When realizing this test, the practitioner is testing the eyelid margin.A Schirmers test can measure the amount of moisture bathing the eye. This test is useful for determining the severity of the condition. A five-minute Schirmers test with and without anesthesia using a Whatman #41 filter paper 5 mm wide by 35 mm long is performed. For this test, wetting under 5 mm with or without anesthesia is considered diagnostic for dry eyes.If the results for the Schirmers test are abnormal, a Schirmer II test can be performed to measure reflex secretion. In this test, the nasal mucosa is irritated with a cotton-tipped applicator, after which tear production is measured with a Whatman #41 filter paper. For this test, wetting under 15 mm after five minutes is considered abnormal.A tear breakup time (TBUT) test measures the time it takes for tears to break up in the eye. The tear breakup time can be determined after placing a drop of fluorescein in the cul-de-sac.A tear protein analysis test measures the lysozyme contained within tears. In tears, lysozyme accounts for approximately 20 to 40 percent of total protein content.A lactoferrin analysis test provides good correlation with other tests.The presence of the recently described molecule Ap4A, naturally occurring in tears, is abnormally high in different states of ocular dryness. This molecule can be quantified biochemically simply by taking a tear sample with a plain Schirmer test.
Dry Eye Syndrome on NHS Choices
Am.J.Managed Care - Dry Eye Disease: Pathophysiology, Classification, and Diagnosis
Dry Eye Syndrome on eMedicine
Nasolacrimal and Lacrimal Apparatus, The Merck Veterinary Manual