Which mechanism is shared by rho-kinase inhibitors and alpha-adrenergic agonists in reducing intraocular pressure?

• A. Increases pupil dilation
• B. Stimulates ciliary muscle constriction
• C. Reduces aqueous humor production
• D. Blocks outflow through uveoscleral pathway

Answer: (C)

The common thread is reducing the amount of aqueous humor produced. Intraocular pressure depends on how much aqueous humor is made by the ciliary body and how easily it drains. Alpha-adrenergic agonists suppress production by activating alpha-2 receptors on the ciliary body, lowering cAMP and fluid secretion. Rho-kinase inhibitors, while best known for easing drainage through the trabecular meshwork by relaxing its cytoskeleton, can contribute to lowering IOP in part by reducing aqueous humor formation as well. So, both drug classes help lower IOP by decreasing the amount of fluid being produced, even though their main effects on outflow and drainage differ.