Delayed optic nerve complications after proton beam irradiation.

We present two cases of delayed optic nerve complications following proton beam radiotherapy. Patient 1 received radiotherapy after surgery for clival chordoma and developed sequential radiation optic neuropathy at 5 and 9 months. Patient 2 developed optic nerve hemorrhage post radiotherapy for optic nerve sheath meningioma. These two cases of blindness demonstrate the risks associated with proton beam radiotherapy.