colorblind
Introduction
Introduction to color blindness Congenital color vision disorder is usually called color blindness. It can't distinguish various colors or certain colors in the natural spectrum. However, if the color discrimination ability is poor, the color is weak. If the color is weak, you can see the color seen by normal people. However, the ability to recognize colors is slow or poor. When the light is dim, some are almost the same as color blindness or appear as color vision fatigue. The boundary between it and color blindness is generally difficult to distinguish strictly, but the degree of lightness is different. Color blindness and color weakness are more common in congenital factors. basic knowledge The proportion of sickness: 0.8% Susceptible people: no special people Mode of infection: non-infectious Complications: congenital nystagmus
Cause
Color blindness
Genetic (30%):
Because the patient does not have normal color discrimination ability since childhood, it is not easy to be found. It is generally believed that red and green blindness is determined by two pairs of genes on the X chromosome, namely the red blind gene and the green blind gene, because these two pairs of genes are on the X chromosome. Closely linked, so a gene symbol is often used to indicate that the red-green blind inheritance is X-linked recessive inheritance. The male has only one X chromosome, so only one color-blind gene is excellent blindness, and the female has two X chromosomes. Therefore, a pair of pathogenic alleles is required to be abnormal. A normal woman is married to a color-blind male. The father's color-blind gene can be transmitted to their daughter along with the X chromosome, and cannot be passed to the son. The daughter then passes the father. The color-blind gene that was passed to her son was called cross-genesis, and there were far more male patients than female patients.
Cell changes (20%):
The corresponding diseased organ is the eye, the detailed point is the retina, and then the cone is detailed.
Cone cell: The morphology of the cell is similar to that of the rod cell. The cell body of the cone is located in the outer part of the outer nuclear layer. The cell nucleus is larger and the staining is shallower. The cone is also divided into the inner and outer segments. Most of the discs are not separated from the cell membrane, and the top membrane disc does not fall off. The membrane disc is embedded with visual pigments that can sense strong light and color vision. It is continuously synthesized and supplemented by the inner segment. There are three kinds of cone cells in humans and most mammals. There are red-sensitive pigments, blue; blue-sensitive and green-sensitive pigments, which are also composed of 11-cis-retinal and opsin, but the structure of opsin is different from that of rod cells, such as lack of red light (or green light). The cone cells cannot distinguish the red (or green) color, and are red (or green) color blind. The end of the cone is swollen and full, and can be dendritic and horizontal with one or more bipolar cells. The cells form synapses.
There are about 120 million rod cells and 7 million cone cells in one eyeball. In the fovea of the macula, there are only cone cells, no rod cells, and there are rod cells at the edge of the fovea. In addition, the rod cells gradually increase, and the cone cells gradually decrease.
Prevention
Color blind prevention
Because color blindness and color weakness are hereditary diseases, they can be passed on to future generations. Therefore, it is an effective preventive measure to avoid the marriage of the close relatives and to investigate the genetic history of the other family before marriage and take measures to reduce the birth rate of the color-blind offspring. Promote prenatal and postnatal care, put an end to close relatives to marry, and do a good pre-marital physical examination to reduce the incidence of color blindness. At the same time, understanding the genetic pattern of color blindness is also an effective way to prevent color blindness in children. Eat more foods containing vitamin A! Foods containing vitamin A can prevent dryness and degeneration of the conjunctiva and cornea, and prevent and treat "dry eye disease". The cornea of the eye is dry and easily invaded by bacteria and can cause perforation, leading to blindness. Vitamin A also enhances the ability of the eye to adapt to the dark environment. It is prone to night blindness when vitamin A is severely deficient.
Complication
Color blind complications Complications congenital nystagmus
Because red and green blind patients can not distinguish between red and green, it is not suitable for art, textile, printing and dyeing, chemical and other color sensitive work.
Drivers must not be red-green and blind, because people with red-green blinds cannot correctly identify traffic command signals, traffic signs, and the color of lights (braking, steering) of vehicles in front; weak people at dusk and night The lights that flash in various colors are also indistinguishable from red or green, which can easily lead to traffic accidents.
Symptom
Symptoms of color blindness Common symptoms Red blind phobia green weak blue yellow weak blind blue yellow blind green blind eye tremor night blind
Color blindness is divided into full color blindness and partial color blindness (red blindness, green blindness, blue-yellow blindness, etc.), and color weakness includes full color weakness and partial color weakness (red weak, green weak, blue yellow weak, etc.).
Full color blindness
It belongs to complete cone dysfunction, which is the opposite of night blindness (rod cell dysfunction). The patient is especially dark, photophobic, and manifested as blindness. The colorful world is gray in his eyes, just like watching black and white TV. There are light and dark points, and there is no color difference, and the red color is dark and the blue light is bright. In addition, there are symptoms such as poor vision, amblyopia, central dark spots, oscillating nystagmus, etc. It is the most serious one in color vision disorder. Kind, patients are less common.
2. Red blindness
Also known as the first color blindness, the patient can not distinguish red, red and dark green, blue and purple and purple can not be distinguished, often see green as yellow, purple as blue, green and blue mixed white There was a middle-aged man who had a heavy weight and bought a gray sweater. After wearing it, he was ridiculed. He was a red-blind patient. He was mistaken red for gray. He had reported in his early years that a red blind patient was a train driver. The train collided because of the wrong signal.
3. Green blindness
Also known as the second color blindness, the patient can't distinguish between light green and deep red, purple and blue, purple and gray, and green as gray or dark black. There is a well-painted child in an art training class. Always paint the sun in green, the crown, the grass is painted brown, it turns out that he is a green blind patient, the clinical red and green blinds are called red and green blind, patients are more common, we usually say color blindness generally refers to red and green Color blindness.
4. Blue and yellow blind
Also known as the third color blindness, the patient's blue-yellow color is unclear, and it is less visible to red and green.
5. Full color weak
Also known as red, green, blue and yellow, its color vision disorder is lower than full color blindness, there is no abnormality in visual acuity, and there are no other complications of full color blindness. When the object is dark and vivid, it can be distinguished; if the color is light and not saturated When it is difficult to distinguish, patients are rare.
6. Partially weak
There are red weak (first color weak), green weak (second color weak) and blue yellow weak (third color weak), among which red and green are weaker, patients are red, green is poor, and when lighting is poor, The color ability is close to red-green blindness; but when the material color is dark, clear and the illumination is good, its color discrimination ability is close to normal.
Examine
Color blind inspection
Color blind (weak) patients are born with no correct color discrimination ability, and think that others are the same as themselves, so they can not be consciously sick, and many color blind patients have no abnormal findings in eye examination.
How to determine color blindness and color weakness? Color blindness and color weakness are mostly checked by subjective inspection, generally in brighter natural light. The commonly used inspection methods are as follows.
False color map : usually called color blind book, it uses the same shades of color and different colors to form numbers or figures. It is read at a distance of 0.5m under natural light. The color blindness should be corrected when checking. For more than 5 seconds, the color vision disorder is difficult to identify, misread or cannot be read, and it can be confirmed according to the color blindness table.
Color wire harness test : It is a mixture of different color and different shades of wool, so that the examinee picks out the same color as the standard harness. This method is time consuming and can only be qualitatively and cannot be quantified. It is not suitable for large areas. Screening check.
Color Mixing Tester : It is a kind of spectrometer designed by nagel based on the principle of red + green = yellow. It can quantitatively record the amount of red and green light matching to determine the red and green anomaly. This method can be qualitative. It can be quantified.
Diagnosis
Color blind diagnosis
diagnosis
If the symptoms and test results are clear, no differential diagnosis is required.
Color blindness and color weakness
Color blindness can not distinguish between various colors or certain colors in the natural spectrum; while the difference in color discrimination is called weak color, the boundary between it and color blindness is generally difficult to distinguish strictly, but the degree of lightness is different, and the color weakness includes full color weakness. Partial color is weak (red is weak, green is weak, blue and yellow is weak, etc.), and color blindness is divided into full color blindness and partial color blindness (red blindness, green blindness, blue-yellow blindness, etc.).
