Closed-angle glaucoma is mostly seen in acute onset glaucoma: the eye pressure rises significantly, manifested by a very red white of the eye, severe eye distension with headache, nausea and vomiting, sharp loss of vision, which can be misdiagnosed as gastrointestinal disease and brain disease. Open-angle glaucoma is chronic, with a mild to moderate rise in IOP in the early stages. Patients feel well and do not notice any changes in their eyes, and there are no warning symptoms. We have found that 1/2 of all glaucoma patients are unaware that they have the disease. In the advanced stages, there is already severe optic nerve damage and loss of vision, so that you can see only the central part of the eye, with serious consequences.