Tonometry is a diagnostic test that measures your intraocular pressure (IOP), or the pressure inside your eye. Tonometry can help your healthcare provider determine if you’re at risk for glaucoma. People with glaucoma have high intraocular pressure because the fluid inside the eye drains too slowly.
Tonometry is a quick test performed by your healthcare provider to measure the pressure inside your eyes.
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Your healthcare provider uses ocular tonometry to see if you’re at risk for glaucoma. In people with glaucoma, the fluid that circulates inside their eye is either produced too fast or drains too slowly. As a result, the pressure inside their eye builds up. Left untreated, increased eye pressure can eventually impact the optic nerve and cause vision loss.
People who have a heightened risk of glaucoma should undergo a tonometry test. There are several factors that increase your risk for glaucoma, including:
You should also schedule a consultation with your healthcare provider right away if you experience:
Ocular tonometry measures the pressure inside of your eye by flattening your cornea. The more force that’s needed to flatten your cornea, the higher the intraocular pressure. People with high intraocular pressure are more likely to develop glaucoma. Tonometry helps detect this problem early on so your healthcare provider can create an effective treatment plan.
Before performing your ocular tonometry test, your healthcare provider will put numbing eye drops in your eyes. This keeps you from feeling anything during the test.
Ocular tonometry may be performed using different methods, depending on your needs. No matter what type of tonometry test is used, the main goal is the same: to measure the pressure inside of your eye by applying force to your cornea.
Your provider can perform several different types of tonometry tests. Your healthcare provider will determine which assessment is best suited to your needs. Some of the most common types of tonometry include:
Unless the pressure is extremely elevated, there’s usually no way to feel if the pressure inside of your eyes is building up. That’s why routine eye exams are so important. Your healthcare provider can detect any problems and treat them before they worsen.
Yes. Unless your healthcare provider is performing air-puff tonometry, an instrument will gently touch your eye during the assessment. You’ll be given numbing eye drops so you won’t feel anything.
Your healthcare provider will know your results immediately in most cases. If your results are abnormal, other tests will likely be performed to confirm your diagnosis.
No. There are no risks associated with having a tonometry test.
Normal eye pressure ranges from 10-21 mm Hg (millimeters of mercury. This refers to the units used to measure eye pressure.) If your eye pressure is higher than 21 mm Hg, then you could have pre-glaucoma or glaucoma.
Low eye pressure usually isn’t a cause for concern. However, the risk of blurred vision increases with eye pressures under 6 mm Hg.
Tonometry doesn’t typically cause side effects. So if you notice any sudden changes in your vision — or if you’re having pain — contact your healthcare provider right away. They can perform further testing to determine the problem.
Tomography is a type of digital imaging. In ocular health, tomography may refer to a cross-section of the retina or optic nerve. Tonometry, on the other hand, refers to the testing method used to measure the pressure inside of your eye.
A note from Cleveland Clinic
Tonometry is a simple and straightforward test that can tell you whether or not you’re at risk for glaucoma. Even though glaucoma can’t be cured, it can be successfully managed with proper treatment. If you notice any symptoms of glaucoma, like tunnel vision, blind spots, eye pain or blurred vision, schedule an appointment with your healthcare provider immediately. Prompt treatment can halt the condition in its early stages and dramatically improve your quality of life.
Last reviewed by a Cleveland Clinic medical professional on 05/25/2022.
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