Presentation on deuteroanomaly, color vision deficiency affecting mostly males by shifting red-green hues perception.

1. DEUTERANOMALYPersonal experience of a specimen of Homo sapiens
and a little scientific background behind it
Jan Stanik
15/7/2014

2. WHAT IT IS
1 most common colour vision deficiency in males
2 impaired ability to recognise red-green hues
3 inherited and linked to X-chromosome
4 mutation of pigment in retinal cone cells
males females

3. WHAT IT IS NOT
1 special in males
• remember, 5% male population, 0.35% female population
• due to being X-chromosome linked
2 colour blindness
3 disease
2 curable
• colour vision deficiency is the preferred term
• colours are recognised

4. JOHN DALTON
1 had deuteroanopia
• dichromatic: only red and blue photoreceptors
• first paper on colour blindness
2 daltonism
3 1794 Extraordinary facts
relating to the vision of colours
• adopted as general form for impaired colour vision
“that part of the image which others call red appears to
me little more than a shade or defect of light. After that
the orange, yellow and green seem one colour which
descends pretty uniformly from an intense to a rare
yellow, making what I should call different shades of
yellow”
1776-1844

5. HOW YOU KNOW
1 people around you notice
• your wife will definitely notice
• not that prevalent in female population
2 after having yourself tested
3 two exactly same fruits taste differently
4 yellow is actually green
• any GP can do the test (likely variant of Ishihara Test)
• to lesser degree of accuracy can be done online
• mandatory for certain professions
• mandatory in certain countries for obtaining a driving license
5 magenta is also green

6. SHINOBU ISHIHARA
2 designer of Ishihara Test
• 1917, 50 years before studies of photopsins
• basic 24 watercolor plates, 37 plates full test
• his assistant was a colour blind
• symbols originally used Japanese script Hiragana
1 Japanese army surgeon
1879-1963plate № 1, displaying number 12
visible to person with deuteranomaly
plate № 11, displaying number 6
invisible to person with deuteranomaly

7. PHOTON
1 eye receives information as rays of photons
• input from environment is transduced in eye
2 particle travelling at speed of light
3 frequency is colour
4 frequency is wavelength
• it is de-facto light
• massless
5 colour ≡ wavelength
f = c/λ
f: frequency
c: speed of light (299 792 458 m/s)
λ: wavelength
• frequency is the energy of photon
• objects in environment emit/reflect photons of different frequencies based on their
surface chemical composition (red surface emits red photons)

8. VISIBLE SPECTRUM
1 390 – 700 nm
• frequency range: 790 – 430 THz
2 recap: color ≡ frequency ≡ wavelength
390 nm
790 THz
700 nm
430 THz

9. CONE CELLS
1 one kind of photoreceptors cell in retina
• the other 2 being rods and photosensitive ganglion cells
• neuron – has synaptic connection to visual cortex
2 responsible for color vision
3 activated at brighter light
4 3 subtypes
5 different pigment in each subtype
• rods are activated in low light intensity (night vision)
• in deuteranomaly sensitivity of opsin in M-cones is closer to that of L-cones
• photopsin (protein) is attached to retinal (vitamin A) to form pigment
• retinal is the same, cells differ in photopsin type

10. CONE CELLS SUBTYPES
L-coneM-coneS-cone
photopsin
OPN1SW
Peak sensitivity
420 – 440 nm
OPN1SW
photopsin
OPN1MW
Peak sensitivity
534 – 545 nm
photopsin
OPN1LW
Peak sensitivity
564 – 580 nm

11. CONE CELLS IN RETINA
1 very few S-cones, 1/10 of M- and L-cones
2 no S-cones in fovea
ratio of cone
cells in retina

12. COLOUR VISION
1 several cones receive stream of photons
• photons in stream have same or very similar wavelengths (colour)
2 pigment in each cell gets activated
3 hyperpolarised at rest
4 3 signals generated
• signal is carried by sodium ions Na+
• in absence of light signal is not generated
• noiseless system
• protein changes shape of retinal
• neurotransmitter flow into the cell is reduced

13. COLOR VISION
1 difference in stimulation of each cell type
• three measures are calculated
brightness = R + G
R: signal from L-cells
G: signal from M-cells
color1
= R - G color2
= B – brightness
B: signal from S-cells
2 model situation: 2 colors
437 nm 533 nm 564 nm
different signal delta

14. DEUTERANOMALY
1 M-cone sensitivity range shifted towards L-cones
2 signal differences in part of spectrum distorted
437 nm > 533 nm 564 nm
3 red-green hues sensitivity impaired
indistinguishable signal delta

15. GENETICS
1 L-cones and M-cones are evolutionary close
• theory that one evolved by mutation of the other
2 sequences for photopsins in X-chromosome
3 males have only one X-chromosome
4 females have two X-chromosomes
• 19 chromosomes and 56 different genes involved in colour vision
5 in general mother is only carrier
• if color vision genes are abnormal they result in color vision anomalies
• if color vision genes in one are abnormal the other takes over
• color vision deficiencies less prevalent in females

16. IMPAIRMENT
1 no
2 unless for professionals, such as graphic
designers, printers, etc.
3 disqualified for driving license in some countries

17. RESOURCES
1 Ishihara Test
http://www.dfisica.ubi.pt/~hgil/p.v.2/Ishihara/Ishihara.24.Plate.TEST.Book.pdf
2 Online Daltonism Test
http://www.opticien-lentilles.com/daltonien_beta/new_test_daltonien.php