What is the normal value for the tear secretion test?

Tear secretion testing is a diagnostic procedure used to evaluate conditions caused by excessive tear production. The normal value for adults is typically 10–25 mm, while in the elderly it is generally less than 10 mm.

When certain eye diseases occur, the quantity or characteristics of ocular secretions may change. The tear secretion test is designed to assess disorders resulting from excessive tear production. During the test, a standardized filter paper strip is placed in the lower conjunctival sac at the inner one-third of the eyelid, and the length of wetting on the strip is measured after a specific period to determine the amount of tear production. Under normal conditions, the moistened length of the filter paper in adults ranges from 10 to 25 mm. In asymptomatic elderly individuals, the wetting length is usually less than 10 mm. If the test result shows a wetting length between 5 and 10 mm, or less than 5 mm, this generally indicates an abnormality, possibly due to conditions such as dacryoadenitis, congenital insufficient tear secretion, or dry eye syndrome, which require prompt treatment targeting the underlying cause.

It should be noted that patients with corneal or conjunctival ulcers or those with ocular surface injuries should not undergo this test, as it may affect the accuracy of results. If any abnormalities are detected, it is recommended to seek medical evaluation at a hospital as early as possible for further examinations to confirm the diagnosis.