Contributor: Gordon K. Klintworth
Optic disc edema (optic nerve head edema, papilledema) is a swelling of the optic nerve head due to edema. The most important cause  of  papilledema is increased intracranial pressure. The numerous other causes include obstruction to the venous drainage of the eye from compressive lesions, such as tumors of the orbit, vascular disorders, especially if they cause ischemia or infaction of the optic nerve (hypertension, anterior ischemic optic neuropathy [optic neuropathy - ischemic anterior], papillitis, optic neuritis and multiple sclerosis. Diseases that can cause edema of the optic nerve head include infections (syphilis, Lyme disease, tuberculosis, cat scratch disease, brucellosis), diffuse unilateral subacute neuroretinitis, and sarcoidosis. Edema of the optic nerve head may be associated with exudation into the Henle fiber layer of the retina and the formation of complete or partial macular star in some conditions (idiopathic optic neuritis, radiation optic neuropathy [optic neuropathy - radiation], malignant hypertension [hypertension - malignant], cat scratch disease, anterior ischemic optic neuropathy, Leber stellate optic neuritis [optic neuritis - Leber stellate]). Papilledema needs to be distinguished from pseudopapilledema, which can be a feature of several syndromes (Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome, Ruvalcaba syndrome, Riley-Smith syndrome).