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.
IVP (Intravenous pyelogram) The use of a dye, injected into the veins, used to locate kidney stones. Also used to determine the anatomy of the urinary system. Mentioned in: Lithotripsy. IVP. intravenous pyelography. See pyelography.