With Cartier earrings, you never lose the backs. I don’t remember what you call it, but the backings are a “push” type backing in order to get on (a locking mechanism).
Therefore, you have to push the backs in order to get it on, and from there, you can move them forward or backward, but in order to get the backs completely off (the lock area), you have to push the two sides of the backs to move past the lock area.
Essentially, the earrings will always stay in place, and you will never lose the backs without first pushing the backs to open so it’s very secure!
Hope that helps!