It is rare for a 12 year old to be nearsighted and not grow, but generally if it is well controlled the growth will be slower, but it will still increase. If myopia is well controlled in a 12 year old child, it will increase by about 50 diopters per year, which is a normal range. There are many reasons for the increase in myopia, such as prolonged use of electronic devices, irregular use of the eyes, excessive close-up use of the eyes, or prolonged excessive use of the eyes in environments with poor visibility, all of which can lead to myopia. If you find that your child is already nearsighted, parents should pay special attention to the usual use of children’s eyes and go to the hospital in time for correction. Usually pay more attention, as far as possible to avoid excessive use of electronic products, or long time high intensity eye use, pay attention to relieve eye fatigue, usually can do eye exercises, long time use of the eyes can look into the distance, to relieve eye fatigue, diet should pay more attention to, usually can consume some good for the eyesight of the food, such as carrots, spinach and other food.