Glaucoma as a neurodegenerative disease

Purpose of review Glaucoma is a leading cause of irreversible world vision loss characterized by progressive retinal ganglion cell death. Elevated eye pressure is a major risk factor for glaucoma; however, despite effective medical and surgical therapies to reduce intraocular pressure, progressive vision loss among glaucoma patients is common. These observations suggest that mechanisms independent of intraocular pressure are also implicated in glaucomatous degeneration. Numerous similarities exist between glaucoma and neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Similarities include the selective loss of neuron populations, transsynaptic degeneration in which disease spreads from injured neurons to connected neurons, and common mechanisms of cell injury and death. Recent findings Glaucomatous injury to retinal ganglion cells has profound effects on target vision structures within the brain, including the lateral geniculate nucleus and visual cortex in experimental primate and human glaucoma. Mechanisms involved in central visual system damage in glaucoma include oxidative injury and glutamate toxicity, as seen in neurodegenerative diseases. Summary Glaucoma as a neurodegenerative disease is a valid working hypothesis to understand neural injury in the visual system. This paradigm may stimulate the discovery of innovative intraocular pressure-independent strategies to help prevent loss of vision in glaucoma patients.