I have just finished with my 6-month course of Accutane, left with some indentations. I have not seen a lot of improvement on the scars, but I heard from doctors here that I can apply Retin-A now to increase the production of collagen and speed up scars healing, should I apply it to the indents only? Also, how often should I use it? Can I replace it with Stieva-A? Thanks.