Types of Glaucoma
There are several different types of glaucoma, including open-angle glaucoma, closed-angle glaucoma and normal-tension glaucoma.
Open-angle glaucoma is the most common form of glaucoma, except in Asia, where narrow angle is more common. It occurs slowly as the drainage area in the eye becomes less functional over time. Inner eye pressure or intraocular pressure (IOP) builds up because the correct amount of fluid can’t drain out of the eye. With open-angle glaucoma, the entrances to the drainage canals are clear and generally work correctly. The problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink. This type of glaucoma usually develops slowly and most people have no symptoms and no early warning signs. If open-angle glaucoma is not diagnosed and treated, it causes a gradual loss of vision, generally from the side or periphery first.
Closed-angle glaucoma is also known as acute glaucoma or narrow-angle glaucoma. It is more rare in the western world and very different from open-angle glaucoma because eye pressure usually rises very rapidly when the drainage area of the eye suddenly becomes blocked or covered over by the iris. With closed-angle glaucoma, the space between the iris and the drain is not as wide and open as it should be and the outer edge of the iris bunches up over the drainage canals when the pupil enlarges too much or too quickly. This can happen when entering a dark room. Symptoms may include headaches, eye pain, nausea, blurry vision and rainbow halos around lights.
Normal-tension glaucoma (NTG) is also known as low-tension or normal-pressure glaucoma. In NTG the optic nerve is damaged even though the pressure in the eye is not very high. It is unknown why some people’s optic nerves are damaged at essentially normal pressure levels. Those at higher risk for this form of glaucoma are people with a family history of NTG and people of Japanese ancestry. NTG is diagnosed by observing the optic nerve for signs of damage.
Secondary glaucoma occurs when another disease causes or contributes to increased eye pressure, resulting in optic nerve damage and vision loss. Secondary glaucoma can occur as the result of an eye injury, inflammation, tumor, or in advanced cases of cataract or diabetes. It can also be caused by certain drugs such as steriods. This form of glaucoma may be mild or severe.
*Information on this page is adapted from www.glaucoma.org, the website of the Glaucoma Research Foundation in San Francisco, California and is copyrighted by the Glaucoma Research Foundation.
Wolfe Eye Clinic has expertise in evaluating and treating all types of glaucoma. Wolfe Eye Clinic offers complete glaucoma treatment services throughout Iowa, including Ames, Cedar Falls, Cedar Rapids, Des Moines, Fort Dodge, Iowa City, Marshalltown, Ottumwa, Spencer and Waterloo.
Please contact Wolfe Eye Clinic at 1-800-542-7956 to ask any glaucoma-related questions or to schedule an appointment with one of our glaucoma specialists: Dr. John Trible, Dr. Benjamin Mason or Dr. Ryan Vincent.