Vergence Eye Movements

This chapter reviews the stimuli for vergence, the properties of fusional and accommodative vergence, as well as vergence made in combination with saccades or vestibular eye movements, or blinks. Different properties of horizontal, vertical, and torsional vergence are discussed. Current models are presented to account for interactions between vergence and saccades. The neural substrate for vergence movements is reviewed from ocular motoneurons to the midbrain supraoculomotor area, to visual cortical areas such as MST and frontal eye field, including pontine nuclei, cerebellar vermis, and fastigial nucleus. Adaptive properties of vergence are reviewed, especially phoria adaptation, discussing the role of the cerebellum. The bedside and laboratory evaluation of vergence is summarized and the pathophysiology of disorders of vergence discussed, including developmental disorders associated with childhood strabismus and acquired disorders such as convergence spasm, convergence insufficiency, vergence forms of nystagmus such as convergence-retraction nystagmus, and effects of focal pontine lesions.