The question is what the benefits of these eye movements are. To put it simply, one can retain the picture of what they want to see on the macula using a complex mechanism involving a tight relationship of the equilibrium system with the brain and the visual system, which helps maximize the vision and prevent the movements of the object, the body or the head from changing the picture. If compensatory mechanisms cannot retain the picture on the retina by causing corrective eye movements in response to the head movements, one cannot obtain a clear vision of the object.
The Following Examples Will Clarify the significance of nystagmus :
- One cannot continuously have a completely clear picture of a mobile object in the absence of smooth pursuit eye movements.
- In the absence of nystagmus movements, we would not be able to watch the outside of a moving train from the inside in real time and the images would pass from our view like a blurry and vague movie. In the present example, we trace the images of the outside objects using a smooth movement in the opposite direction of the train, and the eyes return to their initial point using a saccadic movement when the object disappears from our field of vision.
Causes of Nystagmus
Nystagmus is mostly congenital and can be sensory or motor in type. Sensory nystagmus is associated with an underlying eye disease causing a severe visual impairment since birth, such as cataracts, congenital glaucoma, albinism and congenital disorders of the retina and the optic nerve. Other ocular disorders are absent in motor nystagmus and the patients have good vision.
Nystagmus is rarely caused by brain tumors or severe neurological disorders. Nystagmus may be congenital and is not associated with other diseases.
Nystagmus can also be caused by medications. This type of nystagmus is rarely associated with double vision and often causes problems with peripheral vision. Other causes include heavy drinking or use of medicines for controlling the disease. This type of nystagmus is often relieved by stopping the medication.
Some people can create voluntary nystagmus, as they can move their ears. In other words, they can create horizontal, fast and fine movements and continue them for a short time. This type of nystagmus is often used for drawing attention.
Disease-associated nystagmus is rare and often associated with neurological symptoms showing the disease severity.
The main symptom of nystagmus is the rhythmic movements, which are often detectable by the naked eye. The abnormal compensatory head position in some of the patients is used for minimizing nystagmus. Strabismus may also be present in some patients with nystagmus.
In addition to the above symptoms, other visual symptoms of underlying diseases can be diagnosed in sensory cases, including drooping eyelid, cataracts and the disease of the retina or the optic nerve. If it is diagnosed that nystagmus is likely to be caused by a neurological disorder, the necessary comprehensive examinations should be done in this regard and the child should be immediately referred to a neurologist.