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Overview: What is Color Blindness & What Causes it?
Color blindness, also known as color deficiency, refers to the inability to see colors correctly and difficulty distinguishing between them. Typically, color blindness affects how you see green color shades and red color shades, and sometimes blue colors.
Color blindness occurs in your retina, where there are two types of cells (rods and cones) that detect light. Rod cells help you see in low light, while cone cells help you see in bright light and detect color. Three types of cone cells contain different pigments, called photopigments, which see green, red, and blue. They concentrate in the center of your vision, and your brain interprets the input from these cells to perceive color. If any of these types of cone cells are missing, not working, or detecting a different color than normal, color blindness develops.
When all three types of cone cells are absent, you have severe color blindness, though this is rarer. However, mild color blindness may mean that all three cone cell types exist but one isn’t functioning as it should. Some people with mild color blindness can see fine in well-lighted situations but may struggle in low-light conditions.
Color blindness is typically a condition that affects both eyes from birth and remains stable for your entire life. This can still be dangerous because it affects your vision and could complicate day-to-day life. For example, people with color blindness may have trouble seeing traffic lights. However, color blindness isn’t considered a major safety concern.
If you experience any changes in your color perception, it could be a result of medications or a sign of a more serious condition, such as the following:
- Macular Degeneration
- Alzheimer's Disease
- Parkinson's Disease
- Multiple Sclerosis
- Chronic alcoholism
- Sickle Cell Anemia
It’s important to talk to an ophthalmologist about your color vision concerns as soon as possible.
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What is Normal Color Vision?
With normal color vision, both of your eyes will have three types of properly functioning cone cells in the retina that pick up on greens, reds, and blues to help you perceive all colors correctly.
What Do You See if You are Color Blind?
If you are color blind, you will have trouble seeing some color pigments or distinguishing between them. With complete color blindness you will only see everything—green light, red light, and blue light—in shades of gray. But mild color blindness, which is the more common form of color blindness, might not be so readily apparent.
With mild color blindness, you may have difficulty picking up on greens, reds, and blues. You may not be able to see the difference between colors because of it, or you may have trouble determining different shades of colors.
Color blindness can affect the brightness of colors. It might only affect you in dim settings, or it may affect you in all levels of light.
Different Types of Color Blindness
Different types of color blindness affect people differently. While some people can’t see color at all, some people are blind to specific colors like reds, greens, blues, and more. The extremity of color blindness will also vary.
People with monochromatic vision, monochromacy, don’t see color at all. Instead, they see everything in shades of gray, black, and white. This happens because two or all three (achromatopsia) types of cone photopigmentsare absent. This type of color blindness is extremely rare, but people who live with it will often wear dark glasses to help protect their eyes.
People with dichromacy (dichromats) have only two types of cone cells that perceive color. Meanwhile, the third type of cone pigment is totally absent, making it hard to see some colors. People with dichromacy may have the ability to perceive color in bright- and normal-light situations, but their vision will deteriorate in poor lighting.
Anomalous trichromacy is considered color blindness to some extent, but it’s not as bad as other kinds of color vision complications out there. All three cone types are present to perceive light colors but one of them is slightly off. The color difficulties depend on which cone is faulty.
Tritanomaly makes it hard to see the difference between the colors:
- Blue and green
- Yellow and red
Tritanopia makes it tough to notice any differences between:
- Blue and green
- Purple and red
- Yellow and pink
Tritanopia also makes all of these colors appear less bright.
The most common color confusions for tritanopes include:
- Light blues with greys
- Dark purples with black
- Certains greens with blues
- Oranges with reds
Deuteranopia makes it tough to tell the difference between red and green. And people with deuteranomaly (deuteranopes), which is the most common type of red-green color blindness, see green more like red when it hits their eyes.
Someone with a protanomaly (a protanope) sees red more like green when it hits their eyes. This kind of color vision also makes the red shades look less bright. Meanwhile, protanopia makes it impossible to tell the difference between red and green at all. To a protanope, red and green are the same color.
How to Test Color Vision Deficiency
If you are worried about your color vision, you can get tested to see if you have color blindness. Your eye doctor will show you a circle made up of different colored dots. Those dots create a shape, such as a letter or a number, inside. If your eyes pick up the color wavelengths of light just fine, you will not have any trouble seeing the shape. However, if you have some color blindness, you will have trouble seeing the shape inside the circle.
Remember that mild color blindness is a common type of eye problem. Generally, color blindness is not considered a major safety hazard, and most people live normal, healthy lives with color blindness.
If your color vision bothers you, however, there are some resources available. If your eye doctor does tell you that you have red-green color blindness, blue-yellow color blindness, or even another more severe form of color blindness, you can take steps to help see color more clearly.
Some eyeglasses and special contact lenses help people see color better. They can adjust the way the waves of light hit your eye. Many smartphone apps tell you colors through your phone camera. And many people with color blindness have habits like labeling their clothes, for example, to make it easier to live with their bad vision.