What you can do

Your scan is not diagnostic; it just helps assess your risk. Being aware can lead to early diagnosis and help you avoid complications.

Initially, exfoliation glaucoma causes no symptoms. Your central vision remains normal and there is no pain.

The main sign of glaucoma is a gradual loss of peripheral vision in one or both eyes. Left untreated, your field of vision can gradually narrow until it seems that you are looking through a tunnel. Be sure to get an eye exam if you are not seeing objects that are off to the side of your field of vision. Other possible symptoms include:

• Trouble adjusting to seeing in a dark room
• Difficulty focusing
• Distorted lines, and edges that seem wavy

A complete eye exam may include the following screening tests for glaucoma:

• Applanation tonometry, which measures the pressure in your eyeball. Your doctor will administer anesthetic eye drops to numb your eye and then use a special instrument to apply slight pressure.
• Pachymetry, which uses ultrasound to measure the thickness of your cornea. Experts increasingly think this is important because the relative thickness of the cornea can affect the accuracy of the pressure reading.
• Ophthalmoscopy, which assesses the health of your optic nerve. In this painless procedure your doctor will use eye drops to dilate your pupils and then examine the optic nerve.
• Perimetry, a test to determine if you have suffered any visual loss. With one eye covered, you look straight ahead at a bowl-shaped white area while a computer flashes small lights in different locations around the bowl. You signal each time you see a light. The result is a map of your visual field. Since glaucoma typically starts by robbing you of peripheral vision, perimetry helps track the degree of that loss.

Specifically for exfoliation glaucoma, the doctor will look for tiny white flakes on the internal structures of the eye.

Get your eyes checked. Get a thorough eye exam at age 40 to establish a baseline of your eye health. Then follow that with regular screening tests, every one to two years if you have no risk factors or signs of glaucoma disease, and more frequently if you are at risk or already show signs of the disease. A complete exam should be performed by an ophthalmologist or qualified optometrist.

Cut back on caffeine. There is some evidence that too much caffeine can temporarily raise your eye pressure. Experts advise people at risk of glaucoma to limit themselves to no more than two cups a day.

Get regular exercise. Just as physical activity can improve your blood pressure, it may also help you reduce or maintain your eye pressure. It can also help mitigate other conditions that may be risk factors for glaucoma, such as diabetes and hypertension. In one small study, people who rode an exercise bike for 40 minutes four times a week were able to reduce their eye pressure by an average of 20 percent. The exercise can be running, walking, swimming — anything that elevates your heart rate for at least 20 minutes four times a week.

Stay right side up. If you do yoga, avoid positions that call for you to be upside down. Those inversions can increase the pressure in your eyes.

Avoid chugging water or other liquids. Studies have suggested that people with glaucoma are more likely to experience elevated eye pressure if they drink a quart of water quickly (within 20 minutes). Since many diet programs encourage participants to drink at least eight glasses of water a day, be sure to do it in small amounts throughout the day.

Ginkgo biloba. Though it has never been directly shown to help prevent or delay glaucoma, there is some evidence that the herbal extract ginkgo biloba may improve blood flow through the eye, which some experts believe may help preserve optic nerve cells. Ginkgo biloba can have side effects and, like other herbal remedies, should be taken only after consultation with a physician. It should not be used in conjunction with medicines that thin your blood, such as aspirin, Plavix or Coumadin.

• Make sure your doctor knows if you are at above-average risk for exfoliation glaucoma so he or she can be sure to check for signs of the condition.
• Do you have any signs of glaucoma? Possible clues: a dark spot at the center of your vision or decreasing peripheral vision, including tunnel vision.
• Are you taking any medications that can cause or worsen eye pressure or glaucoma symptoms? Corticosteroids like prednisone are an example.

• Perform a full eye exam, including measuring eye pressure and testing your field of vision to look for blind spots.
• Prescribe medicine to lower your eye pressure, if it is elevated.