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What is a tonometry test?

Laura C. Fine, MD
Ophthalmology
Tonometry is a painless test to measure eye pressure. It can detect possible signs of glaucoma (a group of eye diseases that cause vision loss through damage to the optic nerve) and is also used to monitor glaucoma treatment. The simplest version, known as air-puff or noncontact tonometry, uses an instrument called a tonometer that emits a puff of air to determine what force it takes to flatten the cornea.

Anyone at risk for glaucoma, including anyone who is over age 40 or who has a borderline result with the air-puff test, should be given a more accurate test, known as applanation tonometry. After the eye is numbed with anesthetic drops, the doctor gently touches the cornea with an instrument to measure the eye's internal pressure.

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