What does the medical abbreviation IOP mean?

IOP stands for "intraocular pressure". It refers to the pressure within the eye, which is maintained by the balance between the production and drainage of aqueous humor, a clear fluid that fills the anterior and posterior chambers of the eye. Normal IOP ranges from 10 to 21 millimeters of mercury (mm Hg). Elevated IOP is a major risk factor for glaucoma, a group of eye diseases that can damage the optic nerve and lead to vision loss.