Timolol lowers intraocular pressure in open-angle glaucoma by which mechanism?

• A Increasing uveoscleral outflow through prostaglandin release
• B Constricting the ciliary muscle and opening the trabecular meshwork
• C Blocking beta receptors in the ciliary epithelium, reducing aqueous humour secretion ✓
• D Inhibiting carbonic anhydrase in the ciliary processes

Explanation

Beta-adrenoceptors in the non-pigmented epithelium of the ciliary body facilitate aqueous humour secretion. Timolol blocks these receptors and reduces aqueous production by roughly 50 percent, lowering intraocular pressure. Option A describes latanoprost, option B describes pilocarpine, which increases trabecular outflow, and option D describes acetazolamide. Distinguishing drugs that reduce inflow from those that enhance outflow is a frequently examined distinction in glaucoma pharmacotherapy.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.