Abstract: Tear fluid has rapidly evolved from an obscure biological matrix into a highly prized, minimally invasive source of complex biomarkers. Driven by advancements in detection technologies that have pushed sensitivity from the microgram limits of the 1990s down to modern femtogram and single-molecule resolution, tears allow for the detailed analysis of low-abundance proteins, RNA, lipids, and extracellular vesicles. However, despite this scientific potential, the lack of standardized collection and storage protocols has forced researchers to rely on localized, study-specific setups. This operational guide provides the foundational standardization framework needed to integrate tear fluid into modern biorepository infrastructures smoothly.
The guide outlines a careful balancing act between the two dominant clinical collection methods: Schirmer’s strips (accounting for roughly 40% of current literature workflows) and glass microcapillary tubes (representing 35%). While Schirmer’s strips offer an inexpensive and highly accessible endpoint, they run the risk of introducing reflex tearing and conjunctival cell contamination due to direct ocular contact. In contrast, microcapillaries minimize contamination but require specialized technical expertise and longer collection times. To preserve molecular stability, the framework establishes strict protocols for maintaining an uninterrupted cold chain—detailing both local storage for immediate flash-freezing and dry-ice transport workflows for centralized, ISO-certified biobanks.
Read the full article here: https://www.sciencedirect.com/science/article/pii/S2667376226000326
