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 far sighted
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 neurologic disorders. Nystagmus
can be found in families as an isolated problem, not
associated with other conditions.
If nystagmus is present, what should be done?
A thorough examination by an ophthalmologist and perhaps
other medical specialists is very important. Some forms
of nystagmus have a definite cause. Important clues
relate to age of onset, family history, general health
of the patient, 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,
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?
Medication 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 symptomes
which indicate 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 damage.
Since most blindness is preventable if diagnosed and
treated early, regular medical examinations by an ophthalmologist
are very important.
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