Causes of myopia? More than visual fatigue!

Abstract: when it comes to myopia, many people will think that it is caused by unreasonable use of eyes, such as staring at books for a long time or reading too close to books. In fact, the causes of myopia are not only these, but also different from different angles., When it comes to myopia, many people will think that it is caused by unreasonable use of eyes, such as staring at books for a long time or reading too close to books. In fact, the causes of myopia are not only these, but also different from different angles.      1. Internal causes (1) genetic factors: myopia has a certain genetic tendency, especially for high myopia. But for general myopia, this tendency is not very obvious. Those with genetic factors had earlier onset age, mostly above 6.00D. But there are also high myopia without family history. High myopia belongs to autosomal recessive inheritance, and general myopia belongs to multifactorial genetic disease. (2) developmental factors: infants are hyperopia because their eyeballs are small, but with the increase of age, the ocular axis also gradually lengthens, and their development is normal until puberty. If overgrowth, myopia will be formed. This kind of myopia is called simple myopia, which mostly starts in school age. Generally lower than 6.00D. Development stops around the age of 20. If it progresses quickly in childhood, it will progress faster at the age of 15 ~ 20, and then slow down. This kind of myopia is often higher than 6.00D, and can reach 20d ~ 25d or 30d. This kind of myopia is called high myopia or progressive myopia or pathological myopia. Such myopia can occur and degenerate in old age, so vision can gradually decline, and vision can not be corrected with glasses. Very few have myopia at birth, but very few are congenital.   2. External factors, i.e. environmental factors (1) too close eye distance according to relevant data reports, juvenile myopia is often caused by too close eye distance for a long time. Teenagers have strong eye adjustment. They can still see objects when the distance between books and eyes is up to 7-10 cm. However, if they often read at this distance, writing will make the adjustment of eyes extremely tense, which can form refractive (regulatory) myopia, the so-called pseudomyopia. If the long-term adjustment is excessive, the ciliary muscle can not stretch flexibly. Due to the excessive adjustment, the convergence effect is strengthened, so that the extraocular muscle exerts pressure on the eyeball, the intraocular pressure increases, and the intraocular tissue is congested. In addition, the juvenile eyeball tissue is delicate, the eyeball wall is compressed and gradually extends, and the front and rear axes of the eyeball become longer, exceeding the normal value, axial myopia is formed, The so-called true myopia. The normal reading distance should be 30-35 cm. (2) eye use time is too long. Some teenagers read, write, do homework and watch TV for 3-4 hours without rest, and even go to bed late at night. This not only affects their health, but also overburdens their eyes. Their internal and external muscles are tense for a long time without rest. Over time, when they look at the distance, The muscles of the eyes cannot be relaxed and are in a spasmodic state. In this way, they feel blurred at a distance and form myopia. This is why some students’ eyesight drops significantly after a summer vacation. It is generally advocated that you should take a break or look into the distance for 40-50 minutes of continuous reading, writing or watching TV. (3) the lighting light is too strong or too weak. If the light is too strong, such as sunlight, it will cause strong reflection, stimulate the eyes, make the eyes uncomfortable, and it is difficult to see the font. On the contrary, if the light is too weak, the written lighting is insufficient, and the eyes can’t see the font clearly, the head will move forward and close to the book. In both cases, the eyes are easy to fatigue, Myopia is caused by excessive adjustment or spasm of the eyes. (4) read while driving or walking. Some teenagers make full use of their time to read while walking or in the walking carriage, which is very harmful to their eyes. Because the carriage is shaking and the body is shaking, the distance between eyes and books cannot be fixed, and the poor lighting conditions aggravate the burden on eyes. Often this may cause myopia. Many teenagers like to read in bed, which is a bad habit. Because people’s eyes should keep reading in a horizontal state, so as to make the adjustment consistent with the collection (convergence) and reduce eye fatigue. If you lie down to read, your eyes are not in the horizontal state, the distance between your eyes and the book is inconsistent, the line of sight of your eyes is inconsistent up, down, left and right, and the illumination on the book is uneven, which will make the adjustment of your eyes nervous, and it is easy to move the book close to your eyes, which can increase the burden on your eyes by 2-3 times and form myopia over time. (6) lack of sleep: when the sleep is insufficient, the next day is depressed, dizzy, the brain does not have enough rest, fatigue is not eliminated, increasing the burden on the eyes and promoting the occurrence of myopia. Lack of sleep is a very important cause of myopia. (7) the desk does not meet the requirements, and the writing posture is incorrect. If the desk and chair are too low, the head will lean forward, the spine will be bent, the chest will be compressed, and the eye adjustment will be relatively tight. Or the tables and chairs are too high, the feet are suspended, the lower limbs are easy to swing, and the correct posture can not be maintained, which can cause eye fatigue, and myopia is easy to occur over time. (8) at present, the impact of space radiation} often watch TV, especially in rural areas with insufficient signal and low reception rate. There is no common antenna, the screen is not clear, and there are many snowflakes, which is easy to fatigue the eye muscles. Students who often play video games are more likely to damage their eyesight. The little overlord learning machines sold in shopping malls can directly cause students’ myopia, Nowadays, computer is an indispensable course. Too long operation causes eye dryness and fatigue, which is easy to cause myopia. The use time should be properly controlled. These are the causes of myopia. If you do more of these things, you will become myopia. Protect our eyes.