Glaucoma is a chronic eye disease where increased intraocular pressure with other contributing factors damages the optic nerve. An increase in intraocular pressure is caused by pathological obstruction of the outflow of the aqueous humour from the eye chamber. If glaucoma is not treated, the damage to the optic nerve results in a complete loss of vision due to progressive loss of the visual field. This can occur within months or years depending upon accompanying factors.

The aim of glaucoma treatment is to stop the worsening of the damage to the optic nerve. It is not possible to restore the dead part of the optic nerve and the corresponding loss of the visual field that has already occurred by the time glaucoma is diagnosed. On some occasions the damage to the optic nerve worsens in spite of adequate contemporary therapy, but at lower speeds than without treatment.