Non Interventional Study in Patients With Open Angle Glaucoma and/or Ocular Hypertension Treated With XALATAN®

Inclusion Criteria: * Unilateral or bilateral open angle glaucoma or ocular hypertension (IOP (Intraocular Pressure) ≥ 21 mmHg at diagnosis). * Naive patients (no prior anti-glaucoma pharmacological or surgical treatment) and patients with beta-blockers therapy failure * Visual acuity (best corrected) equal to or better than 6/6 Exclusion Criteria: * closed/barely open anterior chamber angle or history of acute angle closure glaucoma. * history of any antiglaucoma surgical treatment (Argon Laser Trabeculoplasty and/or any ocular filtering surgical intervention). * ocular surgery (on the globe of the eye only), or inflammation/infection within 3 months prior to baseline visit. (Applies to both fellow and study eyes.) * other abnormal ocular conditions or symptoms preventing the patient from entering the study, in the investigator's clinical judgement.