Hyper-acute orbital edema and vision loss following palliative radiotherapy of the lacrimal gland

Breast carcinoma is the most common primary malignancy to metastasize to the orbit. While mild delayed orbital edema is a recognized complication of orbital radiotherapy, hyper-acute severe edema resulting in transient vision loss is rare. A 48-year-old woman with metastatic invasive lobular breast carcinoma and left orbital involvement received a first-dose palliative radiation fraction of 8 Gy to the left orbit. Within 5 hours, she developed severe proptosis, chemosis, elevated intraocular pressure, and monocular vision loss. Computed tomography demonstrated proptosis of the left globe and optic nerve stretching. She received 8 mg of intravenous dexamethasone, and her vision rapidly recovered to baseline with the resolution of her acute compressive symptoms without any change in tumor-directed therapy. This case highlights the rare risk of hyper-acute post-radiation orbital edema within hours of radiotherapy and demonstrates that early, prompt medical management can successfully rescue compressive optic neuropathy.