Purpose of review: Studying eye movements can provide insight into how the normal brain works, how diseases affect eye movements, and how eye movement abnormalities can be used to study diseases and/or their treatments. In this review, we concentrate on recent studies looking at abnormalities of saccades in various diseases.
Recent findings: Various saccadic abnormalities have been found in Parkinson's disease, Huntington's disease, dementia, cerebellar disease, schizophrenia, and several other conditions. In some of these, saccadic abnormalities appear to be capable of distinguishing different subtypes (e.g., progressive supranuclear palsy from idiopathic Parkinson's disease, Alzheimer's disease from frontotemporal dementia, or one type of spinocerebellar ataxia from another). Several studies have looked at functional associations of saccadic abnormalities (e.g., reading in spinocerebellar ataxia or recovery from stroke), which may prove clinically useful. Studies on microsaccades have revealed abnormalities in various diseases, and suggest that they may provide a useful marker of fatigue.
Summary: Saccadic eye movements provide an excellent way of studying the human motor system in health and disease, as well as providing insight into various aspects of cognitive function. Assessment of saccades in the laboratory and at the bedside is likely to become increasingly useful clinically.