Definition
Nystagmus is an involuntary rhythmic shaking or wobbling of
the eyes. The term nystagmus is derived from the Greek word
‘nystagmos’ which was used to describe the wobbly head
movements of a sleepy individual.
Classification of Nystagmus
•
•
•
•
Doctors and researchers classify nystagmus by
the characteristics of the eye movements like:
back and forth like a pendulum
slowly in one direction and then rapidly in
another
laterally or vertically and by how much
how fast do the eyes move
Classification of Nystagmus
However there are over 45 types of nystagmus
but traditionally nystagmus has been divided
into two groups:
• sensory nystagmus (congenital): that begins
very early in life and is related to vision loss.
• motor nystagmus (acquired): and is associated
with neurological disorders and control of
muscle function occurring later in life.
Congenital Nystagmus
• Congenital nystagmus occurs more frequently
than acquired nystagmus. It can be insular or
accompany other disorders.
• Types of congenital nystagmus include:
albinism, aniridia, optic nerve hypoplasia,
achromatopsia, congenital cataracts,
retinopathy.
Pendular Nystagmus
• The most typical nystagmus related to vision
loss during childhood is a pendular nystagmus.
The eyes rotate back and forth evenly, much
like a pendulum.
Pendular Nystagmus
Acquired Nystagmus
•
•
•
•
•
•
•
Nystagmus can be acquired later in life due to
neurological dysfunction, diseases or toxicity
such as:
cerebellar ataxia
thalamic hemorrhage
a head injury
stroke
multiple sclerosis
brain tumors
alcohol intoxication
Acquired Nystagmus
• Unlike nystagmus acquired from early in life,
patients with late onset nystagmus usually notice
movement in their vision related to the movement of
their eyes. This is called oscillopsia. Oscillopsia
causes a person to have dizziness related to the new
movement they experience in their vision.
• Late onset nystagmus is more likely to be directional.
The eye will move slowly in one direction, then
quickly move back.
• The nystagmus may change as the patient looks in
different directions.
• The unexplained onset of nystagmus in an adult may
indicate a serious neurological disorder and an
immediate examination is indicated.
Acquired Nystagmus
•
•
•
•
•
Acquired nystagmus is subdivided into:
Horizontal Pendular Nystagmus.
Vertical Pendular Nystagmus
Seesaw nystagmus
Elliptical nystagmus
Dissociated Nystagmus
Horizontal Pendular Nystagmus
Most frequently, horizontal or pendular
nystagmus is caused by:
• central lesions involving the central tegmental
tract
• damage of the cerebellar nuclei
• lesion near the oculomotor nuclei
Horizontal Pendular
Nystagmus
Vertical Pendular Nystagmus
Vertical nystagmus occurs much less frequently
than horizontal nystagmus and is often, but not
necessarily, a sign of serious brain damage. T
The most common cause vertical nystagmus that
frequently appears after:
• pontine hemorrhage related to damage to the
central tegmental tract.
• toluene sniffing, glue sniffing, usually in
accompaniment with cerebellar deficits
Vertical Pendular
Nystagmus
See saw Nystagmus
• Seesaw or jerk nystagmus is a rare binocular
disorder characterized by alternating vertical
skew deviation and conjugate ocular torsion.
Jerk seesaw consists of torsional slow phases
in one direction and quick phases in the
opposite.
See saw Nystagmus
Fluctuations in Vision
•
•
•
•
Nystagmus patients often experience
fluctuations in their vision. A change in the
speed of the nystagmus leading to a decrease
in vision can be related to:
stress
the patient’s emotional state
fatigue
the direction of view
The Null Position
• Patients with nystagmus often find a unique
position of their head and eyes that slows the
nystagmus allowing them to have better vision.
This is called a null position and varies with
each person.
Treatment
Congenital nystagmus has traditionally been
viewed as non-treatable, but medications
have been discovered in recent years. Several
therapeutic approaches are also proposed,
such as:
• contact lenses
• drugs
• surgery
Treatment
Gabapentin, an anticonvulsant, was found to
cause improvement in about half the patients who
received it to relieve symptoms of nystagmus.
Other drugs found to be effective against
nystagmus in some patients include:
• memantine
• levetiracetam
• acetazolamide
Treatment
• Clinical trials of a surgery to treat nystagmus
known as tenotomy. Tenotomy aims to reduce
the eye shaking (oscillations), which in turn
tends to improve visual acuity.