24h Continuous Intraocular Pressure (IOP) Monitoring vs Goldmann Applanation Tonometry

Inclusion Criteria: * Signed informed consent for the investigation * Patients with primary open angle glaucoma (POAG), defined as open angle ≥ 30°, confirmed visual field loss (Mean Defect/Least Variance ≤ 2dB) and/or optic nerve head damage (cup disc ratio \> 0,5) * Age 40-70 years at inclusion * Not more than 4 diopters spherical equivalent on the study eye * Not more than 2 diopters cylinder equivalent on the study eye * For women of childbearing potential, adequate contraception * Stable anti-glaucomatous therapy 4 weeks before the first 24-hour IOP assessment session and throughout the investigation Exclusion Criteria: * Patients not able to understand the character and individual consequences of the investigation * Patients committed to an institution by virtue of an order issued either by the courts or by an authority * Absence of or withdrawn informed consent * Patients with contraindications for silicone contact lens wear * Wear of full frame metallic glasses during SENSIMED Triggerfish monitoring * Eye disorders including severe dry eye * Eye disorders secondary to POAG * Patient who have had ocular surgery within the last 3 months * Corneal or conjunctival abnormality or irregularity hindering correct contact lens adaptation * Pregnancy and lactation * Allergy to oxybuprocaine (ocular anesthesia) * Simultaneous participation in other clinical research