Comparison of Sensimed Triggerfish (TF) 24 Hour Monitoring of the Eye in Glaucoma Patients Before and After Trabeculectomy

Inclusion Criteria: * Patient must have the willingness and ability to provide signed informed consent * Patient is able to comply with the study procedure * Patient must be ≥ 18 years old * Diagnosis of primary open angle glaucoma (EGS criteria) including pseudoexfoliation glaucoma/ normal tension glaucoma/ pigmentary glaucoma in the study eye * planned trabeculectomy in the study eye * in preparation for trabeculectomy, all preoperative IOP lowering medication has been replaced by Dorzolamid 20 mg/ml + Timolol 5mg/ml preservative free eye drops in the study eye for at least 28 days before Triggerfish® profile * Patient has consented to be in the trial and signed informed consent is available before any study related procedures are carried out * Visual Acuity of 20/200 or better in both eyes * Ability of subject to understand the character and individual consequences of the study Exclusion Criteria: * Subjects with contraindications for wearing contact lenses in the study eye * secondary glaucoma in the study eye * History of refractive surgery in the study eye * History of intraocular surgery in the last three months in the study eye * Severe dry eye syndrome as judged by the investigator in the study eye * Keratoconus or other corneal abnormalities * Any other abnormality in the study eye, that prevents the safe placement of the device after investigators decision * Conjunctival or intraocular inflammation in the study eye * Simultaneous participation in other clinical trials * Previous IOP-lowering intervention in the study eye * Current shift workers (applicable for at least 3 months) * Transmeridian flight \< 2 months before screening (6 hours time shift) * Subjects with pacemaker