The Glaucoma Research Foundation states that normal intraocular pressure ranges from 12 to 22 millimeters mercury. It is normal for eye pressure to vary somewhat from day to day and even hour to hour.Continue Reading
High intraocular pressure, defined as pressure higher than 21 millimeters mercury on at least two occasions, is a risk factor for developing glaucoma, states eMedicineHealth. Eye pressure is measured using an instrument called a tonometer. Glaucoma is diagnosed when increased eye pressure, optic nerve damage and vision loss are all present.
The most common type of glaucoma is caused by the eye's drainage channels becoming blocked, states the Glaucoma Research Foundation. The blockage causes the pressure inside the eye to rise, which causes a gradual loss of vision.Learn more about Medical Ranges & Levels