Ophthalmological aspects of Alzheimer's disease.

Patients with Alzheimer's disease may present to the ophthalmologist with visual symptoms that precede or overshadow the features of dementia. This visual variant of Alzheimer's disease has been recognized only recently and typically appears in late middle age as progressive visuospatial and reading dysfunction, with normal visual acuity and fields. Common features include simultanagnosia and the other features of Balint's syndrome, and variable hemispatial neglect and hemianopia. The neuroimaging and neuropathological findings in this Alzheimer's variant are distinct and suggest disruption of occipitoparietal visual projections. The identification of the visually symptomatic patient who is destined to develop other signs of Alzheimer's disease depends on the use of appropriate screening tests, including text reading, figure-ground discrimination, and other bedside tests of visuospatial attention and perception.