VITAMIN D AND OCULAR SURFACE: ASSOCIATION OF VITAMIN D STATUS WITH OCULAR SURFACE PARAMETERS IN DRY EYE DISEASE (DED)

Abstract

Background: Dry Eye Disease (DED) is a multifactorial disorder of the tear film and ocular surface that results in discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. Vitamin D, a fat-soluble secosteroid with pleiotropic immunomodulatory and anti-inflammatory properties, has recently emerged as a candidate molecule influencing tear film homeostasis. However, data from the Indian subcontinent remain sparse, and the specific mechanistic relationship between serum Vitamin D levels and quantifiable ocular surface parameters in DED patients warrants systematic investigation. Aim: To evaluate serum Vitamin D levels in patients with DED compared with healthy controls and to determine their correlation with key ocular surface parameters including Tear Break-Up Time (TBUT), Schirmer's test, Ocular Surface Disease Index (OSDI) score, conjunctival goblet cell density, corneal staining, tear osmolarity, and inflammatory biomarkers. Methods: A hospital-based observational case-control study was conducted at the Department of Ophthalmology and Biochemistry, Narayan Medical College and Hospital, Sasaram, Bihar, India, over a period from May 5, 2025 to April 30, 2026. Twenty participants (10 clinically diagnosed DED patients and 10 age- and sex-matched healthy controls) were enrolled. Serum 25-hydroxyvitamin D [25(OH)D] levels were estimated using the enzyme-linked fluorescent assay (ELFA) method with standard ELFA kits on the VIDAS analyser (bioMérieux). Ocular surface evaluation included TBUT, Schirmer’s test, OSDI questionnaire, conjunctival impression cytology (goblet cell density), corneal fluorescein staining, tear osmolarity, meibomian gland function scoring, and inflammatory markers (MMP-9, IL-6). Statistical analysis used independent samples t-test, chi-square test, Pearson correlation, and multivariate linear regression (SPSS v25.0). Results: Mean serum Vitamin D was significantly lower in DED patients (14.2 ± 5.8 ng/mL) compared with controls (31.6 ± 7.4 ng/mL; p < 0.001). Vitamin D levels showed strong positive correlations with TBUT (r = +0.812, p < 0.001) and Schirmer's score (r = +0.774, p = 0.002), and a strong negative correlation with OSDI score (r = −0.836, p < 0.001). Multivariate regression identified Vitamin D as a potential predictor of TBUT (β = 0.74) and OSDI (β = −0.79), though findings should be interpreted cautiously given the small sample size. Goblet cell density, tear osmolarity, MMP-9, and IL-6 were all significantly deranged in the DED group (p < 0.001). Conclusion: Vitamin D deficiency appears to be significantly associated with DED severity and measurably impaired ocular surface parameters. These findings suggest that Vitamin D may represent a potentially modifiable systemic factor in the pathophysiology of DED. Routine assessment of Vitamin D status in DED patients and supplementation trials may be considered, pending confirmation in larger studies.