Timolol eye drops are used in open-angle glaucoma. The mechanism of IOP reduction is:
- A Reduced aqueous humor production by beta-2 blockade of ciliary epithelium ✓
- B Increased aqueous outflow through the trabecular meshwork by miosis
- C Uveoscleral outflow enhancement via prostaglandin release
- D Alpha-2 agonism reducing aqueous secretion
Correct answer: A. Reduced aqueous humor production by beta-2 blockade of ciliary epithelium
Explanation
Timolol reduces intraocular pressure by blocking beta-2 adrenoceptors on the ciliary body epithelium, thereby decreasing the rate of aqueous humor formation (secretion). It does not affect pupil size (no miosis) and thus does not alter trabecular outflow, unlike miotics such as pilocarpine. Brimonidine works via alpha-2 agonism; prostaglandin analogues enhance uveoscleral outflow.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.