Inclusion Criteria:
* Diagnosis of mild to moderate OAG, mild to moderate NTG, or stable NPDR in at least one eye.
* Corrected visual acuity in each eye +1.0 logMAR or better by early treatment diabetic retinopathy study (ETDRS) in each eye (equivalent to 20/200).
* Able and willing to give signed informed consent and follow study instructions.
Exclusion Criteria:
* History of active ocular disease other than mild to moderate OAG, mild to moderate NTG, or stable NPDR.
* Patient is using more than 1 ocular hypotensive topical medication for intraocular pressure (IOP) control (prior MIGS and/or laser trabeculoplasty to control IOP is allowed if done at least 3 months from Screening (Visit 1).
* Use of TO β-blockers (i.e. timolol) within 3 months prior to Screening.
* Is noncompliant with current ocular anti-hypotensive medications and/or unwilling to be compliant throughout the study.
* Clinically significant severe retinal disease in either eye that will require treatment during the study (e.g., proliferative diabetic retinopathy, exudative, or severe non-exudative macular degeneration). NOTE: background diabetic retinopathy (BDR) as required for the NPDR subjects is allowed if in the Investigator's opinion the BDR is stable and is expected to remain stable during the duration of the study.
* Anti-VEGF or TO steroid treatment within 3 months prior to Screening or expected treatment while participating in this study. Prior diabetic macular edema (DME) history is allowed if adequately controlled with treatment (anti-VEGFs and steroids not within last 3 months prior to Screening), regimen is stable, and not expected to change during the study. - Corneal pathologic changes preventing reliable measurement (e.g., scarring, opacity, edema, and bullae) in either eye that would inhibit accurate IOP measurements.
* Previously diagnosed, clinically significant systemic or psychiatric disease (e.g., myasthenia gravis, hepatic, renal, endocrine, pulmonary, or cardiovascular disorders) which might compromise the study results or subject safety. For the purpose of this study previously diagnosed, clinically significant renal disease that should be excluded from enrollment will be defined as Stages 3-5 kidney disease and/or an estimated glomerular filtration rate (eGFR) of ≤59.
* Use of calcium channel blockers.
* Labile hypertension and/or hypotension that is inadequately controlled,
