Glaucoma is a serious disease that if left untreated can cause damage to the optic nerve resulting in gradual vision loss and eventually even blindness. Damage to the optic nerve, due to glaucoma, is usually caused by an elevated intraocular pressure (IOP).

A clear fluid, called aqueous humor, fills the front of the eye (anterior chamber) and provides nourishment to the tissues. Like the air in a balloon, the aqueous also provides pressure to help maintain the shape of the eye.