Vitamin D and its receptor polymorphisms are associated with glaucoma.

Purpose: To clarify the association between serum vitamin D levels and its receptor polymorphisms with glaucoma risk.

Methods: A meta-analysis was performed from available studies investigating serum vitamin D levels and vitamin D receptor (VDR) polymorphisms in glaucoma patients and controls.

Results: Twelve studies in total, including 130,676 and 476 subjects, were analysed for the association between serum vitamin D levels and VDR polymorphisms with glaucoma, respectively. Collectively, it was found that glaucoma patients have lower levels of vitamin D compared to controls (SMD=-1.16, 95% CI=-1.56--0.76, P<0.00001). In parallel, the pooled results showed a significant association between glaucoma and allelic (b vs. B, OR=1.84, 95% CI=1.37-2.46, P=0.00001) and recessive (bb vs. Bb+BB, OR=3.16, 95% CI=1.30-7.66, P=0.001) models of VDR BsmI (rs1544410) polymorphism, but not with VDR TaqI (rs731236) or FokI (rs2228570) polymorphisms.

Conclusion: This meta-analysis suggests that patients with glaucoma may have vitamin D deficiency. In addition, the vitamin D signalling cascade may be a contributing factor in developing glaucoma, which is supported by the evidence that b allele carriers of VDR BsmI exhibited an increase in the risk of glaucoma. Thus, dietary supplementation of vitamin D may become an important approach as an additional treatment for glaucoma.