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37 Cards in this Set

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What is an exodeviation?
outward eye turn.
What does the symbol "X" refer to?
Exophoria - latent exo deviation, controlled by fusion - detected by cover test
(T/F) Exos usually have better overall stereopsis than esos.
True
What is the difference between exotropia XT and intermittent exotropia X(T) ?
XT is a manifest exodeviation, X(T) is intermittent & therefore is controlled some of the time by fusion.
How can you distinguish a pseudoexotropia?
Appears exo but negative cover test
Causes of pseudoexotropia?
- large IPD
- positive angle kappa
- exophthalmia
- "large" eyes
- wide palpebral fissures
(T/F) Exotropia is more common than esotropia in children.
False - exo only accounts for 25% of strabismus in children
(T/F) Most causes of exotropia are unknown.
True
(T/F) Like esos, there is usually a refractive error associated with exos.
False
Most common form of exodeviation?
X(T)
phoria, tropia (manifest), or tropia (intermittent)?
Explain why deep amblyopia and abnormal retinal correspondence are not as likely to result from an exodeviation as opposed to an esodeviation.
Exodeviations are usually intermittent in nature - small amount of fusion enough to keep binocularity
Explain Duane's classification of exodeviations.
1. Basic Type: N=D (within 15 p.d.)

2. Convergence Weakness Type (**BAD**) - Exo is greater at near than at distance N>D by 15 p.d. +

3. Divergence Excess Type - N<D by 15 p.d. +
- there are 2 divergence excess type exos: simulated and true
What is meant by the term simulated divergence excess type exodeviation?
Deviation appears larger at distance but in reality N=D (actually is a Basic Type) but they control their turn at near using accommodation. Plus lenses at near will reveal this.
How do primary exodeviations differ from primary esodeviations?
- size
- direction
- control

(usually latent or intermittent, controlled more)
When is the onset of infantile exotropia?
before age 6 months
infantile exo is:

a. constant
b. intermittent
c. constant & alternating
a. constant
(T/F) Children with an infantile exo have good prognosis for binocular potential.
False
What are some causes of Infantile Exotropia?
- Vision Loss (sensory)
- Oculomotor nerve palsy (CN III)
- Craniofacial anomaly
- Duane's syndrome
- Pure congenital
____________ are the most common type of deviations, and are usually seen in early childhood.
Exodeviations
Eso?
Exo?
Hyper?
Hypo?
Briefly explain Calhounz et al's 4 Phases of X(T).
1. 6m: X 1/3m: ortho
2. 6m: X(T) 1/3:ortho/X
3. 6m:XT 1/3m: X/X(T)
4. 6m:XT 1/3m: XT
What is secondary exotropia? Give 2 examples.
An exotropia which results from a prior visual problem or surgery.
- sensory exotropia
- consecutive exotropia
Sensory Exotropia results from? Give an example.
- primary sensory deficit (adults)

ex. sensory exotropia following loss of right visual acuity because of retinal detachment
What is a consecutive exodeviation?
- patient used to have esodeviation and now has an exo
- secondary to surgical or optical treatment (overcorrected patient)
Comitant exotropias are generally _________.
idiopathic (no known cause)
cause?
(T/F) Incomitant exodeviations are usually idiopathic.
False. Comitant exos are idiopathic (usually)
What are some things that could cause an incomitant deviation?
- Innervational problems: Oculomotor paresis (CN III & MR)
- Mechanical/Restrictive (LR restriction)
- Duane's Syndrome
- Myositis (MR myositis)
- Myasthenia Gravis
A 36 year old patient has a right oculomotor (CN III) paresis.

a) Which extraocular muscles will this affect? Will this effect be contralateral or ipsilateral?
b) What is the most likely deviation that this patient will have?
c) Will the deviation be comitant? Why or why not?
a) Oculomotor (CN III) nerve innervates: MR, IO, IR, SR and effect will be ipsilateral in MR, IR, IO contralateral in SR

b) Exodeviation... exo, hypo, incyclotorsion, droopy lid, dilated pupil (in complete paralysis)

c) Incomitant - greater in the field of the affected MR - also if it is a paresis then the nerve is not completely paralyzed and therefore the degree of deviation will vary
What is orbital myositis?
- orbital inflammation or group of pseudotumors
- inflammatory reaction
- pain associated with motility
- limitation of motility of affected muscle
- LR restriction - limits ABduction
- incomitant deviation
Duane's Syndrome Type II is associated with?
- limited ADduction but normal ABduction
Duane's Syndrome Type III is associated with?
- limited ABduction and ADduction
How is amount of control assessed for an X(T)?
- Home - expressed as a %
- Office - how well patient controls during exam (good: breaks with CT but regains fusion quickly)
- Newcastle Control Score - combines subjective (home) and objective (office) scores
There are many factors which can affect the control of a patient with an X(T). Name 5?
- Fixation distance (generally worse at distance)
- Fatigue (usually worse when tired)
- Attention
- Illumination (brighter usually more difficult)
- GH (stress, illness)
- dissociation (CT, patch)
- accommodation
- refractive error
- vision
(T/F) A light can be used in an exam of an exo as an accommodative target.
False - a light is not an accommodative target. The light will bring out the largest deviation using reflexes.
50% of exos usually also have another _________ deviation.
Vertical
How can you measure an exo to confirm the presence of a vertical deviation?
Head tilts
Why is is extremely important to give a good (dissociative) cover test with exos?
Most exos are intermittent and therefore can fuse. To bring out the largest (actual) deviation, must dissociate them completely.
An exo will have worse vision at:

a. near
b. distance
c. neither - same in near and distance
b. distance