Primary open-angle glaucoma progresses with few or no symptoms until the condition reaches an advanced stage. As increased eye pressure continues to damage the optic nerve, you lose more and more of your peripheral vision. Open-angle glaucoma usually affects both eyes, although at first you may have symptoms in just one eye. Other symptoms include:
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- Sensitivity to light and glare
- Trouble differentiating between varying shades of light and dark
- Trouble with night vision
- Blurred vision
- Halos around lights
- Reddening of the eye
- Headache
- Severe eye pain
- Nausea and vomiting
- Hardness of the affected eye
Signs and symptoms of secondary glaucoma vary and depend on what's causing the glaucoma and whether the drainage angle is open or closed.
Causes
The underlying causes of glaucoma aren't completely understood. Evidence suggests that open-angle glaucoma has a genetic link. That is, a defect in one or more genes may cause the disease. People with a family history of glaucoma are more likely to develop it themselves. Nevertheless, the exact genetic defects responsible for its occurrence haven't been identified.
Other factors appear to contribute to the disease, but again, what these factors are and the relationships among them aren't known for certain. Although glaucoma is normally associated with increased eye pressure, people with normal or low eye pressure can experience vision loss. And people with higher-than-normal eye pressure may never experience optic nerve damage.
Doctors have debated for many years about how damage to the optic nerve occurs. One theory holds that the pressure of backed up aqueous humor causes structural damage and ultimately death to the nerve fibers. Another theory suggests that nerve fibers die when small blood vessels that feed the optic nerve become blocked or when the blood supply is disrupted.
The cause of decreased drainage through the trabecular meshwork also presents a puzzle. The changes that slow drainage may be a result of normal aging, yet not all older adults develop glaucoma.
Risk factors
If your lOP is higher than what's considered normal, you're at increased risk of developing glaucoma. Yet most people with slightly elevated intraocular pressure don't develop the disease. This makes it difficult to predict who will get glaucoma. Certain other factors are known to increase your risk. Because chronic forms of glaucoma can destroy vision before any symptoms are apparent, it's important to be aware of these factors:
Age. Open-angle glaucoma is rare before age 40. The risk of developing glaucoma nearly doubles every 10 years after age 50. Approximately 14 percent of people in the United States who are age 80 have the disease. Primary open-angle glaucoma is most common in older adult women.
Race. In the United States, blacks are three to four times more likely to get glaucoma than are whites, and they are six times more likely to suffer permanent blindness as a result. The reasons for this difference aren't known, but blacks may be more susceptible to damage to the optic nerve, or they may not respond to current treatments as well as whites do. Asian-Americans, particularly people of Vietnamese descent, are also at higher risk. Japanese-Americans are more prone to develop low-tension glaucoma.
A family history of glaucoma. If one of your parents has glaucoma, you have about a 20 percent chance of developing the disease. If you have a sibling with the disease, your chance of getting it is about 50 percent.
Medical conditions. If you have diabetes, your risk of developing glaucoma is about three times greater than that of people who don't have diabetes. A history of high blood pressure or heart disease also can increase your risk. Other risk factors include retinal detachment, eye tumors and eye inflammations such as chronic uveitis and iritis. Previous eye surgery may trigger secondary glaucoma.
Physical injuries. Severe trauma, such as being hit in the eye, can result in increased eye pressure. Injury can also dislocate the lens, closing the drainage angle.
Nearsightedness. Severe nearsightedness increases the risk of developing glaucoma. An extensive study of eye health found that nearsighted people had a two to three times higher risk of developing glaucoma than did people who were not nearsighted.
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Prolonged corticosteroid use. Using corticosteroids for prolonged periods of time puts you at risk of getting secondary glaucoma.
Eye abnormalities. Structural abnormalities of the eye can lead to secondary glaucoma. For example, pigmentary glaucoma is a form of secondary glaucoma caused by pigment granules being released from the back of the iris. These granules can block the trabecular meshwork. To find out more, you can check out Sudden Vision Improvement.