Normal eye health involves fluid known as aqueous humor being distributed throughout your eyes’ front portions, with any excess being reabsorbed back by your body as it should. When this doesn’t occur, pressure builds in the eye that can damage optic nerve fibers and lead to vision loss.

Your eye doctor can measure intraocular pressure using a tonometer, which rests against the surface of your eye after administering numbing eye drops to ensure a quick and painless test.