Disorders of the visual system in Alzheimer's disease.

Alzheimer's disease (AD) is associated with disturbances in basic visual, complex visual, and oculomotor functions. The broad range of visual system disorders in AD may result from the concentration of neuropathology in visual association cortex and optic nerves in this disease. AD patients and their caregivers frequently report visuospatial difficulties in these patients. Examination of the visual system in AD may reveal visual field deficits, prolonged visual evoked potentials, depressed contrast sensitivities, and abnormal eye movement recordings. Complex visual disturbances include constructional and visuoperceptual abnormalities, spatial agnosia and Balint's syndrome, environmental disorientation, visual agnosia, facial identification problems, and visual hallucinations. The purpose of this article is to review the spectrum of visual system disturbances found in AD and, in particular, to describe the methods used to screen for complex visual abnormalities in these patients.