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Normal intraocular pressures average between 12-22 mm Hg. The “mm Hg” refers to millimeters of mercury, which is a scale for recording the eye pressure.
Eye pressure can vary hourly, daily and weekly. Many factors can affect the up and down changes in a person's intraocular pressure. These daily changes are normal.
Usually, the higher the pressure, the more risk to the optic nerve. Some optic nerves develop glaucoma even at low pressures (this is called normal-tension glaucoma) so it is important to have the optic nerve examined no matter what the pressure may be.
Read more about eye pressure and glaucoma.
Last reviewed on August 23, 2012