Glaucoma is a chronic optic neuropathy whose main modifiable risk factor is an abnormally elevated intraocular pressure. The aim of glaucoma treatment is to slow the progression of the disease by reducing intraocular pressure.

Prostaglandin derivatives are the most effective topical drugs in reducing intraocular pressure (IOP). Among these, latanoprost was the first agent of this type to be approved for use in patients with glaucoma or ocular hypertension.

These eye drops are available with and without preservatives. There are two commercial brands in our environment, Xalatan®, which contains 0.005% latanoprost and 0.2 mg/ml benzalkonium chloride (BAK) and Monoprost®, which contains the same amount of latanoprost but does not carry a preservative. The prostaglandin analog with a lower concentration of active ingredient available in Spain without preservative is tafluprost 0.0015%, commercially available under the name Saflutan®.

The long-term use of hypotensive eye drops with preservatives generates changes in the ocular surface, such as instability of the tear film, conjunctival inflammation, subconjunctival fibrosis, apoptosis of the conjunctival epithelium and deterioration of the corneal surface, causing symptoms such as stinging, tearing, sensation foreign body, photophobia and blurred vision.

This research will evaluate the changes in the ocular surface and in the expression of inflammatory molecules that occur in the conjunctiva in patients with a diagnosis of glaucoma and ocular hypertension who are under ocular hypotensive treatment with tafluprost, comparing it with the two commercial preparations of latanoprost.

These three groups of patients will have a control group of patients with a diagnosis of ocular hypertension who will not have any topical hypotensive medication.

Inclusion Criteria:

• Patients with primary open angle glaucoma or ocular hypertension as defined in Early Manifest Glaucoma Trial
• > 18 years old
• Signed informed consent
• 3 or more months under monotherapy treatment with tafluprost 0.0015%, latanoprost 0.005% with BAK 0.2mg/ml or latanoprost 0.005%.
• Untreated patients with ocular hypertension must be treatment naïve for the pathology.
• No presence or history of previous ocular diseases other than glaucoma or ocular hypertension, started before the use of hypotensive medication.

Exclusion Criteria:

• Ocular surgery in the previous 6 months.
• Any ocular surface disease not related to inclusion criteria or related issues active within the last 6 months.
• Any topical treatment other than the evaluated in this study in the last 3 months.
• In case of artificial teardrops use, only non conservative ones are allowed, with no more than 4 times per day use, and treatment must be suspended 5 days before inclusion.
• Use of contact lenses in the las 4 weeks.
• Any mental or physical disease that may prevent performing the required tests for the study.

Adult patients with ocular hypertension or primary open angle glaucoma