Types of Color Blindness
"Color blindness" is rarely total. Most people with it see color, just a narrower range, because one type of cone in the retina is missing or shifted. Which cone is affected, and how strongly, defines the type.
By type
Reduced sensitivity to green light, the most common form.
Absent green cones, a stronger red-green deficiency.
Reduced sensitivity to red light; reds look dimmer.
Absent red cones; a strong red-green deficiency.
Reduced sensitivity to blue light; rare.
Absent blue cones; blue-yellow confusion. Rare.
Little or no color vision, seeing mostly in shades.
Guides
Understand color blindness
The three color axes
Human color vision uses three cone types, long (red), medium (green) and short (blue) wavelength. A deficiency in any one shifts how you separate colors:
- Red-green (protan and deutan), the L or M cones. By far the most common, and X-linked, so it mainly affects men.
- Blue-yellow (tritan), the S cones. Rare, and affects men and women equally.
- Total color blindness (monochromacy), little or no cone-based color at all. Extremely rare.
Not sure which applies to you? The quickest answer is to take the color blind test, it estimates your axis and strength in about a minute.
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