Most people have a system in their eyes to perceive different colors, this system consists of three types of, so-called, cones in the retina: each cone is responsible for the perception of blue, red and green; other colors are then produced by mixing the blue, green and red light. Our brain receives signals delivered by these cones, compares them and thus is able to perceive a wide range of visible colors. In case of colorblind people, they mismatch colors from this visible spectrum to varying degrees, depending on the type and severity of their color blindness.
Complete color blindness, the achromatopsia, considerably limits the ability of those who are affected, because they recognize only grayscales, and are able to see glare-free only during dawn. In their cases, all three types of cones are functionless, and they can only see with the help of other light sensory cells, the rods.
Most of the colorblind people, on the other hand, have only one or two types of cones that do not work or work with limited functions. Thereby, they can distinguish a smaller spectrum of colors, or they easily confuse colors; as a result, they see colors differently compared to those with a normal sight – even though they use the same names to call the colors.
Color blindness, or color vision deficiency, can be genetically preconditioned, inherited, or acquired, for example, through cataract, tumor or age-induced macular degeneration (AMD). Colorblind people often do not notice their visual limitations for a long time, since they´ve got used to the way they see the colors and the world.
Possible solutions of colorblindness
Special glasses cannot completely solve the problem of colorblindness, but in some situations, these glasses can help the colorblind people to perceive certain colors better. Filter lenses of these glasses cannot add anything to the light which is reflected by an object (the light is then perceived by brain as a specific color depending on the wavelength). Instead, they “swallow” part of this light and thus part of the color spectrum.
Even though despite the filter, the retina of a colorblind person can still only receive two signals instead of three, the filter glasses make these signals arrive in the eyes in a different way. Thus, the color looks more like another color, which is easier for the colorblind person to recognize, or the color gets more luminosity.
Whether this kind of glasses helps or not depends on the combination of the item color and its surrounding background colors.
If a person wears special glasses and looks at an arrangement of different fruits and vegetables, for this person, red apples and red peppers appear with a brighter orange color and are easier to be distinguished from other fruits. But If this person then looks at plants with similar colors, no color differences will be noticed. Thus, whether special glasses with filter lenses can support a colorblind person in his/her color perception depends on the situation. Unfortunately, these special glasses are incapable of letting colorblind person recognizes a color in way a person with normal vision does.
Source: Translated from https://www.1xo.de/