Tonometry

Glaucoma Screening Test

Results

A tonometry test measures the pressure inside your eye, which is called intraocular pressure (IOP). This test is used to check for glaucoma.

Normal eye pressure is different for each person and is usually higher just after you wake up. IOP changes more in people who have glaucoma. Women usually have a higher IOP than men, and IOP normally gets higher as you get older.

Intraocular pressure (IOP)

Normal:	10–21 millimetres of mercury (mm Hg)
Abnormal:	Higher than 21 mm Hg

High values

• A high IOP may mean that you have glaucoma or that you are at high risk for developing glaucoma. People who have ongoing pressures above 27 mm Hg usually develop glaucoma unless the pressure is lowered with medicines.
• People who have an ongoing IOP higher than 21 mm Hg but do not have optic nerve damage have a condition called ocular hypertension. These people may be at risk for developing glaucoma over time.

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Author:	Douglas Dana Jan Nissl, RN, BS	Last Updated: August 22, 2006
Medical Review:	Adam Husney, MD - Family Medicine Ian MacDonald, MDCM, FRCSC - Ophthalmology
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