Treatment options for old surgical scar on forehead? (Photo)

I am a 72 year old man with an old (40 year) surgical scar on my forehead. In the past I have covered the scar with my fringe but hair loss is limiting this. The photo is a year old - there is a marked depression in the centre of the scar. Early this year I had a course of needle dermabrasion and tattooing which resulted in a more noticeable and darkened scar. I would welcome advice regarding further treatment - there appear to be a range of surgical and non-surgical options.