I was born with high myopia, I was -16 and -18 by the time I was 16. I know I had my first pair of glasses at 18 mths, now drs are better about getting kids glasses.
I can tell u that with high myopia, all physical contact sports are dangerous... And do make it more open for a detachment. But it is like playing bingo, you never know who will get it. I played lots of sports but didn't have my first detachment until I was 20. My cousin had her first detachment when she was 15 and she didn't play sports. So... I don't encourage sports but I do encourage regular retina exams. Since I was told that I have a 50/50 chance of passing it to my children, I take them every 6 months to a retina doctor. They are 9 and 10... So far there is no sign of myopia at all. I don't get it, my cousin has one child and she is only 4 but has obvious signs of myopia already.
Other hints: as your child gets older, keep the shampoo/conditioner bottles in the same place in the shower (she can't see the bottles), as well as the towels, soap, toothbrush, and toothpaste. Whenever you go to a beach or pool, make sure you set up a bright colored area, something that she can recognize without her glasses. She can't see shapes well but blobs of color... (think of looking thru a shower door). Start her early in a routine of putting her glasses in the same spot every night before bed so she can find them in the morning... It helps in the case of an emergency. Routine becomes so important when a person can't see the details but don't hold her back from learning... Nothing is worse than being afraid or having the people around you afraid of every move.
When she goes thru puberty, her vision will change a lot... It sucks but you will have to buy her new glasses every year, maybe sooner depending on how fast her vision changes. This doesn't always apply but usually applies to most high myopic ppl.