This is an important consideration, given the finding that SEMA3A induces retinal oedema in a mouse model of PDR and the observed upregulation of SEMA3A in the retina during the early hyperglycaemic phase in diabetic patients with macular oedema (Cerani et al., 2013) (see Sections 3.3, 3.4). Here, SEMA3A is linked to optic papillitis.