AR-13324 is a small-molecule inhibitor of Rho kinase and a norepinephrine transporter. The objective of this 28-day study was to evaluate the ocular hypotensive efficacy and safety of AR-13324 ophthalmic solution compared with a positive control, latanoprost ophthalmic solution, in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT).