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26 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Classify:
OD HT // OS fixing OD fixing // OS Hypo |
Right hypertropia (RHT)
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Is comitancy common in a vertical deviation?
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No
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(T/F) It is easier to fuse vertically than horizontally.
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False - to the contrary
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(T/F) Vertical deviations generally occur in isolation.
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False - generally have horizontal and torsional components
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Which EOMs are responsible for vertical actions?
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SO, IO, SR, IR
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What is the
a) action of the SO muscle? b) field of action of the SO muscle? |
a) incyclotorsion, depression, abduction
b) down, left or down, right |
Use muscle stars & |_ _| |
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What is a yoke muscle?
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movement of a single muscle is aided by a "partner" in the other eye - the yoke muscle
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What is the yoke muscle of:
a) R MR b) L SO c) R SR |
a) L LR
b) R IR c) L IO |
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A child is unable to elevate his eyes. Which head posture will he adopt?
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head/chin upward
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What is the result of a bilateral Inferior Oblique Overaction?
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crossed hyper - RHT worse on left gaze, LHT worse on right gaze
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Classify:
A patient who has LHT worse on right gaze, RHT worse on left gaze. |
crossed hyper - IOOA or SO underaction
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In relation to IOOA, define the meaning of primary vs secondary over/underaction
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Primary: IO overacts
Secondary: SO underacts, causing IO to overact |
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What pattern does IOOA cause? Why?
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V pattern
- more XT on upgaze - straight in primary - ET in downgaze * IO o/a, SO u/a |
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What pattern does SOOA cause? Why?
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A pattern
- ET on upgaze - straight in primary - XT downgaze * SO o/a, IO u/a |
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Describe the stages of paretic muscle sequelae.
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1. underaction of the paralyzed muscle
2. overaction of the ipsilateral antagonist 3. overaction of the contralateral agonist 4. underaction of the contralateral antagonist [INHIBITIONAL PALSY] |
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What is the reason that we see incomitance in vertical deviations?
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paretic muscle sequelae
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(T/F) In a paresis, the patient can adduct better than he/she can diverge.
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In general, true - ductions better than versions
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In which circumstance(s) is the 3-step head tilt test not reliable?
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- previous surgery
- muscle restriction - bilateral paresis - longstanding problem |
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When is the 3 step head tilt test used?
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To identify which muscle is paralyzed.
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Why are SO muscle palsies so common?
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- SO innervation comes from Trochlear (IV) cranial nerve
- CN IV exits dorsally from brain (only nerve to do this) - CN IV has longest intercranial course this makes CN IV more susceptible to trauma. |
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What adverse effects will a patient have with a CN IV palsy?
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- diplopia - can be vertical, oblique, or torsional
- hypertropia - excyclotorsion - eso |
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(T/F) Most SO palsies are traumatically induced.
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True - CN IV "trauma" nerve
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Classify:
A patient was smacked lightly on the back of the head, resulting in a slight hyper/eso in one eye. |
trauma induced CN IV palsy - most likely secondary to a preexisting condition
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How can you distinguish a bilateral muscle palsy? (Ex. bilateral SO)
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- crossed hyper
- vertical in pp may not be present since bilaterally (if ~same amount of deviation) they will cancel each other - torsion greater than 12 degrees - history of head trauma |
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What is a masked bilateral SO palsy?
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SO palsy originally thought to be unilateral, but post-op the component in the other eye (which was there in the first place) has now been brought out
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What are some factors which could differentiate a longstanding (congenital) SOP from an acquired one?
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- facial asymmetry
- longstanding head tilt - patient thinks head is straight - pictures - stretched vertical fusional amplitudes - normal ~ 2-3 - congenital may suppress diplopia, while acquired will be very aware of it |
