Glaucoma is a disease that causes progressive damage to the optic nerve that leads to slow peripheral vision loss. Of the 2.5 million people in the U.S. with glaucoma, more than half of them don’t realize they have it because there are often no warning symptoms. Dr. Ericksen uses tonometry to measure the pressure inside the eye and ophthalmoscopy to view and document changes in optic nerve structure. OCT and Visual fields provide additional information for diagnosing glaucoma. Primary open angle is the most common form of glaucoma, while acute angle closure glaucoma occurs more rapidly but is less common. Patients have elevated intraocular pressure in glaucoma, however, there is a normal tension glaucoma caused by reduced blood supply.