Highest level of visual acuity
• 3 mechanisms are involved in maintaining
foveal centration of an object of interest:
2- Vestibulo-ocular reflex,
3- Neural integrator.
• Fixation in the primary position involves the
visual system's ability to detect drift of a
foveating image and signal an appropriate
corrective eye movement to refoveate the
image of regard. The vestibular system is
intimately and complexly involved with the
• a complex system of neural interconnections
that maintains foveation of an object during
changes in head position. The proprioceptors of
the vestibular system are the semicircular
canals of the inner ear. Three semicircular
canals are present on each side, anterior,
posterior, and horizontal. The semicircular
canals respond to changes in angular
acceleration due to head rotation
3- Neural integrator
gaze-holding network called the neural
integrator generates the signal. The cerebellum,
ascending vestibular pathways, and oculomotor
nuclei are important components of the neural
• maintain a constant innervation of extra-ocular
eye muscles to avoid backward drift of the eyes.
• deficit in the neural integrator can result in gazeevoked nystagmus and oscillopsia in the eccentric
Movement of eye ball
• The movement are tested uniocular (duction) as
well as binocularly (versions) in all the 9
diagnostic positions of gaze.
• Uniocular –
Adduction, abduction, depression, elevation, de
pression and elevation in adduction and
• Duction: describes movement of one eye
– Supraduction or elevation
– Infraduction or depression
– Incycloduction or intorsion
– Excycloduction or extorsion
• Version: describes movement of two eyes in the
• Vergence: describes movement of two eyes in
Functions of Extra ocular
Superior rectus – moves eye up
Inferior rectus – moves eye down
Medial rectus – moves eye in (a-d-duction)
Lateral rectus – moves eye out (a-b-duction)
IO– moves eye up when it is in an adducted position;
also extorts the eye.
• SO– moves eye down when it is adducted; also intorts
Broad H Test
• Look for lags or overshoots at various diagnostic
positions of gaze
• Look for smooth and accurate pursuit movements
• Look for any gaze restrictions or overactions of
muscle in the 9 positions
• Look for comitancy ( deviation of the visual axes
remains constant in all fields of gaze, there is
• Test set-up is the same as for the broad H test
• Direct patient to look quickly from positions 8
to 2, and then back to 8
• Repeat rapid shifts of gaze from positions 6 to
5, and then back to 6
• Look for accuracy of movement (i.e.,
overshoots and undershoots), speed of
initiation ,latency and velosity.
SYSTEMS THAT CONTROL EYE
Each of these systems are controlled by
different anatomical pathways.
Control of Gaze
1) Gaze Stabilisation system.
2) Gaze alignment system.
Gaze Stabilisation System
Compensates for self-motion stabilising visual
world on the retina to achieve highest vision
-Optokinetic System (fixation)
- Neural integrator.
Gaze Stabilisation System
Main mechanisms of maintaining steady gaze:
1) fixation (Optokinetic System) (vol): >6months
a) prevent retinal image drift
b) suppress unwanted saccades object
2) Vestibulo-ocular reflex (VOR):
is a reflex eye
movement (pursuit) that stabilizes images on the retina
during head movement by producing an eye movement
in the direction opposite to head movement, thus
preserving the image on the center of the visual field.
Gaze Alignment System
Keeps object of interest within the visual
world centred on fovea:
Object Tracking Movements
• Saccade : (voluntary) fast, step-like eye movement
(up to 1000 deg/sec) that places image of the target
on the fovea
-Looking from point A to B
– alternate fixation bet different objects
– How to elicit? 1-Voluntary (internally triggered)
2 -Reflexive (externally trig by visual or auditory
3- Spontaneous (searching, REM of sleep)
4-Fast phases of nystag (physiologl or patholog).
• Pursuit : (reflex) slow, smooth-following movement
(up to 30 deg/sec) that maintains image of the moving
target on the fovea.
The generation of PE movement consists of 3 essential
elements: • A sensory component driven by an
image moving across the fovea.
• A motor component generated near the parieto–
occipito–temporal junction that projects to the
• An attentional–spatial comp for concentration on
selected targets, orientation in space.
Centers of Conjugate eye
• Saccades =contralateral frontal pre-motor area
• Pursuit= ipsilateral occipito-parietal area
• Vestibular reflexes= vestibular nuclei in the Pons:
pathways contain relatively few synapses (23) → very fast response (<6 ms)
• 3 primary reflexes:
– vestibulo-ocular (VOR)
SUPRANUCLEAR GAZE CONTROL
• Signals which control ocular movement are initiated in
the cerebral hemispheres.
They are then transmitted to the gaze centres and
oculomotor nuclei in the midbrain and pons and leave the
brain in the 3rd, 4th and 6th cranial nerves
Supranuclear neuronal pathways: conduct impulses from
cerebral hemispheres to gaze centres
Internuclear pathways: conduct impulses from gaze
centres to ocular motor nucleii
Infranuclear pathways: 3rd, 4th and 6th cranial nerves
There are three forms of conjugate eye movement
• These impulses are transmitted to the gaze centres,
which mediate the conjugate eye movement.
Horizontal and vertical gaze control are quite
The horizontal gaze centre is in the pons at the level
of the 6th nerve nucleus.
Horizontal movement to the left is controlled by the
left horizontal gaze centre and vice-versa for the
The vertical gaze centre is in the midbrain but not
much is known about vertical gaze control.
• Unilateral lesions of the PPRF produce characteristic findings Loss of horizontal saccades directed
towards the side of the lesion.
• Contralateral gaze deviation (acute lesions, such as
• Gaze-evoked lateral nystagmus on looking to the
direction of previous gaze palsy (recovery).
• Bilateral lesions produce horizontal gaze palsy and
slowing of vertical saccades.
Enables eyes to move disconjugately in the H plane
and allows binocular fixation of an object that
moves toward (converg) or away (diverg) from the
The main stimuli for Verg are retinal blur
(unfocused object) and diplopia (fusional disparity);
converg is associated with accommod and miosis
(the near triad).
The pathways that generate Verg are not known
precisely, but the occipital lobe, MB, and
cerebellum play significant roles.
• An inability to make a conjugate ocular movement
in one direction.
• This does not cause diplopia since the visual axes
• By investigating each reflex and conjugate
movement in turn, it is possible to establish where
a lesion exist.
Horizontal Gaze Palsies
Unilateral horizontal GP.
One and half syndrome.
Elderly-small vessel disease
One and a half syndrome
• Complete HGP in one direction and an INO in the
• limitation of horizontal eye movement to abduction
of one eye (e.g. right eye ) with no horizontal
movement of the other eye (e.g. left eye).
• Nystagmus is also present when the eye on the
opposite side of the lesion is abducted.
• Convergence is classically spared as Cranial Nerve
III (oculomotor nerve) and its nucleus is spared
unilateral lesion of the
PPRF and the ipsilat MLF.
An alternative anatomical
cause is a lesion of the
abducens nucleus (VI) on
one side, with interruption
of the ipsilateral MLF after
it has crossed the midline
from its site of
(III) nucleus (resulting in a
failure of adduction of the
parinaud’s Convergenceretraction Nystagmus
• Loss of upword gaze involving all types of ocular
• Upon attempt to upword saccade there is converg with
retraction of the globe followed by diverg. movement
• Not a true nystagmus: co-contraction of horizontal
recti on attempted upgaze
• Loss light reflex
• Commonly associated with dorsal midbrain syndrome
• Localizes to pretectal area, posterior commissure.
• Pineal cyst or tumor, demyelination, stroke.
Skew deviation, is a relatively common supranuclear vertical
divergence of the eyes that is associated with lesions in the
posterior fossa, particularly those involving the brainstem
tegmentum from the diencephalon to the medulla oblongata
With INO higher in the side of lesion.
involuntary rhythmic oscillation
of the eyes that is initiated by a slow phase. The
approximately equal amplitude and velocity
(pendular N) or, more commonly, with a slow
initiating phase and a fast corrective phase (jerk
N) or mixed.
• N is common with a prevalence of around 0.1%.
Examined by fixation of the to 30 degree from gaze
• Saccadic oscillation:
burst of saccades
which may be intermittent or continuous
disrupting fixation ( intersaccadic interval and
back to back saccades).
visual disturbance in which
objects in the visual field appear to oscillate.
• Previously Nystagmus considered untreatable, in
recent years several pharmaceutical drugs have
been identified for treatment of Nystagmus.
•Symptoms : TO and Fro movement of the eye
, reduced visual acuity, blurred vision ,
oscillopsia ( > 8 years).
Repetitive movement of the eye
Binocular or monocular
Effect of gaze
Any change with change posture,
• Nystagmus affects people in different ways. The
most significant effect is the reduced visual acuity
-Factors such as stress, tiredness, and nervousness
can cause changes in ability to focus.
-Distance visual acuity is poorer than near vision.
-Balance may be affected due to poor depth
perception or due to vestibular problems.
-Head nodding is common (corrective).
Also, child will often tilt his/her head to temporarily
• Ask patient to fix and follow on your finger (about
30 cm away)
• Move slowly to Broad H Test waiting 5 seconds at
• Do not move more than 30 degrees from midline
• Nystagmus must be sustained for more than a few
beats to be significant.
Grading System (e.g. for right
• Grade 1 = present in right gaze only
• Grade 2 = present in right gaze and primary
• Grade 3 = present even in left gaze
Classification of Nystagmus
1) Pendular Vs Jerky
2) Physiological Vs Pathological
3) Congenital Vs Acquired
4) Peripheral Vs Central
5) Spontaneous Vs Gaze-evoked
Rapid oscillatory movement of the eye balls
• (cong or acq. central)
-thought to be a result
of a delay in messages
to the brainstem
-characterized by eye
movements that are
equally paced in each
• (phys or path)
-characterized by an
FEM in one direction
-thought to result from
extra input to the
from the brainstem.
• Physiological:- A normal response that is induced
because of excessive demand or imbalance in the
vestibular or ocular motor system.
• Pathological:- An abnormal response that occurs
spontaneously or appears in an individual looking
at a stationary object.
-Congenital (early infancy-6 months)
-Acquired (after 6 months).
• Not due to a disease process.
• Has no benefit, except as a diagnostic tool.
2-End point nystagmus (extreme gaze).
3- Induced caloric testing (vestibulo-ocular reflex).
5- Voluntary nystagmus.
1- Postrotatory nystagmus
• If one spins in a chair continuously and stops
suddenly, the fast phase of nystagmus is in the
opposite direction of rotation, known as the "postrotatory nystagmus," while slow phase is in the
direction of rotation.
2- Gaze-evoked nystagmus
• GEN: healthy subject ; called end-point N (lower
intensity and, more importantly, no other ocular
• Gaze paretic nystagmus (pathological).
• Caloric testing is dependent on endolymph
• Supine position head elevated 30 d 1st 30 Celsius
water 5ml later 44 C in EM.
• Normal response (after 20 sec)
Warm water in the right ear produces a rightbeating nystagmus
Cold water in the right ear produces a left-beating
Significance of caloric test
• 1) Absent reactive eye movement suggests vestibular
weakness of the HSC of the side being stimulated
(canal paresis) (peripheral lesion) .
2) In comatose patients with cerebral damage, the fast
phase of nystagmus will be absent as this is
controlled by the cerebrum. As a result, using cold
water irrigation will result in deviation of the eyes
toward the ear being irrigated. If both phases are
absent, this suggests the patient's brainstem reflexes
are also damaged and carries a very poor prognosis.
• OKN occurs normally in response to a rotation
movement. The OKR allows the eye to follow
objects in motion when the head remains stationary
(e.g., observing telephone poles on the side of the
road as one travels them in a car). The reflex
develops at about 6 months of age.
• How to elicit? OK drum.
• Crude assessment of the visual system, particularly
in infants. When factitious blindness or malingering
is suspected, check for OKN to determine whether
there is an intact visual pathway.
Not true nystagmus but saccadic osscillation.
Pt converge to initiates nystagmus,
maintained up to 30 sec,
Biphasic FAST ONLY
Back to back saccades
onset N’-can be
• pendular, all positions
• Defect in the eye or the visual
pathway from the eye to the
brain (sensory nyst). It can be
a side effect of vision loss from
eye diseases such as albinism,
cataract, and glaucoma.
• People are not likely to suffer
from ‘oscillopsia’- constant
moving image b/c the brain
can adapt. (unaware of it)
• ‘Late onset nystagmus’
• Can be acquired due to
such a stroke, MS, or a
• People are likely to suffer
from ‘oscillopsia,’ which
can cause a vertigo effect.
Dilantin and Phenobarbital
given to prevent seizures
may cause nystagmus.
• usually recognized in first few months of life – life long
• May have good vision idiopathic ( motor, efferent,
oculomotor abnormality) or poor vision (sensory, afferent)
Failure of early sensorimotor integration
Most often occurs in isolation (motor), but may be
associated with albinism or optic atrophy
Uniplanar, horizontal irrespective of gaze position,
Dampened by convergence and darkness, in sleep
increase by fixation , anxiety.
Gabapantin 300mg qid, Memantine 10 mg qid
idiopathic I N
Null zone, in which nystag is minimal & VA
Uncertain; ?? afferent visual system anomalies;
hereditary X linked (e.g., FRMD7 mutations).
Gabapentin (300 mg qid) memantine (10 mg qid).
Monocular nystagmus of childhood
• Usually monocular, vertical, low amplitude oscillation
• Eye with nystagmus may have afferent visual
• Requires neuroimaging (chiasmal glioma).
• Usually appears within first few months of life.
• Horizontal jerk nystagmus appearing only under
monocular viewing conditions.
• Absent in binocular viewing.
• Fast phase beats away from occluded eye
• Strong association with esotropia
• If there is ambylopia it present on binocular
viewing Manifest latent nystagmus.
• Triad of nystagmus, head nodding and Torticollis
(abnormal head posture, not corrective).
Onset 3-15 months with disappear by 3 or 4 years.
it may be present to age 5-6 years.
The nystagmus typically consists of smallamplitude, high frequency oscillations and usually is
bilateral, but it can be mono-cular, asymmetric, and
variable in different positions of gaze.
2% Glioma of the anterior visual pathway. (Requires
• Occurs in many CNS disorders, especially those
involving the cerebellum, brainstem and
• More common in adults
– central vestibular disease/tumour,
– cerebellar damage
– BS diseases
Severe vertigo (closing eye)
Days to weeks duration
Hearing loss, tinnitus
• horizontal with torsion
• unidirectional with the fast
phase opposite the lesion
• Very rarely purely vert or tor
vestibular organ dysfunction:
• None or mild vertigo.
• Often chronic
• visual fixation has no effect
• May be purely vertical or torsion
• the direction of the fast phase is
directed toward the side of gaze
(eg, left-beating in left gaze, rightbeating in right gaze, up-beating in
• Downbeat, upbeat, torsional
vasc, demyelination, pharmacologic,
2- Gaze-paretic nystagmus
• Gaze-paretic N: is most common form of N.,
recovering from a gaze palsy.
Fast phase to direction of gaze.
Defect in NI
Drug (anticonvulsant and tranquilizers)
Asymmetrical dt structural BS or cerebellar.
3-Acquired pendular nystagmus
– Mainly horizontal, vertical, torsional, or any
combination (usually one predominates).
– Oscillopsia ++
– asymmetric or even monocular.
– asymmetric brainstem disease (MS, oculopalatal
– Gabapantin 300mg qid, Memantine 10 mg qid
– Congental due diminution vision ( searching).
4- Oculopalatal myoclonus
• APN (Vertical) (1-4 Hz) associated with rhythmic upward
movement of palate even during Sleep, possibly including
face, neck, upper arm and diaphragm.
• Caudal brainstem pathology: red nucleus, inferior olive,
and dentate nuc Occurs 2-49 months after specific brainstem
injury from stroke, trauma, neoplasm, brainstem angioma,
MS, syringobulbia , encephalitis, degenerating conditions.
• Oculomasticatory myorhythmia: convergence induced
slow 1 HZ V pendular nyst. synchronous jaw
contraction.(somnolence, altered mentation, mild uveitis,
retinopathy) whipple s disease, MS, IS BS.
5- Periodic alternating
• Horizontal jerky N
• Present in primary position
• Cresendodecresendo fashion
• Duration of cycles from 30 seconds to 3 minutes
• Craniocervical j,BS, cerebellar tumour.
• MS, drugs, ethanol, paraneoplastic syndromes
• Baclofen (5-10 mg) (GABAergic) effective
• ?? Memantine (antiglutamate).
6- Upbeat nystagmus
• Present in PP or upword gaze.
• Large amplitude N that increases in intensity with
• Classically localizes to a lesion of ant cerebellar
vermis and pontomedullary junction.
• More generally implicates posterior fossa disease
stroke, cerebellar deg, demyelination,tumours and
Baclofen (5–10 mg tid) 4-aminopyridine (5–10 mg
• Vertical, upward slow drift of eyes.
• Secondary downward corrective fast phase.
• Present in PP or maximal intensity when the eyes are
deviated laterally and slightly inferiorly, supine
posture change to upbeats n.
• Localizes to cervico-medullary junction.
• Arnold-Chiari malformation 1.
Ttt with 4-Aminopyridine (Neurelan in USA) (5–
10 mg tid), 3,4-diaminopyridine (10–20 mg tid),
baclofen (5 mg tid) clonazepam (0.5 mg tid).
8- Torsional nystagmus
• Rotary movement of the globe about its AP axis
accentuated on lateral gaze.
• associated with other types of nystagmus APN .
• lesions of the anterior and posterior SC on the same
side (eg, lateral medullary syndrome). TN with the
fast phase directed away from the side of the lesion.
• accentuated by otolithic stimulation by placing the
patient on their side with the intact side down (eg, if
the lesion is on the left, the nystagmus is accentuated
when the patient is placed on his right side).
9- Horizontal nystagmus
• HN is a well-recognized finding in patients with a
unilateral disease of the cerebellar hemispheres,
especially with large, posterior lesions. It often is
of low amplitude. Such patients show a constant
velocity drift of the eyes toward the intact
hemisphere with fast saccade directed toward the
side of the lesion.
10- Bruns Nystagmus
•Jerky , bilateral N
•Slow, large amplitude nystagmus (gaze paretic N)
when looking towards the side of the lesion (Lt).
•Rapid, small amplitude nystagmus (vestibular N)
when looking away from the side of the lesion.
•Small vestibular schwannoma (11% <3.5 cm)
•Large cerebello-pontine tumour >3.5 cm (CPA)
11- Ataxic Nystagmus
• Abducting nystagmus of INO
• Abducting nystagmus of INO is, as the name
implies, nystagmus in the abducting eye
contralateral to a medial longitudinal fasciculus
• Fast away from side of lesion.
12- Rebound Nystagmus
• Gaze evoked
• Beats transiently in opposite direction after return
to primary position
• 3-25 sec
• Vertical (MB) N (pendular)
• Upward moving eye intorts followed by downward
and extorts other eye that alternates.
• Chiasmal lesions , suggesting loss of the crossed
visual inputs from the decussating fibers of the optic
nerve or lesions in the midbrain-thalamic.
• Bitemporal hemianopia.
• Acquired SSN: suprasellar lesion or leigh disease.
• Congential SSN (REVERSE): achiasma.
common with congenital severe visual impairment,
15- Episodic Nystagmus
• Paroxysmal attacks of Ataxia, Vertigo, N.
• Lasting 24 h.
• Inborn error of metabolism.
• Basilar migraine.
16- Ictal Nystagmus
Occurs during refractory seizures.
?? Vertical (comatosed). ?? monocular.
Fast phase opposite to epileptic focus.
Pupillary dilation even oscillation may occur
• Periodic gaze deviation associated with periodic
head rotation may be clue for seizure.
17- Lid Nystagmus
• Rhythmic jerky movement of the upper eyelid.
• 1st Synchronous with V N (Midbrain tumour)
Synchronous with fast phase of HGEN (
lateral medullary syndrome).
• 3rd type with voluntary convergence evoked nyst.
• Saccadic oscillation:
burst of saccades
which may be intermittent or continuous
disrupting fixation ( intersaccadic interval and
back to back saccades).
• Nystagmus: involuntary rhythmic oscillation of
the eyes that is initiated by a slow phase. The
oscillations may pendular N or, more commonly,
with a slow initiating phase and a fast corrective
phase (jerk N) or mixed.
1-Square-wave saccadic jerks
• (SWJ), the most common saccadic oscillation,
consist of small saccades that take the eyes away
from a fixation target, followed by a saccade in the
opposite direction to bring the eyes back to the
target, with an intersaccadic interval of 200 ms .
• micro healthy individuals,
• Macro in MS&OPCA and PD, PSP.
. ?? cerebellar. NOT in dark
• SWJ rarely degrade vision.
2- Oculomotor apraxia
• failure to initiate saccades on command (congental
or acquired (BS).
• more correctly, congenital saccadic palsy, is more
common in boys than in girls. Children > 4 m often
'thrust' their head from side to side to change the
direction they are looking. 'Head Thrusts' are a
typical movement that helps a child overcome their
difficulty in moving their eyes quickly. Children
may also blink to start a fast eye movement.
• MRI normal or may reveal poor development of
regions of the brain, in particular the corpus
callosum, cerebellum, and/or fourth ventricle.
Association Ataxia T, cerebral whipple s disease.
AE of OMA is usually not determined (idiopathic).
long-term prognosis of children born with OMA The
head thrusts associated with OMA typically diminish
over time, but tend not to completely disappear.
true improvement versus
compensatory mechanism to mask the head thrust.
• Intermittent burst-like, back to back saccadic in Purely
horizontal plane with high frequency, low amplitude.
No intersaccadic latency
aggravated by change posture , attempt to fixation.
Recovering from opsoclonus.
Isolated OF in MS, Cerebellar signs.
Voluntary OF in 8% of population in attempt to converge
Dorsal midbrain lesion so associated with vertical gaze
palsy (parinaud s syndrome).
• Paraneoplastic etiology: SCC of lung, ovarian,
breast CA, 50% of children with OMS have
neuroblastoma , in 2% of children with
Antineuronal abs anti Hu, Ri, Yo, Ma1 and
ttt: propranolol, verapamil, clonazepam.
IVIG in idiopathic and postinfectious.
Brain stem lesion (MB, Pons)
5- Ocular bobbing
• Spontaneous, vertical, Sudden conjugate rhythmic
downward jerk of the eyes followed by a slow
return to the mid position.
paralysis of horizontal conjugate gaze.
pontine hemorrhage (comatosed).
Atypical OB: intact horiz conj g (acute cerebellar
hge, metabolic enceph, obst hydrocephalus).
Reverse OB: fast movement is upward followed by
delayed slow return (TS, EBV encephalitis).
• One major difficulty individuals suffering from nystagmus
face is the lack of knowledge about the disorder, from the
In conversation, sufferers with involuntary head
movement may cause people to think they are disagreeing
with what they are saying.
Reading speed is likely to be affected because of the extra
time and effort it takes to scan words.
Some people are unable to get their driver’s license.
People with the disorder find it difficult to play sports,
especially those involving good hand to eye coordination.
Nystagmus and alcohol
• In police work, testing for horizontal gaze nystagmus is
one of a battery of field sobriety tests used by officers to
determine whether a suspect is driving under the influence
• The test involves observation of the suspect's pupil as it
follows a moving object, noting lack of smooth pursuit,
distinct and sustained nystagmus at maximum deviation,
and the onset of nystagmus prior to 45 degrees.
• published by the National Highway Traffic Safety
• sound-induced subjective and objective responses. The
subject may feel sensations of unsteadiness, imbalance
or vertigo, associated with disturbances of oculomotor
and postural control.
• TP is provoked by very loud sound if physiological. It is
pathological if it is provoked by normal sounds.
Changes to the functioning and/or the morphology of
the labyrinth should be looked for in patients with the
pathological form: decreased thresholds for the
acoustically evoked vestibular potentials, SC
dehiscence, traumatic lesions of the labyrinth, ligament
• Tullio’s phenomenon (TP) is a pattern of sound-induced
imbalance symptoms, motor responses of the eyes
(nystagmus), head (myogenic responses) and other spinal
neuron synkinesis (postural sway).It may be physiological or
• Pathological Tullio’s phenomenon is characterised by
subjective and objective sonovestibular symptoms resulting
from abnormal hypersensitivity to normal sounds of the
vestibular end organs secondary to morphological changes in
vibration and pressure transmission between the external
and the inner ear.