Lutein supplementation may enhance RGC survival in part by improving the axoplasmic flow of neurotrophins between the ganglion cell body and its distal synapse located deep in the brain [53,230]; in fact, lutein was seen to increase retrograde transport of brain-derived neuronal trophic factor (BDNF) in a murine model of diabetic neurodegeneration [205]. This evidence concerns the gene BDNF and diabetes mellitus.