Nystagmus

Nystagmus

Gauri S. Shrestha, M.Optom, FIACLE

What is Nystagmus?
 Involuntary and repetitive oscillatory movement
of one or both eyes
 May be physiological or pathological or idiopathic
 May be early onset or later onset
 Often seriously reduces vision

Gauri S Shrestha, M.optom, FIACLE

Depth of Field
 Reduced by nystagmus
 These patients may be prone to tripping or
clumsiness.
 Co-ordination is usually adequate for most tasks,
but nystagmus patients are unlikely to excel at
sports needing good hand to eye co-ordination

 Nystagmus is actually a sign not the
diagnosis

Description
 Position (Primary or gaze-related)
 Frequency (Rapid or slow)
 Null zone:
 Nystagmus is minimal in this field of gaze (this may be
left or right or on convergence
 Direction
 May be horizontal, vertical or rotational (Described by
the direction of fast phase)
 Waveform (Jerk or pendular)
 Amplitude (How far the eye moves)


Representation
Jerky Nystagmus

Rt. Beating
Lt. beating
Pendular
Intense jerk Nystagmus
o No Nystagmus


Diagrammatic depiction of Nystagmus


Horizontal Nystagmus

Null Zone & Neutral Zone
 Null Zone
 The field of gaze in which nystagmus intensity is
minimal
 The eye position in which a reversal of direction of jerk
nystagmus occurs and in which no nystagmus
 The null and neutral zones usually overlap; however,
several cases have been recorded where they do not.


Incidence
 Nystagmus affects about one in a thousand people.
 One survey identified one in every 670 children by
the age of two as having nystagmus.


What Causes Nystagmus?
 May be inherited or result from a sensory problem
 some cases occur for no known reason
 It can also develop in later life, sometimes as a
result of an accident or a range of illnesses,
especially those affecting the motor system.


What Should We Know?
 Refractive error Correction
 Limitations

 Vision often varies during the day
 affected by emotional/physical factors such as stress,
tiredness, nervousness or unfamiliar surroundings.
 Balance
 Poor depth perception, which can make it difficult to go up
and down stairs.


Classification


Non-Physiological Nystagmus
Based on Appearance of waveform
1. Jerk Nystagmus
 Well-defined slow and
fast phases
2. Pendular Nystagmus
 No defined fast phase
(pendulum movement)


Physiological nystagmus...
 Optokinetic nystagmus (OKN)
 Jerky nystagmus induced by
moving patterned targets across
the visual field.
 Slow phase along the direction
of the moving patterns, followed
by a fast phase in opposite
direction.
 Also called railroad nystagmus.
 Clinical significance in detecting
visual acuity.


Physiological nystagmus
 End point nystagmus
 Fine jerk nystagmus extreme gaze position
 Fixation nystagmus - fine oscilllatory movements
during the maintenance of steady fixation
 Caloric nystagmus
 Jerk nystagmus caused by altered input from the
vestibular nuclei to the horizontal gaze centers.
 Nystagmus induced by caloric test.


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


Congenital nystagmus
 Infrequently observed at birth.
 Onset is usually during the first 3-4 months of life
but may emerge as late as the teens.
 Prevalence is 1 in 6550. (Hemmes in 1927).
 Compensatory head nodding develops at the age
of 20 years.


Congenital Nystagmus
 Latent nystagmus
 Jerky horizontal nystagmus seen when light stimulus
to one or other eye diminished.
 Involuntary rhythmical oscillation of both eyes with
fast phase to the fixing eye
 Latent nystagmus applies to patients with binocular
single vision


Latent nystagmus…


Manifest congenital nystagmus
 Nystagmus evoked when both eyes are open.
 Amplitude doesnot change on covering one eye.
 Sensory defect nystagmus.
 Motor defect nystagmus.


Sensory defect nystagmus
 Basic cause is the inadequate image formation on
the fovea
 As a result of inadequate anterior visual pathway
disease.
 Inadequate image formation interferes with the
oculomotor control of fixation mechanism.
 Always bilateral & horizontal.
 Often is of pendular type
 Assumes jerky character in extreme position of
gaze.


Motor defect nystagmus
 Primary defect is in the efferent mechanism.
 No ocular abnormalities are present.
 Amplitude & frequency may decrease or
nystagmus may disappear completely in one
position of gaze (null point / neutral zone).
 Visual acuity may improve at the null point /
neutral zone.
 Patient may assume anomalous head posture to
 To assume null point.
 To improve visual acuity.


Congenital Nystagmus
 Pendular Nystagmus
 Can be found in patients with known foveal
disorder
 Macular Scarring, Macular Hypoplasia, Optic

Nerve Hypoplasia

 Congenital idiopathic nystagmus
 Bilateral, horizontal and jerky with the fast phase
to the right on right gaze and vice versa.
 There is null point between the two positions and
convergence with improved VA


 Latent manifest nystagmus
 Occurs in children with decreased vision in one eye
where the poorly seeing eye behaves as an
occluded eye.
 May be due to blindness in one eye or by deep
suppression due to strabismus.


Nystagmus blockage syndrome
(NBS)
 Congenital nystagmus dampens
with convergence or adduction.
 Demonstrates an esotropia to
dampen nystagmus.
 Features
 Infantile esotropia
 Pseudoabducens palsy
 Manifest nystagmus occurs when
eye moves from adduction to
abduction.
 All patients with infantile esotropia
should be screened for nystagmus.

Periodic alternating nystagmus
 Unusual form of congenital motor jerk nystagmus
 Patient starts with a jerk nystagmus in one direction &
lasts for 60 – 90 sec & then slowly begins to dampen.
 A period of no nystagmus lasts for 10-20 seconds and then
the nystagmus begins to jerk in opposite direction (60-90
sec).
 Cycle again repeated.
 Etiology not known but is associated with oculocutaneous
albinism.


Characteristics of Congenital
Nystagmus
 Binocular
 Similar amplitude in both eyes
 Usually uniplanar (horizontal) in all gazes
 Distinctive waveforms
 Diminished (damped) by convergence
 Increased by fixation attempt
 Superimposition of latent component
 Intensity increase at lateral gazes – fast phase towards the
direction of gaze
 Associated head oscillation
 No oscillopsia
 Abolished in sleep


Acquired : Spasmus nutans
 combination of nystagmus, involuntary head nodding and
abnormal head posture. Intermittent rapid small oscillation
with onset at 3-18 months, resolution at 36 months.
 A rare constellation of ocular oscillation
 Head nodding &
 Torticollis
 Begins in infancy (usually between 4 and 18 months of age)
 Disappears in childhood (usually before 3 years of age).


Acquired
 Acquired pendular nystagmus - result of cerebellar
or brainstem lesions. equal amplitude of
nystagmus in all gazes
 Acquired jerk nystagmus - (slow and fast phase),
may be horizontal, vertical or rotary, due to
supranuclear defect

 Vestibular nystagmus - horizontal jerky
nystagmus with rotary or vertical element, due to
the destruction of inner ear, vestibular nerves and
vestibular nuclei.

Acquired
 Gaze evoked nystagmus -an inability to maintain the eyes
in a lateral or vertical gaze position. The eyes drift back to
the primary position, then make a correction saccade to
look in the position of defective gaze. Cause is
supranuclear defect

 Dissociated nystagmus -oscillatory movements of eyes,
dissimilar in direction, amplitude and speed. Cause is
internuclear ophthalmoplegia

 Convergence retraction nystagmus -on attempted upgaze,
eyes are converging and retracting with nystagmoid jerk
movements

See-saw nystagmus
 Unusual & dramatic type.
 Has both vertical & Torsional
components.
 Eyes make alternating
movement of elevation &
intorsion followed by
depression & extorsion.
 Often associated with lesions
in the rostral midbrain or the
suprasellar area.
 Visual field defects are
bitemporal hemianopia.
 Neuroradiologic evaluation
mandatory. Gauri S Shrestha, M.optom, FIACLE

 Downbeat nystagmus: jerky vertical nystagmus
seen with increased amplitude on downgaze. The
eyes drift up and beat down again. Cause is CNS
lesion
 Upbeat nystagmus :jerky vertical nystagmus seen
with increased amplitude on upgaze. The eyes
drift down and beat up again. Cause is lesion of
cerebellum or medulla.
 Periodic alternating nystagmus :jerk nystagmus
is seen which alters in direction with every few
minutes. Cause may be drugs or multiple sclerosis

Downbeat nystagmus


Upbeat nystagmus


Nystagmus Management
 Neurological Work-up and appropriate
medical treatment
 Refer if necessary
 Provide Best Corrected VA
 Recommend with contact lenses
 Utilize Null Point
 Certain eye/head position that minimizes
nystagmus
 Vision Therapy


How Can You Utilize Null Point?
 Locate with version (ocular motility) testing
 Use of Prisms:
 Base-Out: if convergence reduces nystagmus
 Yoked: in extreme head turn reduces nystagmus
 Base toward Null point to reduce head turn

 Use Equal power (RE, LE)

 EOM Surgery:
 Move Null point to primary position


Near Work With Nystagmus
 The angle of vision is important.
 Null point. Adopt a head posture
 Small print.
 Visual Aids, Large print materials.
 Good Lighting
 Be Careful with Light sensitive paients
 Reading speed
 Reduced due to the extra time needed to scan
 Should not be taken as a sign of poor reading.


Nystagmus

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