Glaucoma is a common eye disease, especially in older people. It is the second most common cause of blindness in the United States (age-related macular degeneration is the most common cause). Glaucoma is another of those sneaky health problems, like high blood pressure,which can cause damage without any symptoms at first.

Glaucoma causes the pressure in the eye (called "intraocular pressure") to rise, which damages the optic nerve. Since the optic nerve carries the images we see from the eye to the brain, damage to this nerve causes blind spots at first. If it is not treated, glaucoma can eventually destroy the optic nerve, causing complete blindness.

Intraocular pressure increases when the fluid in the front of the eyeball builds up and does not drain properly. (This is a different fluid than tears.)

In the most common type of glaucoma, chronic open-angle glaucoma, intraocular fluid builds up slowly because it cannot drain efficiently.

There are usually no symptoms, although blind spots in vision occur.

A less-common type is called closed-angle glaucoma. With this type,the drainage can become suddenly blocked and eye pressure increases rapidly. Symptoms of blurred vision, headache, eye pain, nausea and vomiting signal an emergency. Immediate treatment is needed to prevent blindness.

You are at risk of developing glaucoma and losing your vision the older you get, especially after the age of 60. Anyone with these risk factors has a higher than average risk:

• High intraocular pressure as measured by your eye doctor.

• A family history of glaucoma.

• A serious eye injury in the past.

• A history of eye problems such as retinal detachment or chronic iritis or chronic uveitis.

• Nearsightedness.

• Diabetes.

• High blood pressure or heart disease.

Also, African-Americans, Asian-Americans and Hispanics are more likely to develop glaucoma than Caucasians. African-Americans tend to be the most severely affected, and the disease strikes earlier, around age 40.

Ophthalmologists and optometrists are two types of eye specialists.

Either type of eye doctor can evaluate your eye pressure and diagnose and treat glaucoma. The difference is ophthalmologists have more advanced training and are able to perform eye surgery when needed.

Optometrists do not do surgery but can prescribe eye drops and other treatments.

Anyone older than age 20 who has a family history of glaucoma or other risk factors should talk to an eye doctor about how frequently you should be tested for glaucoma.

By age 40, everyone (even people without risk factors) should be tested for glaucoma every two to four years. Starting at age 65, everyone should be tested every year or two.

The most common glaucoma screening test is a painless pressure test called tonometry. The eye doctor will apply a puff of air to the front of your eye to measure the pressure needed to flatten your cornea. The more fluid that has built up in your eye, the more pressure it will take. Normally, pressures are around 15 mm. Higher pressures, above 23 mm, signal a need for more testing.

Eye doctors can also look directly at your optic nerve through an ophthalmoscope. Visual field testing shows whether or not any vision has been lost. Your eye doctor may also measure the thickness of your cornea.

If glaucoma is detected, it can be controlled with daily prescription eye drops, which lower eye pressure. Eye drops can prevent future damage to the optic nerve, but pre-existing damage cannot be repaired.

Some people with glaucoma may need to take pills to help keep their eye pressures down. Surgery to improve the drainage of fluid from the eye is another option for some.

Kathryn B. Brown is a family nurse practitioner with a master's degree in nursing from OHSU. Is there a health topic you would like to read about? Send ideas to kbbrown@eastoregonian.com. you can find more local health news and information in the Health section at www.dailyastorian.info

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