The optic neuropathy of Alzheimer's disease

Patients with Alzheimer's disease, or more often their families, frequently complain of problems with vision. Nonetheless, clinicians have tended to attribute these symptoms to impaired cognitive functions. Alzheimer patients have been ascribed to disease in the cerebral cortex. However, we have demonstrated that patients with Alzheimer's disease also have a primary optic neuropathy. Degeneration is noted in the retinal ganglion cell layer of the retina and among axons of the optic nerve. In particular, there appears to be a predilection in early Alzheimer's disease for injury to the largest retinal ganglion cell axons. Clinical assessments of patients with Alzheimer's disease demonstrated that patients with only mild dementia have excellent visual acuity. However, they demonstrate deficits in eye movements, visual evoked responses, and contrast sensitivity functions. Patients with more severe Alzheimer's disease are hard to evaluate but they demonstrate severe impairments of vision of many types including visual acuity. The differential involvement of various types of retinal ganglion cells and of different visual functions in early Alzheimer's disease further emphasizes the nature of parallel processing in human vision.