The present application describes RGM A binding proteins, particularly monoclonal antibodies, and in particular CDR grafted, humanized versions thereof, which have the ability to bind to RGM A and prevent binding of RGM proteins to RGM A receptor and other RGM A binding proteins, and therefore neutralize the function of RGM A, for use in the treatment of retinal nerve fiber layer (RNFL) degeneration as well as methods of therapeutically or prophylactically treating a mammal against RNFL degeneration.