A 58-year-old woman presents with acute primary angle closure with IOP of 56 mmHg. Along with topical agents, intravenous acetazolamide is administered. Acetazolamide lowers intraocular pressure by which mechanism?
- A Increasing trabecular outflow facility by ciliary muscle contraction
- B Decreasing vitreous volume by osmotic withdrawal of water
- C Reducing aqueous humour production by inhibiting carbonic anhydrase in the ciliary processes ✓
- D Relaxing the iris sphincter to deepen the anterior chamber
Correct answer: C. Reducing aqueous humour production by inhibiting carbonic anhydrase in the ciliary processes
Explanation
Acetazolamide inhibits carbonic anhydrase in the ciliary epithelium, reducing bicarbonate formation and thereby decreasing aqueous secretion by roughly 40 to 60 percent. Option A describes pilocarpine, option B describes hyperosmotic agents such as mannitol, and option D is not a pressure-lowering action of any glaucoma drug. Carbonic anhydrase inhibition is independent of outflow pathways, so it works even when access to the angle is blocked.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.