Association between sleep quality and corneal microstructural alterations in patients with dry eye disease: An in vivo confocal microscopy study

PURPOSE: This hospital-based cross-sectional study aimed to investigate the relationship between sleep quality and microstructural alterations of the cornea, specifically focusing on the subbasal nerve plexus (SNP) and dendritic cell (DC) activity, in patients diagnosed with dry eye disease (DED). METHODS: A total of 60 adult participants were enrolled and divided into two cohorts based on their Pittsburgh Sleep Quality Index (PSQI) scores: a Sleep Disorder group (PSQI > 5) and a Control group (PSQI ≤ 5). Comprehensive clinical assessments included the Ocular Surface Disease Index (OSDI), Schirmer I test (SIT), tear break-up time (BUT), and meibomian gland evaluation. In vivo confocal microscopy (IVCM) was utilized to quantify corneal nerve fiber density (CNFD), nerve tortuosity, and DC density. The Insomnia Severity Index (ISI) was further employed to grade sleep disturbance severity. RESULTS: ) and a significant elevation in DC density (median 45 vs. 28.5 cells/mm²) in the sleep disorder group (P < 0.05). Correlation analysis indicated that CNFD was negatively correlated with both PSQI (r = -0.27) and ISI (r = -0.41), while DC density showed a strong positive correlation with these sleep indices (P < 0.001). Furthermore, multivariate linear regression identified SIT as a positive predictor for CNFD and the ISI score as an independent risk factor for increased DC density. CONCLUSION: Sleep disturbances are significantly associated with reduced tear secretion, loss of corneal nerve fibers, and increased immune cell infiltration in DED patients. These findings suggest that systemic sleep quality is a critical determinant of the corneal microenvironment and should be integrated into the comprehensive management of dry eye disease.