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111 Cards in this Set

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What are the four basic things you need to do to properly manage nystagmus?
1. Describe its relevant characteristics
2. Classify the condition
3. Identify possible causes and
associations
4. Determine and implement
appropriate management
Define nystagmus
A series of rhythmic involuntary movements of the eyes as a result of some disorder of the visual apparatus or some neurological or labrynthine disease.
Nystagmus is considered a disorder of what?
The mechanisms that keep fixation stable.
What enables us to hold eccentric positions of gaze?
The neural integrator (a neural network).
What 3 systems allow us to maintain a steady image on the retina?
1. Pursuit
2. Optokinetic
3. Vestibular
Where can a lesion occur that would create an imbalance that can cause nystagmus by making the eyes drift off target?
Any lesion involving the paired nuclei of the neurologic systems involved in maintaining steady gaze.
What are the 2 broadest categories of nystagmus?
1. Infantile
2. Acquired
What are some examples of types of causes for nystagmus?
genetic
traumatic
toxic
metabolic error
developmental
visual deprivation
voluntary
physiologic
What is important about the treatment of acquired forms of nystagmus?

Why?
Immediate Dx
Early management

Reduces long term consequences
Define Congenital (infantile) Nystagmus.

How long does it persist?
All forms of nystagmus either present
1. At birth or
2. Noted in early infancy at the time of development of visual fixation

Throughout life.
How long after birth might infantile nystagmus become evident?

Is it coincident with any obvious general disorders?

Why important?
The first few days or weeks.

No.

Establishment of accurate visual prognosis early on.
What is Infantile nystagmus often associated with?
Many afferent and efferent visual disorders.
What does the severity and extent of visual impairment of Infantile Nystagmus depend on?
Its etioloy
Infantile nystagmus may accompany primary visual defects which may lead to what assumption?
The nystagmus was secondary to poor vision.
When is the only time that the cause-and-effect relationship between primary visual defects and infantile nystagmus can be substantiated?
When it is known that the nystagmus wasn't there in early infancy and did develop as a consequence of poor vision.
What is desirable but usually impossible to identify in infantile nystagmus?
The probable site of the lesion.
Have results from oculography used in systemic investigations found an association between the nystagmus patterns and presence (or absence) of primary vision loss in infantile nystagmus?
No
Which specific association has not been verified for pendular nystagmus?
-Sensory (visual pathway) defect
Which specific association has not been verified for the jerk form of nystagmus?
-Primary motor abnormality
What characteristic about the genetics makes etiology even more obscure?
Heterogeneity
What are the 4 possible mendelian modes of transmission possible for isolated nystagmus?

Which is most common?
1. Autosomal dominant
2. Autosomal recessive
3. X-linked dominant
4. X-linked recessive

X-linked recessive is most common.
Which chromosome has autosomal dominant congenital nystagmus been linked to?
6p12
How is autosomal dominant congenitcal nystamus expressed as far as visual acuity, ocular alignment, and nystagmus waveform go?
Variable expressivity
What does familial variability suggest about expression in autosomal dominant congential nystagmus?
That expression can be modified by environmental influences.
When is genetic counseling easiest with it comes to nystagmus?

When is it more difficult and why?
When the nystagmus is associated with a disease or syndrome

With isolated nystagmus due to heterogeneity.
What are the important things to find out in a case history?
Onset
Associations
Variability
Symptoms
Ocular and General Health Hx
Family Hx!
When asking about associations what should you ask about specifically?
Infection
Fevers
Meds
Trauma
When asking about variability what should you ask about specifically?
Frequency
Amplitude
Gaze
Time characteristics
What type of symptoms are important to look for?
Developmental and Neurological
-Dizziness/nausea
-HA
-Local pain, numbness, tingling,
weakness
-seizures
-tinnitus (preipheral vestibular)
-gait irregularities
How far back should you go in Family health Hx for nystagmus?

What are 3 genetic conditions to watch for?
3 generations

Albinism
Achromatoplasia
Leber's
There are 10 things to observe during an examination with slitlamp and ophthalmoscopy, what are they (generally)?
1. Global positioning
2. Type of nystagmus
3. Direction
4. Amplitude
5. Frequency
6. Constancy
7. Conjugacy
8. Symmetry
9. Latency
10. Field of Gaze Changes
What are you looking for as far as global positioning?
Posture, head position, asymmetry
What are the 3 types of nystagmus?
1. Pendular
2. Jerk
-long foveation
-short foveation
3. Mixed
What are the 3 directions?

What direction do you look at for jerk nystagmus?
X,Y,Z

fast phase of jerk
What is considered a small amplitude?
Less than 2 degrees
What is considered a moderate amplitude?
2-10 degrees
What is considered a large amplitude?
Greater than 10 degrees
What is considered a slow frequency?
Less than 0.5 Hz
What is considered a fast frequency?
Greater than 2 Hz
What are the three possibilities for constancy?
constant, intermittent, periodic
What are the 2 possibilities for conjugacy?
Conjugate
Disjunctive
What are the 3 possibilities for symmetry?
symmetrical
asymmetrical
monocular
What defines a latent nystagmus?
The nystagmus changes with occlusion of either eye.
What is meant by field of gaze changes?
Null point
Dampening
Or increase in a field of gaze or convergence
The diagnostic challenge is to determine the origin. What are the 4 possibilities for the origin?
1. Physiologic
2. Congenital
3. Vestibular
4. Rare type
When does infantile nystagmus present?

What are the common amplitude and frequency?
Before 6 months

Variable.
What waveform is infantile nystagmus?

Most common?
Any

Bilateral and horizontal (uniplanar)
Which direction does the infantile nystagmus often beat when looking in horizontal gazes?
In the same direction as the gaze.
What is Alexander's Law?
Nystagmus increases when gaze coincides with direction of fast phase?
What global movement might be present in infantile nystagmus?
Compensatory head movement, though it doesn't usually compensate.
Why might head shaking in infantile nystagmus inhibit the vestibulo-ocular reflex?
Because the head shaking can be equal in amplitude and opposite in direction to the waveform.
What is the mneumonic for congenital nystagmus?
SLOFUN+
What does the S stand for in SLOFUN+?
Symptoms - none
What does the L stand for in SLOFUN+?
Latency - positive, beats AWAY from the occluder
What does the O stand for in SLOFUN+?
OKN - double fast, inversion, Cogan's I&II
What does the F stand for in SLOFUN+?
Fixation- worse when forced
What does the U stand for in SLOFUN+?
Upgaze- stays horizontal
What does the N stand for in SLOFUN+?
Null Point - Right, Left, Convergence
What does the + stand for in SLOFUN+?
The nystagmus is gone with lid closure and sleep
What percent of infantile nystgamus is caused by afferent problems? efferent problems?
40%
60%
What are the differential diagnoses for afferent causes?
High refractive error
ON hypoplasia or atrophy
Cataracts
Glaucoma
Albinism
Leber's Amarosis
Achromatoplasia
Pupil abnormalities (aniridia)
Retinal abnormalities (with ERG)
What is the incidence of stabismus with infantile nystagmus?

What is the most common type?

What 2 things MIGHT cause it?
50%

Esotropia

1. Cause by same mechanism as
nystagmus
2. Compensates for nystagmus
What 2 other visual abnormalities have a higher incidence with infantile nystagmus?
1. astigmatism
2. accommodative dysfunctions
What is the presentation triad of Spasmus Nutans?
1. Pendular nystagmus (X,Y, or Z,
fast, small amplitude)
2. Head nodding (noncompensatory
and intermittent)
3. Abnormal head position
What about symmetry with Spasmus Nutans?
Tends to be asymmetric
At what age is onset, usually?

How long does it last, usually?
4-18 months

12-24 months
How do you treat?
Rule out pathology with CT scan
Monitor
How does Nystagmus Blockage Syndrome present?

What is unique about it?
As infantile jerk nystagmus

DAMPENS on convergence causing esotropia to reduce the nystagmus and improve visual acuity.
When is the usual onset of Nystagmus Blocking Syndrome?
Infancy with the congenital nystagmus preceding the esotropia.
Which eye is the fixating eye for patients with Nystagmus Blocking Syndrome?

What kind of head tilt do they have?
The adducted eye fixates

Head turned toward the adducted eye.
What would you see on a unilateral cover test with the adducted eye for a patient with Nystagmus Blocking Syndrome?
The eye would stay adducted when the other eye is occluded.
What causes nystagmus to increase for patients with Nystagmus Blocking Syndrome?
Forced primary gaze
Abduction
How can you treat Nystagmus Blocking Syndrome?
Spectacles with BO prism (possibly -1.00 D too)
Refer for surgery (but is very complicated)
What can vertical nystagmus indicate?

What is the common beat pattern for these?
Brainstem or cereballar etiology

Upbeat with upgaze and downbeat with downgaze
In vestibular and cerebellar etiologies it is common to see a jerk nystagmus toward which side?
The side that has the lesion or disease.
Which direction is the nystagmus when it has a vestibular cause?
Any (X,Y,Z)
Which type of vestibular nystagmus typically has more symptomology, central or peripheral?
Peripheral
What can present as a monocular nystagmus with optic atrophy on the affected side?
Chiasmal glioma
Who is it a good idea to consult about these types of cases?

Why?
Neurologist or neuro-ophthalmologist

Because determining etiology is very difficult.
What are the treatment considerations?
1. Refer for Tx of underlying pathology
2. Therapy to dampen oscillations
3. Functional and cosmetic
improvement
What descriptors are used for the diagnosis and management of nystagmus patients?

What is not acceptable?
Dx: Careful
Management: Aggressive

Monitoring without treatment.
What are the 5 steps of steps of sequential management of nystagmus?
1. Correct refractive error
2. Prisms to improve fusion, induce
convergence, and/or reduce head
turn
3. Vision therapy to improve fusion
capability and enhance stability
of fixation.
4. Surgery to reduce head turn or
increase foveation time.
5. Medication in some cases
dampens nystagmus or reduces
symptoms.
What will the best correction of refractive error do?
Improve VAs
AND
Help dampen and stabilize the nystagmus. (primate models)
What type of correction is advocated?

Why?
RGPs

To achieve better control of nystagmus by correcting undetected corneal astigmatism AND by providing tactile feedback through lid interactions with the RGP.
Why would you use a plus add for nystagmus patients?
Increase clarity
Reduce accommodative demand for children with distance Rx.
Why would you prescribe yoked prisms?
To place eyes in the null area and reduce head turn.
If the null area is in right gaze:

What type of head turn will they have?

What type of prism should be used?
Left head turn

Base in over the left eye and equal base out over the right eye.
How many prism diopters will result in a 1 degree reduction in head turn?
2 prism diopters
What is a problem with prescribing prism?
cosmesis
Fresnel prisms can be used for larger prism power, but cosmesis still isn't good and it reduces VAs.
What type of frame should you suggest for a patient that needs a lot of prism to improve cosmesis?
Frames with small eye sizes.
At what point should you decide to refer for surgery rather than correct with prism?
greater than 15 degrees.
What type of prism, besides yoked could you prescribe for infantile nystagmus and why?

What could be a problem?
Base out prism

It stimulates convergence which can dampen the nystagmus and improve VA.

Induced Asthenopia
What are 5 possibilities for VT?
1. Orthoptic Vision Therapy
2. Visual Biofeedback
3. Auditory Biofeedback
4. Intermittent Photic Stimulation
5. Vertical Line Counting
What is orthoptic vision therapy?

What is the goal?
Step 1: antisuppression and sensory fusion therapy
Step 2: enhancement of motor fusion in a natural environement

The goal: decrease the intensity of nystagmus as binocular vision is enhanced.
What is the goal of Visual Biofeedback?

How does it work?
Used to help move the null area toward primary gaze.

Afterimage flash generated foveally is used to give biofeedback when the patient tries to stabilize their eyes on a target of progressively smaller size.
What is the goal of Auditory Biofeedback?

What device used to do this?

What are the results?
Uses IR eye movement monitors to convert the signal to an audible tone so the patient can hear the nystagmus and attempt to control it.

The old eyetrac

Rapid, but difficult to sustain.
What VT technique uses targets in the Major Amblyoscome with detail that the patient counts while the eye is flashed monocularly at 34 Hz for 15-20 minutes.
Intermittent Photic Stimulation
How long does it take for improvement? How long will it last?
6-8 months

About 6 weeks after initial strong improvement.
What does Vertical Line Counting consist of?

How well does it work?

What is a benefit?
The patient counts the number of lines on a sheet of paper at 40 cm, and as the patient improves the lines are moved closer together or the sheet further away.

Good results

Inexpensive and easy
What are the 2 types of Medical Management?
1. Pharmacological
2. Surgical
What is the primary goal of Pharmacological Management?
To compensate for faulty function of neural integrator (GABA/glycinergic)

To relieve oscillopsia
Is pharmacological management more commonly used for congenital or acquired nystagmus?
Acquired
Which drug is the most commonly prescribed drug for acquired nystagmus?
Baclofen
Which drug produces short term relief but is not good for long term management because of side effects?
Clonazepam
Which two drugs are newer meds that have demonstrated promise for some types of acquired nystagmus (vertical and pendular; MS)?
Gabapentin
Memantine
Which drug can also be effective relief of oscillopsia?

What should you do about dosage?
Scopolamine

Keep dosage down so side effects are minimal.
What is the main goal of surgical management?
Reduce head turn in order to move the null area to primary position and improve VA.
What degree of head turn is required for surgery?

What is the minimum age?
greater than 15 degrees

Age 5
What procedure is used for congenital nystagmus to equally recess and resect all four horizontal rectus muscles to move null position to primary gaze?
Success?
Anderson-Kestenbaum procedure

Mixed - confounded by stabismus
What other surgical procedure could be done?

Success?
Surgery to recess, and detach all EOMS to limit movement of the globe.

Not in US, a little better in Europe
Lastly what is the new procedure discussed by Dr. L.H. Dell'Osso?

What is it?

How is success measured?
Four muscle tenotomy

Cutting and reattaching the EOMs changes the afferent-efferent feedback loop.

Measured in increased foveation time.