The tear film is a highly complex structure that nourishes and maintains the homeostasis of the ocular surface. In various ocular surface diseases, the tear film is altered, and its chemical composition can reveal information about the underlying disease pathophysiology. Further, diseases elsewhere in the body can often bring about changes to the tear film, opening the potential for using the tear film as a site for diagnostic applications.

Obtaining biomarkers and characterizing the composition of the tear film is a challenging task. This is primarily due to very low sample volumes, making the detection or accurate quantification of an analyte difficult. There is no universal method for sampling the tear film and the method is dictated by the outcome or analyte of interest.

Despite the technical challenges associated with this work, many groups around the world have successfully developed techniques to characterize and study the composition of the tear film in healthy and disease states. These techniques include, but are not limited to flow cytometry, ‘omics (proteomics, lipidomics, genomics), and multiplexed analyte quantification. The vision research community depends heavily on these techniques to advance the understanding of human ocular surface diseases. Therefore, it would be of great value to have these techniques demonstrated and visualized, especially to help with the training of new and upcoming scientists.