Glaucoma is a disease of the eye caused by damage to the optic nerve. The primary cause of glaucoma is poor drainage of fluid through the drainage angle—known as open-angle glaucoma. Another more dangerous form of glaucoma, known as angle-closure glaucoma, occurs when the iris blocks the drainage angle and prevents drainage, thereby building up fluid pressure in the eye and damaging the optic nerve.

What is a cataract?

What is eye pressure?