The purpose of the study is to assess the safety, tolerability, and IOP effects of RO5093151 following 7 days of topical ocular treatment in patients with primary open angle glaucoma or ocular hypertension.

Inclusion Criteria:

• Diagnosis of ocular hypertension (OHT) or primary open angle glaucoma (POAG) in at least one eye (qualifying eye) as determined by the Investigator at screening or based on a reliable and documented assessment done within the last 6 months prior to screening provided that no progression of visual field damage is expected
• At baseline visit, intraocular pressure (IOP) >= 24 mmHg in the morning and >= 21 mmHg in the afternoon measurement in at least one eye (qualifying eye = study eye) and =< 34 mmHg at all time points in both eyes
• Best corrected logMAR visual acuity score of 0.7 (20/100 Snellen) or better in each eye as measured by ETDRS visual acuity test at screening
• Central corneal pachymetry measurement 420 to 620 micrometer in qualifying eye at screening
• Cup-to-disk ratio =< 0.8 (both eyes) at screening
• Anterior chamber angle is open and non-occludable as confirmed by the Investigator by gonioscopy examination at screening

Exclusion Criteria:

• History of any clinically significant gastrointestinal, renal, hepatic, bronchopulmonary, neurological, psychiatric, cardio-vascular, endocrinological, hematological or allergic disease (multiple allergies, seasonal allergy is acceptable), metabolic disorder, cancer or cirrhosis
• Uncontrolled hypertension (SBP >= 160 mmHg and/or DBP >= 100 mmHg) despite treatment at the time of screening confirmed by the average of >= 3 blood pressure measurements, properly measured with well-maintained equipment
• Clinically significant abnormalities in laboratory test results at screening
• Hypersensitivity to RO5093151 or any of the components of its formulation, or hypersensitivity to latanoprost or any of the components of its formulation (Part B only)
• Donation of blood over 500 mL within three months prior to screening
• Positive result on hepatitis B (HBV), hepatitis C (HCV), or HIV 1 and 2
• Presence of narrow angle (=< grade 2 Shaffer gonioscopic classification) or complete or partial closure, as measured by gonioscopy or at risk for angle closure as assessed by the Investigator
• Other forms of glaucoma than POAG or OHT in the study eye
• Any abnormality preventing reliable applanation tonometry
• Any clinically significant corneal scarring, haze or opacity
• Patient uncooperativeness that restricts adequate examination of IOP, ocular fundus or anterior chamber
• Evidence of clinically significant blepharitis, concurrent infectious/non-infectious conjunctivitis, keratitis or uveitis
• History or signs of penetrating ocular trauma. Uneventful (uncomplicated) cataract surgery performed 3 months prior to screening is allowed
• According to the Investigator's best judgment, risk of visual field or visual acuity worsening in either eye as a consequence of glaucoma progression or consequence of participation in the trial (i.e., during washout of ocular hypotensive medications or treatment with placebo) or any other ocular disease
• Unable to safely stop ocular hypotension medications prior to randomization according to the required minimum washout periods
• History of any ocular filtering surgical intervention, previous glaucoma intraocular surgery, or laser trabeculoplasty
• History of refractive surgery (laser assisted in-situ keratomileusis, laser epithelial keratomileusis, photorefractive keratectomy, phototherapeutic keratectomy)
• Any other intraocular surgery within 6 months of screening
• Advanced age-related macular degeneration (wet or dry), vitreous hemorrhage, diabetic retinopathy or any progressive retinal or optic nerve disease from any cause other than glaucoma