There are three basic types: Primary, Secondary, and Congenital Glaucoma. Primary Glaucoma is the most common type and can be divided into open angle and closed angle Glaucoma. Open angle Glaucoma is the type seen most frequently in the United States. It is usually detected in its early stages during routine eye examinations. Closed angle Glaucoma, also called acute Glaucoma, usually has a sudden onset. It is characterized by eye pain and blurred vision. Secondary Glaucoma occurs as a complication of a variety of other conditions, such as injury, inflammation, vascular disease and diabetes. Congenital Glaucoma is due to a developmental defect in the eye's drainage mechanism.