Eye Health Center

How It Is Done continued...

This type of tonometry is usually done by an ophthalmologist or an optometrist. Your doctor will use eyedrops to numb the surface of your eyes so that you will not feel the tonometer during the test.

You will lie on your back on an examination table. Try to stay relaxed and not cough, blink, or squeeze your eyelids together because these movements can increase the pressure inside your eyes.

You will look up at a spot on the ceiling. Your doctor will gently touch the tonometer to your eye and hold it there for a few seconds. The test may be done on the other eye also.

Do not rub your eyes for 30 minutes until the numbing medicine has worn off.

How It Feels

Tonometry should not cause any eye pain. Your doctor will use eyedrops to numb the surface of your eyes so that you will not feel the tonometer during the test. You may have a scratchy feeling on your cornea. This usually goes away in 24 hours.

Some people become anxious when the tonometer needs to be touched to the eye. In air-puff tonometry, only a puff of air touches the eye.

Risks

There is a very slight risk that your cornea may be scratched during the methods that involve touching a tonometer to your eye. Rubbing your eyes before the anesthesia wears off increases the risk of scratching the cornea. If tonometry causes a scratch on the cornea, your eye may be uncomfortable until the scratch heals, which normally takes about a day.

There is also a very small risk of an eye infection or an allergic reaction to the eyedrops used to numb your eyes.

With the air-puff (noncontact) method, there is no risk of scratches or infection, since nothing but air touches your eyes. But this method is not the best way to measure intraocular pressure.

You should not have any eye pain or vision problems after tonometry. Call your doctor if you feel any eye pain during the test or for 48 hours after the test.

Results

A tonometry test measures the pressure inside your eye, which is called intraocular pressure (IOP). This test is used to check for glaucoma.

Normal eye pressure is different for each person and is usually higher just after you wake up. IOP changes more in people who have glaucoma. Women usually have a higher IOP than men, and IOP normally gets higher as you get older.

High values

• A high IOP may mean that you have glaucoma or that you are at high risk for developing glaucoma. People who have ongoing pressures above 27 mm Hg usually develop glaucoma unless the pressure is lowered with medicines.
• People who have an ongoing IOP higher than 21 mm Hg but do not have optic nerve damage have a condition called ocular hypertension. These people may be at risk for developing glaucoma over time.