visual perception nbeo.txt

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Author:
cjensen20
ID:
305120
Filename:
visual perception nbeo.txt
Updated:
2015-07-13 07:47:09
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Visual Perception NBEO
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Visual Perception NBEO
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  1. At what age should you be seeing 20/100 (6 cycles/degree)?
    6 mo
  2. What is the expected VA at birth?
    20/600 (1 cycle/degree)
  3. When are children expected to be seeing 20/20?
    3-5 yrs
  4. What is the expected VA at 1 yr?
    20/50 (12 cycles/degree)
  5. What does Lax criteria mean?
    High sensitivity and high false positives
  6. What does strict criteria mean?
    High specificity and high false negatives
  7. What does sensitivity mean?
    • Probability of a test giving a positive result given that the signal(disease) is present
    • Disease present =positive
  8. What does specificity mean?
    Probability of a test giving a negative result when signal(disease) is not present
  9. What is a false positive?
    Saying there is a signal when there really isn't
  10. What is a false negative?
    Not saying there is a signal, when really there is
  11. At what nanometer is photopic vision most sensitive?
    555 nm
  12. At what nanometer is scotopic vision most sensitive?
    507 nm
  13. What is Abney's law?
    Different lumens from different wavelengths being summed together as total lumens
  14. What are lambert surfaces?
    Surfaces that scatter light equally in all directions
  15. How sensitive is photopic vision?
    Low sensitivity
  16. How sensitive is scotopic vision?
    twice as sensitive as photopic
  17. What is special about 650 nm wavelength?
    • At this wavelength, there is no difference between photopic and scotopic sensitivities
    • Dusk, both photopic and scotopic is being used
  18. What is the Purkinje shift?
    After 650nm, shorter wavelengths become brighter in scotopic vision and visa versa
  19. What is Weber's Law?
    • How well we pick out a spot of light on a dark background
    • Light adaptation
    • Rod saturation
  20. What is ricco's law?
    Any number of photons within a given set diameter photopic or scotopic will appear as only one light
  21. What is bloch's law?
    • Regardless of number of photons is a given time, it will appear as one single light
    • Photopic 10ms
    • Scotopic 100ms
  22. What is the stiles-crawford effect?
    The angle at which light strikes cones strongly affects the light
  23. What is dicromacy?
    • Missing one of three cones
    • protanope
    • deuteranope
    • tritanope
  24. what is anomalous trichromacy?
    Have all 3 pigments, but one is weaker
  25. what does an acquired blue/yellow defect typically mean?
    Outer retinal disease
  26. What does an acquired red/green defect typically mean?
    • Inner retinal disease
    • Optic nerve
    • Visual pathway
  27. What is hue?
    Color
  28. What is color saturation?
    How vivid the color is
  29. How do you determine MAR?
    • 600/snellen denominator
    • Divide cycles by degree by 30 to get snellen form

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