The test used to measure your intraocular pressure, or the pressure inside your eye, is called tonometry. This test is important in determining if you have glaucoma, which is a disease associated with increased pressure in your eye, and damage to your optic nerve, which can cause blindness.
Intraocular pressure tests include applanation tonometry and noncontact tonometry. Applanation tonometry measures the amount of force needed to temporarily flatten a part of your cornea. This test can be conducted in several ways and generally requires the use of an anesthetic drop to numb the eye. An orange dye, called fluorescein, may be used in some tests. This dye washes out with your tears. Using the slit lamp or other instruments, your provider touches the cornea with a tonometer, which will measure the intraocular pressure. You will not feel it, and the anesthetic will wear off within two hours.
Noncontact tonometry uses a puff of air to test the pressure in your eye. No instruments will touch your eye, so you won’t need an anesthetic. You’ll feel mild pressure on your eye, which may be uncomfortable, but it lasts only a few seconds.