Nystagmus is involuntary eye movement that can cause vision problems. It has many potential causes including issues with the eye, brain, inner ear or genetic conditions. There are different types classified by timing, direction of eye movement, and other factors. Evaluation involves assessing symptoms, medical history and characterizing the nystagmus through observation. Management may include optical corrections, vision therapy, medical treatments, or rarely surgery to improve eye alignment and vision.

1. NYSTAGMUS : ASSESSMENTS
& MANAGEMENT
PRESENTER : MEHEDI HASAN
The largest & oldest multispecialty eye hospital

2. WHAT IS NYSTAGMUS ?
Nystagmus is a condition of involuntary (or voluntary, in rare cases) eye
movement, acquired in infancy or later in life, that may result in reduced or
limited vision. Due to the involuntary movement of the eye, it has been
called "dancing eyes".
Generally, nystagmus is a symptom of another eye or medical problem not a
disease itself. Nystagmus has an incidence rate of 1 in 1,000 people in the
general public and is the most common form of visual impairment among
children.

3. Possible Symptoms
• Noticing involuntary and abnormally
moving of the eyeball.
• Dizziness.
• Vision issues.
• Needing to hold the head in a tilted or
turned position.
• Light sensitivity (mostly in albinism)
• Trouble seeing when it is dark.
• The sensation that the world is
shaking.

4. Nystagmus Causes
Nystagmus usually results from a neurological issue that occurs early in life or is
present at birth. However, a person could develop nystagmus later in life.
In some cases, nystagmus is a symptom of an underlying condition, such as a
stroke, trauma, head injury, etc.
Other possible causes of nystagmus include:
• Children may not develop normal eye movements early in life.
• Astigmatism, nearsightedness, or a very high refractive error.
• Inner ear inflammation.
• Central nervous system diseases.
• Albinism
• Congenital cataracts.
• Anti-epilepsy drugs and certain other medications.

5. Nystagmus Types
• Congenital nystagmus: 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 : 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 nystagmus: Develops later in childhood or adulthood. The cause
is often unknown, but it may be due to central nervous system and
metabolic disorders or alcohol and drug toxicity , diabetic neuropathy, a
brain tumor, or a head injury.

6. Nystagmus Types
• Manifest Nystagmus: With this type, the symptoms are present at all
times.
• Latent Nystagmus: With this type, the symptoms only occur when
the person covers one of their eyes.
• Manifest-latent Nystagmus: With this type, the symptoms are always
there, but when the person covers one eye, the symptoms get worse.

7. Nystagmus Types
The other classifications could be based on the type of oscillations and
direction of oscillations.
Type of oscillations are Jerk , Pendular ,
Mixed (jerk + pendular)
and Torsional .
The direction of nystagmus is defined by the direction of its quick phase.
The oscillations may occur in the vertical, horizontal or torsional direction,
or in any combination. The resulting nystagmus is often named as a gross
description of the movement, e.g. downbeat nystagmus, upbeat
nystagmus, seesaw nystagmus, etc.

8. Nystagmus Types
Two other classifications (Physiological) of nystagmus are :
• Optokinetic (eye related) : tested by using an optokinetic drum —also
called catford drum.
• Vestibular (inner ear related) : tested by doing the caloric reflex test
also called COWS test.

9. Caloric reflex test
• If hot water is irrigated into right ear – patient will develop right jerk
nystagmus.
• and Cold water into right ear will develop – left jerk nystagmus
COWS (cold – opposite, warm – same)
If both ears are stimulated for :
• Cold water – upbeat jerk nystagmus
• Warm water – downbeat jerk nystagmus

10. Approach to a patient with Nystagmus
(Clinical evaluation)
Patient History
• Age of onset (i.e., at birth, before 6 months of age, or specifically when).
• Oscillopsia-a sense of oscillation of environment
• Vestibular abnormalities
• Strabismus/ Amblyopia
• Family history
• Birth history of the patient
• H/O previous treatment taken or not
• Association of the onset with any infection, drugs or medications, metabolic
disease, or trauma.

11. HOW TO TAKE THE VISUAL ACUITY IN
NYSTAGMUS PATIENT
• Acuity testing of patients who read optotypes can proceed in the
standard manner.
• It is often more reliable to determine line or single-letter acuity with
children rather than to assess full-chart Snellen acuity.
• When visual acuity is reduced, a Bailey–Lovie chart or low vision
chart may be needed.

12. • Allow the patient to assume the preferred head position for distance
and near testing.
• When nystagmus increases with occlusion, assess acuity using a
method that does not disassociate the eyes, use a plus lens and blur
one eye while measuring the acuity of the other eye.

13. Evaluation of Nystagmus and what to note on
the work up paper (Documentation)
Type of movement
PENDULAR MOVEMENT : Velocity equal in both directions -horizontal,
vertical and obliquely.
JERKY MOVEMENT : The eyes make a very quick movement in one
direction, followed by a slower movement in the opposite direction.
Mixed : Pendular in primary position, jerk on lateral gaze

14. Direction
• Right or left beating nystagmus
• Upbeat or downbeat nystagmus
• Torsional

15. AMPLITUDE
Amplitude is the extent of excursion of the nystagmus.
HOW TO MEASURE THE AMPLITUDE :
• The amplitude can be estimated using a millimeter ruler .
• As the patient fixates a target at 6 m, measurement of the overall
excursion is made by holding the ruler in front of the eye with the
best acuity (either eye, if the movements are conjugate).

16. • One millimeter of movement at the plane of the cornea translates to
about 22 Δ (12 degrees of visual angle) . Therefore, if 2 mm of
movement is noted, the eyes are moving approximately 24 degrees.
• Fine/ small : less than 5 degree
• Medium/ moderate : 5 -15 degree.
• Coarse/ large : greater than 15 degree

17. FREQUENCY
Frequency is the number of complete to and fro movements in one second.
HOW TO MEASURE THE FREQUENCY :
• One Hertz (Hz) (1 cycle per second) means that the waveform completes
one full rotation in 1 second. Frequencies greater than 2 Hz are considered
fast, and frequencies less than 1 Hz are considered slow.
• Frequencies slower than 2 Hz can be timed with a stopwatch as the
oscillations are counted.
• More rapid frequencies can be estimated with observation under low
magnification of the slit lamp.

18. NULL POINT
The gaze position of least eye movement is the “null point” and tends
to be where vision is best. Tilting or turning the head into this direction
where the movements are least can thus optimize vision.
NEUTRAL ZONE :
• The neutral zone is that eye position in which a reversal of direction
of jerk nystagmus occurs and in which none of the waveforms, or
pendular nystagmus is present.
• It is not synonymous with the null zone.

19. Example of a Nystagmus patient’s
documentation paper

24. Special investigation
• Electronystagmography (ENG) .
• Videonystagmography .
• CT scan / MRI of brain .

25. Management of nystagmus
Optical management :
• Spectacle :
1. Correcting the refractive error,
2. Another option is to give over-minus lenses to stimulate
accommodative convergence and thus dampens nystagmus .
• Contact lens .

26. • Prisms : can help in two ways :
1. Correction of Horizontal or Vertical
head turn. And
2. Base-out/Base-in prisms to improve
visual acuity by stimulating vergence eye
movements.

27. Other managements include :
• Occlusion therapy to improve visual acuity in amblyopia.
• Low vision aids .
• Vision therapy .

28. Medical Treatment
• Botulinum toxin injection.
• Drugs : not preferred because of their side effects and need for
prolonged treatment. Ex: Gabapentin, Scopolamine, Memantine,
Carbamazepine, Clonazepam, Barbiturates, Valproate, Alcohol,
Trihexyphenidyl, Cannabis, Benztropine, Acetazolamide . etc.

29. Surgery
AIM –
1. to shift the null point from eccentric position to
straight ahead position (primary position).
2. To induce extra convergence innervation by
weakening medial recti, to dampen nystagmus
3. To reduce the amplitude of the nystagmus by
weakening the muscle force of all recti.
• KESTENBAUM ANDERSON procedure.
• FADEN procedure.