GRIN2B and juvenile Huntington disease: Excitotoxicity is implicated in the degeneration of RGCs and optic nerves observed under pathologic conditions including glaucoma.5, 34 In addition, overactivation of NMDA receptors is thought to be a key contributing factor in the pathophysiology of many central nervous system disorders, such as Alzheimer's disease35 and Huntington disease.36 In the EAAC1 KO mouse retina, the phosphorylated NR2B expression level was upregulated, and BMD significantly inhibited this effect, suggesting that excitotoxicity is reduced in BMD-treated EAAC1 KO mice leading to increased RGC survival.