Nystagmus

These movements often result in reduced vision and depth perception and can affect balance and coordination. These involuntary eye movements can occur from side to side, up and down, or in a circular pattern. As a result, both eyes are unable to steadily view objects. People with nystagmus might nod and hold their heads in unusual positions to compensate for the condition. Generally, nystagmus is a symptom of another eye or medical problem. Fatigue and stress can make nystagmus worse. However, the exact cause is often unknown.

The forms of nystagmus include:

• Infantile. Most often develops by 2 to 3 months of age. The eyes tend to move in a horizontal swinging fashion. It is often associated with other conditions, such as albinism, congenital absence of the iris (the colored part of the eye), underdeveloped optic nerves and congenital cataract.
• Spasmus nutans. It usually occurs between 6 months and 3 years of age and improves on its own between 2 and 8 years of age. Children with this form of nystagmus often nod and tilt their heads. Their eyes may move in any direction. This type of nystagmus usually does not require treatment.
• Acquired. Develops later in childhood or adulthood. The cause is often unknown, but it may be due to the central nervous system and metabolic disorders or alcohol and drug toxicity.

Causes & risk factors

Nystagmus is most commonly caused by a neurological problem that is present at birth or develops in early childhood. Acquired nystagmus, which occurs later in life, can be the symptom of another condition or disease, such as stroke, multiple sclerosis or trauma.

Other causes of nystagmus include:

• Lack of development of normal eye movement control early in life.
• Albinism.
• Very high refractive error, for example, nearsightedness (myopia) or astigmatism.
• Congenital cataracts.
• Inflammation of the inner ear.
• Medications such as anti-epilepsy drugs.
• Central nervous system diseases.

Symptoms

• Involuntary eye movement.
• Movement can be in one eye or both.
• Objects may appear blurry and shaky.
• Nighttime vision problems or sensitivity to light.
• Balance and dizziness.

Diagnosis

Nystagmus can be diagnosed through a comprehensive eye exam. Testing for nystagmus, with special emphasis on how the eyes move, may include:

• Patient history to determine any symptoms the patient is experiencing and the presence of any general health problems, medications taken, or environmental factors that may be contributing to the symptoms.
• Visual acuity measurements to assess the extent to which vision may be affected.
• A refraction to determine the appropriate lens power needed to compensate for any refractive error ( nearsightedness, farsightedness, or astigmatism).
• Testing how the eyes focus, move and work together. In order to obtain a clear, single image of what is being viewed, the eyes must effectively change focus, move and work in unison. This testing will look for problems that affect the control of eye movements or make it difficult to use both eyes together.

Since nystagmus is often the result of other underlying health problems, a doctor of optometry may refer the patient to their primary care physician or another medical specialist for further testing. Using the information obtained from testing, a doctor of optometry can determine if the patient has nystagmus and advise on treatment options. Other testing may include an ear exam, neurological exam, and/or a brain MRI.

Treatment

While eyeglasses and contact lenses do not correct the nystagmus itself, they can sometimes improve vision. Using large-print books, magnifying devices and increased lighting can also be helpful. Some types of nystagmus improve throughout childhood. Rarely, surgery is performed to change the position of the muscles that move the eyes. While this surgery does not cure nystagmus, it may reduce how much a person needs to turn his or her head for better vision. If another health problem is causing the nystagmus, a doctor of optometry will often work with a primary care physician or other medical specialists to treat that underlying cause.

Prevention

Nystagmus can be hereditary, and a person can be born with it, but it can also be a sign of another medical condition. A comprehensive eye exam completed by a doctor of optometry is recommended to determine the cause and course of action.