In a retinal disease such as diabetic retinopathy, VIP may contribute to the protection of retinal neurons by reducing outer BRB dysfunction [183,184], probably through an inhibition of VEGF and of hypoxia-inducible factor 1α (HIF1-α), the main transcriptional regulator of VEGF expression [185]. The gene discussed is HIF1A; the disease is diabetic retinopathy.