Nystagmus

What is nystagmus?

Nystagmus is a condition which causes rapid, uncontrollable eye movement in the eyes and usually causes vision problems. The eye movements are involuntary, meaning people have no control over them. These movements can reduce vision (reading the chart) but also causes problems with moving targets, time-to-see, scanning complex visual scenes, depth perception, balance and coordination. Most people with nystagmus are registered as sight impaired.

Nystagmus is estimated to affect at least 1 in 1,000 people, though this number is likely to be higher. One UK study suggested it might affect 2.4 in every 1,000 people but even this is thought by many to be an underestimation. 

You might hear terms for nystagmus that describe the direction or the pattern of the eye movement. In most people with the condition the eye movement is from side to side (horizontal nystagmus), but it can be up and down (vertical nystagmus) or in a circular motion (rotary or torsional nystagmus), or a combination of directions. In jerk nystagmus, the eyes drift slowly in one direction and then jerk back in the other. In pendular nystagmus the eye moves slowly in one direction and then slowly back again. If the eyes move quickly at all times (no slow phase) it is not nystagmus and likely to be different eye movement problem.

The two main types of nystagmus are based on when it develops:

• Infantile nystagmus (also called congenital or early onset nystagmus): You can be born with it, but most develop it within the first few months of life.
• Acquired nystagmus: This type appears later in childhood or in adulthood.

What are the different types of nystagmus?

Understanding the specific type of nystagmus can be useful, as it can help understand the cause and guide how it can be best investigated and then managed. The main types are infantile (also called congenital or early onset) and acquired nystagmus. There are also other ways to classify it, for example based on its direction, age of onset, or other associated eye problems.

Infantile nystagmus (congenital nystagmus)

• What is it? Infantile nystagmus, also known as congenital nystagmus or early onset nystagmus, means that it appears very early in life. The term ‘congenital’  is less used now, since it more often develops in the first months of life rather than being already present at birth.
• How does it come about? Infantile nystagmus can happen if there are problems with how the brain and eyes work together to control eye movements. This part of the visual system is still developing in babies.
  
  Infantile nystagmus can occur on its own or with another eye condition that the child is born with, such as albinism, congenital cataracts, aniridia (absence of the iris), underdeveloped optic nerves, or certain retinal disorders like Leber congenital amaurosis.
  
  When the nystagmus seems to be in isolation (no other eye or systemic problems) it is often called idiopathic nystagmus.
  
  Differences in specific genes can sometimes cause infantile nystagmus, meaning it can be passed down through families, whether it occurs in isolation or due to other problems with the eyes or elsewhere (such as albinism).
  
  
• Who does it tend to affect? It affects babies and young children, usually beginning within the first six months of life.
  
  

Fusion maldevelopment nystagmus syndrome (previously Manifest Latent Nystagmus (MLN))

One form is called Fusion Maldevelopment Nystagmus (FMNS), or Manifest Latent Nystagmus (MLN), and is commonly seen in children who have no ability to see in stereo (lack of coordination between the eyes). 

• What is it? A type of nystagmus that starts early in childhood. It gets noticeably worse if one eye is covered up.
• How does it come about? It happens when a child’s eyes don’t work together as they should to send joined-up messages to the brain. It can be caused by any eye problems in the first months of life that mean both eyes don’t work together normally. The most common causes are strabismus (squint) and amblyopia.  
• Who does it tend to affect? It usually starts in the first months of life. It tends not to go away, so people of any age can have it.

Acquired nystagmus

• What is it? Acquired nystagmus develops later in childhood (after six months old) or in adulthood. Unlike infantile nystagmus, people with acquired nystagmus might experience oscillopsia – a sensation that the surrounding environment is shaking or moving.
• How does it come about? Acquired nystagmus can result from a range of factors that affect the parts of the brain and inner ear that control eye movements and balance. Common causes include stroke, multiple sclerosis, head injury, brain tumours, inner ear disorders (like Ménière's disease), side effects of certain medications (such as antiseizure drugs), vitamin deficiencies, or excessive alcohol or drug use.
• Who does it tend to affect? It can affect people of any age. It’s more common in adults.

What are the causes of nystagmus?

Nystagmus happens when there's a problem with the complex systems that control eye movement. This can involve the brain, the inner ear's balance system, or the eyes themselves. There are many potential causes, which include:

• Genetic differences: This means that nystagmus is sometimes passed down through families. Differences in some genes cause apparently isolated nystagmus (e.g. FRMD7) but in more cases they also cause other problems with the eyes or elsewhere (e.g. GPR143 which causes X-linked ocular albinism).
• Other eye conditions: Such as congenital cataracts, aniridia, optic nerve hypoplasia, strabismus, amblyopia, severe refractive errors or inherited retinal dystrophies. If one of these conditions means the eyes are unable to send clear visual information to the brain, particularly from an early age, nystagmus can develop. This can be due to conditions like severe refractive errors, congenital cataracts, or disorders of the retina or optic nerve.
• Albinism: This genetic condition causes a lack of pigment in the skin, hair, and the iris of the eye. That in turn leads to vision problems early in life, which can affect the normal development of the visual pathways and lead to nystagmus. It is one of the most common causes of nystagmus in children.
• Vestibular disorders (inner ear or nervous system issues): The vestibular system controls balance and helps to coordinate eye movements with head movements. Vestibular problems can be caused by problems with the inner ear, or with the central nervous system. Benign paroxysmal positional vertigo (BPPV) and Ménière's disease are examples of vestibular disorders that can lead to acquired nystagmus.
• Neurological disorders (brain-related causes): Conditions affecting the brain areas that control eye movements can cause acquired nystagmus. These include stroke, multiple sclerosis, brain tumours, and head injury.
• Medication side effects: Some medications, such as some anti-seizure medications, can cause nystagmus as a side effect. Often the nystagmus improves when the medication is stopped. 

What are the signs and symptoms of nystagmus?

The main sign of nystagmus is uncontrollable movement of the eyes, but it can have wider effects too. The condition can lead to other symptoms that affect vision and daily life, depending on the type and severity of the nystagmus.

• Rapid eye movements: The eyes move uncontrollably, often side-to-side, up and down, or in a circular pattern. If nystagmus develops early in life, the child may be unaware of these movements.
• Blurred vision: The constant movement of the eyes can make it difficult to focus clearly, leading to blurred or shaky vision.
• Reduced visual acuity: Vision may not be sharp, although this varies a lot between people with nystagmus.
• Difficulty fixating on objects: Maintaining a steady gaze on a particular point can be challenging.
• Head nodding or tilting: Some people with nystagmus find a specific head position (known as a “null point” or “null zone”) where the eye movements are reduced, and vision improves. This can lead to a habitual head tilt or turn.
• Sensitivity to light (photophobia): Some people with nystagmus, particularly those with associated conditions like albinism, may be very sensitive to bright light.
• Oscillopsia: This is a feeling that the surrounding environment is moving or shaking. It is more common in acquired nystagmus, when the brain has not adapted to the new eye movements. It can cause dizziness and disorientation.
• Difficulties with judging distances and depths: Judging distances accurately can be difficult, which can affect activities like sports or navigating stairs.
• Fatigue and eye strain: Constantly trying to see clearly despite the eye movements can be tiring and lead to eye strain.
  
  

Nystagmus in babies

If your baby has nystagmus, symptoms usually become noticeable between six weeks and three months old, although it can sometimes develop later. You’ll probably spot the constant, erratic eye movements in one or both eyes. If you’re worried your baby has nystagmus, speak to your GP or optician, who can refer you to an ophthalmologist. 

As your baby gets older, you might notice that they have difficulty seeing clearly and problems with balance. They might find it more difficult to follow fast movements. 

Nystagmus in children

Nystagmus is the most common visual impairment in school-aged children. How much their eyesight is affected depends whether the nystagmus is caused by another eye problem that means they can’t see clearly. If the nystagmus occurs on its own they may still be able to see quite well.

Large print books can be helpful, particularly when your child is learning to read. They will need extra support and time to read. Before they start school it’s a good idea to talk to their school about what extra help they might need. A specialist teacher for visual impairment might be able to help. You can ask for extra time in school tests, as reading the questions may take your child longer.

Children with nystagmus can feel self-conscious and worry about their appearance, or about bullying. So it’s important that they get lots of support. The Nystagmus Network and Guide Dogs can offer support for children with nystagmus. 

Is nystagmus serious?

Nystagmus itself isn't typically considered dangerous or life-threatening. But it can affect eyesight, making activities like reading, driving, work, and study more challenging. Everyone’s vision with nystagmus is different, but it tends to be worse if the nystagmus is caused by another eye condition.

Nystagmus can be serious in several ways:

• Underlying conditions: Especially if nystagmus develops later in life (acquired nystagmus), it can sometimes be the first sign of a more serious underlying disorder of the eye, brain, or inner ear, such as a stroke, multiple sclerosis, or a brain tumour. Always see a doctor if you suddenly develop nystagmus.
• Impact on vision: Reduced vision can have an effect on education, quality of life, independence, and career opportunities. So it’s important to get support for your child if they need it, and to ask for adjustments that might help you in the workplace. If the nystagmus is acquired, it can come with oscillopsia, which is a feeling that the world around you is in constant motion. This can be difficult to live with.
• Social and emotional impact: Living with nystagmus can sometimes lead to feelings of self-consciousness or anxiety, particularly for children. Some people find they can’t take part in sports, and unfortunately, some children with the condition are bullied at school. 

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What should you do if you’re worried about nystagmus?

If you or your child develops nystagmus, or if existing nystagmus changes or worsens, it is important to see an eye specialist (ophthalmologist) or a GP for a referral. They can investigate the cause and provide advice on management. Early diagnosis and intervention can be important, especially for children, to ensure they receive the right support for their vision and development.

Sometimes nystagmus is caused by another condition, so getting help for nystagmus that has appeared for the first time might lead to diagnosis and treatment for that condition too. 

How is nystagmus diagnosed?

Nystagmus is usually diagnosed through an eye examination, description of the symptoms and general medical history. You might be referred for further tests too. The diagnosis is usually made by an ophthalmologist (a hospital eye doctor) or sometimes by an optometrist with a special interest in this area. Neurologists may also be involved if a neurological cause is suspected.

The doctor will ask about when the nystagmus started, any family history of nystagmus or eye conditions, any associated symptoms (like oscillopsia, dizziness, or hearing problems), and general medical history, including any illnesses and medications. They will do an eye examination and consider what further tests are needed. 

What tests are used to diagnose nystagmus?

As well as a general eye examination and vision test, some of the specific tests that might be used to diagnose nystagmus include:

• Eye examination: This will include a standard vision test. The eye specialist will carefully measure the eye movements. They will also check if the nystagmus changes with different gaze positions or when one eye is covered.
• Refraction test: This helps to decide what strength of glasses or contact lenses are needed to correct any refractive errors like short-sightedness, long-sightedness, or astigmatism.
• Optical Coherence Tomography (OCT): This imaging test can provide detailed pictures of the retina and optic nerve, helping to identify underlying eye conditions which can be associated with nystagmus.
• Electroretinography (ERG): An ERG measures the electrical response of the light-sensitive cells in the retina. It can help diagnose retinal dystrophies that may cause nystagmus.
• Vestibular testing: If an inner ear problem is suspected, there are several different tests of the vestibular system (balance system) that can be used. Some of them involve moving your head in specific ways while the doctor looks at the effect this has on your eye movements.
• Neurological scans: Brain imaging, such as an MRI scan, might be used for acquired nystagmus, or occasionally in children if a neurological condition is suspected.
• Genetic testing: If an inherited cause is suspected, particularly in infantile nystagmus, you may be offered genetic testing to identify specific gene mutations.

Is the diagnosis different depending on age?

The approach to diagnosing nystagmus is similar at any age, involving an eye examination and questions about symptoms, when it started and other factors. However, the emphasis of further investigations may differ.

In babies and young children, the focus is often on identifying eye issues that may have caused the nystagmus, like albinism, congenital cataracts, or retinal dystrophies. Tests like OCT and ERG can be particularly important, as well as observing the child's head posture and how their vision functions in daily activities.

In adults, diagnosis is often geared towards ruling out serious acquired causes like stroke, multiple sclerosis, brain tumours, or vestibular disorders. Tests such as MRI scans may be more likely.

What are the treatments for nystagmus?

Currently, there is no cure for nystagmus itself. Treatments aim to improve vision, reduce the impact of nystagmus, and address any underlying conditions. It's important for anyone with nystagmus to have regular eye check-ups to monitor their vision and so they can discuss the most appropriate management and treatments.

Here are some of the treatment and management options:

• Treating underlying conditions: If nystagmus is caused by another medical issue that can be treated, this can sometimes reduce or resolve the nystagmus.
• Glasses or contact lenses: These are used to correct any refractive errors (like short-sightedness, long-sightedness, or astigmatism) to ensure the person has the clearest possible vision. While they don't stop the eye movements, vision correction is very important, especially for children's visual development. Some people find contact lenses easier than glasses, as they move with the eye and may offer a more stable visual image.
• Surgery: In specific cases, surgery on the eye muscles may be considered. This procedure aims to move the eyes to a position where the “null point” (the direction of gaze where the nystagmus is least and vision is best) is more central. This can reduce the need for an awkward head posture and may sometimes improve vision by slowing the involuntary movements.
• Medications: Several medications, such as gabapentin, baclofen, or memantine, are sometimes used to treat certain types of nystagmus, particularly acquired forms. But their effectiveness varies, and they can have side effects, so their use needs to be carefully considered by a specialist.
• Visual rehabilitation and occupational therapy: Therapists or specialist teachers can help people learn strategies to cope with the visual challenges of nystagmus in daily life, school, and work. This might include advice on lighting, positioning for reading, and classroom or workplace adaptations.
• Prisms: Special lenses called prisms can sometimes be incorporated into glasses. They can help move a person’s centre of vision to the “null point” where there are fewer symptoms. This might reduce the need for head tilting and make some people more comfortable.
• Assistive devices and technology: These might include large print books and materials, different types of magnifiers, screen magnification software for computers, and speech-to-text and text-to-speech software.
• Head positioning (null point awareness): Encouraging individuals, especially children, to use their “null point” (the head position where their nystagmus is least and vision is best) can be helpful.
• Low vision aids: For those with significantly reduced vision due to nystagmus, low vision services can provide a comprehensive assessment and recommend various aids and strategies to maximise remaining vision.

What can help nystagmus?

If you or your child has vision problems from nystagmus, ask for support from your hospital's low vision aid service. Some people find that low vision aids such as telescopic and magnifying lenses may be helpful, as well as large print books. And there is a wide range of assistive technologies that may help people in their daily lives, such as speech-to-text software.

What research is there into nystagmus?

Researchers are working to improve our understanding of nystagmus, develop better treatments, and enhance quality of life for people affected. Fight for Sight is committed to funding research that achieves these aims. Our work has already brought advances in diagnosis and prediction of nystagmus. We’re currently funding more projects focusing on improving vision. It is also important to remember that nystagmus is caused by different things in different people and much research is ongoing into treatingcauses such as retinal dystrophies and albinism, including clinical trials.

Read below for some examples of Fight for Sight-funded work into nystagmus.

Better diagnosis and prognosis

With support from Fight for Sight and the Nystagmus Network, Dr Mervyn Thomas has revolutionised the diagnosis of infantile nystagmus. Our funding enabled him to develop the first gene panel for the condition. A gene panel is a type of genetic test that can look at several or even many genes known to be associated with a particular condition, all at the same time. This dramatically speeds up diagnosis and improves accuracy.

Further Fight for Sight funding helped Dr Thomas create the Leicester grading system for foveal hypoplasia using scans to produce high-resolution images of the retina. This system grades how well-developed the retina is and helps to predict future vision in children with nystagmus, offering families vital prognostic information. 

Our grants are now helping Dr Thomas and his team to discover more about how childhood nystagmus develops, and potential new drugs to treat it, by studying zebrafish.

Read more about Dr Thomas’s research.

Tackling reading difficulty for people with nystagmus

Fight for Sight is currently funding a PhD student supervised by Dr Frank Proudlock at the University of Leicester to tackle the damaging effects of glare for people with albinism and infantile nystagmus. This research aims to develop reliable methods for measuring glare's impact on vision, particularly reading. They will use advanced OCT scans to study differences in the iris (the coloured part of the eye) and assess how effective treatments like tinted lenses are. This project aims to deliver evidence for treatments that can significantly improve daily life for those affected by glare.

Read more about Dr Proudlock's research.