The exact cause of glaucoma is not known. For some reason, there is an overproduction of fluid and/or the passages that normally allow fluid within your eye to drain out become clogged or blocked. This results in fluid building up within your eye and increasing pressure on the optic nerve. The nerve fibers and blood vessels in the optic nerve can easily be damaged by this pressure. An injury, infection or tumor in or around the eye can also cause the pressure to rise.
