What are the three mechanisms by which netarsudil lowers intraocular pressure (IOP)?

• A. Increases outflow through the trabecular meshwork, lowers EVP, and decreases aqueous humor production.
• B. Increases aqueous humor production only.
• C. Decreases outflow through the trabecular meshwork.
• D. Increases episcleral venous pressure.

Answer: (A)

Netarsudil lowers intraocular pressure by three actions: it increases drainage through the trabecular meshwork by relaxing the tissues and widening the conventional outflow pathway; it lowers episcleral venous pressure, which reduces the resistance to outflow at the venous exit; and it decreases aqueous humor production by inhibiting the norepinephrine transporter in the ciliary body.

Together, these reduce the pressure from multiple angles: more fluid leaves through the main drainage route, less pressure opposes that drainage, and less fluid is produced in the first place. This combination is why netarsudil can lower IOP effectively, whereas increasing production or decreasing outflow would not.