Human tear is a biological fluid rich in
lipids that is increasingly collected in clinical and biological research. The repertoire of small
lipids or
lipid mediators (often termed
eicosanoids or
oxylipins) found in human tear provides insight into metabolism of
fatty acids and physiology of the ocular surface and Meibomian glands. Disturbances in the tear
lipid mediators profile also occur during
inflammation of the ocular surface that is not directly linked to lipid metabolism. The changes in the levels of pro-inflammatory and pro-resolution
lipid mediators in the tear help assess the severity and stage of
inflammation in ocular surface tissues. Mass spectrometry, used in the evaluation of tear
lipid mediators, is an emerging tool in clinical diagnostics and
personalized medicine. Here we describe the reproducibility, accuracy, and precision of quantifying
lipid mediators in human tears, with a suggested method for tear collection and sample handling. The ranges of
lipid mediators concentrations in tear fluid of healthy and diseased individuals with
Meibomian gland dysfunction are reported, as well as the impact of age and disease on individual
lipid mediators. We would like to recommend a set of guidelines, which can be further discussed in workshops. This will facilitate harmonization of future tear
lipid mediators data across different instrument platforms in various laboratories. We hope that other fields requiring
lipid mediators assays will also benefit from such an effort.