Taking tests like these are great for keeping your mind active! Can you spot the different one in less than 10 seconds? If you can, well done, your visual skills are astonishing!
Screening for glaucoma
Tonometry measures the fluid pressure inside your eye (intraocular pressure). This is one test that helps your eye doctor detect glaucoma, a disease that damages the optic nerve.
Several methods to measure intraocular pressure are available, including:
Applanation tonometry. This test measures the amount of force needed to temporarily flatten a part of your cornea. You’ll be given eyedrops with fluorescein, the same dye used in a regular slit-lamp examination. You’ll also receive eyedrops containing an anesthetic.
Using the slit lamp, your doctor moves the tonometer to touch your cornea and determine the eye pressure. Because your eye is numbed, the test doesn’t hurt.
Noncontact tonometry. This method uses a puff of air to estimate the pressure in your eye. No instruments touch your eye, so you won’t need an anesthetic. You’ll feel a momentary pulse of air on your eye, which can be startling.
If your eye pressure is higher than average or your optic nerve looks unusual, your doctor might use a pachymeter, which uses sound waves to measure the thickness of your cornea. The most common way of measuring corneal thickness is to put an anesthetic drop in your eye, then place a small probe in contact with the front surface of the eye. The measurement takes seconds.
You might need more-specialized tests, depending on your age, medical history and risk of developing eye disease.