The study is a prospective single-practice with multiple locations, single-surgeon, parallel double arm study in subjects with open angle glaucoma (OAG), who were implanted with Hydrus microstent combined with cataract surgery to be randomized to receive Rocklatan vs. Comparator (artificial tears). Unmedicated MDIOP (mean diurnal intraocular pressure) measurements will be assessed at baseline (after Hydrus, prior to study medication) and at 1-month post-initiation of Study Drop.