In contrast, analyses of chick retina/RPE during the development of form deprivation myopia demonstrated only minimal changes in retinal gene expression, including downregulation of bone morphogenetic protein 2, vasoactive intestinal peptide, preopro-urotensin II-related peptide and mitogen-activated protein kinase phosphatase 2, and upregulation of endothelin receptor type B and interleukin-18 [39]. Here, VIP is linked to myopia.