During childhood and adolescence, which is the period of physical growth and development, the size of the eye, i.e., the anterior-posterior axis of the eye, will also lengthen with age, and most myopia occurs during this period. Myopia will deepen when the eye axis is lengthened, and the eye axis will lengthen when the eye is often in a state of regulatory fatigue due to poor eye hygiene. Some people have calculated that the peak of myopia occurs between the second and fourth grade, that is, between the ages of 7 and 9.
Myopia causes
1. Genetic factors:
Myopia is a genetically related eye disease. Research on myopia genetics started early and there are many claims. For example, recessive inheritance, multi-factor inheritance, multi-factor inheritance for low myopia, single-factor inheritance for high myopia, autosomal dominant inheritance for simple myopia and a few pathological myopia, and recessive inheritance for most pathological myopia.
Children of myopic parents are more likely to develop myopia. The degree of inheritance of myopia increases with the degree of progression. Generally speaking, myopia below -3,00D has little to do with heredity; myopia between -3,00D and -6,00D is closely related to heredity; myopia above -6,00D is almost always related to heredity.
Some people have done a large number of family statistics, also called family lineage surveys, where both parents have myopia in the family, their children have myopia percentage is significantly higher than other family lines. Those with one parent with myopia had the middle child with myopia. Children of parents with no myopia have the lowest prevalence. In addition, the world’s highest prevalence of myopia in the yellow race, Southeast Asia, including China, the prevalence of myopia more than 40%, the Caucasian medium, while blacks, Eskimos myopia is rare, which indicates the role of genetic inheritance. Our experts have made a twin survey, twins suffer from myopia at the same time or not at the same time, that is, consistent rate, the results show that the twin consistent rate (myopia) than non-twins. Among the twins, identical twins have a higher myopia agreement rate than heterozygous twins, which also indicates that myopia is a hereditary disease. Experts have also calculated that genetic factors account for 65% of the causes of myopia through the formula.
In 2003, researchers from the United States and Germany presented a new idea at the 9th International Conference on Ophthalmology: the main cause of myopia should be genetic, and therefore gene therapy will be the direction of myopia treatment in the next 10 to 20 years. Animal models of myopia have been established for research purposes, and the range of myopia-causing genes is slowly narrowing, with at least 20 genes now confirmed to be involved in the formation of myopia.
2. Environmental factors
The most important of the environmental factors is the myopic load, followed by diet and nutrition. Myopic load includes excessive near eye use and prolonged near vision. Close reading distance, long duration, incorrect reading posture, watching TV or using computer for a long time can significantly increase the visual near load, which can cause changes such as eye muscle traction, eye collection strengthening, excessive ciliary muscle tension, eye pressure elevation, etc. Long-term eye congestion causes eye volume increase, sclera stretching, so that the eye development exceeds the normal proportion, finally leading to eye axis lengthening, myopia occurs. Studies have found that the prevalence of myopia among students who read for less than one hour a day is 27.7%, among students who read for one to three hours a day is 32.8%, and among students who read for longer hours a day is 34.6%.
Recent research data, however, indicate that many other factors are involved in the process of myopia.
Disease: A significant number of patients have suffered from infectious diseases such as measles and whooping cough. Most of these sick children have dilated eyes, and when the eyes are in a dilated state, the refractive power of the eyes decreases and the vision is weakened.
Noise: Research by experts shows that when the sound intensity is above 90 decibels, the sensitivity of the optic rod cells in the retina of the fundus to distinguish the brightness of light begins to decline, and the time to recognize the response to low light is prolonged; when it exceeds 45 decibels, 40% of people have dilated pupils, and when it reaches 115 decibels, the adaptability of the eyes to the brightness of light decreases by 20%, accompanied by a weakening of color vision.
Insufficient minerals: Medical research shows that calcium, chromium and other minerals are an important condition to ensure normal vision in children. Calcium has an irreplaceable role in maintaining normal pressure in the eye crystal and chromium in maintaining eye refraction. Special attention should be drawn to the fact that the processing of too fine rice, noodles, will lose 80% of the chromium, deliberately eat some coarse grains beneficial to the health of vision.
Eat too much sweets: sweets are acidic food, on the one hand, a large number of depletion of calcium elements in the body, on the other hand, elevated blood sugar, changing the crystal osmotic pressure, is another bane that leads to the formation of myopia, supervise children to eat less is better.
Passive smoking: German experts found that tobacco contains a more toxic cyanide, which accumulates in the body to a certain extent, can cause toxic amblyopia. And children’s eyes are in the developmental period, more sensitive to the harmful substances in tobacco.
Lack of sleep: 10-13 years old is the peak of myopic eye formation. If children of this age do not get enough sleep, sympathetic and parasympathetic nerve function is out of balance, resulting in disorders in the regulation of the ciliary muscle of the eye, so ensure that you get enough sleep for 9-11 hours every night to protect your eyesight.
Electronic game machine: electronic game machine has a considerable impact on vision. The flickering picture on the fluorescent screen increases the burden on the eyes, forcing the ciliary muscle to be highly tense, making the lens hyperflexic and increasing the refraction, which can lead to ciliary muscle spasm over time, which is also a major cause of myopia. In general, genetic factors are internal factors, which are prerequisites; environmental factors are external factors, which are conditions for myopia to occur.
Myopia prevention
1. Establish an eye care system and regular vision and eye examinations. Parents of myopic children should have their eyesight checked every six months after the age of 5 to detect early vision loss and pay close attention to the early manifestations of myopia.
2. Children must be trained from an early age in good hygiene habits. Cultivate their correct writing and reading posture, do not lie on the table or twist their bodies. Maintain proper reading distance, good lighting environment reading distance to maintain more than 30 centimeters, do not read in direct sunlight or in the dark, do not lie down, lying down or walking, reading when riding in the car also do not. Lighting light is best from the left rear of the head, to 60 ~ 100W light gun, or not flickering fluorescent lamps are available.
3. Avoid excessive use of eye power, and insist on looking far away every day: teach students to write, not too small and too dense, and not to write oblique and cursive characters. Do not spend too much time writing. When working at close range (such as operating a computer), you should take a break of 5-10 minutes every 30-45 minutes, and try to look away for 10 minutes during class breaks.
4, when doing homework in class to blink often, when you feel eye fatigue, you should rub your eyes with your hands or close your eyes for half a minute, which can help prevent myopia.
5, watch TV to maintain the appropriate distance. According to experts, the safe distance to watch TV should be seven times the diagonal length of the TV, less than this distance to the eye damage than in the safe distance will be 3 to 4 times larger. To the general family use of 36 to 42 inches color TV to count, watch TV safety distance should be at least between 5 meters to 7 meters. When watching TV, pay attention to the height of the TV set should be level with the line of sight. After 1 to 1,5 hours of continuous TV watching, there should be a short break (eyes far away).
6, adhere to do eye exercises, twice a day.
7, take enough nutrition: do not be partial food. Recent studies have shown that the lack of high sugar, high protein and certain micro factors may be related to the formation of myopia. Excessive consumption of sweets can contribute to the occurrence and development of myopia. Myopic patients have a significantly lower blood zinc/copper ratio than those with normal vision. The high prevalence of myopia in the Chinese population may be related to a cereal-based diet. These foods are high in phytic acid, which affects the absorption of zinc, and when zinc levels are insufficient, it affects the structure and function of the eye. Eat more foods containing vitamin A, such as lamb liver, pig liver, eggs, milk, carrots and vegetables.
Experts have confirmed that the occurrence of myopia is related to the low intake of a nutrient called “lutein”. Lutein is a “carotenoid”, which is found in high levels in fresh green vegetables and citrus fruits. Lutein has an important protective effect on the “macula” in the retina, and lack of lutein can easily cause macular degeneration and blurred vision. Rural children eat green vegetables and fruits directly from the ground every day, so the intake of lutein is very adequate. While urban children usually eat high protein, high nutrition food, rarely eat fresh green vegetables, so the lutein intake is correspondingly much less than that of rural children. This is the main reason for the huge difference in vision between urban and rural children. Therefore, students must not eat too fine or too fine in their diets, but should reasonably match their dietary structure, with “fine” in “coarse” and “fine” in The “coarse” in “coarse”.