma ultrafiltrate using active transport, forming the aqueous humor that fills the posterior chamber. It then flows through the pupil into the anterior chamber, where it nourishes avascular structures and helps regulate intraocular pressure. The iris does not secrete aqueous humor (it mainly regulates the pupil), the cornea is nourished by the aqueous but does not produce it, and the lens relies on the aqueous for nutrients but does not synthesize it.