Tears as a source of biomarkers for ocular and systemic diseases.

The main focus in clinical proteomics is the discovery of new protein or peptide biomarkers which are correlated with a certain disease. Tear proteins have been investigated extensively in the past and distinct relations between the levels of certain tear proteins to different disorders have been demonstrated. In this review we attempt to summarize proteomic technologies for biomarker identification in tears and some disease related biomarkers in tear fluids that were discovered through different proteomic techniques in different conditions like dry eye, Sjogren's syndrome, contact lens wearers, glaucoma, diabetic retinopathy or cancer. Proteomic analysis of tear fluid has proven to be a promising to gain more information about the pathogenesis of diseases and lead to new diagnostic possibilities. Furthermore, biomarkers represent promising targets for drug development and can be used to monitor the disease state or treatment responses, and accordingly improve the standards of patient care.