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The flashcards below were created by user
cjensen20
on FreezingBlue Flashcards.
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What is donder's law?
The starting location for movement is not important to the orientation of the final destination
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What is listing's law
eyes must rotate around some axes to achieve a given direction of gaze
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what does the VOR system do?
- Hold image on fovea during short motions of the head
- Produce eye movements in the opposite direction of the head
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What is the cold water test testing?
- VOR
- COWS, cold opposite, warm same
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What does the OKN system do?
- Hold an image on the retina during prolonged head movement
- Kids go temp to nasal until 4mo
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What part of the brain controls saccades?
- Frontal eye field
- Superior colliculus
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What test assesses quality and accuracy of saccades?
DEM
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Where in the brain are smooth pursuits controlled?
Parietal lobe
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What is the triad of spasmus nutans?
- Head turn
- Head nodding
- Nystagmus
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What is convergence-retraction syndrome?
- A dorsal midbrain syndrome
- Jerk movements occur with attempted convergence or upgaze
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What three congenital diseases cause nystagmus?
- Albinism
- Aniridia
- Achromatopsia
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What are features associated with congenital nystagmus?
- CONGENITAL
- Convergence and eye closure dampen the nystagmus
- Oscillopsia is usually absent
- Null zone is present
- Gaze position does not change the direction of nystagmus
- Equal amplitude and freq of nystagmus in each eye
- Near acuity is good because convergence dampens the nystagmus
- Inversion of optokinetic nystagmus occurs
- Turning of head or abnormal head posture to allow eyes to enter null zone leads to better VA
- Absent nystagmus during sleep
- Latent nystagmus occurs
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How is nystagmus named?
Direction of fast phase
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Which phase in nystagmus represents the abnormality?
Slow/drift
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What are guideline for potentially amylogenic refractive error?
- Hyperopia>1D aniso>5D OU
- Myopia>3D aniso>8D OU
- Astigmatism>1.5D aniso>2.5D OU
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What is comitant deviation?
- Misalignment of visual axis in all positions of gaze
- Decompensated phoria
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What is non comitant deviation?
- Misalignment of visual axis in all positions of gaze not the same
- Caused by anatomical restriction or muscle palsy
- Require forced ductions
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What conditions can cause non comitant deviations?
- Graves disease
- Tumors
- Duanes retraction syndrome
- Browns syndrome
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What are the 3 types of duane's syndromes?
- Type 1 limited abduction
- Type 2 limited adduction
- Type 3 limited both
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What is brown's syndrome?
- SO tendon sheath syndrome
- Unilateral
- Limited elevation during adduction
- Small hypotropia in primary gaze
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What are test that can be used to non comitant deviations?
- Red lens test
- Hess-lancaster test
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What tests are used to determine fixation disparity?
- Mallet unit
- AO vectograph slides
- Bernell lantern
- Wesson fixation card
- Sheedy disparometer
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Graphically, how is fixation disparity represented?
- Y axis is amount of FD
- X axis is associated phoria
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What is the calculated AC/A ratio?
PD +distance in meters of near object(Phoria @ near + Phoria@distance)
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How are high AC/A ratios controlled?
Control accommodation with lenses
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How are low AC/A ratios controlled?
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What is the avg amplitude of accommodation formula?
18.5-(1/3)age
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What is the min amplitude of accommodation formula?
15-(1/4)age
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What is the most common binocular vision anomaly?
CI
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What binocular anomaly causes photophobia?
DE
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What is anomalous retinal correspondence?
- Both foveas have different visual direction
- Reprogrammed to have "new fovea"
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What is harmonious AC?
- Angle of anomaly = angle of deviation
- Objective anomaly only
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What is unharmonious AC?
- After botched surgery
- Correspondence moves in wrong direction
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