Differential diagnosis of ON

1. Anterior ischemic optic neuropathy (AION) often lacks the pain seen in ON
2. Painless visual loss without improvement over several weeks AION
3. Leber's hereditary optic neuropathy (LHON) occurs inyoung men with a mitochondrial disease; the presentation is unilateral unremitting progressive visual loss to bilateral visual loss over days to months with disc edema, peripappillary telangiectasias, and permanent visual loss.
4. Absent venous pulsations-- enlarged blind spot-- consider increased ICP
5. Orbital mass constricting the optic nerve may cause disc edema, proptosis, and EOM restriction unilaterally
6. Diabetic papillopathy in young diabetics often remits
7. Other inflammatory diseases: HIV, syphilis, TB, cryptococcus, toxoplasma, varicella, histoplasmosis, CMV, and h. zoster all can cause ON.
8. Macular star suggests toxoplasmosis.
9. Optic spinal "Asian" MS may be a form of NMO.