Infiltrative Optic Neuropathy in Advanced Breast Carcinoma.

Infiltrative optic neuropathy is a condition characterized by the invasion of tumor cells into the optic nerve. Breast carcinoma can metastasize to various organs, most commonly the bones, lungs, and liver, and rarely involves the orbit. Orbital involvement may result in debilitating visual impairment and blindness. We report a case of infiltrative optic neuropathy secondary to advanced breast carcinoma. A 39-year-old woman with stage 4 breast carcinoma presented with sudden-onset blurred vision in her right eye for one week. It was associated with a localized scotoma in the visual field. She was previously diagnosed with secondary metastases involving the liver and bone and is currently undergoing treatment with chemotherapy and radiotherapy. Visual acuity in the right eye was 6/7.5, with a positive relative afferent pupillary defect and an inferonasal field defect. The extraocular muscle movement was full, with no significant proptosis. Both anterior segments were unremarkable. Fundoscopy showed a normal optic disc in both eyes, with no optic disc swelling. A computed tomography (CT) scan of the brain and orbit revealed secondary metastases in the dura and right orbital apex. Magnetic resonance imaging (MRI) of the brain revealed right infiltrative optic neuropathy. The patient received whole-brain radiotherapy (WBRT), followed by 12 cycles of chemotherapy. On follow-up, the patient was stable; however, her vision in the right eye deteriorated from 6/7.5 to perception of light. In conclusion, orbital metastasis should be the leading diagnostic consideration when the affected patient has a history of cancer. Early detection, coupled with prompt treatment, can help patients achieve better visual outcomes and, whenever possible, preserve their vision.