papilledema
Swelling with accompanying compression of the optic nerve head, which can be a medical emergency. Causes of papilledema can include bleeding near the vicinity of the optic nerve and abnormally high cerebrospinal fluid (CSF) pressure. Autoimmune disorders, trauma and infections of the central nervous system also can cause papilledema. Optic nerve swelling can result from central retinal vein occlusion or may occur as a side effect of medications such as lithium, tetracycline and corticosteroids.