If you are suffering from red-green color blindness, what are the chances that your neighbour or one of your classmates also suffers from it? What we like are numbers and one of the most often asked and searched for questions about color vision deficiencies is: How many people are affected by color blindness?

Before we digg right into some interesting numbers about red-green color blindness you should be aware of the following facts:

• Tritanopia (blue-yellow color blindness) is rare. Some sources estimate that 0.008% are affected by this type of color vision deficiency.
• Monochromacy (complete color blindness) is very rare. Different sources vary between 1 in 33’000 to 100’000 (0.001%).
• Families are not a good source of numbers concerning color blindness, because vision deficiencies are inherited and therefore some families are affected much more than others.

Red-green color blindness is the most common color vision deficiency; therefore most of the researches found regard this type of colorblind population. The following figures are listed in the book Color Vision: From genes to perception and combine many different surveys spread over the last century.

Four different deficiencies make up the common wording red-green color blindness. People suffering from an anomaly are trichromats but do report problems in color perception in the green-yellow-red sector of the spectrum. The two different types show a less sensitiveness either to red light (Protan) or green light (Deutan). In opposite people suffering from an anopia are dichromats, completely lacking one type of retinal cones.

The figures above basically show the following important facts about red-green color blindness:

• Roughly 8% of men and 0.5% of women are affected. Therefore chances that your neighbour or one of your classmates is colorblind are very high.
• Deutanomaly is by far the most common color vision deficiency regarding red-green color blindness. The other three types are occurring at nearly the same ratio and do affect about one out of 100 persons each.
• Men are approximately 100 times more often affected than women. This shows very nicely that red-green color blindness is a sex-linked trait as described in more detail at The Biology behind Red-Green Color Blindness.

A last note about the figures: If you always thought that you are someone special because of your color blindness, you might be wrong. Especially if you are male and suffering from Deuteranonmaly one could say you are one under many and you can meet fellow sufferers out on the street every day.

Further readings:
Opsin Genes, Cone Photopigments, Color Vision, and Color Blindness
The Perception of Color

Related articles:
The Biology behind Red-Green Color Blindness
Color Blindness Test by Dr Shinobu Ishihara
5 Misbeliefs about Color Blindness