Demyelinating diseases of the central nervous system (CNS) often have neuro-ophthalmological manifestations, and retinal examination can be helpful in making the diagnosis. The latest iteration of optical coherence tomography (OCT)-based criteria for optic neuritis in multiple sclerosis has been developed in the research realm, but its application to clinical practice, and to the more uncommon demyelinating diseases requires further study. The ability to use OCT data to distinguish between various CNS demyelinating disorders could provide additional paraclinical tools to accurately diagnose patients. Furthermore, neuro-ophthalmological testing can define the extent of inflammatory damage in the CNS, independent of patient-reported history. New referrals for OCT at a tertiary multiple sclerosis and neuro-immunology referral centre ( n = 167) were analysed retrospectively for the self-reporting of optic neuritis, serological test results, and diagnosis. Only approximately 30% of patients with a clinical history of unilateral optic neuritis solely had a unilateral optic neuropathy, nearly 40% of those subjects actually having evidence of bilateral optic neuropathies. Roughly 30% of patients reporting a history of bilateral optic neuritis did not have any evidence of structural disease, with 20% of these patients having a separate, intervenable diagnosis noted on macular scans. OCT is a useful adjunct diagnostic tool in the evaluation of demyelinating disease and has the ability to aid in a more accurate diagnosis for patients. Application of the international interocular difference thresholds to a clinical patient population generally reproduces the original results, emphasising their appropriateness. The analysis distinguishing the demyelinating diseases needs to be replicated in a blinded, multi-centre setting., Competing Interests: Peter Sguigna has no disclosures related to this publication. He has received grant support from the NMSS, CTM, PSTP, and the PRC. He has received consulting fees from Medical Logix LLC, Genentech, and Bristol Myers Squibb. Research reported in this publication was supported in part by the National Center for Advancing Translational Sciences of the National Institutes of Health under award number UL1TR001105. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Lauren Tardo has nothing to declare. Kyle Blackburn has nothing to declare. Lindsay Horton has nothing to declare. Darrel Conger has nothing to declare. Robert “Nick” Hogan has nothing to declare. Morgan McCreary has nothing to declare. Benjamin Greenberg has received grant support from the NIH, NMSS, Transverse Myelitis Association, PCORI, Guthy Jackson Charitable Foundation, Chugai, MedImmune, Medday, and Genentech. He has received consulting fees from Alexion, Novartis, EMD Serono, Genentech, and Celgene; he is an unpaid board member of the Transverse Myelitis Association., (© 2022 Taylor & Francis Group, LLC.)