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A tonometer is an eye care instrument used to measure pressure inside the eye, called intraocular pressure. The test that uses a tonometer is called tonometry. Eye pressure measurement is an important part of screening for and monitoring glaucoma, but it does not diagnose glaucoma by itself. Eye doctors interpret the result along with optic nerve findings, visual field testing, corneal thickness, and other exam results.
read more about tonometer ...A tonometer is used to check whether eye pressure is within an expected range or higher than expected. Elevated pressure can increase the risk of glaucoma, a group of eye diseases that can damage the optic nerve. The device is also used to monitor people already being treated for glaucoma or ocular hypertension. Eye pressure can change over time, so repeated measurements may be needed.
Goldmann applanation tonometry is a common clinic method that gently touches the numbed surface of the eye. Noncontact tonometry uses a quick puff of air and does not touch the eye. Rebound and handheld tonometers are portable options used in clinics, hospitals, or certain bedside settings. Each method measures eye pressure differently, so results can vary slightly between devices.
The process depends on the type of tonometer being used. For contact methods, numbing drops and sometimes dye are placed in the eye before the instrument gently touches the cornea. For noncontact methods, the patient looks into the device while a brief puff of air is directed at the eye. The test is usually quick, and patients can return to normal activities unless their eye doctor gives different instructions.
Tonometry is generally safe when performed with clean equipment and proper technique. Mild tearing, blinking, or brief irritation can occur after some contact methods. A higher-than-expected reading does not automatically mean glaucoma, and a normal reading does not rule it out in every patient. Eye pain, sudden vision changes, halos, nausea, or severe redness should be evaluated promptly.
Some tonometers gently touch the numbed surface of the eye, while noncontact tonometers use an air puff instead. The eye care team will explain which method is being used.
Tonometry is usually not painful. Contact methods use numbing drops, and air-puff testing can feel startling but brief.
No. A tonometer measures eye pressure, which is one part of glaucoma evaluation. Diagnosis also depends on optic nerve appearance, visual field testing, imaging, and other findings.
The schedule depends on age, eye history, glaucoma risk, and current treatment. An eye doctor can recommend how often tonometry should be done.
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Intraocular Pressure. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK532237/. Date Accessed June 15, 2026.
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