That is a big issue in training, there is a very good chance that she may lose a contact during the remove, donning and clearing drill. I had it happen to me, never did find the contact. So I just went for a pair of diveoptic inserts when diving. If she have a strong prescription go with a prescription lenses for her mask. During regular diving you do not take of your mask underwater unless you are practicing the drill, which is seldom or if you actually have the mask get caught in strong current. During regular diving it not as much of an issue as during training.
But if she has daily lenses and on during training, it will only impair her vision for a day.