Ocular Tonometry is the measurement of the pressure within the eyeball.
The Tonometer is the device used to measure this pressure. Glaucoma is
the term that refers to the increased pressure in the eyeball. It is an
emergency situation, and if not treated immediately, can lead to
blindness. In a healthy eye, an equilibrium exist between the amount of
intraocular (within the eyeball) fluid produced and the amount of fluid
removed. If the fluid cannot be removed, pressure builds up within the
eye. This elevated intraocular pressure (glaucoma) can cause permanent
damage to the optic nerve, resulting in blindness.