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Understanding Vision Problems -- the Basics

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Glaucoma

More than 2 million adult Americans suffer from glaucoma, making it one of the leading causes of irreversible vision loss. Types of glaucoma include the following:

  • Chronic open-angle glaucoma (COAG), which accounts for 90% of all cases in the U.S., usually appears in middle age and seems to have a genetic component.
  • Acute closed-angle glaucoma accounts for less than 10% of cases of glaucoma, but it comes on quickly, may be quite painful, and requires urgent medical attention.
  • Secondary glaucoma is associated with other eye diseases or medical conditions, trauma to the eye, or the use of steroid drugs.

Doctors often refer to chronic open-angle glaucoma as the "silent thief of sight" because it comes on gradually to steal vision. Damage to the delicate nerve layers of the retina are caused by elevated pressure inside the eye. Most COAG patients have no symptoms whatsoever and can experience profound loss of visual function before it is identified. Regular eye checkups usually include measuring eye pressure and other tests in order to identify glaucoma. Unfortunately, half of all Americans with high eye pressure are unaware of the problem.

If you have sudden, severe pain in your eyes, blurred vision, or rainbow halos -- along with headache, nausea, or vomiting -- it may be an attack of acute closed-angle glaucoma. If left untreated, acute closed-angle glaucoma can damage the optic nerve, which carries visual images from the eye to the brain, causing irreversible blindness.

Secondary glaucoma is the result of another eye disease or medical disorder, including the following:

  • Uveitis (inflammation of the inner eye)
  • Eye injury   
  • Bleeding inside the eye
  • Eye tumor
  • Diabetes (neovascular glaucoma)
  • Congenital problems
  • An extremely mature cataract
  • Steroid medications

People with diabetes are susceptible to neovascular glaucoma, a particularly severe form of secondary glaucoma caused by an abnormal proliferation of blood vessels. Congenital glaucoma is a rare problem in babies and requires surgery to preserve eyesight.

Macular Degeneration

Macular degeneration is the leading cause of vision loss in the U.S., with millions of older Americans showing some sign of the disorder. Because the symptoms usually do not appear in people under 55 years of age, the disorder is more accurately referred to as age-related macular degeneration (AMD).

Since the macula is the central part of the retina, AMD affects central vision, the vision you need for reading and close work like sewing. If you were looking at a photograph, you would not be able to see the middle of the picture but could still see the edges (preserved peripheral vision). The disorder occurs in two forms, dry and wet. The less common wet form of AMD requires immediate medical attention. Any delay in treatment may result in loss of your central vision.

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