bubble_chart Overview

Nystagmus, commonly referred to as eye tremor, is an involuntary, rhythmic, and oscillatory movement of the eyes. It is often caused by disorders of the visual system, extraocular muscles, inner ear labyrinth, or central nervous system. Nystagmus can be classified into two main categories based on disease cause, clinical features, and related neuro-ophthalmic conditions: ① sensory defect nystagmus, such as gaze nystagmus; ② motor defect nystagmus, such as gaze palsy nystagmus.

bubble_chart Clinical Manifestations

1. Jerk type: The eyeball exhibits obvious reciprocating movements at different speeds. When the eyeball slowly turns to one direction to a certain extent, it suddenly returns with a jerky movement. Therefore, this type of tremor has both slow and fast phases. The slow phase is the physiological phase, while the fast phase is the corrective movement of the slow phase. The direction of the fast phase is considered the direction of the eyeball tremor, and the fast phase is related to the disease cause.

2. Pendular type: The oscillation of the eyeball resembles a pendulum, with no fast or slow phases. The speed and amplitude are equal on both sides. It is commonly seen in patients with bilateral amaurosis or amblyopia.

bubble_chart Auxiliary Examination

1. General Examination

Directly observe the patient's nystagmus when they gaze straight ahead or follow the examiner's finger moving in a certain direction. Some examinations require monocular occlusion. For this purpose, the following points should be noted during the examination:

1. Whether the nystagmus is latent or manifest.

2. Whether the nystagmus is conjugate—movements of both eyes are consistent with each other—or dissociated.

3. The type, direction, degree, frequency, and amplitude of the nystagmus.

4. The presence or absence of a resting position.

2. Special Examination

Instrumental examinations such as electronystagmography.

bubble_chart Treatment Measures

1. Disease cause Treatment: Symptomatic treatment.

2. Improve vision: For ocular nystagmus, the focus is on enhancing vision and preventing the primary condition that causes visual impairment. Appropriate prism glasses can also be prescribed to eliminate compensatory head posture and improve vision.

3. Surgical treatment: For congenital jerk-type nystagmus (i.e., gaze-dependent nystagmus), surgery can be performed. The goal is to correct the compensatory head posture based on the "null zone" gaze position, shift the gaze position, reduce nystagmus, and improve vision. Since the extraocular muscles on the slow-phase side are stronger, while those on the fast-phase side are weaker, the two extraocular muscles on the slow-phase side can be recessed to weaken their tension, balancing them with the muscles on the fast-phase side. This shifts the "null zone" gaze position from an eccentric fixation position to a straight-ahead fixation position.

For example, if the left side is the null zone for gaze-dependent nystagmus, the left lateral rectus and right medial rectus can be recessed by 6 mm, while the left medial rectus is resected by 6 mm and the right lateral rectus by 7 mm (typically, the lateral rectus is recessed 2 mm more than the medial rectus), moving the null zone gaze position forward.