Lecture 6 Nystagmus

Question 1

What is nystagmus?

Answer 1

-rhymic, repetitive, involuntary movements of one or both eyes
-can be horizontal, vertical, torsional or a combination
-most common cause of VI in school-aged children

Question 2

What are the different classifications for nystagmus?

Answer 2

physiological- part of vestibular ocular reflex
(optokinetic, vestibular, endpoint, voluntary)

pathological- damage to the vestibular system

infantile/congenital- secondary to visual defect (retinal dystrophy, albinism) or neurological defect (intra-cranial lesions, drug toxicity, stroke, MS)
types: sensory deficit nystagmus, congenital idiopathic nystagmus (CIN)

acquired: upbeat, downbeat, abducting, monocular, see-saw, convergence retraction

Question 3

What type of waveforms can you get?

Answer 3

JERK (vestibular)
*Slow phase (pathological) and fast phase (refixation)
*Described by direction of saccade: right beat, upbeat, downbeat

PENDULAR (optokinetic)
*Can occur in any direction
*No fast phase
*Smooth oscillations

*Waveforms may be a combination of jerk/pendular
*May vary with gaze direction

Question 4

How do you document nystagmus?

Answer 4

*Amplitude: the excursion of the nystagmus
*Frequency: number of oscillations per minute (coarse, medium, or fine)
*Intensity: amplitude x frequency

Question 5

What is the difference between manifest and latent nystagmus?

Answer 5

*Manifest nystagmus: when both eyes are open. May increase when one eye is covered.

*Latent nystagmus: when one eye is covered. Steady fixation with both eyes open. (Result of an early insult to BV e.g., unilateral cataract, early onset strab)

Question 6

When does congenital nystagmus develop?
What are the 2 primary forms?

Answer 6

2-6 months

SDN-sensory deficit nystagmus
CIN-congenital idiopathic nystagmus

Question 7

What is the etiology of CIN?
What is the etiology of SDN?

Answer 7

unknown, may be x linked, autosomal or sporadic.

*Early macular deprivation e.g., dense bilateral cataract, retinal cone dysfunction, albinism (oculo-cutaneous or purely ocular)
*Fundus and media examination, and electro diagnostic testing needed

Question 8

What is Manifest latent nystagmus?
What is it associated with?
when is it usually detected?
when is it more pronounced?

Answer 8

separate diagnosis to congenital nystagmus. always present. worsens when one eye is covered.

early onset strab, DVD

2 years

when one eye is abducted and in abducted position of gaze.

Question 9

What is the waveform like in congenital nystagmus?

Answer 9

*Waveform may change during infancy and may initially be present as large roving eye movements.
-Can develop into pendular/jerk.
*Waveform may vary with position of gaze.

Question 10

What does uniplanar mean?
What direction is congenital nystagmus usually?

Answer 10

horizontal in all directions of gaze (including up and downgaze)

invariable horizontal but may have a rotary component.

Question 11

What is a null zone?

Answer 11

*Position of gaze of the least movement (nystagmus is the most stable so vision is best)
*Called dampening of nystagmus
*May adopt AHP for best VA

Question 12

How should you test vision in people with nystagmus?
What is vision like in children with CIN?
What is vision like in children with SDN?

Answer 12

distance and near
with and without AHP
significant AHP=indicator for active management -REFER

better in CIN can be 6/9
worse in SDN 6/60 or less

Question 13

What symptom is seen in children with congenital nystagmus?

Answer 13

head nodding
compensatory mechanism to improve vision by reducing frequency and asymmetry of nystagmus

Question 14

If px null zone is to the right, which direction will px have a AHP in?

Answer 14

left

Question 15

What is spasmus nutans?
what age does it present?
what is it associated with?

Answer 15

*Cause rapid, uncontrolled eye movements head bobbing and holding the neck in an abnormal position.
* Self-limiting.

-presents at 1-2 months
* Disorder disappears by age of 3-4.

*Some cases associated with chiasmal or super-chiasmal lesions in brain. Need neuroimaging on these babies.

Question 16

What is oscilliopsia?
px with this are likely to have what?

Answer 16

*Not a presenting sign in congenital nystagmus but may be recognised when tired as nystagmus increases in the dark

*Complaints of oscillopsia are suggestive of acquired or voluntary nystagmus

Question 17

What are the examples of acquired nystagmus and what causes them?

Answer 17

*Upbeat: brainstem lesions

*Downbeat: cerebellar lesions

*Abducting nystagmus-INO (inter nuclear ophthalmalgia) (lesion in medial longitudinal fasciculus). Will have limited adduction of contralateral eye

*Monocular nystagmus: spasmus nutans, tumours of optic chiasm or 3rd ventricle

*See-saw nystagmus: alternating elevation/intorsion of one eye and depression/extrusion of the other: chiasmal/parasellar mass lesions

Convergence retraction nystagmus syndrome: parinaud’s/dorsal midbrain syndrome

Question 18

What is the treatment of acquired nystagmus?

Answer 18

Removal of the cause
Drugs
Surgery to shift null zone-variable success
Retrobulbar botulinum toxin-limited success, useful in non-ambulant patients (not able to walk)

Question 19

What is the general management of nystagmus?

Answer 19

*There is no cure for nystagmus
*Need onward referral to ophthalmologist to aid diagnosis.
*Can consult a geneticist
*Correct refractive error to give best VA

Question 20

What is the management of congenital nystagmus?

Answer 20

*Refraction and correction of all refractive errors (cycloplegic refraction)
*Accurate assessment of near and distance VA
*Near VA should be recorded at 1/3m and their preferred distance
*Ophthalmologist may arrange paediatric assessment and genetic counselling
*They will assess consistence and significance of AHP
*They need to be monitored through childhood

Question 21

What are the treatment options for nystagmus?

Answer 21

refractive correction: glasses for best VA, contact lenses move with eye os better VA

LVA: magnifers, tinted glasses for glare

PRISMS: not successful if null zone is in extreme positions of gaze.
-give BI prism if nystagmus reduces on convergence
-pirsm should be same strength in both eyes
-Fresnel prism on glasses (moves images into null zone without AHP)

BT: helpful in people with acquired nystagmus associated with MS. can reduce symptoms of oscilliopsia. effects are temporary

Question 22

WHat drugs can be used in nystagmus treatment?

Answer 22

*Includes alcohol and cannabis
*Gabapentin and Memantine most commonly used

Question 23

What treatments are there to reduce AHP?

Answer 23

*Surgery to EOMs to move null zone into primary position.
*Surgery has little value if AHP is less than 15 degrees. Wait until child is 8 years old (visually mature).
*Prisms to move visual environment to null point.
*Prisms to reduce nystagmus through forced convergence.

Question 24

When is surgery offered?
What are the surgical options for nystagmus?

Answer 24

*Offered where there is a marked head turn due to a null point

*Involves detachment and reattachment of the eye muscles
*Results in more natural head position and clear vision
*Can need follow up surgery for corrections
*Some people perceive slowing of eye movements as a result of surgery
*Most px wont meet driving standard
*ROTATE EYES IN DIRECTION OF HEAD TURN (only 5mm resections, won’t work for typical case)

Question 25

What are the treatments for congenital nystagmus?

Answer 25

*Contact lenses may be preferable to spectacles in high ametropia or eccentric null zone

*Biofeedback – may give some voluntary control over nystagmus but no practical long-term advantage in vision (training ocular motor control)

Question 26

What causes acquired nystagmus?
what are the symptoms?
how do you differentiate between congenital and acquired nystagmus?

Answer 26

intracranial pathology

knosn onset and oscilliopsia

congenital-AHP more likely, no oscilliopisa