1. Color Vision
ณวัฒน์ วัฒนชัย
กิติกล ลีละวงค์
ุ

2. Visual process
ht
lig
object
light source
refle
ct e d
ligh
t/co
lor
eye

3. Electromagnetic spectrum

4. Visible light

normally visible light 400-700 nm

except : beta peak (380-400 nm)
 infant
 aphakic condition

5. color vision

how we can see all these colors?

6. AnaToMy

7. 
Visual process




light pass through
cornea/AC/lens/vit
absorption by the
rod/ cone
photoreceptors
retinal neural circuit
 horizontal cells
 bipolar cells
 ganglion cells
optic nerve
higher visual
centers
 LGB
(parvocellular
portion)
 Cortex

8. Rod and Cone photoreceptors

9. Rod and Cone photoreceptors
<400 nm
400-700 nm
>700 nm

10. Rod photoreceptors




92 millions (100M)
no rod in central 0.25
mm of fovea
peak at 5-7 mm from
foveal center
decrease number with
age

11. Rod photoreceptors



mediate vision at low
illumination levels
(scotopic)
108 range of
illumination from near
darkness to daylight
critical flicker
threshold 20 Hz

12. Cone photoreceptors




4.6 millions (5M)
highest density at
macula
stable numbers, no
relationship to age
Mediate best vision
at daylight levels
(photopic)

13. Cone photoreceptors



Responsible for good
visual acuity and
color perception
1011 range of
illumination from
moonlight nights to
very very bright light
critical flicker
threshold 55-60 Hz

14. Rods and Cones together


Mesopic
photopic + mesopic + scotopic =
1014 range of illumination

15. no rod in central 0.25 mm of fovea, peak
between 5-7 mm from foveal center, while
cone has highest density at macula

this distribution means
 midperiphery of VF  the greatest
light sensitivity (night vision)
 fovea  high acuity, good color
vision

16. Rod and Cone photoreceptors




Rod
SWS cone
MWS cone
LWS cone
(B-cone)
(G-cone)
(R-cone)
507 nm
445 nm
543 nm
566 nm

17. Gene Encoding the Human
Photopigments
chromosome 3

Rhodopsin

Iodopsin (SWS)
chromosome 7
Iodopsin (MWS,LWS) chromosome X


18. Cone cells
S cones
-
longer inner segment
larger inner segment
deeper innervation
patchwork mosaic
low at fovea, peak 1
degree
all ~ 10%
L, M cones
-
very similar
dense hexagonal
packing
L/M ~ 2/1
all ~ 90%

19. genes : L, M cones

located on chromosome X
tandem array ~ 2-6 (1 LWS, >1 MWS)
hybrid
 protan (red-blind)
 deutan (green-blind)

21. Horizontal cells
1.
2.
3.
-
H1 dendrite all cones-axon-rod
H2 contact S cones avoid others
H3 avoid S cones contact others
local-circuit neurons
chromatic organization
opponent color coding
first stage of
wavelength discrimination ?

22. Bipolar cells
For rod : on-cell type (single depol.)
For cone : off and on-cell type
Depolarize (on) : depol. Response to central/direct
illumination
Hyperpolarize (off) : hyperpol. To center
illumination and depol. To surround illumination

23. Ganglion cells
-
-
-
Its axons form optic nerve and terminate at
LGB/ other diencephalic centers/ superior
colliculus
earliest visual neuron to generate true action
potential
neural coding in term of frequency of firing
spatial/color opponent organization
functional classification P & M

24. Ganglion cells
Property
P cells
color selectivity
yes
receptive field size
small
luminance contrast
low
cell size
small
conduction velocity
low
response time course tonic
function in scotopic
no
number of cells
1,000,000
M cells
no
large (~10 times
high
large
high
phasic
yes
100,000

25. 
optic nerve  LGB  cortex/ other
centers

27. Color vision
11 basic color term
4 uniques hue :
red yellow green blue
3 achromatic color:
black white gray
other 4 color :
orange purple brown pink

28. Basic Aspects of Color Vision
human can perceived 8000
colors at a single luminance level
 at optimal cone vision (1000

luminance range) – 8,000,000 sh
ades and tints can be distinguishe
d

29. Theory of color reception


theory of
trichromacy
theory of
opponent color
 opponent cells
 double
opponent cells

30. Color vision : color system 1
CIE color system
Commission international del’Ecalirage
specific luminance
proportion x + y + z = 1
3 dimension
2 dimension
spectral/non-spectral color
white center

31. .
W

32. Color vision : color system 2
Munsell color system
-
-
cylinder
- hue (spectral color)
10 x10 ( R Y G )
Circumferential
- value (lightness) up/down
- chroma (whiteness) radial

34. Factors that modified color
vision






Brightness
Saturation
State of dark adaptation : Perkinje
effect
Adjacent cone : lateral inhibition
Fatique and after image
Optical factors : lens, macula,
chromatic aberration, Stile-Crawford
effect

35. Colorless objects that appear
colored

Blue sky :
blue –
easier
scattered

36. Colorless objects that appear
colored

red sunset

37. Colorless objects that appear
colored
 blue water

38. Color Vision Defect
what is
color?!?!?
moo.o..o...

39. Color Vision Defects
Normal trichromats 92%
 Dyschromatopsia 8%


40. Classification of hereditary
color defect
red
ano. Trichromats
Protanomal
Dichromats
Monochromats
Protanope
green
Deuteranomal
blue
Tritanomal
Deuteranope
Tritanope
Blue cone monochromats
Rod monochromats

41. Dyschromatopsia

Anomalous trichromatism
 Protanomaly
XR


XR
Tritanomaly
AD
Dichromatism
 Protanopia
XR
 Deuteranopia
XR
 Tritanopia
AD
Monochromatism
 Rod monochromatism
AR
 cone monochromatism
XR


Deuteranomaly
1%
5%
0.0001%
1%
1%
0.0001%
0.001%
UK

42. Congenital red-green defect



most common
male 8%, female 0.5%
Cause
 Deletion of R-G pigment gene
 Hybridization of R-G gene

43. Congenital red-green defect

44. Congenital red-green defect

Characteristics
 symmetrically binocular
 constant in type and severity
through out life
 normal VA/ fundus/ photoERG
 name the color correctly

45. HUE DISCRIMINATION DEFECT

46. Acquired color vision
abnormality
 Characteristics
 VA
& VF defect
 Generally varied in type and
severity
 Unstable severity

47. Acquired color vision
abnormality

charateristics
 Affect one eye or asymmetrically
affect
 Use incorrect color name or
report that familiar color
appearance has changed

48. Acquired color-vision
abnormality
Kollner’ rule
B/Y : retinal/choroid
receptor/outer plexiform
R/G : neural disorder
ganglion cell

49. Kollner’s rule
Retinal diseases : B/Y
Eg: RD, RP, ARMD, myopic
degen, chorioretinitis, CRVO,
DR, CSCR
Except : cone-dystrophy,
Stargardt’s

50. Kollner’s rule
Optic nerve diseases : R/G
Eg: optic neuritis, ON
compression, LHON, toxic
optic neuropathy
Except : AD optic atrophy,
glaucoma, AION, OHT

51. Acquired/hereditary color
defect
characteristics
- Color- naming
- unilateral/bilateral
- blue-yellow
- change/ unstable
- other visual symtoms

52. Color Discrimination



Hue
Saturation (chroma)
Brightness (luminance, intensity)

53. 1. Hue Discrimination




hue  wavelength
depend on proportion of cone output
better in intersected sensitivity function
cross point of pigment absorption
sensitivity
yellow(590) red/green
blue-green(490) green/blue

54. Hue Discrimination

55. 1. HUE DISCRIMINATION

56. 2.Saturation
 color
purity
fully saturated color : only 1
wavelength for visible light
 desaturated color : add white light
 perception  depth of color (dark/
light blue)


57. 2. Saturation
Saturation
- how much of one hue must be add
to white to be distinguished
- the more amount, the less
saturation
- many variables purity, intensity,
size, time

58. 2. SATURATION SENSITIVITY
yellow –
lowest
saturation

59. 3. Luminosity
relative brightness/lightness
peak absorption
photopic 555
scotopic 507
Purkinje shift (rod & blue
cone pathway?)

60. 3. LUMINOSITY CURVE
507 555

61. Color vision tests

62. Color vision tests
Patient selection
- screening test in children,
student, worker
- undiagnosed low vision
- recent color disturbance
- Family Hx of color defect
- Occupations

63. Color vision tests

Ideal color vision test
 Detect
the presence or absence
of normal color vision
 Distinguish between R-G and B-Y
defect
 Assess the severity of defect
 comfortable

64. Color vision tests
1.
2.
3.
Screening test
Color discrimination test
Color matching test

65. Color vision test 1:
screening test
1. Color
confusion
1. Ishihara test
2. FD15 test
2. Color saturation
1. AO-HRR test
2.TMC plate

66. Color vision test : Ishihara test
-
Test R-G
-
High sensitivity
for congen R-G
defect

67. Color vision test : AOHRR test
-
24 plates
-
Color
defect or
not
-
Assess
severity (+/-)
R-G and B-Y
-

68. Color vision : FD-15
-
Farnsworth D-15
- line of confusion
- R/G,B/Y
-
separate color handicap

69. FD-15

70. FD-15

71. Color vision tests
1.
2.
3.
Screening test
Color discrimination test
Color matching test

72. Color vision test 2 :
discrimination



Hue discrimination
 FM-100
 Farnsworth desaturated panel D-15
 Lanthony new color test
Lightness discrimination
 Verriest’s lightness discrimination
Saturation discrimination
 Sahlgren’s saturation test

73. Color vision test 2 :
discrimination
 ใช้เวลามาก
 อาศัยความชำานาญ
 ไม่เหมาะกับ
routine exam
 ไม่เหมาะกับเด็กอายุนอยกว่า 10 ปี
้

74. Farnsworth-Munsell 100 hue test
-
85 caps in 4 groups
hue discrimination test
serial color order within 2
min /each group
position&number of error
score

75. FM 100 hue test

Goals
 Grading of color discrimination in
normal subjects
(superior/ average/ low)
 Find zone of color confusion

76. Farnsworth-Munsell 100 hue test

77. Color vision tests
1.
2.
3.
Screening test
Color discrimination test
Color matching test

78. Color vision 3 : matching
Anomaloscope
1. Nagel
R/G
red640 + green545 = yellow589
2. Pickford-Nicolson
B/Y, R/G
3. Sloan’s achromatopsia test
grading severity
Expense

79. ไม่เ ห็น รู้เ รื่อ ง
เลย...ย.........
?