What is the most commonly performed tear film quantity assessment?

• A. Schirmer Tear Test (STT)
• B. Tear osmolarity
• C. Interferometry
• D. Tear break-up time

Answer: (A)

Measuring how much tear fluid the eye produces is a direct test of tear quantity. The Schirmer Tear Test does this best: a small filter paper strip is placed in the lower eyelid for about a minute, and the length the strip wets is read in millimeters. That numeric result gives a straightforward measure of tear production, making it a simple, quick, and widely used baseline test for diagnosing aqueous-deficient tear loss. Other tests focus on different aspects: tear osmolarity assesses tear film composition, interferometry looks at the lipid layer, and tear break-up time evaluates how long the tear film remains stable rather than how much is produced. Because of its direct focus on tear volume and practicality, the Schirmer Tear Test is the most commonly used tear film quantity assessment.