What is the mechanism by which beta blockers help lower intraocular pressure?

• A. Decreased aqueous humor production and potentially increased outflow to decreased IOP
• B. Increased aqueous humor production
• C. Decreased outflow only
• D. No effect on IOP

Answer: (A)

Beta blockers lower intraocular pressure mainly by reducing the production of aqueous humor in the ciliary body. They block beta-adrenergic receptors on the ciliary epithelium, which lowers cAMP and decreases the secretory activity that makes aqueous humor. With less fluid being produced, the anterior chamber pressure falls. There can be a small, secondary effect of slightly improving outflow in some cases, but the primary action is on production. That’s why decreased aqueous humor production best explains how these drugs lower IOP.