Association Between Serum Vitamin D Levels and Retinal Vascular Occlusion: A Systematic Review and Meta-Analysis.

Previous studies found seasonal variations in the incidence of retinal vascular occlusion (RVO), with more occurrence in winter. There is increasing evidence linking vitamin D deficiency and RVO. Therefore, we conducted a meta-analysis to evaluate the association between vitamin D levels and RVO. From inception to February 2024, MEDLINE and EMBASE databases were comprehensively searched. Observational studies comparing 25-hydroxyvitamin D (25(OH)D) levels between adult patients with RVO and non-RVO controls were included. We calculated pooled mean difference (MD) and pooled odds ratio (OR) with 95% confidence intervals (CI) of our data using a random-effects model and generic inverse variance method. Five studies involving 528 patients (228 patients with RVO and 300 controls were included in the meta-analysis. 25(OH)D was significantly lower in patients with RVO (pooled MD of -9.65 (95%CI -13.72 to -5.59, I2 = 92.2%). Vitamin D deficiency (serum 25(OH)D < 20) was significantly associated with RVO with the pooled OR of 14.52 (95%CI 1.72 to 122.59, I2 = 90.5). There was no difference in 25(OH)D levels between patients with central RVO and branched RVO (pooled MD of -0.94 (95%CI -3.91 to 2.03, I2 = 59.1%). In conclusion, our meta-analysis demonstrates that serum vitamin D levels were lower in patients with RVO than non-RVO controls. Clinicians could consider screening for vitamin D deficiency in patients with RVO. Further studies are warranted to determine the correlation between vitamin D levels and disease severity and the role of vitamin D supplements in these populations.