BDNF and glaucoma: In addition, the role of neurotransmitters such as glutamate, glycine, dopamine, serotonin, etc., and neurotrophins, such as the brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3), and neurotrophin-4/5 (NT4/5) in glaucoma, has also been extensively investigated (35, 36).