What are the causes of myopia
summary
Myopia has many causes in eye diseases, and the harm to the eyes is also very serious. Therefore, friends need to clearly understand the knowledge of myopia, and they need to pay attention to the factors that cause myopia. Here, let's introduce the factors that cause myopia. Let's look down and introduce them to you.
What are the causes of myopia
One of the reasons: the eye distance is too close. The most common cause of juvenile myopia is long-term close eye distance. Teenagers have strong eye adjustment. When the distance between books and eyes reaches 7-10 cm, they can still see objects clearly. However, if they often read books at this distance, writing will make the adjustment of eyes extremely tense, which can form refractive (accommodative) myopia, the so-called pseudomyopia. If the long-term regulation is excessive, the ciliary muscle can not flex flexibly, and the effect of convergence is strengthened due to the excessive regulation, so that the extraocular muscles exert pressure on the eyeball, the intraocular pressure increases, and the intraocular tissue is congested. In addition, the young people's eyeball tissue is delicate, the eyeball wall is compressed and gradually extended, and the anterior and posterior axis of the eyeball becomes longer, which exceeds the normal value, and the axial myopia is formed, the so-called true myopia. The normal reading distance should be 30-35 cm.
The second reason is that it takes too long to use eyes. Some teenagers read, write, do homework, watch TV, etc. for 3-4 hours without rest, even go to bed late at night to rest, which not only affects their health, but also makes the eyes overburdened. The muscles inside and outside the eyes are in a state of tension for a long time and can not get rest. Over time, when looking at the distance, the muscles of the eyes can not relax and become spasmodic, which makes them feel fuzzy when looking at the distance And the formation of myopia. This is the reason why some students' eyesight drops obviously after a summer vacation. It is generally advocated that reading, writing or watching TV for 40-50 minutes should take a break or look at the distance for a while.
The third reason: the lighting is too strong or too weak. If the light is too strong, such as sunlight on writing, 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 not see the font clearly, the head will move forward and close to the book. In both cases, the eyes are easy to fatigue, and the eyes are over adjusted or spasmodic, resulting in myopia.
matters needing attention
Therefore, we should pay more attention to the causes of myopia, and let children know what causes myopia.
