Do You Have Symptoms of Dry Eye?What Tests Are There in Ophthalmology?
Measuring Tear Volume
This test measures tear volume. A test strip is placed at the lower lid margin for five minutes and the length of the moistened area is measured. When tear volume is normal, the length is 10mm or more, when it is 5mm or less it is deemed low.
Break Up Time (BUT) Measurement:
Measuring Tear Stability
In this test, the condition of the tears on the surface of the eye is observed for ten seconds, without blinking. Immediately after blinking, the tear film coats the corneal surface uniformly and as time passes, the tear film breaks up and part of the cornea is exposed. The time it takes for this to happen is called the tear film break up time (BUT). A normal BUT is 10 seconds or more; if the BUT is five seconds or less tear stability is deemed to be abnormal.
Examining Damage on the Surface of the Eye
Dry eye can cause damage to the surface of the eye. In this test, a test dye that stains the damaged area of the eye surface is applied, and the surface of the eye is examined.