Nystagmus
In Medicine, the nystagmus is a movement of oscillation involuntary and jerked ocular sphere. Nystagmus is a disturbance of the coordination of the muscles of the eye. It can be caused by a pathology, movements very fast or the abuse certain substances.
The oscillations can occur in a vertical plan, horizontal, of torsion or in a combination of those.
More than forty types of nystagmus would have been classified. necessary
Physiological nystagmus
Physiological nystagmus, is due to a disturbance of the precise and meticulous coordination of the Muscle S of the eye, which ensure normally not only its mobility, but more especially, in the case which interests us, its immobility. Each eye moves thanks to the precise and meticulous coordination of six muscles (the muscles oculomoteurs).
These muscles allow:
-
to direct the Glance towards an object, whatever its situation in the space and whatever the position of the head and the body.
- to stabilize the eye on this object to allow a clear vision. Indeed, there exists on the Rétine only one limited zone where the vision is clear, the eye must thus be directed in such way that the image of this object is reflected on this precise zone (the Fovéa, in the center of the Macula).
- to maintain the eye motionless when one does not fix an object, which is extremely important, in order to prevent in particular that the eyes move in all the directions, for systematically following all the mobile visual events which surround us.
A physiological example of nystagmus is the movement of the eyes of a person sitting in a train and looking at the external landscape ravelling with sharp pace. Its eyes will try to follow certain details all while being frequently readjusted to the center of its field of view.
Pathological nystagmus
Pathological nystagmus originates in either a congenital disease, or an acquired pathology.
It would assign an individual on 5.000 to 10.000. necessary
Congenital nystagmus
At the time of a jerk, the Vision (in connection with the eye itself), is poor and visual perception (in connection with the Cerveau) is repressed, from where the side invalidating of nystagmus.
A pathological nystagmus is frequently accompanied by a strabism, which reduces also the vision into three dimensions.
All that prevents certain people reached of nystagmus to practice certain sports, to lead, to have a professional life…
The stability of the eye is ensured by the coordination of six muscles themselves under the dependence of multiple very complex factors.
Pathological nystagmus asset
-
via other diseases (Disease of Menière, Multiple sclerosis, tumors of brain, Syndrome of Wernicke-Korsakoff, Encephalopathy, side medullary Syndrome, Aniridia, Albinism, Syndrome of Noonan, disease of Pelizaeus-Merzbacher, Toxoplasmose,…)
- by intoxication (Barbiturate alcohol, anticonvulsifs, S, ecstasy,…)
- by accidents (cerebral traumatism, cerebral vascular accident,…)
Similar pathologies
One should not confuse nystagmus with other similar ocular disorders such as the Opsoclonus which is only made up of fast phases, whereas nystagmus is characterized by a succession of phases of slow displacements and phases of displacements jerked of the eye. Without apparatus of recording, the distinction between the two types of oscillations can appear very difficult to establish.
External bonds
Mailing list devoted to nystagmus
| Random links: | Mâyâ (Buddhism) | Longueville (Pas-de-Calais) | Nicolas de Neufville de Villeroy | Galéran IV of Meulan | Lelio Colista | Tam_Dalyell |