Which alpha agonist lowers aqueous production and increases uveoscleral outflow?

• A. Brimonidine 0.1%, 0.15%, 0.2%
• B. Apraclonidine 0.5%
• C. Timolol 0.5%
• D. Pilocarpine 2%

Answer: (A)

Brimonidine is an alpha-2 adrenergic agonist that lowers intraocular pressure by two means: it reduces the production of aqueous humor by limiting sympathetic activity at the ciliary processes, and it also promotes some increase in uveoscleral outflow. This dual action fits the description of an alpha agonist that both lowers production and enhances uveoscleral drainage, making it the best choice.

Apraclonidine is another alpha-2 agonist and can reduce production, but its effect on uveoscleral outflow is less reliable. Timolol is a beta blocker, not an alpha agonist, and mainly lowers production. Pilocarpine is a muscarinic agonist that increases trabecular outflow via miosis rather than increasing uveoscleral outflow, and it doesn’t primarily decrease production.