1. Define bifixation
    when eyes move to place image of object of regard onto foveae
  2. What is normal BV? (5)
    • bifixation
    • appropriate acc enables clarity
    • each image is clear and of similar clarity
    • each image reaches the appropriate neural areas to enable fusion
    • perception and action
  3. Value of having 2 eyes (5)
    • VA - visual summation
    • better contrast sensitivity
    • better visual field
    • stereopsis
    • a spare eye
  4. What is motor fusion
    both eyes pointing at the OOR to allow the images to be on the fovea
  5. What is duction
    monocular eye mvt
  6. What eye movements are there?
    • duction
    • version
    • vergence
  7. what are versions
    both eyes move with the angle between them staying the same
  8. what is vergence
    • both eyes move
    • angle between the eyes change
  9. What CN innervate to EOMs?
    • CN3: IO, IR, MR, SR 
    • SO4
    • LR6
  10. What is the law of equal innervation?
    • Hering's
    • innervation to the muscles of the two eye is equal and simulatenous
  11. What are the requirements for sensory fusion
    • clear 
    • equal in size
    • equal in luminance images
  12. What is the law of reciprocal innervation
    • Sherrinton's
    • any innervation to a muscle to contract (agonist) will be accompanied by an equal inhibitory input to the direct antagonist to relax
  13. What are the levels of fusion of form (5)
    • suppression
    • simultaneous perception
    • superimposition
    • flat fusion
    • stereopsis/"fusion with float"
  14. What is the primary visual direction?
    when the image is on the fovea
  15. what is the secondary visual direction
    when the image is NOT on the retina
  16. what are corresponding points?
    when there is a common visual direction
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