Glaucoma is a group of eye conditions that damage the optic nerve, which sends visual information from your eye to your brain and is vital for good vision. Damage to the optic nerve is often related to high pressure in your eye, but glaucoma can happen even with normal eye pressure. The optic nerve damage is usually related to increased pressure in the eye, which is caused by an abnormality in the eyes drainage system that can cause fluid to build up. However, glaucoma can also occur without any cause, and many factors can affect it, with the most important being intraocular eye pressure. Other causes of glaucoma include blocked drainage, injury, an underlying medical condition, autoimmune and inflammatory disorders, poorly controlled diabetes, and other conditions that damage the blood vessels in the body. Congenital glaucoma can also occur in infants when there are incorrect or underdeveloped drainage canals in the eye during the prenatal period.