Nystagmus: Symptoms, Causes, Treatments
Nystagmus refers to jerky, rhythmic, involuntary eye movements. Pronounced nuh-STAG-muhs, the condition may look like someone trying to track objects from the window of a fast-moving vehicle.
Nystagmus can prevent someone from maintaining a fixed focus on an object. Some forms of it affect only infants and children; others appear later in life.
When nystagmus appears in later life, it’s usually due to an underlying neurological condition. However, temporary nystagmus can also be caused by excessive alcohol intake. In fact, police officers look for nystagmus when stopping a driver for suspected drunk driving.
This is why the officer will instruct the driver to move their eyes to the far left and right while keeping the head still. If the driver is intoxicated, nystagmus will indicate (but not prove) an alcohol blood level too high for the safe operation of a vehicle.
Although not foolproof, nystagmus in an impaired driver is highly suspect and legally sufficient for a presumptive suspicion of drunk driving, especially if the driver refuses to take a breath test.
Alcohol causes temporary nystagmus by affecting the brain’s ability to control the eye’s movement muscles.
The higher the blood alcohol level (BAC), the more obvious the nystagmus will typically be.
Causes of Nystagmus
- These may include:
- Flashing lights in front of the eyes
- Alcohol, nicotine, and certain other drugs
- Vibrations (this is rare)
According to the Investigative Ophthalmology and Visual Science journal, nystagmus is relatively rare, with only about two to three persons per 1,000 showing signs of it.
Although most forms have an underlying neurological disorder causing them, some are caused by an inner ear problem.
Types of Nystagmus Have Two Major Classifications
Also called optokinetic, this is typically associated with a disorder of the eyes or nervous system.
Jerk Nystagmus or Vestibular
This is linked to disorders of the inner ear’s vestibular system. The inner ear’s vestibular system is located between the cochlea and the semicircular canals, which help to maintain balance.
Jerk nystagmus is the less common of the two.
Congenital and Acquired Nystagmus
Within the two major classifications, the condition may be broken down further:
Congenital or Infantile Nystagmus
This is present at birth, although it may not be directly apparent until the child is six months old. According to the National Institute of Health, about one in 5,000 infants is born with it.
The term congenital means present at birth, as opposed to a condition acquired later in life.
This can occur at any time after the age of six months and may be caused by disease, injury, accident, or neurological disease.
This form may be linked to family history, eye conditions like cataracts or strabismus, head injuries, multiple sclerosis, Meniere’s disease, strokes, inner ear disorders, and albinism.
Albinism comes from the Latin word alba, meaning white. Persons with this genetic condition lack pigment in their skin and eyes. The condition is common in rabbits, who often have white fur and pinkish eyes, but is not as common in humans. Human albinos occur at the rate of about one in every 10,000.
Tourette’s syndrome may also be associated with eye movements similar to nystagmus, but these are called optical tics when they occur as part of Tourette’s.
Other Types of Nystagmus
Spasmus nutans is the most common type seen in children ages six months to three years. It usually clears on its own between the ages of two and eight years.
Latent nystagmus occurs only when one eye is covered.
Manifest nystagmus is visibly present at all times.
Manifest-latent nystagmus is visible at all times but worsens when one eye is covered.
Gaze-evoked nystagmus (GEN) is the most common subtype overall. It occurs only when the eyes are directed in extreme positions away from the central visual field.
These may include:
- Problems with balance
- Blurry vision
- Sensitivity to light
- Poor or reduced night vision
- Oscillopsia or the sensation that stationary objects are moving
- Placing of the head in abnormal positions
Infantile or childhood nystagmus may resolve on its own, but other forms are often resistant to treatment. In these cases, therapy focuses on the underlying condition. If it’s not amenable to treatment, nystagmus is likely to persist.
If the cause is ocular, contact lenses and eyeglasses may help nystagmus patients see better. Contacts are preferable because the center of the lens follows the eye’s movements and moves along with them.
Biofeedback may help some patients by teaching them how to control body functions that are normally not voluntary. Biofeedback may help someone to lower their blood pressure or breathing rate, for example.
Some patients may receive good results with medication or surgery. It ultimately depends on the underlying condition’s treatability and patient compliance with the prescribed treatment.
See Your Eye Doctor
Routine eye exams typically include screening for possible nystagmus. People with this condition typically already know something is wrong. An eye doctor can help to pinpoint the problem and refer you to a specialist if needed.
An eye doctor will test you for possible nystagmus with several diagnostic techniques, usually beginning with simple instructions to follow a penlight or finger with your eyes.
If your eye doctor suspects nystagmus from this test, they may refer you to an eye specialist called a neuro-ophthalmologist. As the name suggests, these specially trained eye doctors treat eye problems related to underlying neurological conditions.
Special Tests for Nystagmus
1. Optokinetic nystagmus test: this involves watching your eyes track rapidly moving images.
2. Oscillating tracking test: the doctor will instruct you to focus your eyes on their nose as they turn your head from side to side, alternating between slow and fast movements.
If the eyes indicate a failure to stay on the focal point, this may indicate an inner ear problem.
3. Positional nystagmus test: this is also called the Dix Hallpike test and determines if the cause may be related to the inner ear. You’ll begin by sitting up with your legs out straight. The doctor will turn your head and then lay you down quickly.
Other positions will follow. The idea is to observe your eye movements for nystagmus related to changing directions.
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