Pathophysiologic Saccades
Saccadic oscillations not fitting the normal function are a deviation from a healthy or normal condition. Nystagmus is characterised by the combination of 'slow phases', which usually take the eye off the point of regard, interspersed with saccade-like "quick phases" that serve to bring the eye back on target. Pathological slow phases may either be due to an imbalance in the vestibular system, or damage to the brainstem "neural integrator" that normally holds the eyes in place. On the other hand, opsoclonus or ocular flutter are composed purely of fast-phase saccadic eye movements. Without the use of objective recording techniques, it may be very difficult to distinguish between these conditions.
Eye movement measurements are also used to investigate psychiatric disorders. For example, ADHD is characterized by an increase of antisaccade errors and an increase in delays for visually guided saccade.
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