O2B CV

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Author:
sookylala
ID:
175509
Filename:
O2B CV
Updated:
2012-10-22 03:39:39
Tags:
colour vision protan deutan tritan
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Description:
colour vision
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  1. red/green/blue cone?
    • erythrolabe
    • chololabe
    • cyanolabe
  2. What is dichromacy?
    missing one cone, requires 2 other cones to see full colours
  3. What are the 3 types of dichromacy?
    • protanopia: missing erythrolabe
    • deutanopia: missing chlorolabe
    • tritanopia: missing cyanolabe
  4. What is monochromacy?
    • missing 2 cones
    • total colour deficiency
    • see differences in light
  5. What are the 3 types of monochromacy?
    • pi5- erythrolabe only
    • pi4- chlorolabe only
    • blue monocone- cyanolabe only
  6. What are the 2 subtypes of monochromacy?
    • rod: lacking cone receptors- va poor, aversion to light
    • cone: usually has blue monocone, VA normal/slightly reduced
  7. What is anomalous trichromacy?
    • can visualise 3 colours
    • inherit one anomalous cone
  8. What are the 3 subcategories of anomalous trichromacy?
    • protanomaly- modified erythrolabe cone
    • deutanomaly- modifed chlorolabe cone
    • tritanomaly- modiefied cyanolabe cone
  9. What are the genetic patterns?
    • protan/deutan: x-linked recessive
    • tritan: autosomal dominant, some autosomal/x-linked recessive
    • rod monochromat/blue mono/cone monochromat- autosomal recessive
  10. What colours do protanopes confuse?
    red-green
  11. What colours do deutanopes mainly confuse?
    yellow green, white green
  12. What are the two types of ACVDs?
    • Dsychromatopsias: include congenital
    • Achromatopsias: truly colour blind
  13. What are some of the factors that contribute to ACVDs?
    • Physiological: yellowing lens
    • Pathological: eye disease, systemic disease
    • Psychological: usually colour naming – anomia, aphasia for colour names
  14. What Kollner's rule?
    • Diseases of the outer retina: blue-yellow deficiencies
    • Diseases of the optic nerve and inner retina: red-green deficiencies
  15. What conditions obey Kollner's rule?
    • MS
    • Leber’s optic atrophy
    • Indomethacin maculopathy 
    • ARM
    • Dignoxin neuropathy
    • Chloroquine
    • Diabetes
  16. What conditions do not follow Kollner's rule?
    • Dominantly inherited juvenile optic atrophy
    • glaucoma
  17. What is a type 1 ACVD?
    • Red-greeno
    • Pseudo-protanomaly
    • Cone dystrophies, RPE dystrophies
  18. What is a type 2 ACVD?
    • Red greeno
    • Pseudo – deuteranomaly 
    • Optic neuritis
  19. What is a type 3 ACVD?
    • Blue – yellow
    • Rod and rod-cone dystrophies, retinal vascular, glaucoma
  20. Severity of anomalous trichromats?
    • mild: on confusion lines, colours close together mixed up, colours far apart differentiated
    • severe: on confusion lines, colours far apart confused
  21. Severity in dichromats?
    all severe
  22. What does colour confusion depend on?
    • The  severity  of  CVS
    • Viewing  conditions
    • Available  light
    • Type  of  light
    • Intensity  of  the  colour   –  pale  or  dark
    • Size  of  the  coloured  object
    • Viewing  time
  23. How to minimise colour confusion consequences?
    • use colours that don't lie ont he confusion lines
    • redundant coding
    • use luminance, brightness and contrast
  24. What are the uses of a colour vision test?
    • Detection of a colour vision deficiency- normal or abnormal
    • qualitative diagnosis
    • quantitatice diagnosis
    • congenital or acquired
    • relatable to real life- vocational test
  25. What tests would you choose for the detection of a CVD- normal/abnormal?
    • PIC tests- can separate normals from severe
    • Anomaloscope
  26. What tests would you choose for qualitative diagnosis?
    • OSCAR/Medmont C-100
    • Standard D15
    • Anomaloscope
  27. What tests would you choose for a quantitative diagnosis?
    • D-15
    • TCU
    • FM 100
  28. What tests would you choose for congenital vs acquired testing?
    • FM 100
    • D15
    • Anomaloscope
  29. What tests would you choose that are relatable to real life?
    • Lantern
    • FM 15
    • TCU
  30. What tests would you choose for a general overview of cv?
    • Ishihara- qualitative
    • D15- quantitative
    • Medmont C-100
  31. What do filter aids do for those with CVDs?
    • alter relative brightness of colours- differentiate bw colours due to luminance cue
    • fitted on one eye only
  32. Adv and Disadv of ishihara?
    • gold standard for rapid indentification of congenital RG deficiencies
    • Dis: pass very mild deutans
    • no tritan plate
    • doesnt diagnose severity
  33. How is the ishihara scored?
    • record all responses
    • diagnosis: "A/12"
    • 0-1 error: PASS
    • 2-3 errors: BORDERLINE
    • >3: FAIL
  34. AOHRR?
    • Uses 3 shapes: circle, square and triangle
    • screens for protans, deutans, tritans and tertartans
    • grades severity
    • scoring: record type and severity
  35. SPP?
    • vol 1: RG CVDs, 2 plates for tritans
    • vol 2: acquired CVDs

    adv: not as available, can't memorise
  36. Scoring for SPP?
    • OUT OF 10
    • 1 error: BORDERLINE
    • >1 error: FAIL
  37. CVTME pros and cons?
    • children- symbols
    • passes mild deutans
    • no qualitative diagnosis
    • must know what theyre supposed to be looking for
    • need to know names of shit
  38. Scoring for CVTME?
    >7 answers: PASS
  39. HAHN NEW/MODERN COLOUR VISION TEST pros and cons?
    • congenital CVDs
    • includes a tritan plate
    • Doesn't identify deutans well
  40. Hahn New/ Modern CVT scoring?
    Pass or type and severity
  41. Lanthony's Tritan Album?
    Congenital VS acquired tritan
  42. Scoring of Lanthony's Tritan Album?
    • 0-1 error: PASS
    • >1 error: FAIL
  43. Malingerer plate?
    • significant luminous reflectance contrast with background
    • CV not required
  44. Disappearing/vanishing plate?
    colours straddle confusion lines deutan and protans- both will fail
  45. Combination plates?
    • demonstration+disappearing plates
    • CVD can respond to this- feel like they arent failing
  46. Alteration plates?
    both CVD and CV both can respond-with diff answers thou
  47. Diagnostic/qualitative plate?
    • disappearing, but have 2 images
    • deutan/protan- one will pass
  48. Hidden plates?
    only able to be seen by CVDs
  49. Administering PIC tests?
    • Working  distance  =  normal  reading  distance
    • Time  per  page   –  not  specified  
    • They  are  good  at  screening
    • Fairly  good  at  type  diagnosis   –  qualitative
    • Not  good  for  quantitative
    • Not  relatable  to  real  tas
  50. Administering 100 hue test?
    • 2 minutes per box is reasonable, however there is no time limit
    • Working distance is typical near working disatance
    • The colourmetric construction of the test is shown in the graph
    • It is important that you never let the patient touch the surfaces because the Munsell colours are very absorbent.
  51. How does scoring work for 100 hue?
    • Calculate a score for each colour
    • Calculate an error score for each colour
    • Sum the error scores to a total error score
    • Plot the scores on the polar diagram
    • Total error score = quantitative measure of ability – it is age related
  52. What happens at the end of box?
    • 1. used fixed cap
    • 2. find next movable cap- use this method
  53. What are the typical results of a protanope in the 100 hue test?
    • 3-9 o clock
    • TES: ~150
  54. What are the typical results of a deutanope in the 100 hue?
    • 4-10 o clock
    • TES: ~250
  55. What are the typical results of a tritanope in the 100 hue?
    • 6-12 o clock
    • TES: ~200
  56. Scoring of a D-15 test?
    • > 2 crossings: FAIL
    • 1-2 crossings: BORDERLINE, RETEST
    • 0 crossings: PASS
  57. FARNSWORTH LANTERN?
    • Used by police
    • 2m distance
    • isochromatic colours displayed
    • RGW lie along confusion lines of protan/deutan
    • bright lighting
  58. Scoring/procedure of Farnsworth?
    • 0 ERROR RUN 1: PASS 
    • 1ST ERROR RUN 1: FAIL RUN 1-> RUN 2
    • TOTAL <3 ERRORS RUN 2+3: PASS
    • TOTAL >2 ERRORS RUN 2+3: FAIL
  59. HOLMES-WRIGHT TYPE A?
    • replication of acutal signals
    • RGW colours used
    • used by maritime services
    • 6m distance
    • dark adapt 10-15 mins
  60. Scoring/procedure of Holmes Wright Type A?
    • LARGE APETURE:
    • 0 ERROR RUN 1: SMALL APETURE
    • 1ST ERROR RUN 1: RUN 2
    • IF FAIL RUN 2 CONTINUE SMALL APETURE BUT FAILED OVERALL 

    • SMALL APETURE
    • 0 ERROR RUN 1: PASS
    • ERROR RUN 1: RUN 2
    • ERROR RUN 2 (NO PREVIOUS ERROR): RETEST FROM LARGE APETURE
  61. What is the equation that the anomaloscopes are based on?
    • rayleigh
    • >640nm (red) + 540nm (green) = 590nm (yellow)
  62. What is an endpoint on the anomaloscope?
    GG// and //RR
  63. What is the typical anomaloscope results of a normal?
    • 42 mid point
    • range ~6
    • similar brightness
  64. What is the difference in results between a protanope and a deuteranope on the anomaloscope?
    • Protanope: match across whole range
    • higher intensity at red end

    • Deuteranope: match across the whole range
    • similar intensity throughout
  65. What is the difference in results between a protanomal and a deuteranomal on the anomaloscope?
    • Protanomal: 42more green
    • 55- matching
    • larger matching range than normal
    • intensity increases at red end

    • Deuteranomal: 42 more red
    • 20 matching 
    • larger matching range than normal
    • similar intensity throughout the whole range
  66. What is the difference in results between a protanope and a protanomal on the anomaloscope?
    • protanope will match across the entire range
    • protanomal will match at a higher number ~55

    intensity for both will increase at red end
  67. What is the difference in results between a deuteranope and a deuteranomal the anomaloscope?
    • Both will have similar intensities thorughout the whole range
    • A deuteranope will match for all colours
    • A deuteranomal will match at around ~20
  68. What is the difference in results between a extreme protanomal and an extreme deuteranomal on the anomaloscope?
    • Xpro: match from 42-72
    • intensity will increase at red end

    • Xdeu: match from 0-42
    • intensity will be similar throughout
  69. OSCAR/ Medmont C-100?
    • flicker matching of red and green
    • Protan: need more red
    • Deutan: need more green
  70. Scoring for OSCAR/ Medmont C-100?
    • Mean score >-2: NOT PROTAN
    • Mean score <-1: PROTAN
  71. CITY UNIVERSITY TEST?
    • Uses standard d15 colours
    • shows severity of RGDs
    • tests congenital
  72. Scoring of CUT?
    • OUT OF 10
    • 1 ERROR: BORDERLINE RETEST
    • >1 ERROR: FAIL

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