PURPOSE: To evaluate netarsudil 0.02% ophthalmic solution in patients with open-angle glaucoma (OAG) and ocular hypertension (OHT). DESIGN: Double-masked, randomized, multicenter, parallel-group, noninferiority clinical study. METHODS: After a washout of all prestudy ocular hypotensive medications, 756 eligible patients with elevated IOP were randomized to receive netarsudil 0.02% once a day (q.d.) (251); netarsudil 0.02% twice a day (b.i.d.) (254); or timolol 0.5% b.i.d. (251) for 12 months, as well as a noninterventional Corneal Observation Study (COS) for patients manifesting cornea verticillata. RESULTS: On treatment, mean IOP at 8:00 AM decreased from a baseline IOP of 22.5-22.6 mm Hg to 17.9-18.8 mm Hg, 17.2-18.0 mm Hg, and 17.5-17.9 mm Hg for netarsudil q.d., netarsudil b.i.d., and timolol, respectively, over 12 months. The most frequently reported adverse events (AEs) were ocular, with the most frequent ocular AE being conjunctival hyperemia, with an incidence of 61%, 66%, and 14%, respectively. The next most frequent AEs were corneal deposits (corneal verticillata), with an incidence of 26%, 25%, and 1%, respectively, and conjunctival hemorrhage (typically petechial), with an incidence of 20%, 19%, and 1%, respectively. All 3 AEs were generally scored as mild, with conjunctival hyperemia and/or hemorrhage appearing sporadically during the study. In the observational follow-up component of this study, there was no clinically meaningful impact of corneal verticillata on visual function in affected patients. CONCLUSIONS: In this randomized, double-masked trial, once-daily dosing of netarsudil 0.02% was effective, consistently lowering IOP through 12 months, and was tolerated by the majority of patients.