Excitotoxic damage due to elevated glutamate has been associated with many acute and chronic neurodegenerative diseases of the retina and brain, including stroke, Alzheimer's disease and glaucoma.31, 32, 79 The inner retina is particularly vulnerable to excitotoxic and metabolic stress, which is exacerbated through the release of TNF-α by neighboring astrocytes and Müller glia.28, 33 However, the astrocyte reactivity cascade is a complex process that has both positive and negative aspects. The gene discussed is TNF; the disease is Alzheimer disease.