One test for dry eye is known as the “Tear Breakup Time” test. The Tear Breakup Time test can provide an important measurement of how well a patient’s tears wet and protect the eye’s surface.
For this test, a small amount of fluorescein dye will be applied to the eye so that it mixes with the tear film. The patient is asked to blink, and then asked to keep their eye open for the doctor to see. After each blink, the tear film will thin and evaporate, forming dry spots due to insufficient wetting of areas on the eyes surface. While the patient holds their eye open, the doctor measures how long it takes for the first dry or dark spot in the tear film to appear, indicating the tear film has “broken up.” If tear break up occurs in a very short time, it may be an indication of dry eye.