Nystagmus

Panayiotis Stavrou

DefinitionNystagmus is an involuntary rhythmic shaking or wobbling of the eyes. The term nystagmus is derived from the Greek word ‘nystagmos’ which was used to describe the wobbly head movements of a sleepy individual.

Classification of Nystagmus

Doctors and researchers classify nystagmus by the characteristics of the eye movements like:

• back and forth like a pendulum• slowly in one direction and then rapidly in

another • laterally or vertically and by how much • how fast do the eyes move

Classification of Nystagmus

However there are over 45 types of nystagmus but traditionally nystagmus has been divided into two groups:

• sensory nystagmus (congenital): that begins very early in life and is related to vision loss.

• motor nystagmus (acquired): and is associated with neurological disorders and control of muscle function occurring later in life.

Congenital Nystagmus

• Congenital nystagmus occurs more frequently than acquired nystagmus. It can be insular or accompany other disorders.

• Types of congenital nystagmus include: albinism, aniridia, optic nerve hypoplasia,

achromatopsia, congenital cataracts, retinopathy.

Pendular Nystagmus

• The most typical nystagmus related to vision loss during childhood is a pendular nystagmus. The eyes rotate back and forth evenly, much like a pendulum.

Pendular Nystagmus

Acquired Nystagmus

Nystagmus can be acquired later in life due to neurological dysfunction, diseases or toxicity such as:

• cerebellar ataxia• thalamic hemorrhage• a head injury• stroke • multiple sclerosis• brain tumors• alcohol intoxication

Acquired Nystagmus• Unlike nystagmus acquired from early in life, patients with

late onset nystagmus usually notice movement in their vision related to the movement of their eyes. This is called oscillopsia. Oscillopsia causes a person to have dizziness related to the new movement they experience in their vision.

• Late onset nystagmus is more likely to be directional. The eye will move slowly in one direction, then quickly move back.

• The nystagmus may change as the patient looks in different directions.

• The unexplained onset of nystagmus in an adult may indicate a serious neurological disorder and an immediate examination is indicated.

Acquired Nystagmus

Acquired nystagmus is subdivided into:• Horizontal Pendular Nystagmus.• Vertical Pendular Nystagmus• Seesaw nystagmus• Elliptical nystagmus• Dissociated Nystagmus

Horizontal Pendular Nystagmus

Most frequently, horizontal or pendular nystagmus is caused by:

• central lesions involving the central tegmental tract

• damage of the cerebellar nuclei• lesion near the oculomotor nuclei

Horizontal Pendular Nystagmus

Vertical Pendular Nystagmus

Vertical nystagmus occurs much less frequently than horizontal nystagmus and is often, but not necessarily, a sign of serious brain damage. T

The most common cause vertical nystagmus that frequently appears after:

• pontine hemorrhage related to damage to the central tegmental tract.

• toluene sniffing, glue sniffing, usually in accompaniment with cerebellar deficits

Vertical Pendular Nystagmus

• Seesaw or jerk nystagmus is a rare binocular disorder characterized by alternating vertical skew deviation and conjugate ocular torsion. Jerk seesaw consists of torsional slow phases in one direction and quick phases in the opposite.

See saw Nystagmus

See saw Nystagmus

Fluctuations in Vision

Nystagmus patients often experience fluctuations in their vision. A change in the speed of the nystagmus leading to a decrease in vision can be related to:

• stress• the patient’s emotional state• fatigue• the direction of view

The Null Position

• Patients with nystagmus often find a unique position of their head and eyes that slows the nystagmus allowing them to have better vision. This is called a null position and varies with each person.

Treatment

Congenital nystagmus has traditionally been viewed as non-treatable, but medications have been discovered in recent years. Several therapeutic approaches are also proposed, such as:

• contact lenses• drugs• surgery

Treatment

Gabapentin, an anticonvulsant, was found to cause improvement in about half the patients who received it to relieve symptoms of nystagmus.Other drugs found to be effective against nystagmus in some patients include:

• memantine• levetiracetam• acetazolamide

Treatment

• Clinical trials of a surgery to treat nystagmus known as tenotomy. Tenotomy aims to reduce the eye shaking (oscillations), which in turn tends to improve visual acuity.