1.Two Main Types
With the most common kind of colorblindness, you can’t tell the difference between some shades of red and green. Other people have a type that makes you confuse certain shades of blue and yellow. Either one can be mild, moderate, or severe.
2.How You See Colors
Your retina is a layer at the back of your eyeball that’s sensitive to light. It has two kinds of cells: rods and cones. The rods work in dim light, and the cones react to brighter light. They both respond to colors. Their signals go through the optic nerve to your brain, where they’re combined to make all the colors in the rainbow. About 12% of women have an extra kind of cone that lets them see 100 times more colors than other people.
