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What is donder's law?
The starting location for movement is not important to the orientation of the final destination
What is listing's law
eyes must rotate around some axes to achieve a given direction of gaze
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
What is the cold water test testing?
- COWS, cold opposite, warm same
What does the OKN system do?
- Hold an image on the retina during prolonged head movement
- Kids go temp to nasal until 4mo
What part of the brain controls saccades?
- Frontal eye field
- Superior colliculus
What test assesses quality and accuracy of saccades?
Where in the brain are smooth pursuits controlled?
What is the triad of spasmus nutans?
- Head turn
- Head nodding
What is convergence-retraction syndrome?
- A dorsal midbrain syndrome
- Jerk movements occur with attempted convergence or upgaze
What three congenital diseases cause nystagmus?
What are features associated with congenital nystagmus?
- 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
How is nystagmus named?
Direction of fast phase
Which phase in nystagmus represents the abnormality?
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
What is comitant deviation?
- Misalignment of visual axis in all positions of gaze
- Decompensated phoria
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
What conditions can cause non comitant deviations?
- Graves disease
- Duanes retraction syndrome
- Browns syndrome
What are the 3 types of duane's syndromes?
- Type 1 limited abduction
- Type 2 limited adduction
- Type 3 limited both
What is brown's syndrome?
- SO tendon sheath syndrome
- Limited elevation during adduction
- Small hypotropia in primary gaze
What are test that can be used to non comitant deviations?
- Red lens test
- Hess-lancaster test
What tests are used to determine fixation disparity?
- Mallet unit
- AO vectograph slides
- Bernell lantern
- Wesson fixation card
- Sheedy disparometer
Graphically, how is fixation disparity represented?
- Y axis is amount of FD
- X axis is associated phoria
What is the calculated AC/A ratio?
PD +distance in meters of near object(Phoria @ near + Phoria@distance)
How are high AC/A ratios controlled?
Control accommodation with lenses
How are low AC/A ratios controlled?
What is the avg amplitude of accommodation formula?
What is the min amplitude of accommodation formula?
What is the most common binocular vision anomaly?
What binocular anomaly causes photophobia?
What is anomalous retinal correspondence?
- Both foveas have different visual direction
- Reprogrammed to have "new fovea"
What is harmonious AC?
- Angle of anomaly = angle of deviation
- Objective anomaly only
What is unharmonious AC?
- After botched surgery
- Correspondence moves in wrong direction