optometry students & Entrance preparation

1. Assessment of colorvision
Kapil Gautam
Optometrist

2. Clinical significance
– Idenification and Diagnosis of color deficiencies
– Severity color deficiencies
– Evaluate macular function

3. -Impact on career/daily activities
- clue to sight threatening ocular diseases
-Evaluate aptitude for color discrimination

4. Indications
Children before joining school
Patients on first official visit
Unexplained reduction of VA

5. -Low VA
-Painless photophobia and nystagmus
-Patient with abnormal fundus

6. - Vocational counselling to different
professional-
artists,electrician,drivers etc.
- To assess vision fitness
-Various ocular and systemic diseases
ARMD,DM,HTN ,POAG etc.

7. Color Vision Tests
Pseudoisochromatic Test
Plates
Ishihara Plates
Dvorine
AOHRR Plates etc.

8. • Hue discrimination(Arrangement tests)
-The Farnsworth D-15 test
-The Farnsworth Munsell-100 Hue test

9. • Anamaloscopes
-The Nagel Anamaloscope -
The Neitz Anamaloscope

10. • Color naming and color sorting
-Lantern tests,
-Yarn test etc.

11. Pseudoisochromatic plate tests
Designed on the basis of color confusions made by
color defective person
A figure or symbol in one color is placed on a
background of another color

12. Figure and background are isochromatic for the
color defective.
Confused by color defective but discerned by the
normal.

13. Primarily used as screening tests to identify
those those with inherited color defect
Some tests allow diagnosis of type and
severity

14. • Four types of designs have been used in the
construction of PIC plates.
Viz…
Transformation plates
the color defective person reads one figure while
normal reads another

15. 2-9 plates in ishihara edition
Vanishing plates
color defective person can’t read the
figure.
10 - 17 plates in ishihara plates in
Ishihara 38 edition

16. color defective person can’t read the
figure.
10 to 17 plates in Ishihara 38 edition plates

18. Hidden-digit plates
person with normal CV does not see a figure while a CVD
will see the figure.
18-21 plates in 38 edition ishihara plat
Diagnostic plates
designed to be seen by normal subjects with CVDs seeing
one number more easily than another
20-25 plates in 38 edition ishihara plates

20. • Ishihara plates
First published in 1917
Detection of presence of protan/deutan
Digit or winding paths to be traced

21. Currently available editions are-
38,24 and 16 plate version
Ideal for screening
First - demonstration plate
Rest for detection of color vision defects

23. Testing guidelines
VA > 6/60
Illumination = 500-600 lux
Testing distance= 75 -100 cm .

24. • Observation time = 3 to5 secs per plate ( 10
secs for winding paths)
• Monocularly to the right eye then to the left
eye

25. Interpretation
Count the no. of plates misread
Exclude the demonstration plate from this
total
More than the indicated no. of errors - presence of
protan/deutan defect

26. 38 Plate edition= 4 or less – normal
= 8 or more –deficient
24 Plate edition = 2 or less –normal
= 6 or more –deficient
16 Plate edition = 2 or less – normal
= 4 or more deficient
The no. of errors isn’t reliable estimate of the
severity of any color vision defect.

29. Dvorine test
Widely used screening test for protan deutan
15 plates –Arabic numerals
8 plates –wandering trails
1 plate –demonstration plate

30. Failure -3 or more
Unique feature –PIC plates +a Nomenclature test
Better than ishihara for screening
Severity is according to pt’s error.

32. AOHHR test
Produced by American Optical Company
Named after Hardy , Rand , Ritter
Consists of 24 plates
Background color of every plate is neutral gray
printed with dots of different lightness

33. Failure – symbols in the plate missed or
named incorrectly
test all types of color vision defects
Not commercially available now

34. Hue discrimination test
qualitative test of hue discrimination
permits diagnosis of the type and the degree of color
vision defect

35. Not able to distinguish between dichromats and
anomalous trichromats
consist up of color caps of different hue – to be
arranged in serial order of hue

36. Fransworth d-15 dichotomous test
consist up of 15 color caps in order of hue, one
being reference cap
only diagnose severely color defectives but mild
defect goes undetected

37. useful in fast screening for severe defect
Time – usually takes 2 mins ??
Test dist- 50cm
Error in making arrangement of caps is plot in
circular polar graph and interpreted

43. Interpretation
Two or few crossings – not severe CVD as established
by Ishihara
More than two crossings- severe and lies on certain
confusion line
Monochromats expected to fail
Confusion line lie b/w deutan & tritan axes

44. Fransworth Munsell 100 hue test
An expanded version of Panel D-15 test.
consist up of 85 caps, divided approximately equally
in four boxes

45. Need to arrange the color caps in order of hue
discrimination b/w fixed reference caps
Required 20-25 minutes to complete – not good for
screening purpose (ideal 2-3 mins for one box)
Patient has to arrange the samples into serial order.

46. Recording & scorings
Calculate error score by positional difference b/w caps of
either sides.
e.g. if 6 b/w 5 & 7 ( correct sequence) - score of 2
if 6 b/w 5 & 11 ( incorrect sequence) – score of 6
Error Scoring plotted in circular polar diagram –
correcting order –closer to centre (score of 2)
Incorrect order –further from the centre

47. If plot is horizontally extended
i.e. 10-30 & 55-75 – protan
If Obliquely oriented - deutran , vertical – tritan

48. Protan, Deutan & Tritan CVD orientation

53. L’Anthony’s Desaturated D-15 test
Similar number of caps as that of D-15
Tested after passing D-15
to classify type and assess severity ( in mild
CVD
Tested after Ishihara
to detect acquired tritan defects
Also to monitor & assess the progression of
acquired defect.

54. Interpretation
Two or few crossing – mild protan/ deutan CVD
Two or more crossing & passed D-15 – moderate CVD of
either

55. City University Color Vision Test
Administered after a fail on Ishihara.
Aim to classify severe CVD into either types.
Used as an alternate to D-15
Test based on D-15.

56. Not suitable for screening.
Need illuminant of 600 lux to 900 lux
Ask to match 4 outside spots of color to the middle
spot.

57. Interpretation
Response for the types recorded in ratios separately
e.g. 4 normal response & 6 deutan response -> record
as 6/10 Deutan
6/10 medium deutan defect
10/10 Deutan score sever Deutan defect
Score doesn’t distinguish b/w dichromats &
anomalous trichromats.

58. Anomaloscope
Instruments designed to examine color matching
behavior.
most effective for the classification of R/G defect
very much expensive

59. pt mix the monochromatic R & G color in a proportion
to match given yellow color discs.
Judgment defect made for relative amount of R&G
color used
to match given yellow is taken under consideration to
classify the color vision defect.

60. Nagel Anomaloscope
French manufacturer
First clinical instruments
Use interference filters – very pure color stimuli
Pickford Nicholson Anamalsocope
British manufacturer
more versatile- different color used to match
Use color filters – give less pure colors
Neitz OT Anomaloscope
Japanese version of Nagel Anomaloscope

62. Color naming and color sorting
Lantern test
To identify the color of a signal light in lantern
Hue , brightness and size can be varied
Judgment made by the mistakes
Not popular
Farnsworth Lantern test -
Holmes Wright Lantern test

64. Yarn test
the oldest color sorting test
Relay on brightness difference than on the hue.
Not effective for diagnostic purpose

65. Test require the subject to select from the pile of
colored yarns those which resembles a “standard
skin
Unreliable as dyes are not standardized
Yarns fade & become dirty with handling in a short
time.

66. Recommended sequence of color vision
tests
1) Ishihara Pseudoisochromatic plate
-presence or absence of R /G CVD of
any severity
2) Lanthony‘s Desaturated D-15
-to determine the presence of a tritan
defect OR
Farnsworth F2 plate-
administered after passing Ishihara to
determine presence of a tritan defect .

67. 3) Medmont C100/OSCAR color vision tests
-differentiate between protan and
deutan CVDs ( no severity )
4) Farnsworth Panel D-15
-classify the more severe CVDs

68. 5) Lanthony‘s Desaturated D -15
to determine the classification of
( protan ,deuta ,tritan ) of less severe CVDs
i. e. those passing the D-15
For complete
diagnosis and measurement of
severity above tests should be supplemented
by tests not widely available
-FM 100 hue test
-Anomaloscope testing