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What is nystagmus? | Nystagmus and vision | Causes | Types | Treatment

What is nystagmus?

Nystagmus is involuntary, repetitive movements of the eyes. It usually occurs in both eyes. Generally nystagmus begins when the person is an infant and never goes away. Most often, the eye movements are from side to side, but they may be up and down or in a circular motion. As the child grows, the movements may get smaller. The eye movements may be more noticeable when the child is upset and less noticeable when the child is concentrating on something. They go away when the child is asleep. Some children can feel the movements. People who have nystagmus are often embarrassed and don't want to make eye contact with other people.

Nystagmus and vision

The vision of a person with nystagmus could be compared to taking a rapid series of pictures with a shaking camera. The only time the brain can process the visual image is when the eye is still. This occurs when the eye is changing directions at the end of the movement. The brain suppresses the image when the eye is moving. As a result, the vision of a person with nystagmus is blurred, but not jumpy. People with nystagmus don't see normally. The severity of their vision deficit usually depends on how much the eyes move.

Eye movements may be less intense if the child looks to the side or if the child moves his or her head rhythmically to compensate for eye movements. Nystagmus usually doesn't interfere as much with close vision and reading as it does with distance vision. Over time, nystagmus and a person's vision may improve slightly, but doctors don't know why.

If you or your child are experiencing some of the symptoms described here, it does not necessarily mean you have nystagmus. However, if you experience one or more of these symptoms, you should contact your eye doctor for a complete exam. Click here for information on emergency or immediate care.

Causes

Nystagmus is not usually inherited, and sometimes the cause isn't known. However, it is probably due to a problem in the eye movement control system in the brainstem.

Nystagmus can be the result of other eye disorders such as congenital blindness, Leber's congenital amaurosis or other hereditary retinal diseases, retinopathy of prematurity, retinoblastoma, retinal and optic nerve colobomas, tumors and developmental defects of the optic nerve, congenital cloudiness of the cornea, or achromatopsia.

Nystagmus is sometimes the result of a systemic disorder called albinism. Almost all albinos have nystagmus. Sometimes it is due to a brain disorder such as cerebral palsy or another brain abnormalities.

Types

There are two types of nystagmus. The first is spasmus nutans, which is characterized by very small, rapid eye movements. It usually begins around six to twelve months of age. Children with this type of nystagmus usually nod or tilt their heads with one ear toward their shoulders. This condition may involve just one eye, or one eye more than the other. It may disappear after a year or two and is sometimes the result of a brain tumor.

In latent nystagmus, eye movements are controlled until one eye is covered. Then both eyes start moving rapidly. However, vision is normal as long as both eyes are open.

Treatment

Children with nystagmus are likely to have strabismus, amblyopia, or refractive errors - all problems that need to be treated. Glasses may help align the child's eyes and make his or her eye movements less noticeable. In some cases, surgery on the eye muscles may be helpful.