IGF1 and proliferative diabetic retinopathy: On the other hand, the activation of IGF-1 signaling has been implied in the pathogenesis of ocular diseases characterized by neovascularization, such as age-related macular degeneration (AMD) and proliferative diabetic retinopathy (PDR), principally due to IGF-1-stimulated vascular endothelial growth factor A (VEGF-A) secretion [21].