The people under 18 years old had better not accept myopia surgery, because the refractive state should be stable. Since children under 18 years old is in the growing period of body, their refractive state of the eyes is not stable, if they accept myopia surgery, the vision is likely to fall back after a year or two.
I recommend that children should not accept myopia surgery. They should be given visual acuity corrects first and observe the eye condition till 18 years old. And then you can consider to undertake corresponding treatment.