According to the trichromatic theory, those who can't tell red are red blind, those who can't tell green are green blind, those who can't tell blue are blue blind, and those who can't tell three colors are color blind. Some people can distinguish all colors, but their ability to distinguish them is slow, or they can only recognize them after repeated consideration. This kind of people are weak in color, which shows that their ability to distinguish colors is weakened. Color blindness and color weakness are both congenital genetic diseases, and there is no effective treatment so far.
Color blindness can be divided into congenital color blindness and acquired color blindness. Congenital color blindness is a sex-linked inheritance, with more males than females, normal binocular vision and abnormal color vision. Patients often feel that color discrimination is not difficult, but it is discovered during the examination. Acquired color blindness is often secondary to some fundus diseases, such as some optic nerve and retinal diseases. Monocular color vision disorder is seen in central retinal degeneration or optic neuropathy, which has obvious visual involvement and corresponding color vision involvement. Drug poisoning can also cause binocular color vision disorder. Refractive opacity such as corneal leukoplakia and cataract can lead to low color vision.
The rate of male color blindness in China is 4.7 1+_0.074%.
The female color blindness rate in China is 0.67+-0.036%.
Frequency of color blindness gene carriers in China: 8.98%.
First, the colors of light and objects.
Sunlight is composed of a large number of electromagnetic waves with different wavelengths. The wavelength range of electromagnetic wave is very wide, but human eyes can only see the light with the wavelength of 800~400nm (usually 780~380nm), so the spectrum formed by the wavelength within this range is called visible spectrum. The simplest experiment is to let a beam of sunlight pass through a prism, and the light will bend into a colored light band, that is, a spectrum. It consists of seven colors: red, orange, yellow, green, cyan, blue and purple. Among them, the red light with the longest wavelength is at one end of this visible spectrum; The shortest is violet light, at the other end of the visible spectrum. The wavelengths of them and other colors of light are roughly as follows:
colour
Wavelength (nm)
red lantern
750~630
Orange light
630~600
Yellow light
600~570
permit
570~490
Cyan light
490~460
blue
460~430
purple light
430~380
The parts other than red light and purple light actually have a "spectrum", but the human eye can't recognize it. The wavelength range of the visible spectrum visible to human eyes varies from person to person, and also from light intensity to light intensity.
In the spectrum, from the red end to the purple end, various intermediate colors can be seen in the middle band (region) of two adjacent wavelength ranges, such as orange-red between red and orange; The one between green and yellow is called green and yellow; Something between blue and green is called blue and green. People's vision recognizes wavelength changes differently, because different wavelengths have different light intensities. In some parts of the spectrum, we can see the difference by changing the wavelength of 1nm. However, in most cases, the change should exceed a few nanometers to see its change. The human eye can recognize about one hundred different colors.
The color of an object is determined by the wavelength of reflected light or transmitted light. For example, when sunlight (white light) shines on an object, the surface of the object reflects part of the light and absorbs other parts. If the reflected light is red and absorbs colors such as yellow, orange, green and cyan, then we think the object is red. Another example is that the reflected light is green and the object is green. Because the light reflected by an object is often not a single wavelength, there are many colors of the object.
Transparent objects are a little different, because when they are illuminated by white light, they reflect less, mainly absorbing and transmitting light, and their color is determined by the wavelength of transmitted light. For example, red glass mainly transmits red light, so we think it is red glass.
Second, color vision theory
The human eye can not only recognize the shape and size of objects, but also distinguish various colors. This ability to distinguish colors is called color vision, commonly known as color vision. Its theory mainly includes three-color theory of Yang-Helmholtz and four-color theory of Herring.
Young-Helmhotzr tricolor theory means that Young can produce various colors according to the proper mixture of red, green and blue primary colors, thus inferring that the elements with three colors on the retina are red elements sensitive to red light, green elements sensitive to green light and blue elements sensitive to blue light, and all elements are stimulated by certain colors to form color vision. In 1860, he added that the color-sensitive elements on the retina can not only accept the stimulation of a certain color, but also accept other colors to some extent. Therefore, it is not difficult to understand the color perception when one of the three elements is missing: for example, a person who lacks red element can't feel red light, but this red light can also stimulate green and blue elements, so this person will mistake red for other colors, but the green that this person feels is not the green that normal people feel, because green light not only stimulates green elements, but also stimulates red and blue elements, and this person lacks red elements, so the green he feels is different from the green that normal people feel. It is not difficult to understand why it is difficult for the red blind to correctly identify green, and it is difficult for the green blind to correctly identify red. Therefore, red blindness and green blindness are often called "red-green color blindness". Of course, people who turn a blind eye to red or green have some difficulties in correctly identifying blue. At first, tricolor theory was a hypothesis, but after the research of various scholars in recent years, it gradually formed a theory based on anatomy, histology and physiology.
There are two kinds of visual cells in human retina, namely rod cells and pyramidal cells. The former works in dark light, which is called dark vision; The latter works under strong light and can distinguish between vision and color. There are 65438+ billion rod cells distributed outside the fovea, and the more around, there are no rod cells in the real fovea. There are more than 6 million pyramidal cells, mainly distributed in the macula, the most sensitive part of the retina. The more in the center, the more pyramidal cells without rod cells in the real fovea. Due to the different distribution of visual cells, different regions of retina have different color sensitivity. Normal color vision can distinguish various colors in the central part of the retina, and the color power in the peripheral part gradually weakens or even disappears.
According to the experimental report, rod protein exists in the outer segment of rod cells, and its spectral absorption curve is completely consistent with the visual acuity of dark vision. This shows that the photosensitive substance (pigment) for dark vision of human eyes is rhodopsin, which can bleach light with wavelength of 385-670nm and is most sensitive to light with wavelength of 502nm.
The photosensitive substance of pyramidal cells also exists in the outer segment. Wald( 1937) suggested that an iodophor in chicken retina was the most sensitive to 560nm light. The experiments of Wald, Brown and Macnichol also proved that one kind of pyramidal cells in retina is most sensitive to red, one to green and the other to blue. Tomita et al. recorded the electrical response of fish single pyramidal cells with microelectrodes, and found that red pyramidal cells responded to 6 1 1nm, green pyramidal cells to 529nm and blue pyramidal cells to 462nm. Mark identified three kinds of pyramidal cells in primate retina. Rushton and others also found different spectral absorption curves of red and green pyramidal cells. Liu Yumin and others in China have confirmed the existence of the above three sensory substances in the outer segment of pyramidal cells. The experimenters of many scholars above strongly support the trichromatic light theory.
The four-color theory of Hrting was founded by Hrting( 1878). Suppose there are three kinds of pigments in the retina, namely red pigment-green pigment, yellow pigment-blue pigment and melanin-white pigment. These three substances decompose and synthesize after being stimulated by light, forming a sense of color and a sense of black and white in achromatic color.
Although the above two theories have coexisted for a long time, the trichromatic light theory is dominant, because it perfectly explains the mixing of the three primary colors, so it has been supported by mathematicians.
In modern times, according to the experiments of Svaetichin and Devaloes in studying the retinal and optic nerve conduction pathways of primates and fish animals, it was found that there is a cell that responds to all wavelengths of light in the spectrum, and the response is strongest at 575nm. According to this experiment, it is considered that this kind of cells have four vision, while the other kind of cells (bipolar cells and ganglion cells) and lateral geniculate cells are positive for red light and negative for green light. Other cells react positively to yellow light and negatively to blue light. Therefore, it can be inferred that there are three reactions in the nervous system, namely, ① light reaction, red-green reaction and ③ yellow-blue reaction. The last two pairs of reactions, red+green-(red excites green inhibition) and yellow+blue-(yellow excites blue inhibition), are exactly in line with Herring's four-color substance, which provides experimental basis for the four-color theory. Modern scholars synthesize the above two theories and imagine that the process of color vision can be divided into two stages (the second stage is also the information processing stage):
The first stage: there are three independent color-sensitive substances (pigments) or three pyramidal cells in the retina, each of which selectively absorbs the effects of various colors of light in the spectrum and produces black-and-white reaction at the same time: that is, it produces white reaction under strong light; In the absence of light stimulation, a black reaction will occur.
In the second stage, the pyramidal receptors are reorganized (that is, information processing) in the process of transmitting to the visual center, and finally three pairs of opposing nerve reactions are formed, that is, red-green, yellow-blue and black-white reactions are introduced into the visual center, resulting in four colors of red-green-yellow-blue and black-and-white feelings. This is the so-called modern stage theory, which accords with the three colors of Yang-Helmholtz and Herring.
Third, color blindness and color weakness
People with normal color vision can distinguish the red, orange, yellow, green, cyan, blue and purple colors of the solar spectrum, and even distinguish the colorful colors in the universe in the light. But people with abnormal color vision can't feel these shades more or less. This is the so-called color vision abnormality (color vision disorder), which is customarily called "color blindness". Color blindness can be divided into congenital color blindness and acquired color blindness.
The difference between congenital color blindness and acquired color blindness is that the former is a hereditary eye disease, and the mother has it since birth. The latter is a person with normal color vision. Because some fundus diseases, such as acute and chronic optic neuritis, optic atrophy or macular degeneration, glaucoma and other eye diseases, patients have color vision disorders, accompanied by visual impairment and central scotoma, and this color vision abnormality is often temporary, that is, temporary color blindness occurs during the course of the disease. Once the disease is cured, the central scotoma disappears and the color vision disorder disappears.
Rod monochromator: congenital complete color blindness, unable to distinguish colors. Seeing an object only feels black, white and gray, just like normal people watching black-and-white photos and black-and-white TV. This kind of color blindness is called color blindness, which can be divided into rod monochromaticity and cone monochromaticity. There is only one case in the population of 65438+ 10,000 ~ 200,000, which is rare.
Dichroism: color blindness or partial color blindness. Their eyesight is as good as normal people, but they can't recognize some colors. Among them, it can be divided into red blindness, green blindness and purple blindness (cyan blindness).
Red blindness cannot see the red light in the spectrum. In their view, if the red end of the spectrum is missing, the spectrum will be shortened by one section, and only the yellow to blue section can be seen, and the brightness of the spectrum is different from that of normal people: the brightest part seen by normal people is in the yellow section (wavelength is about 589nm), and the brightest part seen by red-blind people is in the yellow-green section, and there is an achromatic part ("center point") in the spectrum.
The main mistake of red-blind people in seeing colors is that they can't tell light red from dark green, blue-green from deep red (purple, which is not in the spectrum) from purple, and the most easily confused ones are red from dark green, blue from purple.
The spectrum of green blindness is not shortened by a section like that of red blindness, but the brightest part of the spectrum is in the orange part, and the center point is about 500nm. All spectra are light yellow, gray and blue. Green blindness can't tell light green from deep red, purple from cyan. Although magenta and cyan are not confused, they are confused with magenta and gray.
Purple blindness, also known as cyan blindness, is extremely rare in dichroism. They saw that the spectrum was shortened at the purple end. The brightest part of the spectrum is in the yellow part, and there are two upper center points in the spectrum: one in the yellow part (wavelength is about 580nm) and the other in the blue part (wavelength is 470nm). They seem to have only two shades of red and blue, and they can't tell yellow-green from blue-green, and they can't tell magenta from orange.
Abnormal color vision: it is also weak color, green, purple (or cyan), which are the lightest color vision disorders.
Attachment: Spectrum seen by normal people, red blindness and green blindness.