Intraocular Pressure Question and Answer

Q: My doctor said that my intraocular pressure is high and that I need to be monitored regularly. Can you tell me what intraocular pressure is and what level is considered to be normal?

A: The eye's lens and cornea have no blood supply, so the aqueous humor—a clear, watery liquid—supplies nutrients and removes waste from them. Normally, the amount of aqueous humor that the eye produces and then drains into the bloodstream is in balance, leaving a healthy eye with an intraocular pressure (IOP) that ranges from 12 to 22 mm Hg (millimeters of mercury, the same unit of measure used for blood pressure).

The physical forces produced by the IOP are transmitted through the sclera to nerve fibers passing through it. In people at risk for glaucoma, this leads to optic nerve damage, which, if left untreated, can lead to blindness.

Interestingly, glaucoma can develop in people who have a normal or an elevated IOP level. Lowering the IOP is beneficial even when the IOP level is normal and it is lowered beyond that level.

As with high blood pressure, there are no symptoms in the early stages of open-angle glaucoma, which is why your doctor is advising regular monitoring. Studies have shown that eyedrops to lower IOP can prevent the development of glaucoma, and your eye doctor can tell you if and when you might need to begin treatment. Outpatient laser treatment and eye surgery are alternative ways to lower IOP.

Publication Review By: Susan B. Bressler, M.D., Harry A. Quigley, M.D., Oliver D. Schein, M.D., M.P.H.

Published: 01 Mar 2011

Last Modified: 07 Jan 2015