Tear fluid as a source of biomarkers for the neurodegeneration in central nervous system

Abstract

Composition of tear fluid alter not only in ocular diseases but in systemic pathologic processes including central nervous system (CNS) disorders. It is due to the variety of regulatory pathways for the tear production with active participation of CNS. The review represent data about mechanisms of tear production regulation, sources of metabolites present in tears, alterations of tear fluid composition in Alzheimer’s and Parkinson diseases, multiple sclerosis and amyotrophic lateral sclerosis. These neurodegenerative diseases are accompanied by typical alteration of concentrations of different protein bioregulators (cytokines, growth factors, synucleins, etc.) and catecholamines. These alterations often correlate with ones in cerebrospinal fluid appearing even before the clinical manifestation of the disease. Thus tear fluid analyses is a promising non-invasive method for the early diagnostic, prognosis and monitoring of neurodegenerative diseases, and also for the personalized therapy. We tried to represent the most recent data because interest to this problem has increased during the last years, and our own data also.