What is color blindness?
There are a certain number of people in every hundred whose eyes seem to be perfect except in color seeing. One doctor has discovered that one person out of every fifty-five cannot tell red.from green. One in sixty confuses brown and green. Pink and yellow look alike to some people, and blue and green to others. To a very few people everything looks to be black and white. The cause of color blindness is thought to lie in the nerve fibres in the retina, or screen at the back of the eye, on which pictures are thrown. Three nerve fibres are supposed to give sensations of red, green and violet Orange, yellow and blue are seen by combinations of sensations. Now one of these fibres, most often the red, may be non-sensitive. That person will not see red at all. White to him appears bluish-green, with the red rays in the white absent. Violet looks blue, orange yellow. In some cases there may be a total absence or paralysis of a nerve fibre sensitive to a certain color. But in a great many case
Color Blindness, or Color Vision Deficiency, is an eye condition where a person is not able to distinguish certain colors or shades of colors to some degree. Color Blindness does not mean that a person can only see black and white. A person with color blindness is able to see different colors, however they are not able to see some colors due to deficiencies in the eyes. Color blindness is a hereditary condition but can also be caused by eye diseases, damage to the retina and macula, and aging or when the lens is darkened over time from a cataract. Although there is no absolute treatment for hereditary color blindness, there are methods, techniques, and special glasses that may help people with color blindness differentiate different colors but not truly see them. If you have extreme trouble distinguishing the numbers in one of the pictures below or are not able to see them at all, then you may have some degree of color blindness.
Color blindness results from an absence or malfunction of certain color-sensitive cells in the retina. The retina is the nerve layer at the back of the eye that converts light into nerve signals that are sent to the brain. A person with color blindness has trouble seeing red, green, blue, or mixtures of these colors. Normally, the eye has three types of cone cells, which are light-sensitive cells that are located in the retina. Each type is sensitive to either red, green, or blue light. You see color when your cone cells sense different amounts of these three basic colors. When one or more of these types of cone cells is absent or fails to function properly, you may not see one of these three colors or you may see a variation of that color or a different color. Cone cells are concentrated mostly in the central part of the retina (the macula) to provide clear, sharp color vision. They work best in relatively bright light, so it is difficult to see colors in dim light. See a picture of t
Color vision is pretty complicated. If you’re not color-deficient or color-blind then it’s hard to understand what color-blind people see. There are four kinds of color vision: Trichromat Regular vision is Trichromatic – it uses all three colour pigments (red/green/blue). Anomalous Trichromat People with Anomalous Trichromatic vision use all three color receptors but reception of one pigment is misaligned. Protanomaly: reduced red sensitivity. Deuteranomaly: reduced green sensitivity. Tritanomaly: reduced blue sensitivity. Dichromat People with Dichromatic vision use only 2 of the 3 visual pigments – red, green or blue is missing. Protanopia: unable to receive red. Deuteranopia: unable to receive green. Tritanopia: unable to receive blue. Monochromat (Achromatopsia) People with Monochromatic vision can only see one color, so their vision contains no ‘color’. Typical Monochromatic: unable to combine colors. Fully grayscale. Also known as Rod Monochromat. Atypical Monochromatic: very low
Color blindness, more accurately called color deficiency, is a term used for a deficiency in recognizing certain colors. Most color perception defects are for red or green or both. Another form of color blindness; yellow-blue is the second most common form, but it is rare and could be a result of some optic nerve disease. Complete color deficiency, where all colors are seen as varying shades of black and white is almost unknown. About 10% of males have a color perception defect, but this is rare in females.
