Updated January 01, 2014.

Definition: A tool used to measure the pressure of the eye. A tonometer is used to help detect glaucoma. A tonometer measures the production of aqueous humor, the liquid found inside the eye, and the rate at which it drains in to the tissue surrounding the cornea.

For the type of tonometer that actually touches the eye, numbing drops are used. For the air-puff tonometer, though, no numbing drops are needed.

Also Known As: Tonometry