Aims The aim of this study is to provide a clinical update on optic neuritis (ON), its association with multiple sclerosis (MS), and neuromyelitis optica (NMO). Methods This study included a PubMed review of the literature written in the English language.Results ON in adults is typically idiopathic or demyelinating, and is characterised by unilateral, subacute, painful loss of vision that is not associated with any systemic or other neurological symptoms. Demyelinating ON is associated with MS, and we review the key studies of ON including the ON treatment trial and several other MS treatment trials and NMO. Conclusion Acute demyelinating ON can occur in isolation or be associated with MS. Typical ON does not require additional evaluation other than cranial magnetic resonance imaging. NMO is likely a separate disorder from MS and the ON in NMO has a different treatment and prognosis. Methodology The authors conducted an English language search using Pubmed from the years 1964 to 2010 using the search terms 'ON', 'MS' and 'NMO'. The authors included original articles, review articles, and case reports, which revealed new aspects as far as epidemiology, histopathology, clinical manifestations, imaging, genetics, and treatment of ON. Titles were reviewed for topicality and full references were obtained. Letters to the editor, unpublished work, and abstracts were not included in this review.

Non-arteritic ischaemic optic neuropathy (NAION) and optic neuritis may have overlapping presentations, making differentiation between the two difficult. All adults presenting with acute unilateral optic neuropathy (symptoms <3 weeks of onset) between January 2011 and January 2012 underwent complete neuro-ophthalmic examinations and were diagnosed with either NAION or ON. Patients underwent pre-and post-contrast magnetic resonance (MR) with gadolinium, diffusion-weighed imaging (DWI), T2, short tau inversion recovery (STIR), and gadolinium-enhanced fast imaging employing steady state acquisition (FIESTA) sequences of the brain and orbit. A blinded neuroradiologist analysed the images as normal, consistent with NAION, consistent with ON, or unrelated incidental findings and the results were correlated to clinical diagnoses on initial presentation. Sixteen patients were included, 4 of whom had optic neuritis and 12 had NAION. Concordance rate for the blinded neuroradiological diagnosis and the final clinical diagnosis was seen in only 3 of the 16 patients. Nonspecific or unrelated findings were seen in 6 cases. Our study demonstrates a low concordance rate between radiographic and final clinical diagnoses, with only 3/16 patients correctly diagnosed by blinded neuroradiological evaluation. Despite the limitations of our study, we believe that neuroradiologists can assist clinicians in the final diagnosis of in patients in whom the clinical presentation is uncertain. Future work is necessary to determine whether more rapid imaging in these cases might expand the utility of DWI in optic neuropathy.

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The aim of the article is to report the presentation, diagnosis, and treatment of two cases of unexplained painless vision loss attributed to 47-kDa (presumed α-enolase)-positive autoimmune-related retinopathy and optic neuropathy (ARRON); to describe 47-kDa (presumed α-enolase)-positive ARRON as a subtype of ARRON; and to propose that serum anti-enolase antibody might be a serologic marker of the disorder. We have reviewed retrospectively of two patients with ARRON positive for an antibody to a 47-kDa retinal antigen presumed to be α-enolase. The two patients had progressive bilateral visual acuity and/or visual field loss, electroretinographic evidence for retinal dysfunction, and evidence for serum anti-retinal antibodies to a 47-kDa antigen (presumed α-enolase). Although clinically the patients had symptoms of retinal-based visual loss, neither patient had optic disc oedema, optic atrophy, or any ophthalmoscopically visible retinal abnormalities. Both patients were treated with immunosuppressive therapy. One patient achieved improvement in visual acuity with oral corticosteroids alone, but the other patient did not respond to steroid treatment and only achieved improvement in vision following plasmapheresis. After immunosuppressive treatment, follow-up serum antibody levels to a 47-kDa antigen (presumed α-enolase) levels were retested and were undetectable in both patients. We hypothesize that these two patients have a constellation of clinical and electrophysiologic findings suggestive of a 47-kDa (presumed α-enolase)-positive ARRON that we believe is subtype of ARRON and that serum α-enolase antibody might be a marker of the disorder.