Glaucoma is a leading cause of blindness throughout the world. Its exact cause is not known.

Glaucoma refers to a group of eye diseases that have common features including raised intraocular pressure, damage to the optic nerve, and sight loss.

There are several types of glaucoma, including primary open-angle, closed-angle, secondary, congenital, and normal tension.

The most common is primary open-angle glaucoma.