Study of SHP639 Eye Drops in Adults With High Eye Pressure or Primary Open-angle Glaucoma

Inclusion Criteria

• Participants must provide written, signed and dated informed consent to participate in the study in accordance with the International Council for Harmonisation (ICH) Good Clinical Practice (GCP) Guideline E6(R1) and applicable regulations, before completing any study-related procedures.
• Participants must be aged from 18 through 90 at the time of consent. This inclusion criterion will only be assessed at the screening visit.
• Participants must have ocular hypertension (OHT) or stable early primary open-angle glaucoma (POAG) in both eyes with acceptable Humphrey visual fields (HVF). Early POAG for this protocol is defined as healthy appearing anterior chamber angles (Shaffer classification system grade 3 or 4) and focal and/or generalized thinning of the optic disc rim characteristic of glaucomatous disease. An acceptable HVF must have been performed within approximately one year of screening, have a false-positive rate of 25 percent (%) maximum, false-negative rate of 25% maximum, and fixation loss rate of 33% maximum, and mean deviation of no worse than -6.00 decibels (dB).
• On Day -1, participants must have a mean IOP of greater than or equal to (>=) 24 millimeter of mercury (mmHg) at 8:00 AM and a mean IOP of >= 22 mmHg at 10:00 AM in at least 1 eye, with an IOP difference of less than (<) 4 mmHg between eyes at both of these time points. If only 1 eye meets this criterion, then it will be the designated study eye for pharmacodynamic analysis; this eye will also be used for dosing in Cohort A single-dose treatment period (SDTP).
• Participants must have a best-corrected visual acuity (BCVA) in both eyes of 65 letters on the Early Treatment Diabetic Retinopathy Study chart (Snellen equivalent approximately [∼] 20/60) or better at the screening and baseline assessments.
• Participants must be males or females who are non-pregnant and non-lactating at screening (negative serum beta-human chorionic gonadotropin [beta-hCG]); if sexually active during the study, they must agree to comply with the applicable contraceptive requirements throughout the study period and for 60 days following the last dose of investigational product.
• Participants must have a satisfactory medical assessment with no clinically significant or relevant abnormalities as determined by medical history, physical examination, and clinical and laboratory evaluation (hematology, biochemistry, urinalysis) as assessed by the investigator.
• Participants must understand and be able, willing, and likely to fully comply with study procedures and restrictions.
• Participants must be non-smokers or have had stable use of tobacco or nicotine-containing products for a 3-month period before signing the informed consent form (ICF).
• Participants who drink alcohol must have had stable use of alcohol for a 3-month period before signing the ICF.

Exclusion Criteria

• Participant has an anatomically narrow angle, synechiae or evidence of prior inflammation, angle closure glaucoma, normal tension glaucoma, pseudoexfoliation syndrome or pigmentary dispersion syndrome with or without glaucoma, or secondary glaucoma.
• Participant has corneal endothelial cell counts of less than 2000 cells per millimeter^2 (measured by noncontact specular microscopy) at the screening or baseline assessments.
• Participant has central corneal thickness less than 500 micrometer (mcm) or greater than 620 mcm at the screening or baseline assessments.
• Participant has IOP greater than 32 mmHg in either eye before randomization.
• Participant has used topical ocular hypotensive medications as follows: prostaglandin analogs, beta-adrenoceptor antagonists, alpha-adrenergic agonists, or epinephrine-related medications within 4 weeks before the first dose of investigational product; or pilocarpine or carbonic anhydrase inhibitors within 7 days before the first dose of investigational product.
• Participant has a history of angle closure, ocular surgery, microi