Tonometryis a test that measuresintraoculareye pressure (IOP), or the pressure inside your eyes.
It is used to screen you for risk ofglaucoma.
This test is an important part of acomprehensive eye examination.
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It is also used to assess the effectiveness of glaucoma treatment.
Your healthcare provider may use one of several types of tonometry to measure the pressure inside your eyes.
Glaucoma is most common in older adults, but it can happen at any age.
There are several different types.
Open-angle, the most common key in, may take many years to develop.
It does not cause pain and most people don’t have symptoms until the later stages.
Left untreated, it can lead to blindness.
This is why it is important to get a tonometry test even if you have good vision.
It is also possible to have low eye pressure, or hypotony.
This can sometimes happen after eye surgery, but it can also happen because of long-term eye inflammation.
It can lead to problems with vision.
Who Should Be Tested?
Yourophthalmologistwill recommend a schedule for future exams based on your results.
Some conditions can put you at risk for eye disease.
Symptoms can include:
You may also need regular tonometry tests after you’ve been diagnosed with glaucoma.
These will help your healthcare provider monitor how well your treatment is working.
Types of Tonometry Tests
An eye care provider uses a tonometer for this test.
This instrument calculates how resistant yourcorneathe clear, outer layer of the eyeis to an attempt to flatten it.
This is done in different ways depending on the kind of tonometry test used.
Some are more accurate than others, but each has distinct advantages.
Goldmann Tonometry
The Goldmann applanation tonometer is the most common tonometry test.
If you wear contact lenses, you will need to remove them.
Your healthcare provider will put anesthetic eye drops and a small amount of dye into your eyes.
After a few minutes, you will be asked to position yourself in front of aslit lamp.
This is an instrument that allows the provider to shine light into your eye and examine its structures.
You will need to place your chin on a chin rest and your forehead up against a bar.
Leaning forward helps you get into the proper position.
Staying as still as possible, you will be asked to focus straight on something in the distance.
take a stab at stay relaxed and don’t hold your breath.
It gently indents the cornea and the tonometer measures the force necessary to flatten the cornea.
This is then repeated on the other eye.
When done, your healthcare provider records the readings and compares them to prior test results.
Non-Contact Tonometry
With non-contact tonometry (NCT), a gentle puff of air flattens the cornea.
Studies have shown that this test is accurate even if the patient is wearing contact lenses.
The technician will ask you to look straight ahead at a light.
There will be a quick burst of air.
Since blinking invalidates the results, the reading may have to be taken more than once.
The test is then repeated on the other eye.
Electronic Tonometry
An electronic tonometer is a handheld, mobile gadget that looks like a writing pen.
You will need to remove your contact lenses before this test (if applicable).
Typically, this test needs to be repeated a few times so you can produce an accurate measurement.
Overall, it’s not as reliable or accurate as Goldmann tonometry.
The gadget calculates eye pressure by measuring the depth of the indentation on the cornea.
For this test, you will need to remove your contact lenses, if you wear them.
You will lie flat and look at a spot straight above you.
The technician will put a drop of anesthetic in each eye and pull back one eyelid.
When you are relaxed, they will gently lower the probe onto your cornea.
Modern eye care practitioners don’t use this throw in of tonometry as much as the other kinds.
It is sometimes used in more remote prefs, however.
Summary
Tonometry measures the pressure in the eye.
Higher pressure in your eyes could put you at risk of developing glaucoma.
You may undergo a tonometry test as part of a complete eye exam.
There are several different types of tonometry tests.
Most involve touching the eye with a probe.
If your readings are high, however, you will need to see an ophthalmologist for further testing.
High eye pressure alone doesn’t mean you have glaucoma.
Frequently Asked Questions
Tonometry tests typically only take a minute or two.
With contact tests, the probe will only touch your eye for a few seconds.
The results of the test should be available right away.
Your healthcare provider should discuss them with you before your appointment is complete.
Non-contact tonometry is sometimes called a “puff test.”
Many patients prefer it because the machine doesn’t physically hit up the cornea.
The puff test is considered accurate, but it can sometimes overestimate the amount of pressure in the eye.
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American Academy of Ophthalmology.
Eye Wiki.IOP and Tonometry.
American Academy of Ophthalmology.Eye exam and vision testing basics.
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American Academy of Ophthalmology.What is optical coherence tomography?
