A rare neurological condition characterized by a combination of optic nerve atrophy in one eye, swelling of the optic disc in the other eye, and loss of smell (anosmia). It is usually caused by a tumor of the frontal lobe or olfactory sulcus, most commonly a meningioma, which compresses the optic nerve on one side and increases intracranial pressure, causing swelling of the disc in the opposite eye. Symptoms may include vision loss, headaches, and behavior changes. Treatment usually consists of surgical removal of the tumor.