1, genetic qualities: myopia has a certain genetic tendency, has been recognized, for high myopia is even more so. But for general myopia, this tendency is not very obvious. There are genetic factors, the age of the disease is earlier, more in 6.00D above. However, there are also people with high myopia who have no family history. High myopia belongs to autosomal recessive inheritance, and general myopia belongs to multifactorial genetic disease. Developmental factors: Infants are farsighted because of their small eyeballs, but as they grow older, their eye axes gradually lengthen, and develop normally at puberty. If the development is excessive, myopia will be formed, and this kind of myopia is called simple myopia, which mostly starts at school age. It usually starts at school age and is below 6.00 D. It stops developing at around 20 years of age. If myopia progresses rapidly at an early age, then more rapidly at 15 to 20 years of age, and then slows down later, this type of myopia is often higher than 6.00 D, and can reach 20 D to 25 D or 30 D. This type of myopia is known as high myopia or progressive myopia or pathologic myopia. This type of myopia can develop and degenerate in later life, so vision can gradually decrease and prescription glasses cannot correct vision. Few people are born with myopia, but a very small number of them are congenital. 3.Environmental factors: The role of environmental factors is becoming more and more important. Heavy study tasks, the popularization of TV and computer lead to the increase of close eye use and the decrease of outdoor activities have become the main reasons for the increasing rate of myopia among teenagers. When reading and writing and other close work, the eyes need to use a larger adjustment, if there is no long-term, a large number of close eye use environment exists, myopia rate will not be so high. For example, during World War II, when learning was greatly affected, statistics show that myopia rates in countries all over the world have decreased substantially. And in recent decades, the knowledge explosion at the same time, the number of myopia is also rapid and fierce increase, according to incomplete statistics at present, our country’s urban area myopia rate of 20-30% of primary school students, junior high school students 40-50%, high school students myopia rate of up to 70% or more, college students myopia rate is as high as 80% or more. 4, dietary factors: fine diet and partiality, picky eating brought about by the lack of certain trace elements in the eyes of young people in the process of development is also led to some students prematurely appear poor vision. The lack of certain or some important nutrients in the eye during growth and development makes the eye tissues become more fragile. Most myopic children have the habit of snacking, picky eating and partiality. They eat mostly refined grains and fast foods, which lack nutrients or have more nutrient destruction. At the same time, their diet lacks high-quality protein foods such as milk, eggs, milk, fish, meat, chicken and coarse grain foods. The more types of food lacking and the greater the total amount, the higher the incidence of myopia and the higher the degree of myopia.