Isolated Unilateral Infiltrative Optic Neuropathy in a Patient with Breast Cancer

Purpose: Metastasis to the optic nerve is very rare. We report a case of metastatic breast cancer to the optic nerve without the involvement of other ocular or orbital structures. Methods: The patient, a 39-year-old female who had been previously treated for breast cancer, reported a gradually progressive decrement in visual acuity of the right eye during the past two months. Results: Fundus examination of the affected eye revealed swelling of the optic disc which was infiltrated by a yellowish mass. Further evaluation using optical coherence tomography and fluorescein angiography showed the optic disc swelling. B-scan ultrasonography revealed abnormal increasing of the optic nerve sheath diameter. Magnetic resonance imaging revealed no pathologic findings. With a diagnosis of unilateral infiltrative optic neuropathy, we referred the patient to an oncologist for further evaluation. Conclusion: Most patients with optic nerve metastatic tumors exhibit a known diagnosis of a primary malignancy along with other evidence of metastases. Thus, when a known cancer patient develops an optic neuropathy, metastases and infiltration should be suspected as the cause; unless proven otherwise