Tear Film Inflammatory Biomarkers in Keratoconus: Insights into Disease Severity and Diagnostic Potential

Keratoconus (KC) involves a progressive corneal deformation, recognized as having an inflammatory component, despite traditionally being considered noninflammatory. This study investigates the notable tear film cytokines and their correlation with KC disease severity. The objectives of this study were to measure inflammatory tear biomarkers in KC patients and to compare them with healthy controls and to evaluate biomarker levels across different severity stages of KC. This study follows a case-control observational design, comparing inflammatory tear biomarkers in KC patients (cases) and healthy individuals (controls), at a single point in time without intervention.

Eighteen KC patients and 25 healthy individuals were enrolled. Tear samples were collected via Schirmer strips and analyzed for interleukin (IL)-1β, IL-4, IL-6, IL-10, matrix metalloproteinase 9 (MMP-9), and tumor necrosis factor α (TNF-α) using ELISA. Group comparisons were made using nonparametric tests, and Spearman correlation evaluated associations with disease severity.

KC patients showed significantly elevated levels of IL-1β, IL-4, IL-6, IL-10, MMP-9, and TNF-α (p < 0.05). IL-1β, MMP-9, and TNF-α demonstrated strong associations with disease severity, while IL-6 and IL-10 exhibited moderate correlations, and IL-4 showed only a weak association with KC progression.

The study emphasizes inflammation's role in KC and identifies tear film inflammatory markers as promising tools for diagnosis, prognosis, early detection, disease monitoring, and personalized treatment.