Most of the causes of myopia are long anterior and posterior axis (called axial myopia), followed by strong refractive power (called refractive myopia). Myopia often occurs in adolescence, genetic factors have a certain influence, but its occurrence and development are closely related to insufficient lighting, improper reading posture and long-term close work.
It can be summed up as internal cause and external cause. The brief introduction is as follows:
- Internal causes
(1) genetic factors: myopia has a certain genetic tendency. It has been recognized. This is especially true for high myopia. But for general myopia. This tendency is not obvious. There are genetic factors. The age of onset was earlier. Most of them were above 6.00D. But there are also high myopia without family history. High myopia belongs to autosomal recessive inheritance. Generally, myopia is a multifactorial hereditary disease.
(2) developmental factors: infants have smaller eyeballs. So they are hyperopia. But with age. The axial length of the eye was gradually lengthened. The development was normal until puberty. Such as overdevelopment. Then form myopia. This kind of myopia is called simple myopia. Most of them start at school age. It is generally lower than 6.00D. The development stopped at about 20 years old. As a child, progress is rapid. By the age of 15-20, the progress was more rapid. Then it slows down. This kind of myopia is often higher than 6.00D. It can reach 20d-25d or 30d. This kind of myopia is called high myopia or progressive myopia or pathological myopia. This kind of myopia may develop and degenerate in old age. As a result, vision can gradually decline. Glasses can’t correct vision. It is rare to have myopia at birth. But very few of them are congenital.
- External factors are environmental factors.
A person engaged in writing or other close work. Myopia is more common. Myopia is also more common among young students. It shows that the occurrence and development of myopia is closely related to close work. Especially the eyeballs of teenagers. It is in the stage of growth and development. The adjustment ability is very strong. The extension of the ball wall is also relatively large. The adjustment and aggregation of distance working. The external Kendall muscle (mainly the medial rectus muscle) exerts certain pressure on the eyeball. Intraocular pressure also increased. With the increasing number of jobs. The frequency and time of adjustment and assembly also gradually increased. Ciliary and extraocular muscles are often in high tension. Excessive regulation can cause ciliary spasm. This can cause temporary vision loss.