Just because someone has “color blindness” doesn’t mean that they can’t see any color.
Do you have any color deficiencies in your vision? If not, you should clearly see the number 74 above. If so, you might see a 21 or no numbers at all. Image: Wikipedia
The term “color blindness” might conjure up a world that looks like an old school black and white television program. (If you were born in the 1980s or after, you might not have ever seen one of things in person, but trust us, they were real.) While some people with color blindness do experience this, there are actually many ways that condition can manifest itself.
To understand how color blindness works, you first have to understand a little bit about how the human eye detects the colors (red, orange, yellow, green, blue, and violet) of the visible light portion of light. The retinas in the back of our eyes contain millions of light-sensitive nerve cells called “rods” and “cones”. The rods deal with the brightness of light, while cones tackle color in three flavors: red, green, and blue. Both rods and cones have chemicals that change when they are hit by light. This causes an electrical signal to travel to the brain along the optic nerve, which ultimately allows our brain to produce an image in color.
There are times when the rods and cones don’t respond as they should – and this range of scenarios is often lumped together under “color blindness.” In fact, most people who have this condition only have trouble distinguishing between red and green. The reason for this is that the cones in their eyes either lost or never had the correct chemicals to make that distinction for their brain, but other colors remain visible. For more information on color deficiencies, visit the National Eye Institute’s page of the subject.