Colorblindness
What causes it, and what it’s like to
have it
Types of Cones
 There are 3 types of cones in the human retina
Name of Cone
Main wavelength Main color it
it receives
receives
Short (S)
420–440 nm
Blue
Medium (M)
534–545 nm
Green
Long (L)
564–580 nm
Yellow
How you see color
 Light passes through your cornea and lens and hits the retina
 Long wavelengths excited the L cones, short the S cones, etc.
 Your brain determines which cone is excited the most to
determine which color you are seeing
 For example:
 Mostly S and a little M= Blue
 Only S= violet
 Only L= red
 Mostly L and some M = yellow
Types of Colorblindness
 What do you think you could see if you only had S cones?
 What if you only had M and L cones?
 What if your M cones only worked in the very center of
their spectrum and not the whole thing?
Colorblindness tests!
a.
b.
c.
Colorblindness tests!
d.
e.
f.
Types of Colorblindness Con’t
 Monochromacy- when 2-3
types of cones are missing
or non-functioning
 Things are in shades of
grey, white, and black.
 Very rare form of
colorblindness
Types of Colorblindness Con’t
 Protonopia- missing the L
cones (to see red)
 Can’t see the difference
between red and green
 Occurs in 1% of males (sex-
linked gene)
Types of Colorblindness Con’t
 Deuteronopia- M cones are
missing or broken (to see
green)
 Can tell the difference
between red or green
 Also sex-linked affecting
5% of males (most
common type)
Types of Colorblindness Con’t
 Tritanopia- missing S cones
(for blue and violet)
 Hard to distinguish blue-
green-yellow colors
 Very rare, hereditary form
of colorblindness (not sexlinked)