• Adults aged Eighteen (18) years and older with a diagnosis of mild to moderate open-angle glaucoma (OAG), currently on an on-label use of combination topical medication of Cosopt and Latanoprost for a minimum of 1 month. Evidence of optic nerve damage will be based on AAO Preferred Practice Patterns guidelines using either or both of the following:

• Optic disc or retinal nerve fiber layer (RNFL) structural abnormalities

• Diffuse or focal narrowing, or notching, of the optic disc rim, especially at the inferior or superior poles, which forms the basis for the ISNT rule

• Progressive narrowing of the neuroretinal rim with an associated increase in cupping of the optic disc

• Diffuse or localized abnormalities of the parapapillary RNFL, especially at the inferior or superior poles

• Disc rim, parapapillary RNFL, or lamina cribrosa hemorrhages

• Optic disc neural rim asymmetry of the two eyes consistent with loss of neural tissue

• Large extent of parapapillary atrophy

• Reliable and reproducible visual field abnormality considered a valid representation of the subject's functional status

• Visual field damage consistent with RNFL damage (e.g. nasal step, arcuate field defect, or paracentral depression in clusters of test sites)

• Visual field loss across the horizontal midline in one hemifield that exceeds loss in the opposite hemifield (in early/ moderate cases)

• Absence of other known explanations (e.g. optic disc drusen, optic nerve pit)

• Mean diurnal IOP ≥ 18 mmHg and \< 28 mmHg at baseline in at least one eye with an inter-eye IOP difference \< 5 mmHg.

• A central corneal thickness (CCT) within the range of 450-650 µm