In glaucoma, increased fluid pressure occurs inside the eye (raised intraocular pressure). This damages the optic nerve causing partial vision loss and eventual blindness. There are four major types of glaucoma: open angle or chronic glaucoma, closed angle or acute glaucoma, congenital glaucoma, and secondary glaucoma. All four types are characterized by increased pressure within the eyeball, and all can cause progressive damage to the optic nerve. Increased pressure occurs when the fluid within the eye (called aqueous humor), which is produced continuously, does not drain properly. The pressure pushes on the retina at the back of the eye. This reduces the blood supply to the nerves of the retina causing them to die. As the optic nerve deteriorates, blind spots and vision changes develop. Peripheral vision (side vision) is affected first followed by front or central vision. Without treatment, glaucoma can eventually cause blindness.

Glaucoma affects three million people in the U.S. and sixty seven million people worldwide. It is the leading cause of blindness in the U.S. and it is believed that sight loss could be prevented in nine out of ten cases by early detection. It is thought that half of glaucoma patients may be undiagnosed.

Risk factors depend on the type of glaucoma. For chronic glaucoma the risk factors include age over forty years, a family history of glaucoma, diabetes, and near sightedness. The incidence is four to six times greater and symptoms develop at an earlier age among people of African ancestry. It is estimated that between and two percent of people over forty have chronic glaucoma with about one quarter of cases being undetected. About three hundred thousand Americans under thirty five years of age have glaucoma. In the eighty plus age group the prevalence may be as high as fifteen percent. Acute congenital and secondary glaucoma are much less common than chronic glaucoma. Ninety to ninety five percent of all cases are classified as acquired open angle glaucoma, wherein the eye fluid does not drain well.

Glaucoma is a difficult disease to stabilize because many patients have silent recurrences. These recurrences are frequently undiagnosed for some time because there is no single sensitive method of diagnosis. Mitochondrial damage impairs the metabolism of retinal ganglion cells. Neuroprotection of retinal ganglion cells is a useful strategy towards preventing silent recurrence and progression of glaucoma.