Eye pressure is expressed in millimeters of mercury (mm Hg), the same unit of measurement used in weather barometers. While normal eye pressure has historically been considered a measurement of less than 21 mm Hg, this normal "normal" upper limit may vary in different populations.

Ocular hypertension is not the same as glaucoma, which is a disease of the eye often caused by high intraocular pressure. In people with ocular hypertension, the optic nerve appears normal and no signs of glaucoma are found during visual field testing, which tests side (peripheral) vision. However, people with ocular hypertension are considered “glaucoma suspects,” meaning they should be monitored closely by an ophthalmologist (Eye M.D.) to make sure that they do not develop glaucoma.

Intraocular pressure rises slowly with increasing age, just as glaucoma becomes more common as you get older.

Written by
Reviewed by Dr. J. Kevin McKinney on March 1, 2015

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