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.