An 80 year-old woman was referred for a one-eyed palpebral edema. She had ptosis and oblique diplopia resistant to corticotherapy. An orbit magnetic resonance imaging showed a mass infiltrating the optic nerve, with an enhancement of the whole orbital musculature. Biopsies of the lacrimal gland were positive for immunoglobulin light chain amyloidosis. Debulking surgery is the main treatment modality for symptomatic patients with localized orbital amyloidosis. Diffuse orbital involvement may make excision difficult. We managed to treat her through radiation therapy to allow a surgical procedure, delivering 20Gy in 10 fractions. The main aim of radiation therapy was to eradicate the B cells that produced the amyloid light chain deposition. After radiation therapy, the orbital inflammatory caused by the lymphoid infiltration diminished and corticotherapy could be stopped. The surgery could be performed with excellent clinical results. At 2-year follow-up, neither tumor regrowth nor late complications were detected.