Glaucoma is a common eye condition characterized by a buildup of fluid in the eye. When the passages in the eye that drain excess fluid become clogged, the pressure from the fluid can damage the optic nerve. If left untreated, glaucoma can eventually lead to complete vision loss. In fact, glaucoma is one of the leading causes of blindness in the United States.

What is a glaucoma test?

Increased pressure in the eye is a sign of glaucoma, therefore one of the first and most important screening tests used to diagnose glaucoma is an intraocular eye pressure test, or tonometry.

Tonometry determines the amount of fluid pressure in the eye by measuring the tone and firmness of the surface of the eye. The test is conducted with an applanation tonometer or an air puff tonometer. The tonometer calculates intraocular pressure by measuring the eye's resistance to pressure or a puff of air. Patients with high intraocular pressure may be at risk for glaucoma and will be subjected to further testing, including a test for optic nerve damage.

Reasons for administering glaucoma tests

There is no cure for glaucoma, therefore early detection is critical. Glaucoma does not present any visible symptoms until vision loss has already started to occur. That means the only way to preserve vision is to undergo regular glaucoma screening tests. Though there are a variety of tests that can be used to help diagnose glaucoma, the intraocular eye test is an excellent first screening test that is quick and painless.

Performing glaucoma tests

The gold standard of glaucoma testing is the intraocular eye pressure test, or tonometry test.

The first type of tonometry test is the non-contact "puff of air" test. During this test, you place your chin on a chin rest and focus on a light inside a machine. The doctor directs a small puff of air at the open eye, and the machine calculates intraocular pressure based on the eye's resistance to the air.

The second type of tonometry test requires contact but is slightly more accurate. You are given numbing eye drops that contain a dye that glows under light. You are then asked to stare straight ahead while the doctor uses the tonometer to gently make contact with the surface of your eye. The test is painless and takes just a few seconds.

A glaucoma test should be part of your regularly scheduled eye examinations.