There are several different types of glaucoma. Open angle glaucoma is the most common type of glaucoma. It is a condition in which the angle of the eye, where the iris meets the cornea, is anatomically normal and open. However, the drainage canal inside the angle is atypical and becomes blocked, preventing the fluid in the eye from flowing properly. This results in an elevation of pressure inside the eye, which can damage the optic nerve and loss of vision. Open angle glaucoma is typically asymptomatic, so it can go undiagnosed without a proper dilated comprehensive exam. Initially, open angle glaucoma causes loss of side vision, which most patients do not notice. Eventually, as the disease progresses, it can lead to blindness.