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 Nystagmus

How prevalent is nystagmus?
What are the symptoms of nystagmus?
How is nystagmus treated?

Nystagmus is the medical term used to describe a condition in which the eye rhythmically wobbles or oscillates involuntarily, often impairing vision. The term nystagmus originated from the Greek word "nystagmos" which described how a person would nod after having too much to drink or when excessively tired.

Nystagmus often results from the instability or impairment of the system responsible for controlling eye movements and, therefore, the eye or usually both eyes are unable to maintain a steady fixation. Nystagmus that begins in infancy is called congenital or early-onset nystagmus and is usually inherited. When the condition develops after infancy (usually later than six months) or occurs later in life, it is called acquired nystagmus.

How prevalent is nystagmus?

Nystagmus affects about 1 in 1,000 people worldwide, and congenital nystagmus often runs in families. The disorder can result from a neurological dysfunction and can also be associated with other optical conditions such as albinism, corneal opacity, cataracts, optic atrophy, and others. Nystagmus may also be a reaction to certain drugs or medications. In some cases, the disorder occurs for unknown reasons.

What are the symptoms of nystagmus?

Nystagmus is characterized by involuntary, repeated oscillations of one or both eyes, and the disorder often affects the nerves behind the eye and not the eye itself. Movements may be horizontal, vertical, circular, or a combination of various motions and speeds. Nystagmus affects people in varying ways and degrees. Although most affected people view objects as stationary because the brain is thought to make the necessary adjustments, many often have reduced acuity because of the challenge to maintain a fixed focus. People with nystagmus tend to see objects in lower contrast, and many experience problems with depth perception that affect balance and coordination. Some of those affected with the disorder tilt their heads or display nodding to compensate for the impairment or symptoms.

Many people with nystagmus are considered partially sighted; some are registered legally blind; and most are unable to drive. Generally, the faster the oscillation, the lower the visual acuity, and, conversely, the slower the movement, the higher the visual acuity. It is important to point out, however, that vision impairment may also be a result of other underlying visual problems. Most people with nystagmus have a null point, which is a specific viewing angle when eye movement is reduced and vision is improved. Affected people often develop a certain head posture or body posture such as sitting to one side of a television, movie screen, etc., in order to get the best view.

How is nystagmus treated?

Unfortunately, to date, there is no cure for nystagmus, which is often a life-long condition. Some types of nystagmus improve throughout childhood, and visual acuity may improve with the use of prism optical devices, specialty lenses and, in some cases, muscle surgery. Corrective lenses or contacts do not correct nystagmus, although they can still be used by persons with the disorder to help in correcting other visual acuity problems.

Because nystagmus responds to physical and emotional triggers such as fatigue and stress, it is important for people to maintain a healthy lifestyle in order to optimize visual acuity. Other helpful aids currently available include reading devices, large-print books, magnifying devices, and improved lighting sources. In a majority of cases, people with nystagmus lead relatively normal, fulfilling lives. As in any case of vision problems, see an ophthalmologist or other medical specialists for a thorough evaluation and treatment.

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