Tears stop the surface of the eye from drying out. But tears evaporate, which means they dry up and disappear into the air the same way water and other liquids do.
For about 9 out of 10 people with dry eye, a damaged tear film allows too many tears to evaporate.
That means tears cannot stay on the surface of the eye long enough.
Download a printer-friendly Your eyes have a system of glands, which produce your tears.
Healthy eyes have a natural protective outer layer that holds in the watery component of the tear film.
When the tear system doesn’t function properly and can’t help form the tear film correctly, too many of your tears evaporate, leading to the signs and symptoms of dry eye.
Blinking less often. This can happen when concentrating on activities like reading, driving, or looking at a screen. Normally, someone blinks about 20 times per minute. But a study showed when reading a book, you may only blink 10-15 times per minute. And when looking at a screen you may only blink 7 times per minute.
Medications. Certain medicines, including antihistamines, decongestants, acne medication, and antidepressants, can lead to increased evaporation.
Aging. Dry eyes are a part of the natural aging process. The majority of people over age 65 experience some symptoms of dry eye, many of which can be attributed to tear evaporation.
The environment. Wind, smoke, or dry air from the environment, as well as air conditioners, can speed up evaporation.
Inflammation. Damage to the eye's surface from too much tear evaporation can also lead to inflammation.
Meibomian gland dysfunction. The meibomian glands create a protective oily layer that keeps tears in place. But when they can’t function properly, the oily layer doesn't form as it should, and tears begin to evaporate too quickly.
Tear evaporation is a leading cause of dry eye, but not all treatments target this underlying issue.
Even if you keep adding more tears, you aren't addressing the actual reason for your symptoms.
It's a lot like pouring more water into a leaky bucket without patching it up first.
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