The cause of myopia may be,
The curvature radius of corneal and lens refraction surface is too small, the focal power is too large, and the deflection of Zhi light is too strong (this is called refractive myopia);
Or the anteroposterior diameter of the eyeball is too long (this is called axial myopia).
In addition to a small number of high myopia and genetic related, the occurrence of common myopia is usually due to not paying attention to eye hygiene.
Formation factors of myopia
Myopia has a certain genetic tendency, especially for high myopia. The heritability of myopia in both parents was higher than that in one parent. But for general myopia, this tendency is not very obvious. The patients with genetic factors were older than 6.00D.
Because of the small eyeballs of infants, they are hyperopia. With the growth of age, the axial length of the eye is gradually lengthened, and the development is normal until puberty. This is the process of emmetropia of the eyes. For example, in this process, due to the influence of various factors (such as light intensity, long time of using eyes at close range, etc.), the eyes may receive various abnormal visual experiences or excessive eye fatigue As a result, the eyeball is over developed and the axial length of the eye increases, which leads to myopia.
Compared with genetic factors, scientists believe that environmental factors play a greater role in the occurrence of myopia. Recent studies have shown that long-term close eye use is a high-risk factor for the development of myopia. In addition, studies have shown that outdoor exposure time is long enough to prevent myopia, and visible light intensity indirectly or directly affects the occurrence and development of myopia. Attention to eye environment and eye hygiene also play an important role in the occurrence and development of myopia.