Nystagmus

What is nystagmus?
Nystagmus is an unintentional jittery movement of the eyes. Nystagmus usually involves both eyes and is often exaggerated by looking in a particular direction.

What causes nystagmus?
Many conditions are associated with nystagmus. Sometimes, the brain's control of eye movements is poor, resulting in an inability to look steadily at an object. Some forms of nystagmus are associated with reduced vision, such as occurs in albinos, extreme near or farsighted people, or in those with scars in the retina or optic nerve. Rarely, nystagmus can occur as a result of brain tumors or in serious neurological disorders. Nystagmus can also be found in families as an isolated problem, not associated with other conditions.

If nystagmus is present, what should be done?
A thorough evaluation by an ophthalmologist and perhaps other medical specialists is very important. Some forms of nystagmus have a definite cause. Important clues are related to age of onset, family history, general health of the patients, or the use of certain medications. Your ophthalmologist may examine the pattern of the nystagmus, its speed and direction and look for other eye problems such as a droopy lid, cataract, or an abnormality of the retina or optic nerves. Blood tests or special x-rays may be useful in determining the cause.

Can nystagmus be cured?
Sometimes removal of the cause may improve nystagmus. Often, however, nystagmus is permanent. The reduced vision may be improved with glasses and low vision aids. The eyes are more stable looking in a certain direction and glasses with prisms or eye muscle surgery may improve the head position and allow better vision. Medications and biofeedback have rarely helped to control nystagmus.

What are the most common forms of nystagmus?
Motor nystagmus (or congenital nystagmus) tends to begin between six weeks and three months of age. Other family members may have similar unusual eye movements. The motion is usually horizontal. Often focusing up close or looking in an odd direction reduces the nystagmus intensity and improves the vision. Fortunately, patients do not see the world moving as their eyes move. Vision may be reduced at distance, but is almost normal up close.

Sensory nystagmus (or acquired nystagmus) is associated with reduced vision of any cause. Sensory nystagmus usually begins at 6 to 8 weeks of age. The eyes appear to rove, sometimes slowly and sometimes quickly. Very often the eyes will also rotate upward, and the eyelids may flicker as well. As a baby becomes older, he may poke at his eyes or wave his hand in front of them. Sometimes the cause for the reduced vision is treatable, as in babies who are born with cataracts. Other conditions which lead to sensory nystagmus may not be treatable. Nevertheless, understanding the underlying cause is of great importance to predicting how the baby will do in the future.

What are other causes of nystagmus?
Medications or drugs can cause nystagmus. Rarely, this nystagmus can be associated with double vision and is often worse looking to the side. Causes include excessive drinking of alcohol or use of medications such as those given for seizure control. Often, the nystagmus will improve if the medication is stopped.

Voluntary nystagmus can be created by some people, much in the same way as ear wiggling. Fine, rapid, horizontal movements can be produced and sustained for a short period of time. Often, this kind of nystagmus is used to gain attention.

Disease-induced nystagmus is less common. It is often associated with neurological signs and symptoms which indicates the seriousness of the problem.

Summary
If nystagmus is present, a full eye examination by an ophthalmologist is needed. Underlying causes which determine the effect on the patient's life and vision vary greatly.

Why are regular medical eye examinations important for everyone?
Eye disease can strike at any age. Many eye diseases do not cause symptoms until the disease has done extensive damage. Since most blindness is preventable if diagnosed and treated early, regular medical examinations by an ophthalmologist are very important.