Glaucoma is a group of eye diseases which result in damage to the optic nerve and vision loss.
The most common type is open-angle glaucoma with less common types including closed-angle glaucoma and normal-tension glaucoma.
Open-angle glaucoma develops slowly over time and there is no pain. Side vision may begin to decrease followed by central vision resulting in blindness if not treated.
Closed-angle glaucoma can present gradually or suddenly.