Myopia has mild myopia and severe myopia. In mild myopia, it is very clear to see things close to each other, and to see things in the distance, especially the characters will be very fuzzy.
Severe myopia to see what things will be very paste, can not see clearly, need to wear glasses. If you look at some things, there will be some fuzzy shadows, which are not very clear. There will be some shadows in front of you.
Myopia has a lot of, have true myopia and pseudomyopia, average adult is true myopia. In addition, genetic factors can cause myopia,