Normal eye pressure is between 12 and 22 millimeters of mercury, according to Glaucoma Research Foundation. In the United States, the average intraocular pressure is between 14 and 16, states The Glaucoma Foundation.
Fluctuation in eye pressure is normal, says Glaucoma Research Foundation. Pressure sometimes changes from hour to hour, day to day, or week to week. Doctors consider several variables when evaluating eye pressure, reports The Glaucoma Foundation. These include race, family history and corneal thinness.
Typically, high-intraocular pressure is associated with glaucoma, so an elevated level puts an individual at risk, Glaucoma Research Foundation advises. However, in normal-tension glaucoma, pressure is not high. Therefore, a glaucoma diagnosis must involve both pressure readings and examination of the optic nerve.