1) Open Angle Glaucoma.
This is the most common form of glaucoma in Western populations and is caused by the trabecular meshwork becoming silted up.
2) Chronic Closed Angle Glaucoma.
This is caused by blocked drainage through a narrow angle between the iris and the cornea with resultant scarring of the trabecular meshwork. It is more common in Asian and Chinese populations.
More about Glaucoma supplemented with animations here…