Optic disc edema

Optic disc edema refers to unilateral or bilateral swelling of the optic disc. 

Terminology 

Optic disc edema describes the swelling of nerve fiber layer at the optic nerve head, and it is the consequence of many different pathological processes. Optic disc edema is sometimes mistaken for papilledema because both refer to the swelling of the optic disc. Optic disc edema refers to the general swelling of the disc; meanwhile, papilledema is a subset of optic disc edema and is exclusively used for optic disc swelling due to increased intracranial pressure ¹. 

Pathology 

Etiology

• causes of raised intracranial pressure and papilledema (e.g. idiopathic intracranial hypertension, intracranial mass)

• non-arteritic anterior ischemic optic neuropathy

• optic neuritis (and causes thereof)

• optic perineuritis (and causes thereof)

• compressive optic neuropathy

• neuroretinitis

• hypertensive papillopathy

• retinal vein occlusions

• papillophlebitis

• diabetes mellitus papillopathy ^2,3

Radiographic features

MRI

Magnetic resonance imaging (MRI) demonstrates optic nerve sheath enlargement ⁴. 

Optical coherence tomography 

Optical coherence tomography (OCT) presents an elevation of optic nerve head because of the peripapillary hyperreflective ovoid mass-like structures. Additionally, in patients with optic disc edema other than papilledema, optical coherence tomography shows an either flat or V-shaped retinal pigment epithelium/ Brunch's membrane (RPE/BM) layer ^5,6. 

Treatment and prognosis

Treatment of optic disc edema is directed towards the underlying cause, but may include medications such as acetazolamide and/or corticosteroids ³. 

Differential diagnosis 

Differential diagnosis for optic disc edema includes ¹:

• optic disc drusen 

• Bergmeister papilla

• peripapillary mass

• intraocular hypotension 

• Leber hereditary optic neuropathy