Nystagmus is mainly a defect of efferent mechanism, which is related to Congenital heredity, but not necessarily related to myopia.
Nystagmus refers to the involuntary and rhythmic eye movement. According to the direction of nystagmus, it can be divided into horizontal type, vertical type and rotation type.
According to the amplitude and speed of tremor, it can be divided into swing type and impulsive type. The latter has the difference of fast phase and slow phase, that is, one direction is slow phase. After the eyeball slowly turns to one side, it suddenly turns to the opposite direction in a beating manner, forming a fast phase. Generally speaking, the fast phase represents the direction of nystagmus, and the fast phase is the compensatory movement to restore the fixation position. Swing type nystagmus is from the center to both sides of the swing, the swing amplitude and speed is approximately the same.
The causes of nystagmus are congenital and acquired. The visual impairment caused by congenital eye deformity, albinism, cataract, total color blindness, macular damage and so on. Due to the lack of fixed fixation ability, the eyeball shows horizontal tremor, which is called ophthalmic tremor.
Adult long-term work in the dark can also cause nystagmus, known as miner’s nystagmus. Central nervous system disease, such as cerebellar disease, vestibular nucleus disease caused by nystagmus is called central nystagmus. Labyrinthine nystagmus is a disease of the middle ear or inner ear, which causes irritation or inhibition of the labyrinth, and can cause horizontal or rotational nystagmus,
In addition, nystagmus can be induced when the normal person’s eyes are extremely fixed on both sides or on a fast-moving train, which is a physiological phenomenon.