Glaucoma Testing

Glaucoma rarely causes pain or other symptoms, so it can be a difficult disease to recognize. However, detection and prevention of glaucoma are possible through routine eye exams.

Some forms of glaucoma, however, can be recognized by their symptoms. For instance, angle closure glaucoma can cause:

  • Abrupt decrease of vision
  • Extreme eye pain
  • Headaches
  • Nausea and vomiting
  • Light sensitivity, glare or rainbows around lights

There are five main methods to test for glaucoma. These are tonometry, ophthalmoscopy, perimetry, optic nerve fiber layer analysis, and gonioscopy.

Tonometry
With tonometry, your eye is numbed to measure its intraocular pressure (IOP). Your eye doctor might use a puff of air or a fluorescent dye and touch the surface of your eye with a tonometer to test for glaucoma.  

Ophthalmoscopy
With opthalmoscopy, your eye doctor will use drops to dilate your pupil. The doctor then projects a beam of light from an ophthalmoscope through your pupil to examine the back of your eyeball and view your optic nerve.

Perimetry
A Perimetry, or visual field test, measures all aspects of your eyesight. You will look into a perimeter—a bowl-shaped instrument—and press a button each time you notice lights flashing. A computer records whether there are areas of your vision where you didn’t see the flash. Loss of peripheral vision is a general indication of the early stages of glaucoma.

Optic Nerve Fiber Layer Analysis
One of the latest technologies available to test for very early damage to the optic nerve is optic nerve fiber layer analysis.  With this advanced method, a simple, painless light scan measures the thickness of the fibers that make up the optic nerve in the eye.  We all lose some of these fibers with normal aging; however, there can be greater loss in the eyes that have or are developing glaucoma.  This test is also used to detect any worsening of glaucoma in patients who are under treatment.

Gonioscopy
Gonioscopy is a test in which your eye doctor numbs your eye, and then uses a special contact lens to magnify the inside of your eye—both the front side and the part between your cornea and iris. The doctor will determine whether the area where fluid is draining out of your eye is opened or closed. This helps to diagnose what kind of glaucoma you may have.