Nystagmus

Nystagmus is abnormal movement of one or both eyes. This sheet tells you about this condition. It also tells you about diagnosis and treatment options.

Eye Movements with Nystagmus

With nystagmus, eye movements are quick and repetitive. They can be continuous (all the time) or paroxysmal (happening "on and off"). They are always involuntary (not controlled by the person). The direction of eye movements can be:

• Horizontal (side to side)

• Vertical (up and down)

• Rotary (around in a circle)

• See-saw (one eye goes up while the other goes down)

• Any combination of the above

Because of these abnormal movements, the eyes can't focus well. This impairs vision. To see better, a person may hold the head in an unusual position. This is done to access the "null point." This is an angle of vision that helps limit abnormal movement of the eyes. A person may also nod the head to reduce eye movement.

Types and Causes of Nystagmus

There are two main types of nystagmus. Each type can have one or more causes. But the exact cause is often unknown. Most cases of nystagmus are permanent.

• Congenital (or infantile) nystagmus. This is the most common type. The child is born with it. Symptoms appear soon after birth. This type has two main causes: sensory problems and neurologic problems. It can also be linked to other health conditions.

  • Sensory problems. Vision problems such as cataracts (a clouded lens of the eye) or glaucoma (increased pressure within the eye) may be a cause of nystagmus. Another possible cause is a problem with the retina (the light-sensing layer of nerves that lines the back of the eye) or the optic nerve (the nerve that connects the eye to the brain).

  • Neurologic problems. Problems in the brain can cause nystagmus. This is because the brain and the eyes must work closely together to make good vision possible.

  • Other conditions. Albinism (lack of pigment in the skin and eyes) and aniridia (absence of the iris of the eye) are linked to nystagmus.

• Acquired nystagmus. This type is not present at birth. It has several possible causes. These include:

  • Alcohol use

  • Use of certain medications (most often anti-seizure medications)

  • Inner ear disorders, such as Meniere's disease

  • Disease in the brain, such as multiple sclerosis or a brain tumor

  • Stroke

  • Injury to the head

Symptoms of Nystagmus

Symptoms depend on the type of nystagmus. With the congenital type, impaired vision may occur. But the eye movement may not be bothersome. With the acquired type, the eye movement may be more pronounced and bothersome. Blurry vision may occur. Also, depth perception may be affected. This can impair balance and coordination. It can also cause dizziness.

Diagnosis of Nystagmus

The doctor or eye care provider will take a health history. A physical exam, including an eye exam, will be done. And certain tests may be done. These include:

• CT (computed tomography) or MRI (magnetic resonance imaging) scan of the head. These imaging tests create pictures of the brain. They can show any swelling, stroke, or tumors that may be causing nystagmus.

• Electro-oculography (EOG). This tests the function of the retina. It does this by recording movement of the eyes.

• Vestibular testing. This checks for problems in part of your inner ear (the vestibule). This part of the ear helps control eye movement.

• Lab tests. These check for infections, an imbalance of chemicals in the body, and tumors.

Treatment of Nystagmus

In most cases, treatment helps reduce symptoms but does not eliminate them. Treatment depends on the cause of the nystagmus. There are five main treatment options:

• Treatment of the underlying cause. If there seems to be a clear cause, it is addressed. For instance, a cataract is treated or a tumor may be removed. If a medication is the cause, it may be stopped or replaced. Unlike with other causes, when these underlying causes are treated, nystagmus may be cured.

• Treatment of related vision problems. For instance, contact lenses or eyeglasses can help correct problems such as near- or farsightedness. Special prisms may be used to adjust the gaze. This helps reduce symptoms.

• Medications. These can help reduce symptoms, such as eye movement and vision loss.

• Botulinum injections. These weaken certain muscles within the eye. This helps reduce symptoms.

• Surgery. This procedure alters the position of the muscles that move the eyes. It does not cure nystagmus, but may reduce the amount the head needs to turn to see best.