I have tried toothpaste and it does work. It needs to be the type that is slightly abrasive ("whitening"). The scratches were so shallow in the plastic lenses that you could rub hard and eventually remove them. It takes quite a lot of rubbing though!

Turtle Wax also has an abrasive, so should work the same way, but I haven't tried it.

It all depends of course on what coating you have on the lenses. In some cases the rubbing can remove the coating, and this seems to make it all worse. You can continue and remove all the coating, but again that takes ages.