Colour vision tests

Question 1

what is a protan described as

Answer 1

a general term stating that the long cone photo-pigment is different from normal

Question 2

what is a deutan described as

Answer 2

a general term stating that the medium cone photo-pigment is different from normal

Question 3

what is a tritan described as

Answer 3

a general term stating that the short cone photo-pigment is different from normal

Question 4

what is the name if someone who has a missing long/L photo-pigment cone

Answer 4

protanope

Question 5

what is the name if someone who has a missing medium/M photo-pigment cone

Answer 5

deutranope

Question 6

what is the name if someone who has a missing short/S photo-pigment cone

Answer 6

tritanope

Question 7

what is the name if someone who has one of their L, M or S cones missing

Answer 7

dichromat

Question 8

what is the name if someone who has all three cones S, M and L present, but one is anomalous (different from normal)

Answer 8

trichromat (S, M or L spectral sensitivity is anomalous)

Question 9

what is is called if someone has an anomalous L cone spectral sensitivity

Answer 9

protanomalous

Question 10

what is is called if someone has an anomalous M cone spectral sensitivity

Answer 10

deutranomalous

Question 11

what is is called if someone has an anomalous S cone spectral sensitivity

Answer 11

tritanomalous

Question 12

what is a normal trichromat

Answer 12

there are 3 cones with L, M and S in the ‘normal group’

Question 13

what is a cone monochromat

Answer 13

when two cones are missing

Question 14

what is a rod monochromat

Answer 14

when all three cones are missing

Question 15

list the three main colour vision tests

Answer 15

• ishihara
• anomoloscope
• 100 hue and D15

Question 16

which type of plates does the ishihara test use

Answer 16

pseudoisochromatic plates

Question 17

which colour vision test uses colour matching

Answer 17

the anomoloscope

Question 18

which test uses confusion lines

Answer 18

100 hue and D15

Question 19

what is the general layout of the ishihara test plates

Answer 19

• groups of spots with similar hues and lightness seen as a number or symbol
• confusions affect the shape seen

Question 20

what are the 3 main advantages of the ishihara test

Answer 20

• quick, simple and cheap
• screens main deficiencies
• good sensitivity and useful specificity

Question 21

how many plates are in a ishihara test

Answer 21

38 plates

Question 22

how many errors will most normals make with a ishihara test

Answer 22

less than 5 (0-5)

Question 23

hw many errors will a RGD make with a ishihara test

Answer 23

9 or more errors

Question 24

what is the lighting recommendation when testing with the ishihara test

Answer 24

300 - 500 lux

excellent colour rendering e.g. 
- north sky daylight 
or 
- standard illuminant D65
 or
- macbeth lamp

Question 25

which lighting conditions are not idea when testing with the ishihara test and why

Answer 25

tungsten, LED and fluorescent lighting | to avoid disadvantaging the subject with low levels of colour rendering

Question 26

list the 4 types of patients that the ishihara test is used on

Answer 26

- all new patients - children - to see if occupational tests are required - general use for reports of colour disturbance, pathology and medication

Question 27

what is plate 1 of the ishihara test and who is it seen by

Answer 27

a demonstation plate - seen by all observers

Question 28

what are plates 2-9 of the ishihara test and who is it seen by

Answer 28

transformation plate - detected by normals but not RGDs

Question 29

what are plates 10-17 of the ishihara test and who is it seen by

Answer 29

vanishing digit - detected by normals but not RGDs

Question 30

what are plates 18-21 of the ishihara test and who is it seen by

Answer 30

hidden digit - not detected by normals but seen by RGDs

Question 31

what are the plates 22-25 of the ishihara test and who is it seen by

Answer 31

it is used to differentiate between protan and deutan

Question 32

which type of colour deficient people does the ishihara test for and which types are not detected

Answer 32

detects of red-green colour deficients (RGDs) | not tritan defects (but this is not a serious drawback)

Question 33

what is a disadvantage to the ishihara plate test

Answer 33

unable to differentiate reliably between whether its anomalous trichromats or dichromats

Question 34

if a fire fighter fails the ishihara plate test, what is the next test that needs to be carried out

Answer 34

farnsworth D15

Question 35

if a firefighter fails the farnsworth D15 test, what is the next test that needs to be carried out

Answer 35

nagel anomoloscope

Question 36

which type of cone photo-pigment abnormality will not be suitable for fire fighting

Answer 36

protan or deutan (red or green deficiency)

Question 37

what is the concept of the nagel anomaloscope

Answer 37

- a yellow (589nm) is matched with a mixture of red (670nm) and green (546nm) - this is a standard RGB match but no blue primary, B is required (=zero)

Question 38

what must the subject do in a nagel anomaloscope test

Answer 38

adjust the proportions of R and G and the brightness of the yellow

Question 39

what is the indicator of someones colour vision with the nagel anomaloscope test

Answer 39

the chosen R/G and Y

Question 40

which types of patients is the nagel anomaloscope good at idenifying

Answer 40

- normals - anomalous protans and deutrans - dichromat protans and deutrans

Question 41

how is the farnsworth D15 test used

Answer 41

subject places 15 caps of a munsell value 5 and chroma value 4 in order the results are plotted onto a circular diagram P, D and T the subjects makes errors along the confusion axis

Question 42

which types of colour vision anomalies does the ishihara plate test detect

Answer 42

protan and deutan screening (either anomalous or dichromat)

Question 43

what is the main justification of optometric screening of colour deficiencies

Answer 43

to inform the subject of their problem in time and to give appropriate advice

Question 44

list 2 reasons for normal age related colour changes

Answer 44

- yellowing of the ocular media (nuclear cataract) | - changes in retinal sensitivity

Question 45

list the non age related causes of colour deficiencies and what is affected in particular with these

Answer 45

arise from: - ocular disease - trauma - medication - exposure to toxic substances - commonly affect one eye or more - affects males and females equally - often affects blur perception (so is easily missed in many CV tests as they mainly screen red-green defects)