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

Tear test; Tearing test; Dry eye test; Basal secretion test

The health care provider will place a special paper strip inside the lower eyelid of each eye, under the eyelid (usually the bottom one). Both eyes are tested at the same time. Before the test, you will be given numbing eye drops to prevent your eyes from tearing due to irritation from the paper strips.

The exact procedure may vary somewhat. Most often, the eyes are closed for 5 minutes. Close your eyes gently. Closing the eyes tightly 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.

The phenol red thread test is similar to the Schirmer's test, except that red strips of special thread are used instead of paper strips, and no numbing drops are needed.

You will be asked to remove your contact lenses before the test.

Some people find that holding the paper against the eye is irritating or mildly uncomfortable. The numbing drops often sting at first.

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 after 5 minutes is a sign of normal tear production. Both eyes normally release the same amount of tears.

Dry eyes may result from:

• Aging
• Blepharitis
• Climate changes
• Corneal ulcers and infections
• Eye infections (for example, conjunctivitis)
• Laser vision correction
• Leukemia
• Lymphoma
• Rheumatoid arthritis
• Previous eyelid or facial surgery
• Sjogren syndrome
• Vitamin A deficiency

There are no risks with this test.

Do not rub the eyes for at least 30 minutes after the test. Leave contact lenses out for at least 2 hours after the test.

Even though the Schirmer's test has been available for more than 100 years, several studies show that it does not properly identify a large group of patients with dry eye. Newer and better tests are being developed. One test measures a molecule called lactoferrin. Patients with low tear production and dry eye have low levels of this molecule.

Another test measures tear osmolarity, or how concentrated the tears are. The higher the osmolarity, the more likely it is that you have dry eye.

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