Abstract: genetic factors myopia has been recognized to have a certain genetic tendency, especially for high myopia. But for general myopia, this tendency is not very obvious. Those with genetic factors have an earlier age and more than 600 degrees. But there are also high myopia without family history.
in the relaxed state, the parallel light is focused in front of the retina after passing through the ocular refractive system, which is called myopia. Myopia is also called myopia, because this kind of eye can only see near, not far. When the eye is at rest, the parallel light from an infinite distance passes through the refraction of the refractive system of the eye, gathers into a focus in front of the retina, and forms an unclear image on the retina. The far vision is significantly reduced, but the near vision is still normal.
1. Internal cause
(1) Genetic factors myopia has been recognized to have a certain genetic tendency, especially for high myopia. But for general myopia, this tendency is not very obvious. Those with genetic factors have an earlier age and more than 600 degrees. However, those with high myopia have no 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. However, with the increase of age, the ocular axis gradually lengthens and develops normally after the age of 6. If they are over developed, they form myopia. This kind of myopia is called simple myopia, which usually starts in school age and is lower than 600 degrees. It stops developing when they are about 20 years old. For example, it progresses quickly when they are young, and it progresses faster when they are 15 ~ 20 years old Speed, then slow down. This kind of myopia is often higher than 600 degrees, up to 2000 ~ 2500 or 3000 degrees. This kind of myopia is called high myopia or progressive myopia or pathological myopia. This kind of myopia can degenerate in old age, so the vision can gradually decline, and the vision can not be corrected with glasses. However, very few are congenital and have myopia at birth.
2. External factors
are environmental factors. People engaged in writing work or other close work have more myopia, and there are also more myopia among young students. Moreover, the prevalence rate has increased significantly since the fifth and sixth grades of primary school. This phenomenon shows that the occurrence and development of myopia are closely related to close work. The eyeballs of teenagers, in particular, are in the stage of growth and development, with strong adjustment ability and large extension of the ball wall. The adjustment and collection function of reading and other close work makes the internal rectus muscle exert certain pressure on the eyeballs, and the intraocular pressure increases accordingly. With the continuous increase of work, the frequency and time of adjustment and collection also gradually increase, Ciliary muscle and extraocular muscle are often in a high tension state. Excessive regulation can cause ciliary muscle spasm, resulting in temporary vision loss. However, vision may improve or completely recover after rest or use of ciliary muscle erosion agent. Therefore, some people call this myopia functional myopia or pseudomyopia.