Compositional profiling and biomarker identification of the tear film.

Identification of tear film proteins and lipids is important for the elucidation of contact lens incompatibilities, tear film instabilities, dry eye syndromes, and other eye diseases. Compositional analysis of the tear film has been hampered in the past by the complex nature of the fluid and small sample size. Previously, all analytical methods required pooling of tear samples and molecular manipulation for detection of proteins and lipids, all of which skewed the resultant data. With the advent of nanoscale detection and analysis methods, it has become possible to identify specific tear components. This paper reviews the recent advances in tear sampling, proteomics, and lipidomics. Compositional profiling techniques, such as multi-dimensional electrophoresis, high performance liquid chromatography, and mass spectrometry, are assessed. Application of these techniques to identify potential biomarkers for specific tear disease conditions, such as blepharitis and dry eye, are evaluated.