What color-blind people see and don't see can vary based on what rods and cones of the eyes are affected. Rod and cones are photoreceptor cells that deliver information that the brain interprets as color and shade. Cones detect red, blue, and green colors, while rods describe lightness and darkness. If any of these cells are not functioning as they should, color blindness can occur.
Color-blind people see differently depending on what form of color blindness they have. Some people may not be able to tell certain colors from others, or the colors may appear muted or washed out. In rarer cases, someone who is color blind may not see any color at all.
This article describes the various types of color blindness and what causes them. It also explains how color blindness is diagnosed and how color-blind people adapt to situations where color might otherwise seem essential.
Color blindness doesn't always mean a person only sees in shades of gray. This type of color blindness is considered the most severe, but it's uncommon. Most people with color blindness simply see a narrower range of color than someone with full-color vision. What this means in terms of their vision can differ.
People with color blindness may:1
Confuse certain colors: For example, the color red may look the same as the color green.
Have difficulty seeing colors in certain light: Some people with mild color blindness can see colors normally in good light but not in dim light. Not see certain or any color no matter the light.
There are several different types of color blindness based on which cone (or cones) in the eye are affected. Each type affects color vision in a specific way.
Color blindness usually affects both eyes but can sometimes affect one eye, a condition referred to as unilateral color blindness or unilateral dichromacy. It is more often caused by an injury or disorder in later life and less likely to be the result of a congenital abnormality you are born with.
The most common type of color blindness is red-green color blindness which affects the ability to distinguish between red and green. It occurs in about one in 12 males and one in 200 females of northern European ancestry.4
There are four types of red-green color blindness: Protanomaly: This causes red colors to look green due to malfunctioning red cones. Protanopia: This causes red colors to look green due to nonfunctioning or missing red cones.