Recent studies have reported a possibility that blockade of axonal transport in glaucoma leads to deficits in the neurotrophic factors and subsequent RGC death in adult eyes.38 Retrograde transport of radiolabeled BDNF was impaired following IOP increase in rats, and accumulation of TrkB immunolabeling was found in the optic nerve head in this model.39 Therefore, supplementation therapy using neurotrophic factors is an attractive method for protection of RGCs and axons in glaucoma. This evidence concerns the gene NTRK2 and glaucoma.