Owl to Zuko
I have a friend who refuses to get rid of any his scars because they're survival badges, according to him. Though I'd never be able to do that; I'm far too vain.
...Which eye, left or right?
If your father cursed the lantern, or cursed the wound while it was healing, that might account for why you can't cover up the scar now. Though it seems to go beyond 'hard' into 'cruel' if you don't mind me saying so. Why would he punish you like that? Magical fire shouldn't scar unless it's Cursed fire, or possibly from a dragon or a Dark Creature.