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38 Cards in this Set
- Front
- Back
Superior Rectus:
Angle of insertion Actions |
23 degrees
elevation incyclotorsion adduction |
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Inferior rectus
Angle of insertion Actions |
23 degrees
depression excyclotorsion adduction |
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Superior oblique
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54 degrees
incyclotorsion depression abduction |
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Inferior oblique
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51 degrees
excyclotorsion elevation abduction |
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Describe Hering's Law of Equal Innvervation
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muscles work in pairs to move 2 eyes equally. Paired/yoked muscles = LR and MR, SR and IO, SO and IR.
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Sherrington's Law
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Muscles "share" an arm
agonist and antagonist are reciprocally innervated. See Duane's Syndrome |
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Listing's Law
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Eye rotates around certain axes (Listing's plane)
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List latency (slow to fast):
saccades smooth pursuit VOR vergence (disconjugate movements) |
saccade - 200 ms
vergence - 160 smooth pursuit - 125 VOR - 15 |
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List speed (slowest to fastest):
saccades smooth pursuit VOR vergence (disconjugate movements) |
vergence - 10 deg/sec
smooth pursuit - 50 VOR - 300 saccade - 1000 |
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Microsaccades
Microtremors Microdrifts What is each used for? Which is fastest? Which are yoked and disconjugate? |
Microsaccades: yoked, used for reading
Microtremors: disconjugate, fastest Microdrifts: used in slow eye movements micro -saccades and -tremors counteract errors in monocular fixation |
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VOR
1 - What kind of movements is it good for? 2- How long does it last? 3 - Sign of vestibular dz? 4 - Water in ear causes what? |
1 - Works for fast head movements, not slow, steady movements.
2 - Only lasts for 30 sec, at which point OKN takes over. 3 - Acute vestibular dz or lesion can cause horizontal nystagmus 4 - COWS refers to direction of fast-phase |
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How to decrease nystagmus
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-Conv (BO; minus lens at dist, plus at near)
-Yoked prism to null-point -CL (increase pt awareness) |
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Describe Foster-Kennedy syndrome eye movement dysfunction.
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Lesion on right side of frontal eye field = no saccade to left, can pursuit to left.
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What part of brain controls pursuits?
What is the limit for speed? 20, 50, 70 deg/sec |
Parietal lobe. Lesion on right = can't pursuit right but can saccade right.
Limit = 50 deg/sec. Beyond this, saccades pick up foveation. |
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Which type of vergence is initiated by diplopia, and which is initiated by blur?
Tonic, proximal, fusional, accommodative |
diplopia: fusional
blur: accommodative |
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What is a comitant deviation/strabismus? Noncomitant? Where do the following fall:
decompensated phoria, anatomical restriction, innervation problem |
Comitant deviation: misalignment that's same in all positions of gaze. Example: decompensated phoria.
Noncomitant: No same. Example: anatomical restriction or muscle palsy |
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Explain 3 types of Duane's Retraction Syndrome.
Explain the neuro wiring problems and what they cause |
Type 1 - limited abDuction. CN6 affected or absent.
Type 2 - limited aDDuction (CN3 dually innervating MR and LR) Type 3 - limited abDuction & aDDuction (3 D's; co-innervation of MR and LR by CN3, as well as loss of innervation of LR). Globe retraction and narrowing of palp fissure may be present in types 2 and 3. |
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Describe Brown's syndrome
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Acquired (scarring or inflamm) or congenital (SO too short of tendon inelastic) SO tendon sheath syndrome. (+) Forced duction when adducted and pushing up.
Present w/small hypotropia in primary gaze. |
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Park's 3 step:
Does it work w/2 muscles? Patient presents with head tilt left. Which SO affected? Example: OD hyper, worse when look right, worse head tilt right |
Only works w/1 muscle
Right SO. Rt SO can't intort, but left eye can, so tilt head to compensate. Example: OS IO |
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Expected phoria findings for non-presbyope for distance & near?
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Distance: 0-2 XP
Near: 0-6 XP |
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Describe the Phi phenomenon during cover test
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Esophore perceives object as moving in opposite direction of paddle; exophore same direction.
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Crossed diplopia = eso or exo?
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Exo (x = crossed). The object crosses before the eyes.
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Describe the 4 types of fixation disparity curves. What do the x & y intercepts represent?
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X: BI to BO
Y: eso to exo Type 1: normal Type 2: eso (top half of type 1, eats up BO) Type 3: exo (bot half of type 1, eats up BI) Type 4: Narrow |
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What is the difference between calculated AC/A and Gradient AC/A?
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Calculated: distance and near (like Newman's examples). Remember: PD of 60 convergence demand at 40 cm = (6.0)(2.5) = 15 prism D.
Gradient: same distance, dif lenses. (2 exo, 6 thru +1 = 4/1 ratio) |
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How to test PFV?
How to test NFV? |
PFV: BO or plus lenses
NFV: BI or minus lenses |
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Expected findings for NPC (know this):
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5 cm break, 7 cm recovery
beyond 10 cm is abnormal |
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How does minus lens test compare to push-up test?
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Minus lens to blue shows 2 D less than push-up (due to minification of minus lens, lateral mag of push-up, and extra proximal accomm w/push-up)
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Expected findings for vergence facility and accomm facility
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Vergence: 12 BO, 3 BI; normal 15 cyc/min
Accomm: +/- flippers, 11 cpm monoc, 8 cpm binoc |
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Describe amblyogenic factors.
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Strabismic amblyopia: suppressing fovea prevents confusion; suppr periph retinal counteracts diplopia
Occlusion (deprivation) amblyopia Refractive amblyopia: Myopia: more than 8 or 3 aniso Hyperopia: more than 5 or 1 aniso Ast: more than 2.5 or 1.5 aniso |
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Hirschberg:
1- Measures lambda or kappa? 2- How much is a shift of 1 mm? 3- Does this measure or neutralize deviation? |
1- Lambda. If done monoc, measures kappa
2- 1 mm shift = 22 prism D 3- measures. Krimsky allows you to change prism on fixating eye until non-fixating eye matches. |
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What is ARC?
What are the types of ARC? |
Definition: reprogramming of fovea to match an eye turn.
Harmonious AC: angle of anomaly equals the angle of deviation. Unharmonious AC: angle of anomaly is less than angle of deviation (reprogramming doesn't move enough to eliminate diplopia) Paradoxical type I AC: new fovea moves in wrong direction. |
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Explain the Bagolini lenses.
What do exo & eso strabs see? |
Right eye sees /; left eye sees \
Ortho: sees X w/light ball in middle Exo: the 2 lines cross higher w/balls under Eso: the 2 lines cross lower w/balls above |
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On Bruckner test, which eye is brighter w/a strabismic
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the non-fixating eye
Bruckner measures strab, microtropia, aniso, media opacities |
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4 BO test.
What does this test screen for? Explain the normal response. |
Screens for microstrabismus.
Normal response: versional movement of both eyes toward apex of prism, then convergence refixation of non-covered eye. Microtropia: Prism over good eye = no convergent refixation of non-covered tropic eye Prism over microtropic eye = nothing happens (falls w/in suppression scotoma) |
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Visuoscopy: if the scope grid is between fovea and nerve in right eye, is it nasal or temporal eccentric fixation?
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nasal eccentric fixation.
If grid is superior = superior ecc. fix. |
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Red lens sees:
Red light as _______ Green light as ______ White light as ______ |
Red as red
Green as black White as red |
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W4D
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---R
-G--G ---W |
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If a pt has a lag on FCC, which lines are clearer?
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Horizontal. FCC creates interval of sturm and if lagging, horizontal (more anterior; vertical more posterior) are closer to retina.
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