NGF and diabetic retinopathy: Altered VEGF/NGF synthesis and/or changes in the expression and activation of their specific receptors; namely, vascular endothelial growth factor 2 (VEGFR2) and tropomyosin-related kinase A (TrkA), respectively, have also been found to contribute to retina degenerative events, involving both the vascular system and the neurons similarly occurring in diabetic retinopathy (DR) [7,8].