Which drug class increases uveoscleral outflow?

• A. Cholinergic agonists
• B. Beta-blockers
• C. Alpha-2 agonists
• D. Prostaglandins

Answer: (D)

Prostaglandin analogs increase uveoscleral outflow by stimulating changes in the ciliary muscle that remodel the extracellular matrix, making the uveoscleral pathway more permeable. This opens the unconventional drainage route so aqueous humor can flow through the supraciliary/scleral areas more readily, lowering IOP mainly through increased drainage via this pathway.

Cholinergic agonists raise outflow by contracting the ciliary muscle to widen the trabecular meshwork pathway, boosting trabecular outflow rather than uveoscleral. Beta-blockers and alpha-2 agonists primarily reduce aqueous production at the ciliary body; any effect on uveoscleral outflow is secondary and not the main mechanism.