Red-Green Color Blindness
Red-green color blindness appears to be the most common form of color blindness among people. This is a genetically passed mutation that is generally linked to sex, as it affects men more often than women. The reason why men are more prone to this type of color blindness is because it is transmitted via the X chromosome.
If, for example, a woman is a carrier of one of the four causes of red-green color blindness (protanopia, deuteranopia, protanomaly, or deuteranomaly), she has a fifty percent chance that her son will display symptoms of the disorder because he only has one X chromosome. If, on the other hand, a woman has a daughter with a man who has normal color vision, there is only a 50% chance that the child will be a carrier of the gene and no chance that she will be affected by it. Only when a man and a woman with the same bad gene have a daughter will the daughter exhibit any issues with these types of color blindness. Additionally, some of the few women that are affected by this type of color blindness actually see normally even though they are affected.
The way red-green color blindness affects people is by distorting the light wavelengths of the color spectrum that are related to those colors. When someone views a color that contains certain shades of these colors, they become indistinguishable by hue and only distinguishable by shade, relative brightness or in very rare cases, they appear to be a different color entirely. The tests for these types of color blindness are relatively simple and can be done in a matter of minutes while visiting your optometrist or ophthalmologist for your routine eye exam. This type of color blindness hasn't been solidly linked to poor eyesight.
The row of pictures on the right is how people with red-green color deficiency sees things. You can take a color blind test here to determine if you have red-green color blindness.