What Is Nystagmus? - Definition, Causes, Symptoms & Treatment

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

Nystagmus is characterized by rapid, involuntary movements of the eyes. It may be present at birth or develop later in life. Read this lesson to learn about the different types, causes, symptoms, and treatment options of nystagmus.

Nystagmus Definition

What exactly is nystagmus? Well, it's a condition that causes rapid, involuntary eye movements that often impair a person's vision. It can affect one or both eyes, and the direction of movement may vary. Horizontal nystagmus means the eyes dart from one side to the other, vertical nystagmus means the eyes dart up and down, and rotary or torsional nystagmus means the eyes move in a circular motion.

Causes of Nystagmus

Nystagmus is caused by abnormal functioning in the part of the brain that is responsible for controlling eye movements. Sometimes the cause can be identified, and sometimes, there is no obvious reason for the movements to occur (called idiopathic nystagmus). Some common causes of nystagmus include a lack of development of eye movement control in early life, severe nearsightedness or astigmatism, or problems in the inner ear.

Types and Symptoms of Nystagmus

There are two primary types of nystagmus: infantile nystagmus syndrome (INS) and acquired nystagmus. Let's look at each of these.

  • Infantile nystagmus syndrome (INS): this type of nystagmus is present at birth and is usually mild. It typically manifests in horizontal nystagmus. Even though the movements may not be noticeable, they might still impair the infant's vision. If the movements are identified and the cause is known, they can often be surgically fixed. So what causes INS to develop in the first place? It's usually caused by a congenital disorder. The different types of congenital disorders that can cause nystagmus include congenital cataracts, albinism (a lack of skin pigment), a missing iris (the colored part of the eye), or underdeveloped optic nerves (which transmit information from the eye to the brain).
  • Acquired nystagmus: this type develops later in life. It can be caused by drug or alcohol use, medications (especially anti-seizure medications), head injury, inner ear disorders or inflammation, stroke, vitamin deficiencies, metabolic disorders, central nervous system disorders, or conditions like tumors or multiple sclerosis.

Additional symptoms of nystagmus include dizziness, sensitivity to light, impaired vision at night, and feeling like the world is shaking. These symptoms may be aggravated with stress and fatigue and can affect depth perception, balance, and coordination. People with nystagmus sometimes find that holding their head in a certain position or nodding can help counteract the eye movements.

Treating Nystagmus

So, how is nystagmus treated? Well, there is no cure for INS, but medication, surgery, and prism therapy may help with symptoms. Eyeglasses or contact lenses won't stop the eye movements, but they can improve vision.

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