Medical Condition Library

Information Centers

Wellness Centers

Helpful Resources

Tonometry

(Intraocular Pressure [IOP] Measurement)

by Amy Scholten, MPH

Home | Health Information Center | Procedure & Surgery Fact Sheets | Article

Definition

Reasons for Test

Possible Complications

What to Expect

Call Your Doctor

En Español

Definition

Tonometry tests the amount of pressure in the eye. This is known as intraocular pressure (IOP).

Reasons for Test

Eye damage can happen when pressure in the eye is too high. This is called glaucoma.

Glaucoma

Possible Complications

There are no major complications associated with this procedure.

What to Expect

Prior to Test

The care team may ask about any medicines, herbs, and supplements that you take. You will also be asked to remove eyeglasses or contact lenses.

Description of the Test

There are two tonometry methods. Both flatten the layer on the front of the eye using gentle pressure. The type of tonometry that is done depends on the equipment your doctor has.

You will be asked to sit in an exam chair. A chin cup and forehead rest will steady your head.

Non-contact Method

You will be asked to look into an instrument. A puff of air will be blown into the eye.

Applanation Method or the Goldmann Tonometry

Numbing drops will be put in your eyes. A small amount of an orange dye drops may also be used to view the eye better. You will be asked to look into an instrument with a blue light. A tiny device will gently press against your eye.

A handheld device shaped like a pen may be used instead. It will be pushed against the front of your eye.

There are other devices that are used to check eye pressure. These are the most common.

After Test

The numbing drops and dye wear off in about 20 minutes. The eye should not be rubbed during this time. It may cause damage.

How Long Will It Take?

A few seconds

Will It Hurt?

This test should be painless. Some people have a slight sting from the eyedrops.

Results

A person having the test done to screen for glaucoma will talk to their doctor about whether treatment is needed.

A person having the test to monitor glaucoma will talk to their doctor about whether changes need to be made to their treatment plan.

Call Your Doctor

After the test, call your doctor if you have:

Burning
Excessive itching
Swelling
Pink or reddish color that does not go away
Problems seeing
Any other eye problem

If you think you have an emergency, call for medical help right away.

RESOURCES:

Glaucoma Research Foundation
http://www.glaucoma.org

National Eye Institute
http://www.nei.nih.gov

CANADIAN RESOURCES:

Canadian Association of Optometrists
http://www.opto.ca

Canadian Ophthalmological Society
http://www.eyesite.ca

References:

Angle-closure glaucoma. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/angle-closure-glaucoma. Accessed December 11, 2020.

Five common glaucoma tests. Glaucoma Research Foundation website. Available at:
...(Click grey area to select URL)
Accessed December 11, 2020.

Primary open angle glaucoma. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/primary-open-angle-glaucoma. Accessed December 11, 2020.

Tonometers. The College of Optometrists website. Available at:
...(Click grey area to select URL)
Accessed December 11, 2020.

Last reviewed September 2020 by EBSCO Medical Review Board Marcin Chwistek, MD
Last Updated: 4/23/2021

EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

To send comments or feedback to our Editorial Team regarding the content please email us at healthlibrarysupport@ebsco.com. Our Health Library Support team will respond to your email request within 2 business days.