Nystagmus is when one or both eyes move abnormally. The eye movement can't be controlled.
Eye movements with nystagmus
With nystagmus, eye movements are quick and happen again and again. They may happen all the time (continuous). Or they may happen suddenly and then stop (paroxysmal). The eye movements can’t be controlled (involuntary).
The direction of the eye movements can be:
Side to side (horizontal)
Up and down (vertical)
Around in a circle (rotary)
One eye goes up while the other goes down (see-saw)
Any combination of the above
Because of these abnormal movements, the eyes can’t focus well. This affects the person’s vision. To see better, people with nystagmus may hold their head in an unusual position. They may tilt or turn their head. They do this to get to the null point. That is the angle of vision where the person’s eyes move the least. It’s also the most visually comfortable position. Nodding the head may also reduce eye movement.
Types and causes of nystagmus
There are two main types of nystagmus: congenital or acquired. 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. A child is born with it. Symptoms appear soon after birth. It may be caused by:
Sensory problems. Vision problems, such as a clouded eye lens (cataracts) or increased pressure in the eye (glaucoma), may cause nystagmus. Another possible cause is a problem with the light-sensing layer of nerves in the back of the eye (the retina). Or there may be a problem with the nerve that connects the eye to the brain (the optic nerve).
Neurologic problems. Problems in the brain can cause nystagmus. This is because the brain and the eyes must work closely together for good vision.
Other conditions. Disorders linked to nystagmus include a lack of pigment in the skin and eyes (albinism). Another cause may be not having an iris, or colored part, in the eye (aniridia).
Acquired nystagmus. This type happens later in life. There are a few possible causes, including:
Some medicines (most often antiseizure medicines)
Inner ear disorders, such as Meniere disease
Brain disease, such as multiple sclerosis or a brain tumor
Symptoms of nystagmus
Symptoms depend on the type of nystagmus:
Congenital. Vision may be affected. But eye movement may not be a problem.
Acquired. Eye movement may be more obvious and annoying. Blurry vision may happen. Depth perception may also be affected. This can harm balance and coordination. It can also cause dizziness.
Diagnosis of nystagmus
A healthcare provider or eye doctor will take a medical history. A physical exam will be done, including an eye exam. Certain tests may also be done, such as:
CT scan or MRI of the head. These imaging tests create pictures of the brain. They can show any swelling, stroke, or tumors that may be causing nystagmus.
Electroretinography (ERG). This tests how well the retina is working.
Vestibular testing. This checks for problems in part of the 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
Children should see a pediatric ophthalmologist. This is a medical doctor with special training in diagnosing and treating children with eye disorders.
In most cases, treatment helps reduce symptoms. But it doesn’t get rid of them. Treatment depends on the cause of the nystagmus. There are five main treatment options:
Treatment of the underlying cause. Sometimes there is a clear cause that can be addressed. For instance, a cataract may be treated or a tumor may be removed. If nystagmus is caused by a medicine, it may be stopped or replaced. When these underlying causes are treated, nystagmus may be cured.
Treatment of related vision problems. Contact lenses or eyeglasses can help correct problems such as nearsightedness or farsightedness. Special prisms may be used to adjust eye gaze. This helps to get the best possible vision and reduce symptoms.
Medicines. These can help reduce symptoms, such as eye movement and vision loss.
Botulinum shots (injections). These weaken some eye muscles. This helps reduce symptoms.
Surgery. This procedure alters the position of the muscles that move the eyes. It does not cure nystagmus. But it may reduce the amount a person must turn his or her head to see well.
January 01, 2018
Bogus, William J, OD, FAAO,Haupert, Christopher L., MD