Types of Glaucoma

There are three basic types: primary, secondary and congenital.

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. According to the Glaucoma Research Foundation (GRF) (http://www.glaucoma.org), it occurs when the eye's drainage canals become clogged over time. This increases inner eye pressure since enough fluid cannot drain out of the eye.

Closed angle glaucoma, also called acute glaucoma, has a sudden onset in people with anatomically narrow angles. It is characterized by severe eye pain and blurred vision. According to the GRF, eye pressure increases very quickly because "the drainage canals get blocked or covered over" with closed angle glaucoma. "The iris and cornea are not as wide and open as they should be. The outer edge of the iris bunches over the drainage canals when the pupil enlarges too much or too quickly."

Secondary glaucoma occurs as a complication of a variety of other conditions, such as injury, inflammation, vascular disease and diabetes. Congenital glaucoma is elevated eye pressure present at birth due to a developmental defect in the eye's drainage mechanism.