What is tonometry?
Tonometry is a simple eye test used to measure the pressure inside your eyes, known as intraocular pressure (IOP). This test is crucial for detecting glaucoma, a condition that can lead to vision loss if not treated early. Tonometry helps eye care professionals identify abnormal pressure, which may be a sign of glaucoma even before the symptoms are apparent.
The procedure is quick, painless, and non-surgical, and it plays a critical role in maintaining overall eye health. Tonometry testing at regular intervals is vital for all people, but even more so for those who are at higher risk of glaucoma, such as older individuals or those with a family history of glaucoma.
Who needs a tonometry test?
Tonometry is an essential test for detecting and monitoring glaucoma, and it's commonly used by eye specialists, particularly ophthalmologists and optometrists. The test is recommended for various groups of people who may be at higher risk of developing eye conditions, such as:
People at risk of glaucoma, especially those over 40 years old:
As the risk of developing glaucoma increases with age, individuals over 40 should consider having their intraocular pressure checked regularly.
People with eye injuries:
Any previous eye injury can impact eye pressure and increase the likelihood of developing glaucoma, making tonometry an important test for these individuals.
People with eye symptoms:
If you experience eye pain, blurry vision, or eye redness, it's crucial to undergo tonometry to rule out any serious conditions, including glaucoma.
People taking certain medications:
Some medications, such as corticosteroids, can cause an increase in intraocular pressure. If you’re on such medications, regular tonometry tests are essential to monitor any potential changes in eye pressure.
People with glaucoma:
For those already diagnosed with glaucoma, tonometry is used to monitor the effectiveness of treatment and ensure that intraocular pressure is being properly managed.
People before and after eye surgery:
If you're about to undergo eye surgery or have recently had one, tonometry is vital in assessing eye pressure, ensuring healing, and preventing complications.
Are you experiencing any of these listed symptoms? Request an appointment today to get a tonometry test and ensure that your eyes are still in good condition.
How should I prepare for a tonometry test?
Preparing for a tonometry test is usually simple and requires minimal effort. Since it is a quick and non-invasive procedure, most people won’t need to make any major changes to their daily routine. However, here are a few tips to help you get ready:
Inform your eye specialist about any medications:
Let your optometrist or ophthalmologist know if you are taking any eye drops, steroid medications, or other treatments, as some can affect your eye pressure.
Remove contact lenses if required:
Depending on the type of tonometry used, you may be asked to remove your contact lenses before the test, especially if eye drops are involved. It's a good idea to bring your glasses as a backup.
Avoid caffeine before the test:
In some cases, caffeine can temporarily increase eye pressure. To be safe, try to avoid coffee, tea, or energy drinks for at least a few hours before your appointment.
Stay relaxed:
Try to remain calm and relaxed. The procedure is painless and takes only a few minutes. Staying still during the test helps ensure accurate results.
No need for fasting:
You can eat, drink, and dress normally.
Avoid wearing a tight-collared shirt:
You may be advised not to wear a tight collar or tie during the test, as pressure around your neck can potentially raise intraocular pressure readings and affect the results.
If your tonometry test involves the use of eye drops to numb your eyes (for applanation tonometry), your vision may be slightly blurred for a short while afterwards. It’s best to avoid driving immediately after the test, just in case.
Preparing for a tonometry test is easy, but being aware of what to expect can make the experience even smoother. If you have any concerns, request an appointment with our ophthalmologists to get personalised guidance.
What happens during a tonometry test?
During a tonometry test, your healthcare provider will begin by applying eye drops that contain a mild anaesthetic and a dye called fluorescein. These drops help numb your eyes and make the test more comfortable.
You’ll be asked to sit still and look straight ahead. Using a special device, your eye care professional will gently bring a small tip into contact with the surface of your eye (the cornea). The device measures how much pressure is needed to slightly flatten the cornea. This pressure reading helps determine your intraocular pressure (IOP).
The test is quick, painless, and usually over within a few minutes. It’s a simple but important step in detecting and managing conditions like glaucoma.
Tonometry test results
Normal results
A normal eye pressure reading typically falls between 10 and 21 mmHg. This may indicate that you do not have glaucoma. However, it’s important to note that some people can still have glaucoma even if their eye pressure is within the normal range. Such a condition is known as normal-tension glaucoma and requires further testing to detect.
Abnormal results
High eye pressure (ocular hypertension): An IOP above 21 mmHg may suggest a higher risk of glaucoma, even if you don’t have symptoms yet. Further tests may be needed to assess the optic nerve and rule out or confirm glaucoma.
Low eye pressure (hypotony): An IOP below 10 mmHg could indicate problems such as eye inflammation, past injury, or complications after eye surgery.
Price of tonometry in Singapore
In Singapore, the cost of a tonometry test typically ranges from S$50 to S$200, depending on the scope of the consultation and whether the test is included in a more comprehensive eye examination package.
A basic eye screening, which usually includes vision testing, refraction, and tonometry, may cost around S$50–S$80. However, if the test is part of a specialised glaucoma or cataract assessment, the price may increase to S$150–S$200, as these packages often include additional diagnostic tests such as optic nerve imaging or visual field analysis.
Prices may also vary between public and private providers, and some insurance or health screening packages may help offset the cost. For the most accurate pricing, it's best to check directly with your eye care provider.
Where to do tonometry in Singapore?
Tonometry tests are widely available across Singapore and can be done at various healthcare facilities, including:
Public hospitals and polyclinics:
Government hospitals and polyclinics often offer tonometry as part of routine eye screening or specialist eye care services. These are suitable for patients seeking subsidised rates or referrals from general practitioners.
Private eye clinics and medical centres:
Many private eye specialists and ophthalmology clinics offer tonometry, either as a standalone test or as part of comprehensive eye check-up packages. These clinics typically provide quicker appointments and shorter waiting times.
Optometry chains and optical shops:
Some established optical retail outlets with in-house optometrists also offer tonometry, especially non-contact (air-puff) tests, during eye health screenings.
Specialist eye centres:
Specialist centres that focus on glaucoma, cataracts, or retinal issues commonly include tonometry in their diagnostic process.
At Thomson Medical, we provide tonometry as part of our comprehensive eye screening services. Our team will guide you through the process and ensure you receive the appropriate test based on your eye health needs. If you're unsure whether you need a tonometry test, you can always request an appointment for a personalised assessment.
Risks of tonometry test
Tonometry tests have a low risk of complications and are generally safe for most people. However, as with any medical procedure, there are some potential risks to be aware of:
Corneal scratches:
In rare cases, the device may slightly scratch the surface of the eye (cornea), especially during contact methods.
Eye infection:
If proper hygiene is not maintained, there is a small risk of infection, though this is very uncommon.
Allergic reaction to the eye drops:
Some individuals may react to the anaesthetic or dye used during the test, resulting in redness, itching, or discomfort.
Eye pain:
Mild discomfort or stinging may occur after the test, particularly with contact tonometry.
These risks are minimal, and most people experience no issues during or after the procedure.
FAQ
What is a tonometry test for?
A tonometry test measures the pressure inside your eyes (intraocular pressure) to help detect and monitor glaucoma.
What is the normal range for eye pressure (IOP)?
The normal range for eye pressure is typically 10 to 21 mmHg (millimetres of mercury).
Is tonometry painful?
No, tonometry is not painful. You may feel a brief puff of air or light pressure, and numbing eye drops are used for contact methods to ensure comfort.
What are the symptoms of increased eye pressure?
Symptoms of increased eye pressure may include:
Blurry or hazy vision
Eye pain or discomfort
Headaches
Seeing halos around lights
Redness in the eye
Nausea or vomiting (in severe cases)
However, many people with high eye pressure have no symptoms at all.
How accurate is tonometry?
Tonometry is generally very accurate, especially when performed using applanation tonometry, which is considered the gold standard for measuring intraocular pressure (IOP). Other methods like non-contact (air puff) and rebound tonometry are also reliable, though slight variations may occur depending on technique and eye condition.
Accuracy can be influenced by factors such as:
Corneal thickness
Patient movement
Proper calibration of the device
Your eye specialist may consider these factors and use additional tests to confirm a diagnosis if needed.
Does a tonometer touch your eye?
It depends on the type of tonometry used:
Applanation tonometry and rebound tonometry:
Yes, the tonometer gently touches the surface of your eye. Numbing drops are applied to ensure it's painless.
Non-contact tonometry (air-puff test):
No, the device does not touch your eye. It uses a puff of air to measure pressure instead.
Your eye specialist will choose the method based on your needs and comfort.
The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.
For more information, contact us:
Thomson Specialists Paragon (Health Screening)
- Mon - Fri: 8.30am - 5.30pm
- Sat: 8.30am - 12.30pm
Call: 6735 0300
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