Is it ever mentioned how All for One become blind? Was he born blind or he got blind fighting All Might or in any other situation?
Because of the fight between All Might and All for One where All Might takes his big wound that causes him not being able to use his quirk at any time or lets say in a time limit, All for One also took serious wounds. Most visible one being his face. Yes because of this he is blind however thanks to an infrared vision quirk he can "see".