Nystagmus

Advances in understanding the organization of the ocular motor system, including its anatomy and pharmacology, have provided new insights into the pathogenesis of various forms of nystagmus. The discoveries of fibromuscular pulleys that govern the pulling directions of the extraocular muscles has provided a new conceptual framework to account for the different axes of rotation of vestibular and other types of movements that may contribute to nystagmus. Theoretical and experimental evidence has suggested that acquired pendular nystagmus, which is commonly due to multiple sclerosis, arises from the neural network that normally guarantees steady gaze by integrating premotor signals. Pharmacologic inactivation studies have implicated both gamma-aminobutyric acid (GABA) and glutamate as important transmitters in the neural integrator and suggested new drug therapies. New electro-optic devices may eventually prove to be effective treatment for the visual symptoms cause by acquired nystagmus. The demonstration of proprioceptive mechanisms in the distal extraocular muscles has provided a rationale for new operative treatments for congenital nystagmus.