Dry eye happens when your eyes don’t make enough tears to stay wet, or when your tears don’t work correctly. This can make your eyes feel uncomfortable, and in some cases it can also cause vision problems.
If your eyes feel dry and scratchy, see your eye doctor. Your eye doctor can do tests to see if your eyes are making enough tears. If the tests show you have dry eye, your doctor can recommend treatment.
Slit lamp test
In a slit lamp test, your eye doctor will use a microscope called a slit lamp to see if your eyes are making enough tears. First, they’ll put a drop in your eye that will make your tears easier to see. Then, they’ll shine a thin, bright light into your eye and look at your eye and eyelids with a microscope.
A Schirmer’s test also tells your eye doctor if your eyes are making enough tears. Your eye doctor will give you eye drops to numb your eye. Then they’ll put a small piece of paper on the edge of your eyelid and ask you to close your eyes for 5 minutes. After 5 minutes, your doctor will see how much moisture (wetness) is on the paper.
Tear break up time (TBUT)
A TBUT test checks how long your tear film (layer of tears on your eyes) lasts after you blink.
Your eye doctor will place a small amount of dye in your eye, and you’ll blink to make the dye fully cover your eye. Then, you’ll look forward without moving your eyes or blinking. Your eye doctor will watch to see how long the dyed tear film covers your whole eye. If your tear film does not last long, you may have dry eye.