Nystagmus causes,symptoms,diagnosis

Nystagmus can have a number of causes. In some cases, no cause can be identified. In other cases, nystagmus may be associated with other eye disorders or, more often in the case of acquired nystagmus, with serious medical conditions or substance use.  

Strabismus or misaligned eyes

Among the known causes of nystagmus are:

• Heredity. Nystagmus can be inherited, with a strong family historyof the disease increasing the risk for developing it;
• Albinism (lack of skin pigmentation);
• A wide range of eye disorders, including cataracts, strabismus and severe refractive errors;
• Diseases such as Meniere's disease, multiple sclerosis, or stroke. Stroke is a common cause of acquired nystagmus in older people;
• Injury to the head. This is a common cause of acquired nystagmus in younger people;
• Use of certain medications, such as lithium or antiseizure medications;
• Alcohol or drug use;
• Inner ear problems.

The movement of your eyes is controlled by your brain. Your eyes move reflexively to adjust for slight movement of your head. This stabilizes the image that you are looking at and allows you to see a sharper image. In people withnystagmus, the areas of the brain that control eye movements do not function normally.

The movement of your eyes is controlled by your brain. Your eyes move reflexively to adjust for slight movement of your head. This stabilizes the image that you are looking at and allows you to see a sharper image. In people withnystagmus, the areas of the brain that control eye movements do not function normally.

The primary symptom of nystagmus is involuntary eye movement. Usually the movement is side-to-side (horizontal nystagmus), but it can also be up and down (vertical nystagmus) or circular (rotary nystagmus). The movement can vary between slow and fast, and it usually involves both eyes.

Nystagmus Symptoms

In addition to eye movement, nystagmus symptoms include sensitivity to light, dizziness, difficulty seeing in darkness, vision problems, holding the head in a turned or tilted position or feeling that the world is shaking.

Nystagmus Diagnosis

Nystagmus is diagnosed by an ophthalmologist (Eye M.D.) who will examine the inside of the eyes and 

test

 vision. Your Eye M.D. will also look for other eye problems that may be related to the nystagmus, such as strabismus, cataracts, or abnormality of the optic nerves or retina.

One way to observe nystagmus is by spinning an individual around for about 30 seconds, stopping, and then having them try to stare at an object. If nystagmus is present, the eyes will first move slowly in one direction, then move rapidly in the opposite direction.

Among the other tests that may be used to diagnose nystagmus are:

• Eye-movement recordings — to verify the type of nystagmus and determine the details of the movements;
• Ear exam;
• Neurologic exam;
• Computerized tomography (CT) — X-rays of the brain;
• Magnetic resonance imaging (MRI) — magnetic and radio waves used to make images of the brain.

What causes uncontrolled rapid eye movements (congenital nystagmus)?conditions!

What Is Nystagmus?

Nystagmus is a condition that causes involuntary, rapid movement of one or both eyes. The eye(s) may move from side to side, up and down, or in a circular motion. Nystagmus is often accompanied by vision problems, including blurriness.

Nystagmus rapid eye movements 

Nystagmus refers to rapid involuntary movements of the eyes that may be:

• Side to side (horizontal nystagmus)
• Up and down (vertical nystagmus)
• Rotary

Depending on the cause, these movements may be in both eyes or in just one eye. The term "dancing eyes" has been used in regional dialect to describe nystagmus.

Uncontrollable eye movements are involuntary, rapid, and repetitive movement of the eyes.

The involuntary eye movements of nystagmus are caused by abnormal function in the areas of the brain that control eye movements. The part of the inner ear that senses movement and position (the labyrinth) helps control eye movements.

The exact nature of these disorders is poorly understood.

There are two forms of nystagmus:

• Congenital nystagmus is present at birth. This is the most common type.
• Acquired nystagmus develops later in life because of a disease or injury.

CONGENITAL NYSTAGMUS

Congenital nystagmus is usually mild, does not change in severity, and is not associated with any other disorder.

Affected people are not aware of the eye movements, although they may be noticed by a careful observer. If the movements are of large magnitude, visual acuity (sharpness of vision) may be less than 20/20. Surgery may improve visual acuity.

Rarely, nystagmus occurs as a result of congenital diseases of the eye that cause poor vision. Although this is rare, an ophthalmologist should evaluate any child with nystagmus to check for eye disease.

ACQUIRED NYSTAGMUS

Inner ear disorders such as labyrinthitis or Meniere's disease can lead to acquired nystagmus. However, the most common cause is probably toxic -- certain drugs or medication, including Dilantin (an antiseizure medication), alcohol intoxication, or any sedating medicines can harm the labyrinth.

In young people, a common, serious cause of acquired nystagmus is head injury from motor vehicle accidents.

In older people, a common, serious cause is stroke (blood vessel blockage in the brain).

Any disease of the brain (such as multiple sclerosis or brain tumors) can cause nystagmus if the areas controlling eye movements are damaged.

What to Expect at Your Office Visit

Nystagmus may be observed through the following procedure: If the affected person spins around for about 30 seconds, stops, and tries to stare at an object, the eyes will first move slowly in one direction, then move rapidly in the opposite direction. If you have nystagmus due to a medical condition, these eye movements depend on the underyling cause.

Your health care provider will take a careful history and perform a thorough physical examination, which will emphasize the nervous system and inner ear. The doctor may ask you to wear a pair of goggles that magnify the eyes for part of the neurological examination.

Questions asked in a medical history may cover the following areas:

• When was it first noticed?
• How often does it occur?
• Has it ever happened before?
• Is it getting better, worse, or staying the same?
• Are there side-to-side eye movements?
• Are there up-and-down eye movements?
• What medications are being taken?
• What other symptoms are present?

Diagnostic tests that may be performed include:

• CT scan of the head or MRIMRI of the head
• Electro-oculography: An electrical method of measuring eye movements using tiny electrodes.
• Vestibular testing – recording the movements of the eyes and response to caloric stimulation

There is no 

therapy

 for most cases of congenital nystagmus. Treatment for acquired nystagmus depends on the cause. In some cases, nystagmus is irreversible. In cases due to medications or infection, the nystagmus usually goes away after the initial cause has resolved.

What Is Nystagmus?

Nystagmus is an involuntary, rapid and repetitive movement of the eyes. Usually the movement is side-to-side (horizontal nystagmus), but it can also be up and down (vertical nystagmus) or circular (rotary nystagmus). The movement can vary between slow and fast, and it usually involves both eyes.

People with nystagmus may not be aware of their eye movements because what they see usually does not appear shaky to them. People with nystagmus may tilt or turn their head in order to see more clearly. This helps to dampen or slow down the eye movements.

There are two types of nystagmus: congenital and acquired. Congenital nystagmus develops in infancy, usually between six weeks and three months of age. Sensory nystagmus also occurs early in life and is related to poor vision caused by a variety of eye conditions, including cataract (cloudiness of the eye's lens),strabismus (eye misalignment) and optic nerve hypoplasia. As they get older, children with nystagmus don't see the world as shaky, but they will probably develop less clear vision.
Acquired Nystagmus 

Nystagmus may be defined as a periodic rhythmic ocular oscillation of the eyes. The oscillations may be sinusoidal and of approximately equal amplitude and velocity (pendular nystagmus) or, more commonly, with a slow initiating phase and a fast corrective phase (jerk nystagmus).^{[1, 2]}

Nystagmus may be unilateral or bilateral, but, when the nystagmus appears unilateral, it is more often asymmetric rather than truly unilateral. Nystagmus may be conjugate or disconjugate (dissociated). It may be horizontal, vertical, torsional (rotary), or any combination of these movements superimposed upon each other.

Nystagmus may be congenital or acquired. When acquired, it most often is caused by abnormalities of vestibular input. Congenital forms may be associated with afferent visual pathway abnormalities (sensory nystagmus).^[3]

To understand the mechanisms by which nystagmus may occur, it is important to discuss the means by which the nervous system maintains position of the eyes. Foveal centration of an object of regard is necessary to obtain the highest level ofvisual acuity. Three mechanisms are involved in maintaining foveal centration of an object of interest: fixation, the vestibulo-ocular reflex, and the neural integrator.

Fixation in the primary position involves the visual system's ability to detect drift of a foveating image and signal an appropriate corrective eye movement to refoveate the image of regard. The vestibular system is intimately and complexly involved with the oculomotor system.

The vestibulo-ocular reflex is a complex system of neural interconnections that maintains foveation of an object during changes in head position. The proprioceptors of the vestibular system are the semicircular canals of the inner ear. Three semicircular canals are present on each side, anterior, posterior, and horizontal. The semicircular canals respond to changes in angular acceleration due to head rotation.

The third mechanism is the neural integrator. When the eye is turned in an extreme position in the orbit, the fascia and ligaments that suspend the eye exert an elastic force to return toward the primary position. To overcome this force, a tonic contraction of the extraocular muscles is required. A gaze-holding network called the neural integrator generates the signal. The cerebellum, ascending vestibular pathways, and oculomotor nuclei are important components of the neural integrator.

Nystagmus — A Guide

Nystagmus most commonly causes the eyes to look involuntarily from side to side in a rapid, swinging motion rather than staying fixed on an object or person. Some nystagmuses, however, cause the eyes to jerk sideways or up and down.

Aside from being a condition I see professionally, nystagmus also affects a very close friend of mine. So I can discuss this eye problem from several points of view.

Nystagmus is usually infantile, meaning people have it from a very early age. Experts say that about one child out of every several thousand has nystagmus. Different kinds of nystagmus include:

• Manifest nystagmus
• Congenital nystagmus
• Manifest-latent nystagmus
• Acquired nystagmus
• Latent nystagmus

Congenital nystagmus is present at birth. With this condition, your eyes move together as they oscillate (swing like a pendulum). Most other types of infantile nystagmus are also classified as forms of strabismus, which means the eyes don't necessarily work together at all times.

Manifest nystagmus is present at all times, whereas latent nystagmus occurs when one eye is covered.

Manifest-latent nystagmus is continually present, but worsens when one eye is covered.

Acquired nystagmus can be caused by a disease (multiple sclerosis, brain tumor, diabetic neuropathy), an accident (head injury), or a neurological problem (side effect of a medication). Hyperventilation, a flashing light in front of one eye, nicotine and even vibrations have been known to cause nystagmus in rare cases. Some acquired nystagmuses can be treated with medications or surgeries.

Nystagmus Causes, Symptoms and Challenges

As mentioned above, most people with nystagmus are born with the condition or develop it early in life. Unless induced by trauma or disease, nystagmus almost always is caused by neurological problems.

The two basic types of nystagmus are:

• Optokinetic (eye related)
• Vestibular (inner ear related)

People with inner ear problems can develop something called "jerk nystagmus" — the eyes drift slowly in one direction and then jerk back in the other direction. Because of the motion of the eyes, people with this condition can develop nausea and vertigo. This type of nystagmus, usually temporary, also can occur in people with Meniere's disease (inner ear disorder) or when water settles into one ear.

Taking a decongestant sometimes can clear up this type of nystagmus.

Taking a decongestant sometimes can clear up this type of nystagmus.

Helping Children With Nystagmus

Usually, nystagmus is discovered at a very young age. Parents and caretakers, here's how you can help a child who has nystagmus:

• Find an eye doctor you trust who understands and treats nystagmus.
• Make sure your child's glasses or contact lensesare always up-to-date and that vision is corrected to the maximum level possible.
• Help your child's teachers understand the basics of nystagmus, including how the condition affects ability to see, learn and interact with other children.
• Develop a comfort level with explaining nystagmus to family, friends and others who notice your child's eyes swinging back and forth. Keep your explanation short, to-the-point and positive.
• Don't lower your expectations for your child. Most people with nystagmus can see, learn and interact well enough to lead very normal lives.
• Be positive. Nystagmus, while a visible "disability," is not the end of the world. As they grow up, children with nystagmus need help in understanding why their eyes are different. Reassure children that nystagmus won't stop them from being normal kids and normal adults. — Dr. Dubow

All forms of nystagmus are involuntary, meaning people with the condition cannot control their eyes. Nystagmus improves slightly as a person reaches adulthood; however, it worsens with tiredness and stress.

Having nystagmus affects both vision and self-concept. Most people with nystagmus have some sort of vision limitations because the eyes continually sweep over what they are viewing, making it impossible to obtain a clear image.

Some people with nystagmus have so many vision problems that they can be considered legally blind.

If you have nystagmus, not only is your appearance affected, but you literally see in a way that is different from people who don't have the condition. Your eyes are in constantmotion.

To see better, you may need to turn your head and lock your eyes into what's called the "null point." This is a certain head angle that makes the eyes move the least, stabilizing the image for better vision.

When you have nystagmus, you must deal with the personal and social consequences of this difference.

Nystagmus can affect nearly every aspect of your life, including how you relate to other people, your educational and work opportunities and your self-image.

Counseling may be helpful as you face the social and personal challenges often associated with nystagmus.

Can Nystagmus Be Treated?

Several medical and surgical treatments that sometimes help people with nystagmus are available. Surgery usually reduces the null positions, lessening head tilt and improving cosmetic appearance.

Drugs such as Botox or Baclofen can reduce some nystagmic movements, although results are usually temporary. Some people with nystagmus benefit from biofeedback training.

If you have nystagmus, make sure you undergo regular eye exams so you can be monitored for both health and vision issues.

Both eyeglasses and contact lenses can help people with nystagmus see better, but I have found contact lenses to be the superior alternative for many with nystagmus. With glasses, the eyes sweep back and forth over the lens centers and vision is not as clear. With contacts, however, the lens centers move with the eyes.

Congenital Nystagmus

Nystagmus /nɪˈstæɡməs/ is a condition of involuntary^[1] eye movement, acquired in infancy or later in life, that may result in reduced or limited vision.^[2] Due to the involuntary movement of the eye, it is often called "dancing eyes".^[3][a]

When the head rotates about any axis, distant visual images are sustained by rotating eyes in the opposite direction on the respective axis.^[4] The semicircular canals in the vestibule sense angular momentum. These send signals to the nuclei for eye movement in the brain. From here, a signal is relayed to the extraocular muscles to allow one’s gaze to fixate on one object as the head moves. Nystagmus occurs when the semicircular canals are being stimulated while the head is not in motion. The direction of ocular movement is related to the semicircular canal that is being stimulated.^[5]

There are two key forms of nystagmus: pathological and physiological, with variations within each type. Nystagmus may be caused bycongenital disorders, acquired or central nervous system disorders, toxicity, pharmaceutical drugs, alcohol, or rotational movement. Previously considered untreatable, in recent years several pharmaceutical drugs have been identified for treatment of nystagmus. Nystagmus is occasionally associated with vertigo.

Diagnosis

Nystagmus is very noticeable but rarely recognized. Nystagmus can be clinically investigated by using a number of non-invasive standard tests. The simplest one is the caloric reflex test, in which one ear canal is irrigated with warm or cold water or air. The temperature gradient provokes the stimulation of the horizontal semicircular canal and the consequent nystagmus.

The resulting movement of the eyes may be recorded and quantified by special devices called electronystagmograph (ENG), a form of electrooculography (an electrical method of measuring eye movements using external electrodes),^[6] or even less invasive devices called videonystagmograph (VNG),^[7] a form of video-oculography (VOG) (a video-based method of measuring eye movements using external small cameras built into head masks) by an audiologist. Special swinging chairs with electrical controls can be used to induce rotatory nystagmus.^[8]

Over the past forty years, objective eye-movement-recording techniques have been applied to the study of nystagmus, and the results have led to a greater accuracy and understanding of the condition.

Orthoptists may also use an optokinetic drum, or electrooculography to assess a patient's eye movements.

Nystagmus can be caused by subsequent foveation of moving objects, pathology, sustained rotation or substance use. Nystagmus is not to be confused with other superficially similar-appearing disorders of eye movements (saccadic oscillations) such as opsoclonus or ocular flutter that are composed purely of fast-phase (saccadic) eye movements, while nystagmus is characterised by the combination of a smooth pursuit, which usually acts to take the eye off the point of regard, interspersed with the saccadic movement that serves to bring the eye back on target. Without the use of objective recording techniques, it may be very difficult to distinguish between these conditions.

In medicine, the presence of nystagmus can be benign, or it can indicate an underlying visual or neurological problem.^[9]

Pathologic nystagmus[edit]

Pathologic nystagmus is characterized by a biphasic ocular oscillation alternating a slow eye movement, or smooth pursuit, in one direction and a fast eye movement, or saccadic movement, in the other direction. The velocity of the slow phase eye velocity (SPEV) and the fast phase eye velocity (FPEV) are related to each other and can be considered as a measurement of the efficiency of the system stimulus/response.^[10]

When nystagmus occurs without fulfilling its normal function, it is pathologic (deviating from the healthy or normal condition). Pathological nystagmus is the result of damage to one or more components of the vestibular system, including the semicircular canals, otolith organs, and the vestibulocerebellum.^{[contradiction]}

Pathological nystagmus generally causes a degree of vision impairment, although the severity of such impairment varies widely. Also, many blind people have nystagmus, which is one reason that some wear dark glasses.^[11]

Variations[edit]

• Central nystagmus occurs as a result of either normal or abnormal processes not related to the vestibular organ. For example, lesions of the midbrain or cerebellum can result in up- and down-beat nystagmus.
• Peripheral nystagmus occurs as a result of either normal or diseased functional states of the vestibular system and may combine a rotational component with vertical or horizontal eye movements and may be spontaneous, positional, or evoked.
  • Gaze induced nystagmus occurs or is exacerbated as a result of changing one's gaze toward or away from a particular side which has an affected vestibular apparatus.
  • Positional nystagmus occurs when a person's head is in a specific position.^[12] An example of disease state in which this occurs is Benign paroxysmal positional vertigo(BPPV).
  • Post rotational nystagmus occurs after an imbalance is created between a normal side and a diseased side by stimulation of the vestibular system by rapid shaking or rotation of the head.
  • Spontaneous nystagmus is nystagmus that occurs randomly, regardless of the position of the patient's head.

Physiological nystagmus[edit]

Physiological nystagmus is a form of involuntary eye movement that is part of the vestibulo-ocular reflex (VOR), characterized by alternating smooth pursuit in one direction andsaccadic movement in the other direction.

Variations[edit]

The direction of nystagmus is defined by the direction of its quick phase (e.g. a right-beating nystagmus is characterized by a rightward-moving quick phase, and a left-beating nystagmus by a leftward-moving quick phase). The oscillations may occur in the vertical,^[13] horizontal or torsional planes, or in any combination. The resulting nystagmus is often named as a gross description of the movement, e.g. downbeat nystagmus, upbeat nystagmus, seesaw nystagmus, periodic alternating nystagmus.

These descriptive names can be misleading however, as many were assigned historically, solely on the basis of subjective clinical examination, which is not sufficient to determine the eyes' true trajectory.

• Opticokinetic nystagmus; a nystagmus induced by looking at moving visual stimuli, such as moving horizontal or vertical lines, and/or stripes. For example, if one fixates on a stripe of a rotating drum with alternating black and white, the gaze retreats to fixate on a new stripe as the drum moves. This is first a rotation with the same angular velocity, then returns in a saccade in the opposite direction. The process proceeds indefinitely. This is optokinetic nystagmus, and is a source for understanding the fixation reflex.^[14]
• Postrotatory nystagmus; if one spins in a chair continuously and stops suddenly, the fast phase of nystagmus is in the opposite direction of rotation, known as the "post-rotatory nystagmus", while slow phase is in the direction of rotation.^[14]

Causes[edit]

The cause for pathological nystagmus may be congenital, idiopathic, or secondary to a pre-existing neurological disorder. It also may be induced temporarily by disorientation (such as on roller coaster rides) or by certain drugs (alcohol and other central nervous system depressants, inhalant drugs, stimulants, psychedelic drugs, and dissociative drugs).

Early-onset nystagmus[edit]

Early onset nystagmus occurs more frequently than acquired nystagmus. It can be insular or accompany other disorders (such as micro-ophthalmic anomalies or Down Syndrome). Early-onset nystagmus itself is usually mild and non-progressive. The affected persons are not normally aware of their spontaneous eye movements, but vision can be impaired depending on the severity of the movements.

Types of early-onset nystagmus include the following:

• Infantile:
  • Albinism
  • Aniridia
  • Bilateral congenital cataract
  • Bilateral optic nerve hypoplasia
  • Idiopathic
  • Leber's congenital amaurosis
  • Optic nerve or macular disease
  • Persistent tunica vasculosa lentis
  • Rod monochromatism
  • Visual-motor syndrome of functional monophthalmos
• Latent nystagmus
• Noonan syndrome
• Nystagmus blockage syndrome

X-linked infantile nystagmus is associated with mutations of the gene FRMD7, which is located on the X chromosome.^[15][16]

Infantile nystagmus is also associated with two X-linked eye diseases known as complete congenital stationary night blindness (CSNB) and incomplete CSNB (iCSNB or CSNB-2), which are caused by mutations of one of two genes located on the X chromosome. In CSNB, mutations are found in NYX (nyctalopin).^[17][18] CSNB-2 involves mutations of CACNA1F, a voltage-gated calcium channel that, when mutated, does not conduct ions.^[19]

Acquired nystagmus[edit]

It may be acquired from:

• Diseases. Some of the diseases that present nystagmus as a pathological sign:
  • Aniridia

• Benign paroxysmal positional vertigo ^[20]
• Brain tumors (medulloblastoma, astrocytoma, or other tumors in the posterior fossa.)
• Head trauma
• Lateral medullary syndrome
• Ménière's disease and other balance disorders
• Multiple sclerosis
• Optic nerve hypoplasia
• Pelizaeus–Merzbacher disease
• Superior canal dehiscence syndrome
• Stroke (the most common cause in older people)
• Tullio phenomenon
• Wernicke–Korsakoff syndrome
• Whipple's disease

• Toxic or metabolic reasons could be the result of the following:

• Alcohol intoxication
• Amphetamines
• Barbiturates
• Benzodiazepines
• Ketamine
• Lithium
• Other anticonvulsants or sedatives
• Phencyclidine (PCP)
• Phenytoin (Dilantin)
• Salicylates
• SSRIs
• Thiamine deficiency
• Wernicke's encephalopathy

• Central nervous system (CNS) disorders, such as with a cerebellar problem, the nystagmus can be in any direction including horizontal. Purely vertical nystagmus is usually central in origin, but it is also a frequent adverse effect of high phenytoin toxicity. Causes include:

• Cerebellar ataxia
• Chiari Malformation
• Multiple sclerosis
• Stroke
• Thalamic hemorrhage
• Trauma
• Tumor

Other causes[edit]

• Non-physiological
• Trochlear nerve malfunction^[21]
• Vestibular Pathology (Ménière's disease, SCDS (superior canal dehiscence syndrome), BPPV, Labyrinthitis)

Alcohol[edit]

Main article: Positional alcohol nystagmus

In the United States, testing for horizontal gaze nystagmus is one of a battery of field sobriety tests used by police officers to determine whether a suspect is driving under the influence of alcohol. The test involves observation of the suspect's pupil as it follows a moving object, noting

1. lack of smooth pursuit,
2. distinct and sustained nystagmus at maximum deviation, and
3. the onset of nystagmus prior to 45 degrees.

The horizontal gaze nystagmus test has been highly criticized and major errors in the testing methodology and analysis found.^[22][23] However, the validity of the horizontal gaze nystagmus test for use as a field sobriety test for persons with a blood alcohol level between 0.04–0.08 is supported by peer reviewed studies and has been found to be a more accurate indication of blood alcohol content than other standard field sobriety tests

Treatment

Congenital nystagmus has traditionally been viewed as non-treatable, but medications have been discovered in recent years that show promise in some patients. In 1980, researchers discovered that a drug called baclofen could effectively stop periodic alternating nystagmus. Subsequently, gabapentin, an anticonvulsant, was found to cause improvement in about half the patients who received it to relieve symptoms of nystagmus. Other drugs found to be effective against nystagmus in some patients includememantine,^[25] levetiracetam, 3,4-diaminopyridine, 4-aminopyridine, and acetazolamide.^[26] Several therapeutic approaches, such as contact lenses,^[27] drugs, surgery, and low vision rehabilitation have also been proposed.

Surgical treatment of Congenital Nystagmus is aimed at improving the abnormal head posture, simulating artificial divergence or weakening the horizontal recti muscles.^[28] Clinical trials of a surgery to treat nystagmus (known as tenotomy) concluded in 2001. Tenotomy is now being performed regularly at numerous centres around the world. The surgery developed by Louis F. Dell'Osso Ph.D. aims to reduce the eye shaking (oscillations), which in turn tends to improve visual acuity.^[29]

Acupuncture has conflicting evidence as to having beneficial effects on the symptoms of nystagmus. Benefits have been seen in treatments where acupuncture points of the neck were used, specifically points on the sternocleidomastoid muscle.^[30][31] Benefits of acupuncture for treatment of nystagmus include a reduction in frequency and decreased slow phase velocities which led to an increase in foveation duration periods both during and after treatment.^[31] By the standards of Evidence-based medicine, the quality of these studies can be considered poor (for example, Ishikawa has a study sample size of just six, is unblinded and without proper control), and given high quality studies showing that acupuncture has no effect beyond placebo, the results of these studies have to be considered clinically irrelevant until higher quality studies are produced.

Physical Therapy is also used to treatment nystagmus. The specialized field is called Neurological physical therapy. Treatment consist of learning compensatory strategies to take over for the impaired system.

Epidemiology[edit]

Nystagmus is a relatively common clinical condition, affecting one in several thousand people. A survey conducted in Oxfordshire, United Kingdom found that by the age of two, one in every 670 children had manifested nystagmus.^[2] Authors of another study in the United Kingdom estimated an incidence of 24 in 10,000 (~0.240 %), noting an apparently higher rate amongst white Europeans than in individuals of Asian origin.

Background

Congenital or infantile nystagmus is a clinical sign that may take many different forms. Involuntary, rhythmic eye movements are characteristic, as they are inacquired nystagmus. Waveform, amplitude, and frequency can vary with changes in focal distance, direction of gaze, and under monocular or binocular viewing conditions.

Oscillations are usually horizontal in direction but may be primarily vertical, torsional, or any combination of these three. Infantile nystagmus often is associated with other ocular conditions that impair visual acuity and occasionally can herald life-threatening conditions. Prompt assessment by an ophthalmologist with knowledge of infantile nystagmus to establish the need for and urgency of additional evaluation is extremely important.^[1] Some other associated conditions include achromatopsia, Leber congenital amaurosis, anorexia, and ocular albinism.