Nystagmus is an involuntary rhythmic back and forth movement of the eye, referred to as nystagmus. 1, Peripheral lesions of the vestibular system, central lesions and certain eye diseases can cause nystagmus. 2. The observation indicators of nystagmus include the direction, frequency, intensity, amplitude, latency and duration of nystagmus. The direction of nystagmus can be classified as horizontal, vertical, rotational and diagonal. The slow phase of nystagmus is a slow movement of the eye in a certain direction caused by vestibular stimulation, while the fast phase is a central corrective rapid eye movement, with the slow phase toward the side with lower vestibular excitability and the fast phase toward the side with higher vestibular excitability. The direction of the fast phase is usually taken as the direction of nystagmus. The intensity of nystagmus can be divided into 3 degrees: Ⅰ° nystagmus only appears when gazing to the fast phase side, Ⅱ° nystagmus appears when gazing to the fast phase side and forward, and Ⅲ° nystagmus appears when gazing forward and to the fast and slow phase directions. Vestibular nystagmus is characterized by: 1) rhythmic, with the fast phase facing the affected side in the early stage of the disease and turning to the healthy side in the late stage; 2) generally medium frequency, small amplitude, and intensity of I-II degrees; 3) mostly mixed horizontal and rotational nystagmus, and occasionally pure horizontal or rotational nystagmus, but no vertical and diagonal nystagmus; 4) short duration, mostly accompanied by vertigo, tinnitus, and deafness.