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.
IOP (intraocular pressure): The pressure created by the continual renewal of fluids within the eye. The normal IOP varies among individuals. The intraocular pressure is increased in glaucoma. In acute angle-closure glaucoma, the intraocular pressure rises rapidly because the iris blocks the angle in the front of the eye where the anterior chamber fluid normally drains out.