Glaucoma is a progressive eye disease that causes irreversible damage to the optic nerve due to high eye pressure (intraocular pressure). The optic nerve helps your brain form a picture for you to see. It is estimated that there are currently over 67 million cases of glaucoma worldwide. Nearly 10% of people over 70 have glaucoma. In addition, glaucoma is the leading cause of blindness in people over 60.