Doctors use applanation, electronic indentation or noncontact tonometry to check a patient's eye pressure, according to WebMD. Although noncontact tonometry is the least accurate method, this test remains popular because it's easier to screen children for abnormal intraocular pressure with this approach.
A doctor who uses noncontact tonometry has his patient rest his chin on a stand. He focuses the patient's eye with a light and uses a machine to send a small puff of air into the eye. The machine quickly records how the light reflection changes when the air puff hits the cornea, explains MedlinePlus.
Applanation tonometry requires the doctor to numb and then temporarily stain patient's eyes. The patient places his head into a stand and keeps his eyes open. The doctor extends an eye probe until it hits the cornea and uses a slit lamp to record a pressure reading. This method is the most accurate way of reading eye pressure, notes MedlinePlus.
A doctor who chooses electronic indentation tonometry numbs the patient's eyes and then uses a probe to touch the surface of each cornea and receive an instant reading, according to MedlinePlus.
Doctors measure intraocular pressure to screen for glaucoma. This eye disease damages the optic nerve and may lead to blindness, explains WebMD.