Tim J. Anderson, Michael R. MacAskill

The neural pathways and brain regions involved in eye movements during ocular fixation and gaze control include the cerebrum, brainstem and cerebellum, and abnormal eye movements can indicate the presence of neurodegeneration. In some patients, oculomotor signs are key to making a diagnosis. Careful clinical examination of eye movements in patients with neurodegenerative disorders is, therefore, an invaluable adjunct to neurological and cognitive assessments. Eye movement recordings in the laboratory are generally not necessary for diagnostic purposes, but can be a useful addition to the clinical examination. Laboratory recordings of eye movements can provide valuable information about disease severity, progression or regression in neurodegenerative disease, and hold particular promise for objective evaluation of the efficacy of putative neuroprotective and neurorestorative therapies. For example, aspects of saccade performance can be tested to probe both motor and cognitive aspects of oculomotor behaviour. This Review describes the oculomotor features of the major age-related movement disorders, including Parkinson disease, Huntington disease, dementia and other neurodegenerative disorders. Findings in presymptomatic individuals and changes associated with disease progression are discussed.