Schirmer's test is a diagnostic procedure used to measure tear production in the eyes. It is commonly employed in ophthalmology to assess the presence and severity of dry eye syndrome, also known as keratoconjunctivitis sicca. The test involves placing a standardized strip of filter paper inside the lower eyelid, typically at the junction of the middle and outer third of the eyelid margin. The patient is usually asked to close their eyes, and after a set time—typically five minutes—the amount of moisture that has wicked along the paper is measured in millimeters.
There are two variations of the test:
- Schirmer's test without anesthesia: Evaluates both reflex and basal tear secretion.
- Schirmer's test with anesthesia: Primarily measures basal tear secretion by eliminating reflex tearing caused by irritation from the paper strip.
Normal results generally indicate tear wetting of 10 to 15 mm or more within five minutes. A measurement of less than 5 mm is typically considered indicative of significantly reduced tear production.
The test is non-invasive and widely used in clinical settings, though it may be influenced by factors such as age, environmental conditions, and systemic diseases like Sjögren's syndrome. While Schirmer's test provides a quantitative assessment, it is often used in conjunction with other diagnostic tools, such as tear film break-up time and ocular surface staining, for a comprehensive evaluation of dry eye disease.