Glaucoma remains the leading cause of irreversible blindness worldwide. Glaucoma represents a group of diseases that lead to optic nerve damage and corresponding deterioration of the visual field. Elevated intraocular pressure remains the most important risk factor. Interestingly, glaucomatous damage sometimes occurs despite seemingly normal intraocular pressure. Recent studies suggest pressure peaks, which are missed under the current practice of spot intraocular measurements during office hours. In order to detect pressure peaks diurnal measurements are mandatory. Costly in-hospital diurnal measurements are the current standard. The primary study objective is to verify that self-tonometry at home can provide valuable information when looking for pressure peaks in patients with glaucoma.