How It Is Done continued...
Do not rub your eyes for 30 minutes until the numbing medicine has worn off.
Noncontact (or air-puff) method
This type of tonometry is done by an ophthalmologist or an optometrist. You do not need drops to numb your eye for this method.
You will rest your chin on a padded support and stare straight into the machine. A brief puff of air is blown at your eye. You will hear the puffing sound and feel a coolness or mild pressure on your eye. The tonometer records the intraocular pressure (IOP) from the change in the light reflected off the cornea as it is indented by the air puff. The test may be done several times for each eye.
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.
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 numbing eyedrops wear 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.