Unit 2 - Colour Vision

Question 1

What colour do you see when all spectral colours are added together?

Answer 1

White

Question 2

What colour to do you get when all pigment colours are added together?

Answer 2

Black

Question 3

What does Hue describe?

Answer 3

Specific wavelength

Question 4

What does saturation describe?

Answer 4

The intensity of colour

Question 5

What term described the intensity of the light being emitted?

Answer 5

Brightness

Question 6

What is the peak sensitivity of the cone system?

Answer 6

555nm

Question 7

What is the peak sensitivity of the rod system

Answer 7

500nm

Question 8

What phenomena describes red roses looking black in twilight?

Answer 8

Purkinje shift

Question 9

What photoreceptors would you have if you had rod monochromacy?

Answer 9

Only rods

Question 10

what photoreceptors would you have if you had cone monochromacy?

Answer 10

Rods and only one set of cones

Question 11

Which cones do you lack if you have protanopia?

Answer 11

Long wavelength cones i.e. red

Question 12

Which cones would you be lacking if you had deutranopia?

Answer 12

Medium cones or green cones

Question 13

Why are red/green colour deficiencies more common?

Answer 13

They are on the X chromosome

Question 14

Where is S-cone opsin encoded genetically?

Answer 14

chromosome 7

Question 15

what is hering’s opponent colour theory

Answer 15

Idea that we have three opposing colour pairs blue/yellow, red/green and black/white. Explains after images. Activation of one pair leads to inhibition of the other in the pair.

Question 16

What does trichromatic theory of Young-Helmholtz fail to explain?

Answer 16

The perception of black

Question 17

What is Kollner’s rule?

Answer 17

Roughly explains colour vision anomaly by position of retinal problem.

Question 18

According to Kollner’s rule which defects would cause blue/yellow defects?

Answer 18

Media and outer retina

Question 19

According to Kollner’s rule which defects would lead to red/green defects?

Answer 19

Inner retina and pathway issues e.g. optic atrophy, toxic amblyopia and pathway lesions

Question 20

Verriest classified colour vision defects into type 1,2 and 3. To which does each type correspond?

Answer 20

Type 1 - protan like
Type 2 - deutran line
Type 3 - Tritan like

Question 21

Which colour vision test is useful in MR clinics and why?

Answer 21

Hardy, Rand, Rittner because is can still be used with v/a down to 6/60

Question 22

What v/a do you need to use Isihara colour vision tests?

Answer 22

6/18

Question 23

What is the definition of colour?

Answer 23

The sensation that allows us to discreminate uniform surfaces of equal brightness.