Due to the irreversible nature of myopia, prevention is the key to myopia. If you can anticipate that your child is “nearing myopia” and prevent it early, you can maximize the control of myopia progression and even prevent it from occurring. Therefore, parents are most concerned about how to detect the “first signs of myopia”. Traditionally, parents suspect that their child’s vision is abnormal and that he or she may be myopic when they notice that he or she likes to see things close, has an abnormal head position (oblique), squints when watching TV, is lonely, or is “oblivious”. However, when we find these conditions, often myopia has already occurred, and even high myopia is present. It is not uncommon to see high myopia of 600 degrees or more on the first clinical examination. So how do you anticipate impending myopia before the symptoms of myopia manifest themselves, or even before there is any myopia at all? This is done with the help of science. As the eye develops, the eye axis grows and the refractive state evolves from hyperopia to orthopia. A short eye axis corresponds to a hyperopic eye and a long eye axis corresponds to a myopic eye; that is: maintaining a moderate amount of hyperopia in children is a very good mechanism for myopia protection, and the hyperopic state is a necessary reserve for myopia prevention. If the eye axis develops ahead of time and “eats up” the farsighted reserve in advance, myopia will be inevitable as the eye continues to develop and the eye axis grows, although the naked eye visual acuity is expressed as normal (0.8 or more). The hyperopic state is a myopia protection mechanism and a necessary reserve to prevent myopia. The hyperopic reserve of children before the age of 8 is often still relatively large (above +1.20D to +1.50D), and there is an “uneaten” hyperopic reserve; after that, the “eaten” hyperopic reserve ” situation, myopia is immediately expressed. This is the reason why most myopia is concentrated at the age of 9 to 13 years old (corresponding to 5th grade to middle school) and does not appear earlier. We can check the “farsightedness reserve” of school-age children and find “myopia” when the reserve is “insufficient” or “just finished eating the reserve”. Myopia prevention and control is most effective when the first signs of myopia are detected. In addition, because the development of height reflects the physical development of children, it is also related to the development of the eye and the growth of the eye axis. If a child is in a period of rapid height development, the eye axis may also be in a period of rapid development, also known as the “myopia progression period”. Parents should also pay attention to the refractive development of their children during this period. “Rapid height development” may also be the first sign of myopia. The best way to check a child’s hyperopic reserve is to establish a dynamic refractive development monitoring system through the establishment of a refractive development profile. We can regularly follow up the situation of the hyperopic reserve to detect the first signs of myopia that have “eaten up the hyperopic reserve” and make effective prevention in time.