How To Prepare continued...
If you wear
contact lenses, remove them before the test. Do not put your contacts back in
for 2 hours after the test. Bring your eyeglasses to wear after the test until
you can wear your contact lenses.
Loosen or remove any tight
clothing around your neck. Pressure on the veins in your neck can increase the
pressure inside your eyes. Stay relaxed.
Numbing eyedrops are used
for the methods that use a tonometer to touch your eye. You will not feel the
tonometer touch your eye. No numbing eyedrops are needed when an air-puff
(noncontact) tonometer is used.
Results from tonometry are most
accurate when you:
- Do not drink more than
2 cups (500 mL) of fluid 4
hours before the test.
- Do not drink alcohol for 12 hours before the
- Do not smoke marijuana for 24 hours before the test.
How It Is Done
Tonometry takes only a few minutes to
Applanation (Goldmann) method
This type of
tonometry is 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. A strip of paper containing a dye (fluorescein) will
be touched to your eye, or eyedrops containing the dye will be applied. The dye
makes it easier for your doctor to see your cornea.
You will rest
your chin on a padded support and stare straight into the microscope (slit
lamp). Your doctor sits in front of you and shines a bright light into your
eye. Your doctor gently touches the tonometer probe to your eye. Your doctor
checks the tension dial on the tonometer that measures the IOP of your
Do not rub your eyes for 30 minutes until the numbing
medicine has worn off.
Electronic indentation method
can be done by a technician, an optometrist, an ophthalmologist, or a family
medicine doctor. Your doctor will use eyedrops to numb the surface of your eyes
so that you will not feel the tonometer during the test.
stare straight ahead, or sometimes look down. Your doctor gently
touches the tonometer probe to your eye. Several readings will be taken on each
eye. You will hear a clicking sound each time an reading is obtained.
After enough accurate readings have been obtained, a beep will sound, and the averaged IOP
measurement will appear on the instrument's display panel.
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
Indentation (Schiotz) method