Glaucoma Tests: MedlinePlus Medical Test

What happens during a glaucoma test?

Glaucoma tests are done as part of a comprehensive (complete) eye exam. A complete eye exam checks both your vision and your eye health. These exams can be done by:

• An ophthalmologist, a medical doctor who specializes in preventing, diagnosing, and treating all types of eye disease, including doing eye surgery.
• An optometrist, a health care professional who specializes in diagnosing and treating vision problems and certain eye disorders.

If you're unsure which type of eye specialist should check you for glaucoma, talk with your provider.

Glaucoma tests check different parts of your eyes and vision, including:

• Your eye pressure. There are a few ways to measure eye pressure using tonometry tests:
  • Air-puff test. You'll rest your chin on a machine and your eye care specialist will blow a puff of air into your eye. This quick and painless test is used as part of a routine glaucoma screening. If the results show that your eye pressure is high, your provider will do other eye-pressure tests to get a more accurate measurement.
  • Applanation tonometry. Your provider will numb your eyes with drops before measuring your eye pressure using one of these methods:
    • You'll rest your chin on a special magnifying device called a slit lamp. Your eye care specialist will examine your eye through the slit lamp while gently pressing a special tool on your eye to test the pressure.
    • Your eye care specialist will gently press a handheld device against your eye. The device measures your eye pressure.
• The thickness of your corneas. The cornea is the clear outer layer at the front of your eye. Its thickness can affect the results of your eye-pressure measurements. If your eye pressure is high, a pachymetry test gives your eye care specialist more information about how high it may be. To do the test, your eye will be numbed with drops and your eye care specialist will place a small device on your cornea to measure the thickness.
• Your optic nerves. Your eye care specialist will do a dilated eye exam to look for damage to your optic nerve. This exam is part of a routine glaucoma check-up. It's also called ophthalmoscopy. You'll be given eye drops that widen (dilate) your pupils (the openings that let light into your eyes). You'll look straight ahead while your eye care specialist looks into your eye using a device with a light and magnifying lens.
• Your peripheral (side) vision. A visual field test, also called perimetry, measures how well you can see using your side vision. There are different ways to do the test. In general, you'll look straight ahead. Objects will be shown off to the sides of your vision. Without moving your eyes, you'll say when you can see the objects.
• The canals where fluid drains out of your eyes. If your eye care specialist thinks you have glaucoma, you may have a gonioscopy to see if your eye's drainage system is opened (open-angle glaucoma) or closed (close-angle glaucoma). Your eyes will be numbed with drops. Then your provider will hold a special contact lens on your eye. The lens has a mirror that shows the area where fluid drains out of your eye.

Some eye care specialists may use other tests to check for glaucoma, such optical coherence tomography (OCT). This test makes images of the back of your eye that can show damage to the optic nerve.