(Intraocular Pressure [IOP] Measurement)
Pressure in the eye is called intraocular pressure (IOP). Tonometry tests the amount of pressure in the eye.
Reasons for Test
Elevated eye pressure can lead to eye damage. This may be part of a disease called glaucoma. If left untreated, glaucoma can cause blindness. Tonometry is used to screen for glaucoma. It is also used to monitor the treatment of glaucoma.
You may have ocular hypertension. This happens when pressure is elevated but is not caused by glaucoma.
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There are no major complications associated with this procedure.
What to Expect
There are two main types of tonometry: the non-contact air puff method and the applanation method that flattens the cornea with pressure. The type of tonometry that is done will depend on the equipment your doctor has and the type of test they decide to do.
Prior to Test
You may be asked to remove corrective lenses, such as contacts.
Description of the Test
For both methods, you will be asked to sit in an exam chair. You may be asked to place your chin in a special cradle and rest your forehead against a bar. The chin cup and forehead rest will balance and steady your head.
You will be asked to look into an instrument. A puff of air will be blown into the eye. No instruments come in contact with the eye.
Applanation Method or the Goldmann Tonometry
Your doctor will place anesthetic drops in your eyes before the test. This will numb your eye. Your doctor may also place a small amount of an orange dye into your eye. When your head is balanced and steady, you will be asked to look into an instrument with a blue light. A prob