Binocular micromovements in normal persons.

Under physiological viewing conditions, binocular micromovements in normal subjects showed multiple saccadic formations which, in their vertical and horizontal components, combined to produce different forms of overshoot which were usually large. On comparing the right and left eyes, micromovements were considerably incongruous, though rough direction identity and absolute synchronism of saccades and drifts were given. Vertical, horizontal and overshoot components of saccades show good correlation in their amplitude/velocity relationship, as seen in voluntary large saccades. Formation, frequency and direction of saccades showed intra-individual similarity rather than dependence on viewing conditions. From our results, we concluded that a central generating process rather than the primary retinal error signals are the source of micromovements during fixation.