High School Earth Science/Geologic Time Scale - Lesson Summary. 1  The Earth is very old, and the study of Earth's past requires us to think about times that were millions or even billions of years ago. Scientists use the geologic time scale to illustrate the order in which events on Earth have happened.
Medical Definition of intraocular pressure. : the pressure within the eyeball that gives it a round firm shape and is caused by the aqueous humor and vitreous body.
Intraocular pressure. Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk from glaucoma. Most tonometers are calibrated to measure pressure in millimeters of mercury (mmHg).