BDNF and optic nerve disorder: Different approaches have been used to manipulate BDNF levels, such as intravitreal injection of BNDF protein, infection with adeno-associated virus expressing BDNF for gene therapy, and transplantation of stem cells in animal models of experimental glaucoma or optic neuropathy (Mey and Thanos, 1993; Chen and Weber, 2001; Martin et al., 2003; Harper et al., 2011).