Nystagmus

Ocular Ataxia

What is Nystagmus?

Nystagmus is an uncontrollable (involuntary), repetitive, rhythmic movement of the eyes. The movement is usually horizontal, but can be vertical or in a circular direction. Nystagmus is classified in terms of the fast and slow components of movement, character (regular, irregular, rotary or circular), and degree of involvement of either eye. In almost all types, both eyes move together. Nystagmus may occur only when the individual looks in one direction or it may be present continuously. It is noticeable and aesthetically disturbing.

Nystagmus is caused by a disorder of the nervous mechanisms that hold the eyes steady. It is almost always present at birth (congenital) but may caused by disease. It is not usually associated with any other abnormality of the eyes. The cause is unknown. In jerky nystagmus, the most common type, the eyes repeatedly move slowly in one direction, then jerk rapidly in the other. Because jerky nystagmus is permanent, making steady gaze impossible, there is almost always moderate to severe loss of visual acuity (clearness, sharpness).

Nystagmus can be the result of other severe congenital defects including congenital cataract, retinal disease, or optic atrophy. Nystagmus also occurs in congenital albinism (absence of pigment in skin, hair, and eyes) because the choroid (layer of blood vessels behind the retina at the back of the eye) is not adequately protected from light due to lack of pigment.

When it appears later in life, persistent nystagmus indicates the presence of a nervous system disorder, such as meningitis, brain tumor, or multiple sclerosis. It may occur as a result of a balancing mechanism disorder in the inner ear. Nystagmus can also occur as a side effect of anticonvulsant, barbiturate or sedative medications, or of alcohol. Three types of nystagmus are normal and can be produced by artificial stimulation. For example, optokinetic nystagmus occurs as a normal response to an individual's attempt to follow a sequence of objects rapidly passing the eyes.

How is it diagnosed?

History: Symptoms of Nystagmus include the inability to hold a steady gaze upon an object with resulting decreased vision. Objects may seem to move (oscillopsia). There may be dizziness, ringing in the ears (tinnitus), or hearing loss.

Physical exam: Eye movements are observed. Past pointing and head tilting in an attempt to control nystagmus may be noted.

Tests done to detect visual impairment may include visual acuity (measures sharpness and visual discrimination) and visual field (measures the total area in which visual perception is possible). Electronystagmography (method of recording eye movements), caloric, and optokinetic stimulation tests may be done to help classify the type of nystagmus.

How is Nystagmus treated?

Treatment is directed at the underlying cause. In some cases, prism glasses or surgery may help to improve vision.

Medications

Information Brand Generic Label Rating
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Phenergan (Promethazine), Klonopin (Clonazepam)

What might complicate it?

The inability to hold a steady gaze almost always results in moderate to severe loss of visual acuity. Each eye may have its own independent movements, which can cause additional vision impairment.

Predicted outcome

Depending on the cause, nystagmus may disappear with appropriate treatment of the underlying condition. When part of a congenital disorder, nystagmus tends to be permanent.

Alternatives

Conditions with similar symptoms include brain disorders such as macrosquare wave jerks, ocular dysmetria, ocular flutter, and opsoclonus.

Appropriate specialists

Ophthalmologist, internist and neurologist.

Last updated 21 December 2011


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