VEGFA and vitamin D deficiency: As vitamin D directly affects the vascular endothelial stability, its deficiency will most likely affect the incidence of RoP in premature infants who are at risk of vitamin D deficiency.32 The inflammatory and angiogenic effects of vitamin D deficiency can cause early damage to the retinal blood vessels.33In vitro studies have shown that vitamin D improves the angiogenic properties of precursor cells through upregulation of the expression of vascular endothelial growth factor.