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People with normal vision can distinguish about 160 different shades, but the colorblind find it difficult even to distinguish the bright primary colors from each other.

Color blindness does not mean a blindess to color, but a confusion as to what color is since certain colors such as green, yellow, orange, brown and red are seen as identical. The condition is sometimes also referred to as defective color vision and affects more men than women.

At the back of the eye there are special nerve cells which allow us to see intricate details and colors in daylight. They receive and process light, sending color messages to the brain. Within each cell there are three different chemicals enabling it to respond to blue, red or green light. Color blindness is normally due to a fault in one of these sets of chemicals. The type of color deficiency depends on which group is defective and how severely. The most common is in the red-green spectrum. It is much rarer to have a deficiency in the blue region or to see the world in black and white.

In most cases color blindress is inherited and passed down through the male line. A female can only inherit defective color vision if her father is affected and her mother is a carrier or is herself colorblind. In rarer cases color blindness is developed after using certain drugs or after suffering from certain conditions such as eye disorders, liver diseases or diabetes. When color blindness is not inherited the condition may improve with treatment.