According to the data, more and more people are suffering from myopia, and the trend is increasing. What are the causes of myopia? The following is a detailed introduction. The causes of myopia are internal and external, as follows: Internal: (1) Genetic quality: Myopia has a certain genetic tendency, which has been recognized, especially for high myopia. However, for general myopia, this tendency is not so obvious. In those with genetic factors, the age of disease is early, mostly above 6.00D. However, there are also people with high myopia who have no family history. High myopia is an autosomal recessive inheritance, while general myopia is a multifactorial genetic disorder. (2) Developmental factors: Infants are farsighted because their eyes are small, but as they grow older, the eye axis gradually lengthens until puberty when it develops normally. If the development is excessive, myopia will be formed, which is called simple myopia and starts in the school age. Myopia is usually below 6.00 D. The development stops at the age of 20. Rarely is myopia present at birth, but very rarely is it congenital. External factors: i.e. environmental factors, myopia is more frequent in people who work in writing or other close work, and myopia is also more frequent in teenage students, and its prevalence rises significantly from the fifth or sixth grade onwards.