A recent meta-analysis conducted in China confifirms an association between vitamin D and dry eye disease (DED). The results suggest vitamin D deficiency is associated with worse subjective symptoms and less tear production in patients with dry eye.

Researchers analyzed 10 studies (n=18,919 patients) and found that DED patients had a lower mean serum vitamin D level than healthy controls by 3.99ng/ml. The mean Ocular Surface Disease Index (OSDI) score was higher by a mean difference of 10.70, and the Schirmer’s test without anesthesia results were lower by a mean difference of 6.38 mm/5min in patients with vitamin D deficiency compared with controls. The reduction in tear production would account for the worse symptoms reflflected by higher OSDI scores in patients with vitamin D defificiency, the researchers noted in their paper. However, the tear break-up time score was comparable between patients with vitamin D defificiency and controls.

 The researchers believe the mechanism of vitamin D’s effect on tear production and tear film stability as well as vitamin D’s protective role in the development of dry eye requires further investigation. Still, they believe vitamin D supplementation could be a potential therapeutic strategy for patients with vitamin D defificiency and DED resistant to conventional treatment.