Direction of the nystagmus
When fixing a point while driving, the eye moves slowly in vertical direction against the driving direction. The movement is very slow. This eye movement is followed by a fast reset nystagmus in the direction of travel.
The same sequence of movements is triggered during the swivel chair test. At first, the eye movement takes place against the direction of rotation, followed by a fast movement in the direction of rotation. After stopping the chair, the directions of rotation change for a short moment, which is attributed to the inertia of the endolymph.
After a short time, the eye is then again in a resting state. In thermal testing of the nystagmus, the direction of vision depends on the temperature used. For example, a rinsing with a cool liquid would direct the nystagmus in the direction of the opposite ear, while a warm solution used would cause a nystagmus in the direction of the rinsed ear. Pathological nystagmus, due to damage or injury to the brain stem, can lead to both left- and right-turning nystagmus, as well as to fast but also very slow eye movements.
Nystagmus in the baby
If a nystagmus occurs in newborns, caution is advised. Because there can always be a serious illness behind it. Also known as congenital nystagmus, this is a congenital eye tremor that usually increases when a point is fixed.
It has a horizontal flapping direction and is usually irregular. In certain directions of gaze, this eye tremor is attenuated, while in others it is increased. The cause of congenital nystagmus can be disturbances in the oculomotor system, i.e. disturbances in the coordination of the eye muscles.
In addition to this cause, severe ametropia can also trigger a congenital nystagmus in newborns. The eye tries to collect many points of view in its surroundings because it is not able to represent a point more precisely. This results in a nystagmus.
Tumors or damage to the central nervous system are practically never the cause of a congenital nystagmus. Nevertheless, imaging of the head should be performed, even in newborns, if no other causes for the nystagmus can be found.
