What Are Dry Eyes?

What Are Dry Eyes?

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What Are Dry Eyes?

Do your eyes ever sting, burn, or feel scratchy? To be comfortable, your eyes need to be lubricated, or bathed, with tears. Normally, there is always a film of tears on the surface of your eyes. But if your eyes don’t produce enough tears, the surface gets irritated. This is known as “dry eyes.”

Front view of eye and nose showing glands above eye and in eyelid, and tear duct in nose. Glands in eyelid produce lubricating tears to keep eye moist. Drainage canals lead from eye to tear duct and allow tears to flow out of eye into passages in nose. Glands above eyelids produce reflex tears. Puncta are small holes in upper and lower eyelid at inside corner of eye. Puncta act like drains, connecting upper and lower eyelids to drainage canals.

Not Enough Lubricating Tears

When you cry, your eyes make reflex tears. Each time you blink, another kind of tears, called lubricating tears, spread over the surface of your eyes. These tears keep the eyes moist and comfortable. You aren’t aware of these tears because they stay on the surface of the eyes. But without them, your eyes get dry. Then they burn or sting and feel scratchy. They may also water. This doesn’t relieve the dryness, however, because the eyes water with reflex tears, not lubricating tears.

What Causes Dry Eyes?

  • Aging

  • Heaters and air conditioners

  • Wind, smoke, or dry weather

  • Allergies such as hay fever

  • Medications

  • Eyelid problems, injuries to the eye, or diseases like rheumatoid arthritis

How Lubricating Tears Flow

Lubricating tears flow from glands in the upper eyelid over the surface of the eye. From the eye, the tears drain into canals that lead to the nose.