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?

Many things can cause your eyes to become dry. These include:

  • 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.
  • Glands in the eyelid produce lubricating tears to keep the eye moist.
  • Glands above the eyelid produce reflex tears.
  • Drainage canals allow tears to flow out of the eye into passages in the nose.
  • The puncta act like drains, connecting the upper and lower eyelids to the drainage canals.

How Are Dry Eyes Diagnosed?

Be sure to tell your doctor about:

  • Any medical conditions you have
  • Any medications you use, such as eyedrops or antihistamines
  • Any contact lenses you wear

Examining Your Eyes:

Your eye doctor looks at your eyes through a special microscope called a slit lamp. This allows him or her to examine the tear film. Your eye doctor may also use eyedrops with dye to help show any dry spots.

Testing Your Tear Production: Your eye doctor also measures the amount of tears your eyes produce. First, your eyes may be numbed with anesthetic drops. Then, your doctor folds filter paper over your lower lids. You’re asked to sit with your eyes closed for about 5 minutes. The paper absorbs the tear film. The amount of fluid in the paper tells your eye doctor the amount of tears your eyes produce.