The formation of myopia is influenced by genetic and environmental factors, which cannot be expressed exactly yet. In summary, it may be related to the following factors: 1. autosomal recessive inheritance; 2. long-term close work; 3. long-term unreasonable light illumination and adverse eye irritation; 4. prematurity; 5. systemic wasting diseases; 6. insufficient intake of trace elements; 7. adverse environmental effects, such as pesticides and industrial exhaust pollution, etc. So it is not possible to generalize when myopia will be absolutely stable. Your statement that myopia will be fixed when people reach the age of 40 and their eyes start to get old is a conceptual error. The clinical manifestation of myopia is blurred vision in the distance and good vision in the near. Presbyopia is an impairment of near vision caused by physiological weakening of regulation due to age, and its neutralizing effect on myopia is limited to seeing near. In other words, presbyopia occurs later in myopes compared to both orthoptics and hyperopes. Current myopia is closely related to excessive near work time from an epidemiological point of view and can be said to be one of the causes of unstable myopia. Generally speaking should be limited to continuous close work eye time, close reading and writing for more than one hour in a row. In addition, we should also pay attention to diet and nutrition, not to be picky about food, and pay attention to outdoor physical activities. In short, good eye habits will benefit the eyes for life.