Differential of Optic Disc Edema with preserved vision

Papilledema (increased ICP) usually bilateral but may be unilateral in IIH. Most such patients do complain of headache. If severe enough, consider cerebral venous thrombosis (CVT), hydrocephalus, meningitis, or malignant hypertension. Transient obscurations of vision with postural changes that are recurrent are not specific.

Compressive or infiltrative lesion (tumor, Graves' disease, optic perineuritis)

Central retinal vein insufficiency may see optociliary shunt vessels indicating prior retinal vein event. CAVEAT if disc pallor and decreased optic nerve function are seen, consider optic meningioma. May see central retinal hemorrhages

Benign optic disc vasculitis

Toxic optic neuropathy (amiodarone, cyclosporine, methanol (retrobulbar neuritis with blocked axoplasmic flow), hypervitaminosis A (like cyclopsorine causes increased intracranial hypertension)

Malignant hypertension may see central retinal artery hemorrhages or cotton wool spots, or macular stars. May be associated with reversible posterior leukoencephalopathy.

Low grade ischemia (diabetic papillopathy, pre-AION)-- exam might show segmental optic disc swelling, disc pallor, splinter or flame shaped hemorrhages, or macular stars. Diabetic papillopathy is a diagnosis of exclusion after evaluation.

Posterior uveitis (sarcoid, granulomatous disease, birdshot choroidopathy)

Acute zonal occult outer retinopathy

Neuroretinitis-- macular stars are a defining feature.

Hypotony