The effect of Vitamin D supplementation on clinical and biological markers of keratoconus progression

Abstract

Purpose : To test whether vitamin D (Vit D) supplementation impacts clinical progression, and the levels of systemic biomarkers of collagen metabolism and inflammation in adolescent patients affected with keratoconus (KC)

Methods : This study enrolled forty adolescent patients (age range: 12-19) affected with KC and Vit D insufficiency (< 30 ng/mL). The patients received vitamin D supplementation for 6 months, and were followed up for additional 6 months (total study duration: 12 months). Clinical parameters, including best spectacle-corrected visual acuity (BSCVA), maximal keratometry (Kmax), and thinnest corneal thickness (TCT) were measured at each visit. Moreover, serum biomarkers of Vit D metabolism, collagen degradation, and inflammation were quantified by ELISA or RT-PCR.

Results : We found that Vit D supplementation arrested KC progression in two-third of patients. Notably, Vit D levels were significantly increased already after 4 months of treatment (P < 0.0001), and remained stable up to the 12 month follow up visit (P < 0.0001). Moreover, at month 6 the expression of VDR was upregulated in clinically stable patients (P < 0.01). Systemic biomarkers of collagen degradation showed decreased levels of type I collagen degradation product (ICTP; P < 0.01), procollagen type I carboxy-terminal propeptide (PICP; P < 0.0001), and the ratio between matrix metalloproteinase 9 and tissue inhibitor of matrix metalloproteinase-1 (MMP-9/TIMP-1) (P < 0.05). In addition, Vit D supplementation significantly modulated systemic inflammation, as suggested by the increased expression of CD14 (P < 0.0001) and decreased levels of lactoferrin (P < 0.0001).

Conclusions : Our findings show that Vit D supplementation reduces systemic inflammation and collagen catabolism, which is associated with substantial clinical stabilization of KC progression in adolescent patients. Moreover, these data provide preliminary evidence that KC could be a systemic disease.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.