Glaucoma is a major cause of blindness. The inability to predict a patient's IOP response to medications is a critical barrier for the clinician to consistently provide highly effective IOP-based treatments. Current trial-and error approaches to glaucoma management are inefficient and have not addressed this barrier as there are no predictive factors for drug response. Our long-term goal is to improve outcomes by identifying biomarkers and environmental factors that profile a patient at risk for glaucoma by age-of-onset, rate of disease progression, "poor response" to treatment, and large IOP fluctuation. Our purpose of this research project is to address this critical barrier by focusing on physiological factors that predict IOP response to drugs.

Inclusion Criteria:

• Either gender.
• Any self-declared ethnoracial category.
• Greater than or equal to 40 years.
• Healthy eyes with the crystalline lens, without glaucoma (cup:disc ratio < 0.8 both eyes; asymmetry of cup:disc ratio between eyes < 0.2).
• Open angles.
• Ability to cooperate for aqueous humor dynamic studies.
• Nonprescription and prescription topical ophthalmic products and systemic medications other than those mentioned in the exclusion criteria will be allowed during the study.
• Contact lenses removed prior to topical fluorescein instillation, and not used until the end of each fluorophotometry session.
• Able to participate on site over the multi-visit study period.

Exclusion Criteria:

• Women who are pregnant due to IOP changes.
• Any form of glaucoma, including extremely narrow angle with complete or partial closure.
• Current use of any glaucoma medication, either topically or orally.
• Chronic or recurrent inflammatory eye disease.
• Ocular trauma within the past 6 months.
• Ocular infection or ocular inflammation in the past 3 months.
• Clinically significant retinal disease.
• Any abnormality preventing reliable fluorophotometry of either eye, such as corneal scarring or severe dry eye that results in punctate fluorescein staining of the cornea.
• Intraocular surgery within 6 months.
• Serious hypersensitivity to any components of the study medications or risk from treatment with glaucoma medications, such as severe asthma or emphysema.
• Subjects must be on a stable regimen for at least 30 days prior to the Visit 1 regarding a chronic systemic medication that may affect IOP (i.e., sympathomimetic agents, beta-blockers, alpha-adrenergic agonists, alpha-adrenergic blockers, calcium channel blockers, angiotensin converting enzyme inhibitors, etc.). Any change of such medication during the study period will result in exclusion.
• Use of any glucocorticoid by any route. Subject must be washed out of the glucocorticoid for at least 2 weeks before study entry.

In addition to the 119 participants who were randomized to actual treatment, the baseline population includes the 9 who came for full baseline measurements before they were excluded or chose to withdraw.

16 weeks