Biomarkers in tear fluid in keratoconus

This review presents literature data indicating that tear fluid composition in keratoconus reflects the course of metabolic processes in this disease. In keratoconus, tear fluid shows changes in the activity of lysyl oxidase, prolidase, and heparanase, which participate in corneal structure remodeling. Tear fluid also shows enhanced free radical reactions, reduced intensity of energy processes, and disturbances in the protease-inhibitor balance and cytokine status. Despite the absence of visible signs of inflammation, tear fluid changes confirm the role of inflammation in the pathogenesis of keratoconus. Significant correlations between clinical study findings and tear levels of markers of these metabolic processes allow their use as biomarkers for detecting early stages of keratoconus, assessing disease severity, predicting progression, identifying therapeutic targets, and objectively evaluating treatment effectiveness, including after corneal cross-linking.