Brinzolamide 1% is a topical carbonic anhydrase inhibitor used for glaucoma. Its primary mechanism in reducing IOP is:
- A Reducing aqueous humour production by inhibiting carbonic anhydrase II in the ciliary body ✓
- B Increasing uveoscleral outflow via prostaglandin pathway
- C Decreasing episcleral venous pressure
- D Constricting the pupil to widen the trabecular meshwork
Correct answer: A. Reducing aqueous humour production by inhibiting carbonic anhydrase II in the ciliary body
Explanation
Topical carbonic anhydrase inhibitors (brinzolamide, dorzolamide) reduce IOP by inhibiting carbonic anhydrase II (CA-II) in the ciliary body epithelium, thereby reducing bicarbonate secretion and consequently aqueous humor production by approximately 15–20%. They do not affect uveoscleral outflow, episcleral venous pressure, or pupil size. Prostaglandin analogues (latanoprost, travoprost) increase uveoscleral outflow. Miotic agents (pilocarpine) act by pupillary constriction and ciliary muscle contraction to widen the trabecular meshwork.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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