1. Defective Color Vision
Gauri S. Shrestha, M.Optom, FIACLE

2. Color Vision Deficiencies
Monochromacy
Only one Pigment Type is present
Dichromacy
Only two Pigment Types are present
Trichromacy
All three Pigment Types are present

3. Monochromacy-Shades of Gray
3 Types
Rod Monochromats
• Most Common Type: 10 in 1 million people
• No cones, very poor visual acuity
Blue Cone Monochromats
• Colorblind in photopic and scotopic conditions
• Narrow range of mesopic conditions that they are not
colorblind
Cone Monochromats
• Rarest Type: Only 1 in 100 million people
• Acuity is fine during photopic conditions
Patients learn to label colors by other cues

4. Monochromats
These patients can match any wavelength in
the spectrum by changing the intensity of
another wavelength
Termed: COLOR BLIND
Poor Visual Acuity
Sunglasses are a must!
Depending on rod system for vision

5. Monochromacy
10/1,000,000 - rod vision only
Only see shades of lightness
S M L Also poor visual acuity
ROD
70
0

6. Dichromacy-2 Pigment Types
More common than Monochromacy
3 Types
Protanopia-Missing long wavelength (red)
pigment
Deuteranopia-Missing middle wavelength
(green) pigment
Tritanopia-Missing blue pigment

7. Dichromacy
• Protonopia S+ L+M+S+ L+
– No L cone; X linked L-M- L-M-S- M-
– 1% males, 0.02% females
• Deuteranopia
S M L
– No M cone; X linked
– 1% males, 0.01 %females
• Tritanopia
– No S cone; Autosomal dominant
– 0.002% males, 0.001% females

8. Neutral Points
The wavelength where the two remaining
pigments cross
Colors look very desaturated and whitish
Patients cannot distinguish colors in this area of
the spectrum
• Colors at this wavelength are perceived as gray

9. Dichromatic Neutral Points

10. Trichromacy-3 Pigment Types
There is no ‘neutral point’
3 Types
Protanomaly-shifted red pigment
Deuteronomaly-shifted green pigment
Tritanomoly-shifted blue pigment

11. Anomalous Trichromat
• L&M pigment spectra shifted closer together
S M L
Match colors differently from
ROD
normal trichromats
Some colors less discriminable
70
0

12. Hereditary Color Vision Defects
DEFECT PREV. IN MALES TRANSMISSION
Deuteronopia 1% X-linked recessive
Protonopia 1% X-linked recessive
Deuteronomaly 5% (Most Common) X-linked recessive
Protonomaly 1% X-linked recessive
Tritanopia & .005% (Most Rare) Autosomal
tritanomaly Dominant

13. Replacement model of Dichromacy
Missing photopigment is replaced by a
remaining photopigment
Deuteranope: chlorolabe is replaced by
erythrolabe
Protanope: missing erythrolabe is replaced
by chololabe
Exception: missing cynolabe is not replaced
by another photopigment

14. M-cone displaced toward L-cone displaced toward
long wavelengths short wavelengths

15. Spectral sensitivity: Chromatic
System
Presentation: Large stimuli (1°) and long
duration (200msec) background moderately
bright (1000 trolands)

16. 440 520 620
nm nm nm

18. Spectral sensitivity: Luminance
Function
660nm

19. Wavelength Discrimination
Wavelength
discrimination=
absent
Color
discrimination=
545 luminance
profile
490

20. Wavelength Discrimination
Wavelength
discrimination at
longer wavelength
Poor wavelength
discrimination at
495nm

21. Color confusion lines
Green=reddish
purple
Essential
monochromat
above 545nm

22. Color confusion lines
Red-green confusion
Essential monochromat
above 545nm

23. Color confusion lines
Confusion b/w Blue-
violet & yellow

24. Saturation
Neutral point: desaturated appearance of spectral
stimuli at specific wavelength
570nm

25. Saturation

26. Color labeling 4
9
5
9
0 0
Color labeling is
remarkably good
in color vision
deficiency
However,
Industrial color
labeling is
difficult, such as
stripe/pattern
analysis

27. Color Vision and Females
Tend to be carriers
Tend to have normal color vision
20 times less likely to have a color vision
deficiency

28. Transmission of X linked, red-green
defects from parents to offspring
X X X X
X XX XX  X X
Y XY XY Y XY XY
Father Normal (XY) Father Defective ( Y)
Mother Normal (XX) Mother Normal (XX)

29. Transmission of X linked, red-green
defects from parents to offspring
   X
X X X   X
Y Y Y Y Y XY
Father Normal (XY) Father Defective ( Y)
Mother defective ( ) Mother Normal ( X)

30. Transmission of X linked, red-green
defects from parents to offspring
 X
X X XX
Y Y XY
Father Normal (XY)
Mother carrier ( X)

31. Congenital vs. Acquired
CONGENITAL ACQUIRED
Affects both eyes equally One eye only OR asymmetric
Usually a R-G defect B-Y OR R-G
Other visual functions normal Other visual functions abnormal
Stable through lifetime Variable, dependant on test and
diseases conditions
Learned to adapt-can label Cannot name color correctly
objects

32. Congenital vs. Acquired
CONGENITAL ACQUIRED
More prevalent in male Equally prevalent in male and
female
Not associated diseases or Classification not
toxicity straightforward with standard
clinical color test

33. Kollner’s Rule
Outer retinal diseases and media changes result in blue-
yellow color vision defects
Inner retina, optic nerve visual pathways and visual cortex
diseases result in red-green defects
Location Defect condition
Media B-Y Nuclear sclerosis
Outer retina B-Y AMD, DR
Inner retina R-G Optic atrophy, toxic amblyopia
Pathway R-G Lesions

35. Chromatopsia
These patients have no trouble
distinguishing wavelengths, but perception
of colors is altered
Similar to wearing a filter over the eyes
May occur in patients taking various
medications
Xanthopsia-slightly yellow tint (Digitalis)
Cataract Formation
• Patients notice blue tint upon cataract removal

38. We can measure
2. the reflectance of an object
2. brain responses
3. behavioral responses
But we can only guess whether your sensations are really the same
as mine …

39. Kollner’s Rule
BE CAREFUL-IT DOESN’T ALWAYS WORK
Blue-Yellow Defects
Associated with outer-retina problems (diseases that
effect the photoreceptors)
Ocular Media-Cataracts
Red-Green Defects
Associated with inner-retina problems (ganglion cells
and visual pathways to the brain

40. LOCATION DEFECT CONDITION
Media Blue-Yellow Nuclear Sclerosis
Outer Retina Blue-Yellow ARMD
Diabetic Retinopathy
Inner Retina Red-Green Leber's Optic
Pathways Atrophy
Toxic Amblyopia
Inner Retina Red-Green Lesions
Pathways