The optic nerve head, also called the optic disk or papilla, is the area where the optic nerve (the nerve that carries messages from the eye to the brain) enters the eyeball.
The finding of papilledema is made with the ophthalmoscope (the instrument that shines light through the pupil illuminating the retina while the doctor looks through it).
The optic nerve head is abnormally elevated in papilledema, almost always in both eyes.
The causes of papilledema include cerebral edema (swelling of the brain, as from encephalitis or trauma), tumors and other lesions that occupy space within the skull, increased production of cerebrospinal fluid (CSF), decreased resorption of CSF (because of venous sinus thrombosis, meningitis, or subarachnoid hemorrhage), obstruction of the ventricular system within the brain, hydrocephalus, craniosynostosis (premature closure of the sutures of the skull), and a condition called pseudotumor cerebri.