GLAUCOMA

If you're one of the 1 million Americans who have been diagnosed with glaucoma...

You've been given the opportunity to preserve your vision, because vision loss from glaucoma can be prevented if it is caught and treated in time. Many others are not so lucky. Almost 80,000 Americans are blind from glaucoma, and another million are at risk for vision loss because they don't know they have it.

In fact, glaucoma is one of the leading causes of preventable blindness in the U.S., and the single most common cause of blindness among African-Americans.

Glaucoma is often called the "sneak thief" of sight because the most common type causes no symptoms until vision is already damaged. That's why the best way to prevent vision loss from glaucoma is to know your risk factors and have medical eye examinations at appropriate intervals. (Your ophthalmologist can help you determine how often you should have your eyes examined.)

What is glaucoma?

Glaucoma is a condition in which the optic nerve, which carries the images we see to the brain, is damaged. The optic nerve is like an electric cable containing about 1.2 million wires. Glaucoma can damage nerve fibers, causing blind spots to develop.

What causes glaucoma?

Many people know that glaucoma has something to do with pressure inside the eye the intraocular pressure (IOP).

Pressure builds up in the eye when the clear liquid called the aqueous humor, which normally flows in and out of the eye, is prevented from draining properly. This can happen in different ways, depending on the type of glaucoma. The resulting increase in pressure within the eye can damage the optic nerve.

Ophthalmologists used to think that high intraocular pressure was the main cause of optic nerve damage in glaucoma, however we now know that even people with "normal" IOP can experience vision loss from glaucoma -- so-called "normal tension glaucoma".

 Some people with high intraocular pressure (also known as ocular hypertension) never develop the optic nerve damage of glaucoma. (These people need to be followed carefully by an ophthalmologist, because they are considered "glaucoma suspects.")

There may be other factors which affect the optic nerve, even when IOP is in so-called "normal" range. Elevated IOP is still considered a major risk factor for glaucoma, though, because studies have shown that the higher the IOP is, the more likely optic nerve damage is to occur.

Most people who have glaucoma don't notice any symptoms until they begin to lose some vision.
As optic nerve fibers are damaged by glaucoma, small blind spots may begin to develop, usually in the side --or peripheral -- vision. The top photo at left shows how a scene would be viewed by a person with normal vision. The bottom image shows the same scene as viewed by a person with glaucoma. Many people don't notice the blind spots until significant optic nerve damage has already occurred. If the entire nerve is destroyed, blindness results.

• One type of glaucoma, acute angle-closure glaucoma, does produce noticeable symptoms. In angle-closure glaucoma, there is a rapid buildup of pressure in the eye (intraocular pressure, known as IOP), which may cause any of the following:
   
  • blurred vision
  • severe eye pain
  • headache
  • haloes (which may appear as rainbows) around lights
  • nausea and vomiting

  
  Angle-closure glaucoma is a rare, but serious, form of the disease. If you have any of these symptoms, call your ophthalmologist immediately. Unless treated quickly, blindness can result.