What is nystagmus?
Nystagmus is an involuntary, fast movement of the eyes that causes some degree of vision loss.
Eye movement can be horizontal, vertical, or in a circular motion and the eyes may appear as if they are shaking or jerking side to side.
No two cases of nystagmus are the same. The direction and intensity of movement and the amount of vision loss can vary from person to person.
What causes nystagmus?
There are two main types of nystagmus:
Nystagmus that occurs at birth can be called congenital nystagmus, infantile nystagmus, or early onset nystagmus.
The onset of congenital nystagmus is typically from 6 weeks to 6 months in age. It can be caused by an underlying sensory or motor abnormality.
Nystagmus is often secondary to various vision conditions such as, albinism, optic nerve hypoplasia, congenital cataracts, and coloboma.
Acquired nystagmus can occur after 6 months of age and into adulthood.
It can be a symptom of various conditions, diseases, or trauma. Neurological problems and drug toxicity can also be causes.
What are the effects of nystagmus?
Children with nystagmus see the world with some blurriness.
Those with poor vision typically have an underlying sensory condition causing significant vision loss, but even though their eyes appear to shake the world is not shaking.
Those with acquired nystagmus may experience oscillopsia (the experience of objects jumping, wiggling, or moving when they are stationary), vision loss, and/or poor balance.
The severity can change depending on the direction of the persons gaze. Individuals may have a null point, or angle of gaze where the eye movement is reduced, and vision improves. People may adopt an abnormal head tilt or position to reach the null point to improve vision.
Stress or sleep can also cause the condition to worsen.
The following ocular and medical conditions can be associated with nystagmus:
- Retina coloboma
- Severe refractive error, myopia or astigmatism
- Other optic nerve and retina disorders
- Medication side effects
- Vitamin deficiency
- Multiple sclerosis
- Head Injury
- Diabetic neuropathy
- Brain tumor
- Inner ear (vestibular) problems
- Fetal alcohol syndrome
How is nystagmus diagnosed?
Nystagmus is diagnosed from a comprehensive exam with an ophthalmologist. The doctor will look at the inside of the eyes and test visual acuity.
As stated above, nystagmus is often a symptom of an underlying condition. The ophthalmologist will look for other eye conditions including strabismus (misalignment of the eyes), cataracts (cloudy lens), and other retina or optic nerve issues.
Other tests to diagnose nystagmus include:
- A neurological exam
- Vestibular testing such as a videonystagmography test
- A computerized tomography (CT) scan or magnetic resonance imaging (MRI) for images of the brain
- Eye-movement recordings to confirm movement and intensity of nystagmus
How is it treated?
Treatment of nystagmus depends on the cause. Congenital nystagmus cannot be corrected, however, glasses or contact lenses can be used to improve vision and slow eye movements.
Eye muscle surgery does not eliminate nystagmus, but it can help alleviate a significant head tilt and can sometimes improve vision.
If nystagmus is caused by another health condition, your primary care physician and other specialists will work to treat the underlying cause.