Glaucoma (eye pressure) is a disease that causes vision loss due to the increase in intraocular pressure enough to destroy the optic nerve. In a normal eye, the eye fluid is constantly produced and emptied by being absorbed in a balanced way. Thus, intraocular pressure remains at normal levels. In general, eye pressure below 20–21 mm Hg is normal. However, glaucoma can be seen even at lower levels of blood pressure. If the discharge of the eye fluid is prevented, the intraocular pressure increases and open-angle glaucoma occurs, which is the most common form of glaucoma. Here, there is a blockage in the canals that allow the eye fluid to reach the blood vessels, which should not normally exist, and the accumulated eye fluid increases the intraocular pressure. High intraocular pressure damages the optic nerve and, if left untreated, can lead to vision loss leading to blindness. It is seen in 2% of the people over the age of 40 and 10% over the age of 60 in the society. There are other types of glaucoma seen in infancy (congenital glaucoma) and childhood. Initially, there is usually no symptom, no visual disturbance and no pain. If the disease is not diagnosed early and progresses, blind spots occur in the visual field due to damage to the optic nerve. Then, as if looking through a pipe, the surrounding objects become invisible. In the rare closed-angle type of glaucoma, the eye pressure reaches very high values, causing severe pain and blurred vision. This is usually observed in hyperopia patients. It can be treated with medication, laser or surgery.