Nystagmus

1. Nystagmus
la rhythmic oscillation of the eyes. It has
many different patterns, and may be
physiological or pathological

2. Physiological Nystagmus
lnot due to a disease process
lHas no benefit, except as a diagnostic tool
lEnd point nystagmus
lPostrotational nystagmus
lInduced caloric testing
lOptokinetic nystagmus
lVoluntary nystagmus

3. Pathological nystagmus

4. Classification
lWhen describing the nature of nystagmus,
the following terms should be used:
»Congenital/acquired
»Jerk/Pendular
»Direction of fast phase
»Frequency
»Amplitude
»Grading system for gaze

5. Pendular Nystagmus:
lUsually congenital, or onset in early
childhood,
ldue to low vision
lBoth phases have similar speed.

6. Jerk Nystagmus:
lcan be congenital or acquired.
lVision is reduced by varying degree
(unpredictable), but is the result rather than
the cause of the nystagmus
lWave form: slow movement (pursuit) in one
direction (the defect)
lfast movement (saccade) in other direction
(the correction).

7. Grading System: eg for right
beating nystagmus
lGrade 1 = present in right gaze only
lGrade 2 = present in right gaze and primary
position
lGrade 3 = present even in left gaze

8. CONGENITAL NYSTAGMUS
ldue to a congenital anomaly of the motor
system or to a congenital disorder of vision.
lmay appear during early childhood but is
rarely present at birth.

9. Low Vision Nystagmus (syn.
Pendular nystagmus)
lCharacterised by slow pendular oscillations
l generally the wave form is very variable.
lEstablished pendular nystagmus (by about 6 months in
congenital visual deprivation) has a poor visual prognosis.
lRarely ever better than 6/36.
lCauses:
»Failure of the fixation reflexes during the critical period
(first 3 months) due to
»eg bilateral corneal scarring, infantile glaucoma, dense
cataracts, ocular albinism, optic nerve hypoplasia, optic
atrophy, macular hypoplasia, rod monochromatism,
Leber’s amourosis.

10. Nystagmus with relatively
normal vision
lCongenital idiopathic jerk nystagmus
lall types of manifest nystagmus without a
primary visual defect, either present at birth
or developing during the first few weeks of
life as the visual fixation reflexes develop

11. lBilateral nystagmus
lEyes otherwise healthy
lPredominantly in one plane, usually horizontal
lMay start as pendular, but becomes jerky with fast phase to
right on right gaze and left on left gaze.
lNull zone somewhere in between, where acuity usually
quite good.
lVision often improves on convergence
lIntensity of the nystagmus increases on attempting fixation

12. lMay have a superimposed latent component
lReduced lid closure
lOscillopsia is rare
lOften face turn, voluntary convergence or head shaking or
nodding to minimise nystagmus
lCommonly hereditary (irregular X-linked dominant)
lPrecise mechanism unknown

13. Management :
ltreatment rarely required, unless an extreme
AHP is adopted to achieve maximum VA,
when prisms or surgery to centralise the null
point can be tried.
l Occasionally base-out prism to induce
convergence

14. Latent and Manifest Latent
Nystagmus
lHorizontal jerk nystagmus presents when
the light stimulus is reduced to either eye
(eg by occluding).
lIn latent, no observable movement is present
on uncovering and full BSV is restored.
lIn manifest latent nystagmus the nystagmus
has a reduced amplitude but remains when
both eyes are open.

15. ACQUIRED NYSTAGMUS
lOccurs in many CNS disorders, especially those involving
the cerebellum, brainstem and vestibular mechanism.
lMore common in adults
»labyrithitis,
»central vestibular disease/tumour,
»cerebellar damage
»gaze evoked nystagmus
»convergence retraction nystagmus (Parinaud,s
syndrome)
»INO

16. Nystagmus
lThe presence of nystagmus should be treated as a sign,
rather than a diagnosis and there is great variation and
variability in its appearance
lHowever there are characteristics of the different types
which can aid diagnosis, whilst not being conclusive eg
direction, speed and persistence.
lNystagmus may be the first sign of a serious neurological
defect, and this should always be considered.

17. Two acquired conditions occurring in
childhood are as follows:
lSpasmus Nutans
lSee-Saw nystagmus

18. Spasmus Nutans
lNystagmus, involuntary head movements, AHP
lOnset 3-18 months of age
lFine rapid eye movements; jerky, small amplitude, high
frequency
lHorizontal, vertical or rotary, or a combination of these
lConsiderable variation in nystagmus in different positions
of gaze
lInvoluntary head movements comprising nodding or
shaking, or a combination of both; variable.

19. Spasmus Nutans
lThese do not appear to compensate for eye movement as
they are of different frequency
lMost cases resolve spontaneously by age 3 years.
lBenign, but can be associated with CNS disease, therefore
should be investigated.

20. See-Saw nystagmus
lUsually an acquired motility disorder
associated with chiasmal lesions
lwhere one eye elevates and intorts followed
by depression and extorsion of the other eye
lRare

21. Clinical procedure for
nystagmus cases
lClose questioning as to the onset of the nystagmus, family
history, general health, medication, history of CNS
disorders, associated symptoms (oscillopsia, vertigo,
unsteadiness and loss of vision all imply acquired forms)
lCarefully note the type of nystagmus, distance/near,
latency, AHP etc
lVA recorded uni- and binocularly, with and without AHP,
dist and near and compared
lFull ophthalmoscopic, slit-lamp (transillumination), and
binocular vision assessment

22. lUnless 100% sure the nystagmus is
congenital or longstanding, refer for further
investigation.
lNeurological causes are rare, but serious and
diagnosis of congenital nystagmus should
only be made by exclusion of other causes.
l electro-diagnosis is very valuable as Lebers
amaurosis or rod monochromatism cannot
be detected ophthalmoscopically.

23. SUPRANUCLEAR GAZE
CONTROL
lSignals which control ocular movement are initiated in the
cerebral hemispheres.
lThey are then transmitted to the gaze centres and
oculomotor nuclei in the midbrain and pons, and leave the
brain in the 3
rd
, 4
th
and 6
th
cranial nerves
lSupranuclear neuronal pathways: conduct impulses from
cerebral hemispheres to gaze centres
lInternuclear pathways: conduct impulses from gaze centres
to ocular motor nucleii
lInfranuclear pathways:3
rd
, 4
th
and 6
th
cranial nerves
lThere are three forms of conjugate eye movement (ie as a
yoked pair), and each has a different control centre.

24. lSaccades =contralateral frontal pre-motor area
lPursuit= ipsilateral occipito-parietal area
lVestibular reflexes= vestibular nuclei in the pons
Conjugate eye movement
Control centre

25. lThese impulses are transmitted to the gaze centres, which
mediate the conjugate eye movement.
lHorizontal and vertical gaze control are quite separate, and
therefore should be investigated separately.
lThe horizontal gaze centre is in the pons at the level of the
6
th
nerve nucleus.
lHorizontal movement to the left is controlled by the left
horizontal gaze centre, and vice-versa for the
right.
lThe vertical gaze centre is in the midbrain but not much is
known about vertical gaze control.

26. Gaze Palsies
lAn inability to make a conjugate ocular
movement in one direction.
lThis does not cause diplopia since the visual
axes remain parallel.
lBy investigating each reflex and conjugate
movement in turn, it is possible to establish
where a lesion exists

27. GAZE PALSIES Examples
lsupranuclear lesions do not affect vestibular reflexes, so
these remain intact (test by calorics or dolls head reflex)
lfrontal lesions cause unilateral saccadic palsies
loccipital lesions cause unilateral pursuit palsies
lpontine lesions affect horizontal gaze but not vertical
lupper midbrain lesions affect vertical gaze
lHorizontal saccadic gaze palsies are most common

28. Parinauds Syndrome
lVertical gaze palsies usually form part of a triad of signs,
which is known as Parinauds syndrome.
lThis is relatively rare and is caused by lesions in the upper
midbrain.
lThe signs are
»vertical gaze palsy (saccadic upgaze affected first
»loss of light reflex (near reflex intact)
»convergence retraction nystagmus

29. Parinauds Syndrome
lThe convergence retraction nystagmus is seen
spontaneously or (more usually) on attempted upgaze.
lThe lesion is thought to cause disinhibition of the ocular
motor nuclei allowing bursts of co-firing of the extra-ocular
muscles.
lAs the MR is the most powerful muscle this results in
convergence and a retraction of the globe
lCauses:
»Tumours of the pineal gland *(most common)
»Atherosclerosis
»Embolism, Vasculitis

30. Internuclear Ophthalmoplegia
lCaused by lesions in the medial longitudinal fasciculus
(MLF), the area carrying internuclear neurones between 6
th

and 3
rd
nerves.
lType depends on the precise location of the lesion in MLF.
lIt can be unilateral or bilateral:
lUnilateral: interneurones from one 6
th
nerve nucleus
affected, causing loss of adduction of the affected MR on
attempted conjugate gaze.
lSaccadic, pursuit and vestibular systems are all affected.
lAlso get abducting nystagmus of the other eye (reason for
this is not clear)
lConvergence can remain intact

31. Internuclear Ophthalmoplegia
lBilateral:interneurones from both 6
th
nerve nuclei affected.
Often assymetric.
lPatients rarely complain of diplopia
lCause; MS is the commonest cause of unilateral (&often
bilateral) INO in the younger patient (may be the
presenting feature)
lIn the older patient, small blood vessel occlusion is likely
in unilateral INO, and tumour is a possibility in bilateral
lMost spontaneously recover, except if tumour.

32. Paralytic Pontine Exotropia (The “One
and a half” syndrome)
lLesion affecting both the horizontal gaze centre
and the adjacent MLF = gaze palsy + INO.
lThe only remaining horizontal movement is
abduction of the unaffected LR with abducting
nystagmus ie gaze palsy to one side, INO to the
other.
lComplete “one and a half” syndromes are
uncommon, but partial is more common.
lCause : tumour is likely.

33. Pseudostrabismus
lEpicanthus in infants can be more or less pronounced.
lEpicanthus can obscure the inner canthus giving rise to the
appearance of esotropia when none is present.
lIn time epicanthal fold usually disappears with the
development of the bridge of the nose
lOther examples of pseudostrabismus include
»facial asymmetry
»failure of the optical (centres of the cornea and lens) and
visual axis (fovea to fixation point) to coincide