We have repeatedly stressed the need to protect children's vision, the main measure is to improve the lighting of classrooms and libraries. Parents buy the best table lamps for their children and improve their nutrition. The result is more and more myopia.
More than 30 years ago, primary and secondary school students wore very few glasses, especially in the countryside, where glasses were rare. Today, there are still fewer children wearing glasses in the country. According to statistics, the proportion of middle school students in urban myopia is 4 to 5 times that of rural areas.
There are many children with myopia in the city. One of the reasons is that the lighting conditions are too good.
When analyzing rural children with less myopia, many people will come down to learning, short reading time, and low work pressure. Of course, this is the reason for one side. However, when those children who had studied hard under the oil lamp for many years, why did they have improved their lighting conditions at night after going to college, but they put on their glasses? In the past few years, I heard from an old man from the countryside that the cityâ€™s myopia is mostly Because the light is too bright. At that time, I only thought that this made sense, but I could not tell the reason.
Once upon a time, we repeatedly emphasized the need to protect children's vision. The main measure is to improve the lighting of classrooms and libraries. Parents buy the best table lamps for their children and improve their nutrition. The result is more and more myopia. Now we know that the desk lamp is a sight killer. The old man from the country is right. There are many children with myopia in the city. One of the reasons is that the lighting conditions are very good.
Why is it not easy to be nearsighted when the lighting is dim?
Let us first see why it is nearsighted. When looking at a close object, if it is not adjusted, the object is imaged behind the retina, of course, it is not clear. At this time, by shrinking the ciliary muscle, the diopter of the lens is increased, and the object can be imaged onto the retina, which can be seen clearly. However, if you look at the near object for a long time, the ciliary muscles will contract frequently and you will not get a rest, which will cause the anteroposterior diameter of the eyeball to gradually become longer. In this way, the contraction of the ciliary muscle is less needed, and the object can be imaged on the retina, making it easy to see objects at close range. However, the axis of the eye is elongated. When looking at the distant object, the imaging is in front of the retina, and the eye muscles cannot be adjusted. The diopter of the eye can only be corrected by wearing glasses, so that the distant object can be imaged on the retina. It can be seen that the essence of myopia is the adaptive response of the eye axis to long-term close objects. This elongation can not be reversed, or there is no condition of reversal, such as people can not engage in close-range study and work for a long time.
Why is it difficult to have nearsightedness when the light is dark? There is a phenomenon called night myopia, which means that the vision is clear during the day, but it is necessary to wear a myopia at night. The reason is that there is a difference in refractive at night, and the imaging of the object is partial.
Experiments have shown that keeping monkeys in a dark house can cause the monkey to be farsighted. Therefore, in the darker light, the object is imaged earlier than the light under the bright table lamp, and the light is brighter and backward. In this way, when the light is bright, the elongation of the eye shaft naturally adapts to the reaction.
How to prevent myopia in children?
First of all, home lighting should not be too bright. Children's books and homework are generally large, and it should not be a problem to see clearly. In addition, after studying for a while at night, you have to go outside for a while. Activity in darker light is a good adjustment to vision. The worst situation is that under a bright table lamp, reading a novel for a few days and nights, so that in a few days, it is impossible to wear glasses.
Editor: Li Jie
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