 The phenomenon can be interpreted as an adaptation of rapid binocular eye movements to the statistics of the 3D environment, in order to minimize the need for corrective vergence movements at the end of 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.