A Comparison of Xalatan (Latanoprost) to Apo-latanoprost and Co-latanoprost in the Treatment of Glaucoma

Inclusion Criteria: * Patients ≥ 18 years old, diagnosed with primary open angle glaucoma or ocular hypertension * IOP currently controlled on prostaglandin analogue monotherapy (latanoprost, bimatoprost or travoprost), as judged by the investigator Exclusion Criteria: * Best corrected visual acuity worse than 0.6 logMAR or 20/80 Snellen in either eye. * Patients in whom the mean IOP in either eye at the screening exam visit is greater than 36 mmHg * History of ocular trauma within the past six (6) months. * History of ocular infection or ocular inflammation within the past three (3) months. * History of chronic or recurrent severe inflammatory eye disease (i.e., scleritis, uveitis) * History of severe or serious hypersensitivity to any components of the study medications. * Any abnormality preventing reliable applanation tonometry of either eye. * Intraocular surgery within the past six (6) months as determined by patient history and/or examination. * Patients with cup/disc ratio greater than 0.80 in either eye. * Patients with severe central visual field loss in either eye defined as a sensitivity less than or equal to 10 dB in at least two (2) of the four (4) visual field test points closest to the point of fixation. Visual field test must be within 6 months of eligibility assessment. * History of clinically significant or progressive retinal disease such as retinal degeneration, diabetic retinopathy or retinal detachment. * Current use of ANY glucocorticoid administered by any route. Patient must have washed out of the glucocorticoid for at least 4 weeks prior to study entry. * Use of any systemic prostaglandin or prostaglandin analogue within the last three months. * Current use of topical non-steroidal antiinflammatory agents which inhibit cyclo-oxygenase and prostaglandin analogue synthesis. * Any form of glaucoma other than open-angle glaucoma (with or without a pigment dispersion or pseudoexfoliation component). * Current use of topical non-steroidal anti inflammatory agents which inhibit cyclo-oxygenase and prostaglandin analogue synthesis. * Angle grade less than 2 (extreme narrow angle with complete or partial closure) as measured by gonioscopy.