Myopia has become a household word today, especially among teenagers, one out of every two to three people is myopic, which shows how closely myopia is related to us. So what is myopia all about? Some people say that myopia means to look at things close up, while others say that myopia means squinting to see. In fact, these statements are incomplete and only describe the phenomenon of myopia, but do not reveal the essence of myopia. To figure out what myopia is all about, we must first understand the structure of our eyes, the windows of our minds. The main part of our eyes that we use to see things is the eyeball. The structure of the eye is like a camera, which includes the lens DD cornea, aperture DD pupil, focusing device DD lens, air DD vitreous, negative DD retina, dark box DD eye wall and other major parts, the refractive system of the eye is equivalent to the lens of the camera, focusing device and air, the length of the eye is equivalent to the length of the dark box. To take a clear picture, the camera must make the light pass smoothly through the lens, aperture, focusing device, air and finally focus on the negative; and the eye to see external objects clearly, it must also ensure that the light passes through the transparent cornea, lens, vitreous humor and other refractive interstitial, accurately focused on the retina. If the focal point is located on the retina, it is called orthoptic eye, and the object seen at this time is the clearest; if the focal point falls behind the retina, it is called hyperopic eye, and in front of the retina, it is called myopic eye, and in both cases the light forms a diffuse aperture on the retina, so it cannot form sharp vision. We now know that myopia is caused by the refractive system of the eye focusing light in front of the retina, and there are only two reasons for this: one is that the length of the eye is too long for the normal refractive system to focus light on the retina; the other is that the length of the eye is normal, but the refractive power of the refractive system is too strong to cause light to come into focus before it reaches the retina. In short, it is the result of a mismatch between the length of the eye and the refractive power. The vast majority of myopic eyes fall into the former category, called axial myopia. The longer the length of the eye, the deeper the myopia. Thus, a normal human eye is round and spherical, while a myopic eye, especially a highly myopic eye, has an oblong eye, like a rugby ball. The length of the eyeball can be measured in the hospital with a special instrument. The length of a normal human eye is 22 to 24 mm, and every 1 mm increase in the length of the eye is equivalent to a 300 degree increase in myopia. The latter condition is called refractive myopia and is seen in diseases such as cone cornea, spherical lens and senile cataract, all as a result of increased refractive power of the cornea or lens due to various causes. When children are found to have myopia, parents always ask anxiously, “Is this true myopia, or is it pseudomyopia?” Some parents may think that myopia is always pseudomyopia at first, and that it will become true myopia over time. Is this really the case? Let’s first figure out what pseudomyopia is. Here we now introduce a very important function of the eye, DD regulation function. In normal eyes, when looking at an object at infinity, the light is focused on the retina, but when looking at a near object, the light is focused on the retina, at this time the ciliary muscle-lens adjustment system in the eye should play its adjustment zoom function, the ciliary muscle contraction, so that the lens becomes convex, increasing the refractive power, so that the focus is shifted forward, thus ensuring that the eye is able to focus when looking at the near. The ciliary muscle contracts, causing the lens to become more convex, increasing the refractive power and shifting the focus forward, thus ensuring that the eye is able to focus on the retina when looking at the near; then the ciliary muscle relaxes when looking away. This ability to adjust the focal distance when looking close is the eye’s regulation function, which relies on the automatic contraction and relaxation of the ciliary muscle. Children’s adjustment function is particularly strong, if they do long time to read, write and other close work, the ciliary muscle will always keep contracted work state can not get rest, time ciliary muscle want to relax also can not relax down, that is, adjustment spasm. When looking at a distance, the ciliary muscle is still tense and the refractive power of the lens is still very strong, so the focus of distant objects falls in front of the retina, resulting in so-called pseudomyopia. Pseudomyopia can be recovered, as long as the ciliary muscle has enough rest time to recover from “fatigue”, it can regain its ability to contract and relax automatically, thus ensuring that the lens has a different refractive power when looking at distance and near, so that distant and near objects can be focused on the retina. Therefore, when children find that their vision is declining, they should not rush to wear glasses, but should go to the hospital to rule out pseudomyopia. The doctor will use drugs such as atropine or bixin to relax the ciliary muscle before the eye test, at which point the myopia detected is true myopia. Through the above introduction, you should have an understanding of the nature of myopia, in fact, myopia is not terrible, as long as you pay attention to eye hygiene, avoid long hours of close work, there is a certain degree of prevention. Even if you have myopia, there is no need to worry, people have come up with many ways to treat myopia, such as OK lenses, excimer laser, etc. have achieved very good results.