Glaucoma has two main types: open angle (most common) and angle closure. Learn more about these and rarer types of glaucoma.
The most common type is open-angle glaucoma; approximately 70 to 90 percent of Americans with glaucoma have this type. The disease is progressive with no noticeable symptoms in its early stages.
High eye pressure is the most significant risk factor for the development and progression of the disease. As eye pressure builds up, it gradually leads to:
- Damage of the optic nerve
- Loss of peripheral vision
- Without treatment, total blindness
An eye doctor can screen for open-angle glaucoma by measuring eye pressure (intraocular pressure, or IOP) during an eye exam with dilation.
In the United States, open-angle glaucoma strikes African Americans and Hispanics at higher rates than other ethnic groups.
The second most common type of glaucoma is angle-closure glaucoma, which can be either chronic or acute:
The chronic type progresses slowly and, like open-angle glaucoma, can result in optic nerve damage until vision is lost.
The acute (also called closed-angle) type begins suddenly when the normal flow of aqueous humor between the iris and lens is blocked. This condition is a medical emergency and must be treated immediately. Without treatment, blindness can result in one or two days.
Less Common Types of Glaucoma
Normal-tension glaucoma occurs when eye pressure is normal, yet the optic nerve is damaged and peripheral vision is lost. Lowering eye pressure through medication sometimes slows the progress of the disease, but this type of glaucoma may worsen despite low pressure. Treatment is generally the same as for open-angle glaucoma with high eye pressure.
Childhood glaucoma is a disease of the optic nerve, and is often associated with elevated eye pressure. There are many different types of childhood glaucoma, and one way of categorizing them is by the age of onset.
- Congenital glaucoma affects infants born with defects that prevent the normal drainage of fluid from the eye.
- Infantile glaucoma is present from 1-24 months of age.
- Glaucoma with onset after these ages could be considered juvenile glaucoma, and affects children, adolescents, and young adults.
Secondary glaucoma can be open-angle or closed-angle and is the result of some other medical condition in the eye or the body. Examples of secondary glaucoma include:
- Pigmentary glaucoma occurs when pigment granules from the iris flake off into the eye fluid (aqueous humor) and clog the eye's drainage system (trabecular meshwork).
- Pseudoexfoliation syndrome occurs when white material appears to flake off the lens of the eye and block normal flow of the aqueous humor.
- Iridocorneal Endothelial Syndrome (ICE) has a number of features, including cells that break off from the cornea, which block the drainage channels in the eye and lead to increased eye pressure. Scars may also connect the iris to the cornea. ICE usually is present in only one eye.
- Neovascular glaucoma occurs when abnormal blood vessel growth blocks the eye's fluid drainage channels and leads to increased eye pressure. This abnormal growth can be caused by:
- Low blood supply to the eye due to diabetes
- Insufficient blood flow to the head because of blocked neck arteries
- Blood vessel blockage in the back of the eye