Schirmer's test determines whether the eye produces enough tears to keep it moist.

The health care provider will place paper strips inserted under the eyelid, usually the bottom one. Both eyes are tested at the same time. Before the test, you may be given numbing eye drops to prevent tearing due to the irritation from the paper.

The exact procedure may vary somewhat. Most often, the eyes are closed for about 5 minutes. Close the eyes gently. Tight closing of the eyes or rubbing the eyes during the test can cause abnormal test results.

After 5 minutes, the doctor removes the paper and measures how moist it is.

Remove contact lenses before the test.

Some people find that holding the paper against the eye is irritating or mildly uncomfortable.

This test is used when a person experiences very dry eyes or excessive watering of the eyes.

More than 10 mm of moisture on the filter paper in 5 minutes is normal. Both eyes normally secrete the same amount of tears.

Dry eyes may result from:

• Aging
• Corneal ulcers and infections
• Eye infections (for example, conjunctivitis)
• Vitamin A deficiency
• Sjogren syndrome
• Tearing problems due to disorders such as lymphoma, leukemia, and rheumatoid arthritis
• Previous eyelid or facial surgery
• Climate changes

The inability of tears to drain into the nose can occur with:

• Some eye infections
• Blockage of the tear duct

There are no risks with this test.

Do not rub the eyes for at least 30 minutes after the test. Contact lenses should be left out for at least 2 hours after the test.

Even though Schirmer's test has been available for more than a hundred years, several studies show that it does not properly identify a large group of patients with dry eyes. Newer and better tests are being developed. One test measures a molecule called lactoferrin. Patients with low tear production and dry eyes have low levels of this molecule.

Another test involves fluorescein eye drops, which contain a dye that is placed in the eye. Tears should flush the dye into the nose within 2 minutes. It will take longer in persons with dry eyes.