Types of Color Blindness
Color blindness can be classified into various types. Each type is defined according to which types of cones are malfunctioning. To learn and understand the types of cones, it is important to know a bit about cones.
Cones are nerve cells in your eyes that identify colors within the visible spectrum of light. This spectrum contains all the wavelengths that humans can see. They range in length from 380 nanometers (short), or nm to 700 nanometers (long). The human eye normally contains three types of cones:
- Red-sensing cones (L cones): These cones detect long wavelengths (around 560 nanometers).
- Green-sensing cones (M cones): These cones detect middle wavelengths (around 530 nanometers).
- Blue-sensing cones (S cones): These cones detect short wavelengths (around 420 nanometers).
Most people possess all three types of cones, and they work as they should. However, people with color Vision deficiency may have at least one type of cone that isn’t working properly. Problems with your cones usually affect your ability to see colors in the normal way.
There are general categories that describe how many types of cones you have, and how well they work. They include:
- Trichromacy: All three types of cones are present and functioning well. You can see all colors on the visible spectrum of light in the normal way. This is also called full-color vision.
- Anomalous trichromacy: This is usually characterized by the presence of all three types of cones, but one type is not as sensitive to light in its wavelength as it should be. As a result, you cannot see colors in the traditional way, with variations from normal. Ranging from mild to severe. People with mild cases may just find it difficult to identify pale or muted colors. However, people with severe cases usually find it more difficult to identify vivid and pure (fully saturated) colors. These types of color blindness possess names that end in “anomaly” (which means partial vision of a certain color).
- Dichromacy: In this category, one type of cone is missing. So, you only have two types of cones (usually S cones along with either M cones or L cones). You can only see colors via the wavelengths that fall within wavelength of those two types of cones. People with dichromate may find it difficult to identify fully saturated colors. These types of color blindness are usually characterized by names that end with “anopia,” which means lack of vision of a specific color.
- Monochromacy: In this category, you only have one type of cone, or you have no cone at all. People in this category may find it difficult to see any color. Instead, they may see the world in varying shades of gray.
Within the categories discussed above, there are numerous certain types of color blindness. Let’s take a look at these types of color blindness: