Color Vision

Question 1

What does metamers mean

Answer 1

Two physically different lights that appear identical
E.g
Red and Green wavelengths= yellow

Question 2

Univariance

Answer 2

You can’t tell which colour of photons has been absorbed. You only the number of photons that have been absorbed.

Question 3

How is metamers possible

Answer 3

Because 3 cone receptors underlie colour vision
- short wavelength sensitive- blue
-middle wavelength sensitive- Green
-long wavelength sensitive-red

Question 4

Trichromacy

Answer 4

indicates that we can receive 3 types of colors (red, green, and blue) and that the cones vary the ratio of neural activity

Our colour is 3d

Question 5

Colour deficiencies?

Answer 5

-Protanopia
-deuteranopia
-tritanopia

Question 6

Colour deficiencies?

Answer 6

-Protanopia
-deuteranopia
-tritanopia

Question 7

Protanopia

Answer 7

Cant see L light- red

Question 8

Deuteranopia

Answer 8

Cant see m light- green
No m cones

Question 9

Tritanopia

Answer 9

No s cones
Cant see s light- blue

Question 10

What cones are quite similar

Answer 10

L and m

Question 11

White light?

Answer 11

All 3 cones give equal output

Question 12

Where is the gene which causes red-green blindness found and who is it more common in

Answer 12

Found on X chromosome
More common in men as men only have x and Y chromosome whereas females have XX

Question 13

What tests can be used to diagnose colour deficiencies?

Answer 13

-Ishihara
- fansworth musell D15
-city university colour

Question 14

Ishihara colour vision tests

Answer 14

-qualitative screening test- pseudo isochromatic
- test distance:75cm
- age ability: 6+ years knows numbers
Modified version for 3-6 years some plates allow for gross non- verbal testing

Question 15

FMD-15 ?

Answer 15

-Qualitative screening test
- test distance: 50cm
- age ability: 5+ years knows numbers, some plates for gross non verbal testing

Question 16

City university colour

Answer 16

-qualitative
-screening test
Test distance: 40 cm
Age ability- 10+ years

Question 17

What applies when testing using the Ishihara colour vision test?

Answer 17

-if the patient provides incorrect responses to plates 1-17, use plates 18-24
-tilt the book so it’s at right angle to their line of vision
- hold the plates at 75cm from the patient

Question 18

Human colour is?

Answer 18

Trichromatic since the retina contains 3 univariate come receptors with different spectral sensitivities. The colour of a light is encoded by the relative outputs in the 3 cone receptor classes (L,M,S)

Question 19

The optic disc is referred to as the blind spot bc?

Answer 19

It’s has no photoreceptors

Question 20

Which test can differentiate between Protanopia, deuteranopia and tritanopia?

Answer 20

Farnsworth munsell D15