The study investigated the 24-hour efficacy and ocular surface health with preservative-free tafluprost and a combined preservative-free regimen (tafluprost and dorzolamide/timolol fixed combination) in open-angle glaucoma patients insufficiently controlled on latanoprost monotherapy and showing signs, or symptoms of ocular surface disease with preservative-containing latanoprost monotherapy. This trial randomized open-angle glaucoma patients insufficiently controlled (IOP > 20 mm Hg) on branded, or generic latanoprost monotherapy who required further IOP reduction and who demonstrated clinical signs, or symptoms of ocular surface disease.

Inclusion criteria

• Open-angle glaucoma patients (primary open-angle glaucoma, exfoliative, or pigmentary glaucoma) insufficiently controlled on branded, or generic latanoprost monotherapy (IOP > 20 mm Hg as determined by 2 separate IOP measurements at 10:00 ± 1 hour)
• Patients with signs, or symptoms of ocular surface disease.
• Only those open-angle glaucoma subjects who, according to the opinion of the principal investigator, require further IOP reduction.
• Patients must have demonstrated at least 20% IOP reduction at 10:00 (± 1 hour) and who are treated with branded, or generic latanoprost monotherapy for at least 3 months.
• Only subjects with open-angle glaucoma that have exhibited (prior to latanoprost therapy) untreated, sitting IOP evaluated with Goldmann tonometry between 25-39 mm Hg at 10:00 (± 1 hour).
• Age between 21-85 years
• Mild to moderate glaucomatous disc damage and visual field loss (less than -12 dB mean deviation visual field loss attributed to glaucoma
• Those with 0.8 or better vertical cup-to-disc ratio and visual acuity greater than 0.1 in the study eye.
• Open anterior chamber angles.
• Those who have to demonstrate a reliable visual field (at least two visual fields with less than 20% fixation losses, false positives, or negatives)
• Patients who understand study instructions, are willing to attend all follow-up appointments and will comply with study medication usage.

Exclusion criteria

• Patients with a history of less than 10% IOP decrease on any IOP-lowering medication.
• Those with evidence of concurrent conjunctivitis, keratitis, or uveitis in either eye.
• Subjects with a history of inadequate adherence; intolerance, or contraindication to either prostaglandins, β-blockers, dorzolamide, or benzalconium chloride (BAK)
• Patients with severe ocular surface disease, previous intraocular conventional or laser surgery in the study eye (within 6 months prior to enrolment); previous history of ocular trauma; use of corticosteroids (within 3 months before the enrolment) and use of contact lenses.
• Those that on baseline examination show clinical evidence of inflammation, signs of ocular infection (except blepharitis), signs of any corneal abnormality that will affect subsequent IOP measurements
• Subjects that show unwillingness to participate in the trial.
• Females of childbearing potential or lactating mothers.