I don't know your glasses' scratches is on which position of the frames. If it is on the end of the frames or inside, I think it would be unnecessary care about, because others can not see it and would not affect its beauty, could not affect your vision either.
If it have affected the glasses' beauty, you can choose to use a toothbrush brush with toothpaste lightly, seeing whether can clean out or not. If no, I suggest you can go to the shops you bought the glasses and ask if they have the corresponding treatment measures. If they do not have a way to the case, you can only buy the same frames, and also can save more money than you change a pair of new glasses.