Tonometry Test: Importance, Procedure, Types and Results

What to Expect During the Tonometry Test?

What to expect during a tonometry test will be determined by which method or which type of tonometry test is used. A non-contact tonometry test will not touch the eye and shouldn’t be painful, but may feel like a small amount of pressure. An electronic indentation or applanation tonometry test are contact tonometry tests that use force to flatten the cornea. An optometrist may use numbing eye drops so a patient does not feel the force from an electronic or applanation tonometry test.

How Often Should You Have an Eye Test?

A person should have a regular eye test at least once every 1-2 years. An optometrist will advise a patient if they need more frequent eye tests. Factors that may inform how often a person gets an eye test include age or eye conditions that need monitoring, such as glaucoma. A person will typically get a tonometry test as part of a regular eye test.

1. Electronic Indentation Tonometry

Electronic indentation tonometry refers to a tonometry test in which an optometrist will place the rounded tip of a tool onto the cornea with the results sent to a computer, according to My Health Alberta. The principle behind indentation tonometry is that an object will sink further into a soft eye than a hard eye, according to the American Academy of Ophthalmology. A hard eye can be caused by an increase in intraocular pressure. Numbing eye drops may be used so a patient does not feel the force during an electronic tonometry test.

2. Applanation (Goldmann) Tonometry

Applanation tonometry refers to a tonometry test using a small disk to flatten an area of the cornea. The principle behind applanation tonometry is based on Imbert–Fick law, which theorises that the pressure inside a sphere can be measured by how much force it takes to flatten certain areas of the sphere, according to Aziz and Friedman in Tonometers-which one should I use? In applanation tonometry, a small disk is used to flatten an area of the cornea. According to the American Academy of Ophthalmology, intraocular pressure is then determined by the applanation force of the area of the cornea that is flattened. A person may be given numbing eye drops for this test so they do not feel the force of the test.

3. Non-contact Tonometry

Non-contact tonometry refers to a tonometry test that uses a small puff of air from a machine to test intraocular pressure, without needing to touch the eye directly. The air is directed into the eye until the cornea flattens. According to MyHealth Alberta, non-contact tonometry is not the most accurate test of intraocular pressure but is a quick way of seeing if a person has high ocular pressure.

What is an Example of a Tonometry Test Result?

Eye pressure is measured in millimetres of mercury, according to the American Academy of Ophthalmology and is abbreviated to mm Hg. According to Mount Sinai Medical Centre, the normal eye pressure range is within 10 - 21 mm Hg.

How Accurate is the Tonometry Test?

Certain types of tonometry tests are more accurate at measuring eye pressure than others, with the applanation (Goldmann) tonometry test considered the most accurate, according to Glaucoma Australia. Applanation tonometry testing involves a tool that flattens the cornea to measure eye pressure.

What Happens if IOP is Too High?

If intraocular pressure (IOP) is too high, it may lead to ocular hypertension and eye conditions such as glaucoma. Ocular hypertension refers to high intraocular pressure, caused by fluid not draining from the eye properly. Ocular hypertension does not mean a person has glaucoma but they may be considered more at risk of developing it. Glaucoma is an eye condition in which damage to the optic nerve causes vision loss. Glaucoma can be caused by high intraocular pressure.

Is a Tonometry Test only used to Diagnose Glaucoma?

A tonometry test is performed to assess a person’s intraocular pressure as a way to screen for glaucoma. While tonometry is used to diagnose glaucoma, it also measures how well glaucoma treatment is working, according to Medline Plus. Glaucoma refers to a group of eye conditions or diseases in which damage to the optic nerve causes vision loss.

Is a Tonometry Test Expensive?

At Oscar Wylee, a tonometry test is a standard part of a regular eye test which is offered at a bulk billed price for eligible Medicare cardholders.

Does Oscar Wylee Offer a Tonometry Test?

Yes, Oscar Wylee offers a tonometry test to patients who book an eye test. At the start of every Oscar Wylee eye test, an optical dispenser or member of our retail staff will perform a non-contact tonometry test to assess intraocular pressure. After the tonometry test, the patient will be passed along to an Oscar Wylee optometrist to continue their eye test appointment.