Neurotrophic factors have also been studied as potential neuroprotective factors in neurodegenerative diseases, with brain-derived neurotrophic factor (BDNF) and ciliary-derived neurotrophic factor (CNTF) both having been shown to protect axotomized RGC [54–56] and RGC in animal models of glaucoma [16, 57–61]. Here, BDNF is linked to neurodegenerative disease.