Eye Pressure
Eye pressure—also called intraocular pressure or IOP—is a measurement of the fluid pressure inside the eye. Measuring it is like measuring blood pressure.
The eye has a jelly-like substance called vitreous humor filling most of the back part of the eye. A more-watery liquid called aqueous humor also is present. Much of the aqueous humor is in the front part of the eye, behind the cornea and in front of the iris.
In a healthy eye, a small amount of new aqueous humor is always entering the eye while an equal amount drains out. Most of the aqueous humor flows out of the eye through the drainage angle, in front of the iris. This equal flow maintains a stable pressure.
