Nystagmus is a condition in which there is involuntary and rhythmic
movement or oscillation of the eye. It is often caused by an underlying
ocular or neurological disorder.
The eye movements associated with nystagmus are varied. They can be either
pendular, in which the oscillations are equal in all directions and or
jerk, in which the movements may be faster in one direction than another.
The frequency of the oscillation or movement and the amplitude of the
oscillation also vary. The movements themselves may be vertical,
horizontal, circular, or oblique in direction. Nystagmus can be sensory
and develop as a result of poor vision, or it can be motor and develop as
a result of a neurological problem.
Nystagmus may be congenital, or it may be acquired. Congenital, or
infantile, nystagmus appears within the first few months of life.
Congenital nystagmus is usually binocular and affects both eyes, is
horizontal in direction, and does not occur while the child is sleeping.
It decreases when the child's eyes converge or move inward. Most of
these cases of nystagmus develop because of poor vision and do not have an
underlying neurological cause.
Children with congenital nystagmus usually have a point in their eye
movement in which the intensity of the nystagmus is decreased. This is
called the null point, and the child may adopt a head tilt or rotation to
help maintain his or her eyes at this position. This point is usually not
in straight ahead or in a primary gaze position. Children with nystagmus
who have their the null point located at a position in which the eyes are
positioned inward may develop an esotropia, a form of
or eye turn.
One variant of congenital nystagmus is spasmus nutans, which appears as a
triad with accompanying head nodding and torticollis (head turn or tilt),
and is seen between four months and three-and-a-half years of age and
usually resolves without treatment within one to two years of onset.
Rarely does it persist past age five. Usually spasmus nutans appears
bilaterally, and the nystagmus is in a horizontal direction. When the
nystagmus of spasmus nutans is vertical or rotary, the child does not have
a head tilt.
There are various types of nystagmus. Downbeat nystagmus is characterized
by a nystagmus that is more pronounced when the child looks down,
especially when looking to the side, or in lateral gaze. An accentuated
oscillation when looking up is seen in upbeat nystagmus. Seesaw nystagmus
is an unusual type of in which one eye moves in and down and the other out
and up. A periodic alternating nystagmus (PAN) is observed in primary gaze
when the patient is looking straight ahead and is characterized by eye
movements that continuously change direction and speed. Peripheral
vestibular nystagmus may be accompanied by vertigo,
, and tinnitus, or ringing in the ears. This type of nystagmus is not
always apparent but can be seen by a doctor when he or she looks in the
back of the eye with a direct ophthalmoscope.
Latent nystagmus appears only when one eye is covered. This is a
congenital nystagmus caused by an ocular motor disturbance rather than
visual deprivation. It is often accompanied by strabismus or an eye turn.
A child with latent nystagmus will not see well when one eye is covered.
Gaze evoked nystagmus occurs only when one is looking to the side in
extreme lateral gaze. This type of nystagmus can be caused by ethanol and
recreational drug use, but is seen in myasthenia gravis and thyroid
disease as well.
Some types of nystagmus are normal. If one looks at an object in extreme
gaze for a long period of time, endpoint nystagmus may be noted.
Optokinetic nystagmus (OKN) is a nystagmus that can be elicited
involuntarily when a rapidly moving striped object is passed in front of
an individual's eyes.
Congenital nystagmus may be transmitted genetically, either as an
autosomal recessive or dominant, or as an X-linked recessive trait. It can
also be associated with other conditions that are genetically transmitted.
For example, Leber's amaurosis is an autosomal dominant trait and
Congenital nystagmus occurs twice as frequently in males than in females.
The prevalence of nystagmus in the pediatric population is .015 percent.
Eighty percent of nystagmus is congenital, and the remaining 20 percent is
Causes and symptoms
The eyes of an individual with nystagmus cannot remain still and oscillate
in some position of gaze. Those
with nystagmus usually have decreased vision and poor depth perception,
although those born with nystagmus, may not realize that their vision is
poor. Those with acquired nystagmus may experience double vision or
oscillopsia, or that objects in their visual space appear to move. An
acquired nystagmus may be accompanied by other symptoms such
, difficulty with balance, hearing loss, poor coordination, and
. If an individual with nystagmus experiences oscillopsia, then the
nystagmus is acquired.
The primary cause of congenital nystagmus is visual deprivation, and the
causes of visual deprivation in an infant include cataracts,
oculoalbinism, glaucoma, retinal detachments, Leber's amaurosis,
developmental abnormalities of the optic nerve such as a coloboma, and
achromatopsia, a condition in which the infant cannot see color.
Acquired nystagmus can be caused by demyelination of nerve fibers, such as
occurs in multiple sclerosis, lesions or tumors of the vestibular or
visual pathways, strokes of the central nervous system, and drug use, both
recreational as well as a side effect of prescribed drugs, such as those
used to treat seizures and depression. Other causes of acquired nystagmus
are Arnold-Chiari malformations, vitamin deficiencies, syphilis,
Wernicke's encephalopathy, Behcet's syndrome, and
Since nystagmus can be caused by tumors,
, and trauma or neurological disorder, any type of nystagmus must be
evaluated by a qualified practitioner. The nystagmus can be a sign of a
serious problem. For example, a type of tumor called chiasmal glioma has
signs and symptoms similar to spasmus nutans.
Diagnosis of nystagmus is made primarily by patient history as reported by
a parent, the age of onset, and observation of any accompanying signs such
as a head turn, tilt or tremor, or oscillopsia. If possible, the infant or
child's best visual acuity is determined. If the onset is acute,
then usually the nystagmus is acquired.
The type of nystagmus can accurately be determined by eye movement
recordings, which map direction, frequency, null point, and amplitude of
the nystagmus. For the infant with congenital nystagmus, evoked response
potential (EVR) and electroretinogram (ERG) give the doctor objective
information about visual potential, and
magnetic resonance imaging
(MRI) can determine if and where a lesion is located. For the infant or
young child, some of these tests may be done under anesthesia.
The treatment for nystagmus, once the etiology is determined and treated,
includes optical devices such as
and glasses, medication, and surgery.
For individuals with nystagmus correction of refractive error with glasses
or contact lenses is the first step in treating the condition. For 85
percent of children with nystagmus, a spectacle prescription improves
vision significantly. For those with congenital nystagmus, prism may be
put in glasses to help position the eye at its null point or to help the
eyes converge. For some people contact lenses are prescribed. Contact
lenses slow down eye movements, and because the optical center of the
prescription is always centered on the eye with the contact lens, vision
improves. Low vision aids such as telescopes assist those whose vision
cannot be fully corrected with spectacles and contact lenses alone.
Tinting of the glasses or sunglasses may decrease the nystagmus of
individuals with albinism. For the patient with oscillopsia, grinding
prism into the spectacles may move the visual field to a point of
Congenital nystagmus, when due to a visual deprivation, is rarely improved
by surgery. But when a head tilt or head turn accompanies nystagmus,
surgery to correct a muscle imbalance may improve nystagmus and visual
acuity. Surgery on the extraocular muscles of the eye may be helpful when
the child's null point is in not in primary gaze but located at
least 30 degrees from straight-ahead vision. When a tumor or stroke has
caused an acquired nystagmus, then neurosurgery, if indicated for the
underlying cause, may lead to resolution of the nystagmus. When surgery is
considered, the risks of anesthesia must also be considered.
If oscillopsia is a co-existing symptom, then drugs can be given to reduce
the ocular oscillations. Vestibular nystagmus can be treated by diazepam
or scopolamine. Drugs called GABA agonists, such as baclofen and
carbamazepine, are useful in treatment of seesaw nystagmus and PAN, if the
nystagmus is acquired and not congenital. Baclofen cannot be given to
toxin) injections can temporarily control the eye movements, but because
of side effects such as double vision and ptosis or drooping of the
eyelid, and because it is not a permanent solution, Botox is not used
If the nystagmus is due to drug toxicity, then reducing or discontinuing
the drug eventually resolves the problem.
Acupuncture and biofeedback and vision therapy have been successful for
Congenital nystagmus is usually a benign condition. It is not curable, but
its symptoms can be diminished with spectacles or contact lenses. The best
corrected vision for most individuals with congenital nystagmus is between
20/40 and 20/70, but correction to 20/20 is possible for some. Nystagmus
associated with spasmus nutans resolves spontaneously before the child
reaches school age.
The prognosis for an acquired nystagmus depends on its cause. If the
condition is due to a side effect of a drug, then decreasing or changing
the treatment drug eventually resolves the nystagmus.
In general nystagmus cannot be prevented. Since the cause of acquired
nystagmus can be due to a co-existing neurological condition, prompt
attention to other neurological signs that may accompany nystagmus, such
as dizziness, may prevent or decrease the severity of nystagmus itself.
Careful monitor of dosage of those drugs with nystagmus as a side effect
may prevent the condition.
—Based on the same traditional Chinese medical foundation as
acupressure, acupuncture uses sterile needles inserted at specific
points to treat certain conditions or relieve pain.
—An inherited condition that causes a lack of pigment. People
with albinism typically have light skin, white or pale yellow hair, and
light blue or gray eyes.
—Relating to any chromosome besides the X and Y sex chromosomes.
Human cells contain 22 pairs of autosomes and one pair of sex
—Affecting or having to do with both eyes.
—A training technique that enables an individual to gain some
element of control over involuntary or automatic body functions.
—A birth defect in which part of the eye does not form
—A disruption of the normal structure and function of a tissue by
an injury or disease process. Wounds, sores, rashes, and boils are all
—A disorder in which the eyes do not point in the same direction.
Also called squint.
—A gene carried on the X chromosome, one of the two sex
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Ophthalmology Clinics of North America
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