What conditions need to be met for upper eyelid scar revision?

I wanted to know what basic conditions need to be met in order to do a scar revision in patient who has a very hideous scar 2 yr post op (right eye only) there were complications during surgery then I had severe allergic reaction to ointment during healing causing one side of my eye have massive inflammation which persisted for weeks and possibly suture granulomas not sure. i also did not have proper post op guidance 2 handle issues. Any advice is appreciated. Left eye looks fine