Nystagmus

How nystagmus works

Three brain systems normally keep the eyes steady: fixation (holding gaze on a target), the vestibular system of the inner ear (which compensates for head movement), and gaze-holding networks in the brainstem and cerebellum. A fault in any of them, or poor visual input in early life, can let the eyes drift. The brain then makes a quick corrective movement, producing the to-and-fro rhythm.

Types of nystagmus

By when it starts

• Infantile nystagmus syndrome (congenital nystagmus): appears in the first 6 months. It is usually horizontal, increases when looking at objects, and lessens with convergence (looking at something close) and at the null point. People rarely see the world moving.
• Fusion maldevelopment nystagmus (latent nystagmus): appears when one eye is covered. It is linked to infantile strabismus.
• Spasmus nutans: nystagmus with head nodding and tilt starting in infancy, usually disappearing by age 3 to 5. Brain imaging is often done to rule out an optic pathway tumor.
• Acquired nystagmus: develops later in childhood or adulthood, usually with oscillopsia (the world appears to bounce).

By pattern

Causes

Infantile nystagmus

• Albinism, both oculocutaneous and ocular
• Congenital cataracts or other early clouding of the eye
• Retinal conditions: Leber congenital amaurosis, achromatopsia, congenital stationary night blindness
• Optic nerve hypoplasia (underdeveloped optic nerve)
• Aniridia (missing iris)
• Idiopathic: no other eye problem, sometimes inherited via the FRMD7 gene, more often in boys

Acquired nystagmus

• Inner ear disorders: BPPV, vestibular neuritis, Meniere's disease
• Multiple sclerosis
• Stroke affecting the brainstem or cerebellum
• Chiari malformation and other brain structural problems
• Brain tumors
• Head injury
• Medicines and toxins: alcohol, phenytoin, carbamazepine, lithium, benzodiazepines
• Nutritional deficiencies: thiamine, vitamin B12, magnesium
• Severe vision loss later in life

Diagnosis

An ophthalmologist, often with a neuro-ophthalmologist or pediatric specialist, will:

• record the direction, speed and pattern of the movements, sometimes with eye movement recordings
• measure visual acuity and refraction (prescription), check for strabismus and the null point
• examine the retina, optic nerve and lens
• in children, possibly order electroretinography (ERG) to test retinal function and genetic testing

New or acquired nystagmus usually needs MRI of the brain, hearing and balance testing, and blood tests depending on the suspected cause.

Treatment

There is no single cure, but several treatments improve vision and comfort.

Optical treatments

• Glasses or contact lenses: correcting nearsightedness, farsightedness and astigmatism is the first step. Contact lenses may also dampen the movement slightly through feedback from the eyelids.
• Prisms: shift images so the eyes rest at their null point or encourage convergence.
• Low vision aids: magnifiers, large print, tablets with zoom, and good lighting.

Medicines

For acquired nystagmus causing oscillopsia, gabapentin and memantine can reduce pendular nystagmus. Baclofen helps periodic alternating nystagmus. 4-aminopyridine (dalfampridine) can help downbeat nystagmus. Some of these have also been tried in infantile nystagmus. These are prescribed by specialists.

Surgery

• Anderson-Kestenbaum procedure: moves the eye muscles so that the null point shifts to straight ahead, reducing an abnormal head turn.
• Tenotomy and reattachment of the horizontal eye muscles may modestly reduce the movements and improve acuity.
• Surgery for strabismus if present.

Treating the cause

Acquired nystagmus often improves when the cause is treated: repositioning maneuvers for BPPV, adjusting medicines, thiamine replacement, MS treatment or surgery for Chiari malformation.

Botulinum toxin

Injections into the eye muscles can temporarily reduce nystagmus but may cause drooping eyelids or double vision, so they are used selectively.

Living with nystagmus

• Vision is typically reduced but varies widely. Many people with infantile nystagmus read, use computers and work normally, sometimes with adjustments.
• Stress, fatigue and illness make the movements worse.
• Head position: let children adopt their preferred head turn or tilt, as it helps them see better.
• School support: seating near the front, large-print materials, extra time and screen magnification help children with nystagmus learn.
• Driving: some people with nystagmus meet the vision standard for a driver's license, while others do not. Eligibility depends on visual acuity and field rules in each state or country.
• Support groups such as the Nystagmus Network and the American Nystagmus Network provide information and community.

Outlook

Infantile nystagmus usually stays stable through life and often improves slightly during childhood. Acquired nystagmus depends on its cause: inner ear and medicine-related causes often resolve, while nystagmus from stroke or degenerative conditions may persist.

Frequently asked questions

What are the types of nystagmus?

Nystagmus is grouped by when it starts (infantile or acquired) and by its pattern: jerk or pendular, and horizontal, vertical (upbeat or downbeat) or torsional. Special forms include latent, periodic alternating, gaze-evoked and see-saw nystagmus, and spasmus nutans in toddlers.

Is nystagmus genetic?

Some forms are. Idiopathic infantile nystagmus can be inherited, often through the FRMD7 gene on the X chromosome, and many conditions that cause nystagmus, such as albinism and inherited retinal diseases, are genetic. Acquired nystagmus is usually not inherited.

Can nystagmus be cured?

Infantile nystagmus cannot usually be cured, but glasses, contact lenses, medicines and surgery can improve vision and reduce the movements. Acquired nystagmus may disappear when its cause, such as an inner ear problem or a medicine, is treated.

Can people with nystagmus drive?

Some can. It depends on whether their vision meets the legal standard for acuity and visual field where they live. Many people with mild infantile nystagmus are licensed. An eye specialist can measure vision and advise on local driving rules.

Does nystagmus get worse with age?

Infantile nystagmus usually stays stable or improves slightly in childhood and early adulthood. It can look worse when tired, stressed or unwell. A noticeable change in long-standing nystagmus should be checked, as it may signal a new problem.