How to Test for Glaucoma

Glaucoma is optic nerve damage that occurs in one or both eyes. It's often caused by high fluid pressure in the eyes. Glaucoma can cause permanent vision loss, so it's important to have a glaucoma test at every eye exam.

Symptoms

• The first symptom of glaucoma is a slow loss of side (peripheral) vision. By the time you notice a change in your vision, however, the damage may be permanent. Glaucoma tests can alert your doctor to optic nerve damage before you even notice a problem.

Types

• There are three kinds of glaucoma tests. The most basic exam is the tonometry exam. It measures the amount of fluid in your eye, or intraocular eye pressure (IOP). Next are exams that check your optic nerve and the vessels and fluid drainage system in your eye itself. The last type of exam measures your peripheral vision to see if your field of vision has shrunk.

Basic Test

• The most basic glaucoma test is the tonometry test. This is done with a small machine, called a tonometry machine, that measures your eye pressure (IOP).

  If you've had glaucoma tests in the past, you may remember the "puff of air" test where you rested your chin and forehead on a machine and looked at a light--that was a glaucoma test. With the newer test, your eyes are numbed with eye drops, and a tiny, specially calibrated device touches your cornea to measure your IOP.

  This first-line test is usually the only glaucoma test people get. The results of the tonometry test will tell your eye doctor whether you need further glaucoma testing or not.

Further Testing

• If your IOP is high, your doctor will next look at your optic nerves. For this test, the room will be darkened, and your eyes will be dilated with eye drops. Your doctor will look into each eye with a special light and magnifying lens called an ophthalmoscope. Your doctor will be looking for any damage to the optic nerve, which is located in the back of your eye.

  She will also check your peripheral vision, either by using a visual field testing machine or by placing a light to the side of your face and asking when you see it. This will tell your doctor if your peripheral vision is unusually narrow.

  Finally, your doctor may measure your cornea or look more closely at the vessels in your eyes using a special mirrored contact lens.

Prevention/Solution

• Although there's no way to prevent glaucoma, there are many treatments available if you have it. But successful treatment depends on early diagnosis, regular testing and medication. Glaucoma tests are painless and easy to perform, and they can help prolong your vision down the road.