Types Of Colour Blindness
There are several types of colour blindness. Which one are you?
Normal colour vision uses all three types of light cones correctly and is known as trichromacy. People with normal colour vision are known as trichromats.
People with ‘faulty’ trichromatic vision will be colour blind to some extent and are known as anomalous trichromats.
The different anomalous conditions are protanomaly, which is a reduced sensitivity to red light, deuteranomaly which is a reduced sensitivity to green light and is the most common form of colour blindness and tritanomaly which is a reduced sensitivity to blue light and is extremely rare.
The effects of anomalous trichromatic vision can range from almost normal colour perception to almost total absence of perception of the ‘faulty’ colour.
People with dichromatic colour vision have only two types of cones which are able to perceive colour i.e. they have a total absence of function of one cone type. Lack of ability to see colour is the easiest way to explain this condition but in actual fact it is a specific section of the light spectrum which can’t be perceived.
For convenience we call these areas of the light spectrum ‘red’, ‘green’ or ‘blue’.
People suffering from protanopia are unable to perceive any ‘red’ light, those with deuteranopia are unable to perceive ‘green’ light and those with tritanopia are unable to perceive ‘blue’ light.
Protanopes are more likely to confuse:-
1. Black with many shades of red
2. Dark brown with dark green, dark orange and dark red
2. Some blues with some reds, purples and dark pinks
3. Mid-greens with some oranges
Deuteranopes are more likely to confuse:-
1. Mid-reds with mid-greens
2. Blue-greens with grey and mid-pinks
3. Bright greens with yellows
4. Pale pinks with light grey
5. Mid-reds with mid-brown
6. Light blues with lilac
The most common colour confusions for tritanopes are light blues with greys, dark purples with black, mid-greens with blues and oranges with reds.
The images show how the beautiful colours of the pigments are lost to people suffering with each type of dichromatic vision.
People with monochromatic vision can see no colour at all and their world consists of different shades of grey ranging from black to white, rather like only seeing the world on an old black and white television set. Achromatopsia is extremely rare, occurring only in approximately 1 person in 33,000.