Neuromyelitis Optica Optic Neuritis Research Articles

Перспективы диагностики оптического неврита при оптиконейромиелите Девика

The review presents data on the prospects for the diagnosis of optic neuritis in neuromyelitis optica (NMO). The differential diagnosis of NMO with multiple sclerosis and other autoimmune diseases is complicated by the similarity of the clinical manifestations of optic neuritis. The diagnostic approach, tactics of using and interpreting the results of modern laboratory, instrumental and hardware research methods are described. Additional diagnostic criteria are described for AQPR4-IgGseronegative patients with clinical symptoms of acute urinary tract infections. NMO is characterized by severe unilateral damage to the optic nerve with poor recovery of visual functions after conservative therapy, frequent recurrences of optic neuritis in one or both eyes, bilateral simultaneous damage to the optic nerves or chiasm. Timely diagnosis makes it possible to prescribe pathogenetic therapy for NMO and reduce the number of relapses of optic neuritis and prevent patients’ blindness. Key words: neuromyelitis optica, optic neuritis, OCT, multiple sclerosis, neuromyelitis optica spectrum disorders, AQPR4

Detecting seasonal trends in optic neuritis within the Ottawa region

ObjectiveIn this study we aim to determine seasonal patterns underlying optic neuritis (ON) onset that may provide valuable epidemiologic information and help delineate causative or protective factors. DesignSingle-centre retrospective chart review. MethodsA database search of centralized electronic health records was completed using diagnostic codes employed at the Ottawa Eye Institute for data collection. Charts were reviewed for documentation supporting a diagnosis of ON falling into the following categories: multiple sclerosis ON and clinically isolated syndrome ON, myelin oligodendrocyte glycoprotein ON, neuromyelitis optica ON, and idiopathic ON. Date of onset, biological sex, and age were extracted from each chart. Data were analyzed for calculation of frequency by season and overall pooled seasonal trends of all cases of ON. ResultsFrom the 218 included patients with ON, there was no statistically significant seasonal correlation. The overall trend of ON was lowest in winter and spring (22% and 23%, respectively) and highest in summer and fall (28% and 27% respective). Divided further, multiple sclerosis ON or clinically isolated syndrome ON rates (n = 144) were lowest in the spring (21%) and highest in fall (29%); myelin oligodendrocyte glycoprotein ON rates (n = 25) were lowest in winter (16%) and highest in summer and fall (both at 32%); neuromyelitis optica ON rates (n = 16) were lowest in fall (12.5%) and highest in winter and summer (both at 31.25%); and idiopathic ON rates (n = 33) were lowest in fall (18%) and highest in spring (33%). ConclusionsThe overall ON seasonal trend appears to have a predilection for the summer and fall months, which may be explained by warmer weather and viral infections as risk factors for multiple sclerosis relapse during those seasons.

Bruch Membrane Opening Minimum Rim Width in Neuromyelitis Optica.

Optical coherence tomography (OCT) analyzes the neurodegeneration in neuromyelitis optica (NMO) and multiple sclerosis (MS) and quantifies optical atrophy. The retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness are decreased, and this structural change is correlated with visual function of patients, including contrast vision and visual field deviation. The main objective of this study was to evaluate the Bruch membrane opening minimum rim width (BMO) of the patients with NMO. We studied the thickness of the BMO by OCT, in patients with NMO (n = 25; 34 eyes), MS (n = 50; 70 eyes), and a control group (n = 51; 100 eyes). The study evaluated the structure-function relationship with the correlation between OCT and visual function: Visual acuity, Pelli-Robson score, Sloan 2.5 and 1.25, color vision, standard automated perimetry (SAP), and frequency-doubling technology perimetry (FDT). The average thickness of BMO was significantly reduced in NMO and MS with or without a history of optic neuritis (ON). Significant thinning of the average, nasal, and inferonasal BMO in the absence of ON in NMO was found compared with controls (P = 0.022, 0.006, and 0.026, respectively). BMO was strongly correlated with Pelli-Robson score (P < 0.001), Sloan 2.5 (P < 0.001), and mean deviation of SAP and FDT (P = 0.004). The sectorial study found a high correlation between the BMO and the corresponding sector of the visual field. The BMO thickness is decreased after ON in NMO and MS. This study showed an improved ability of BMO over RNFL and GCL to detect infraclinical impairment in patients with NMO without a history of optic neuropathy. Like the RNFL and GCL, BMO is well correlated with visual function, including contrast vision and visual field deviation.

Radiomics Analysis of DTI Data to Assess Vision Outcome After Intravenous Methylprednisolone Therapy in Neuromyelitis Optic Neuritis.

Neuromyelitis optica-optic neuritis (NMO-ON) patients are routinely treated with intravenous methylprednisolone (IVMP). For the patients nonresponsive to IVMP, more effective but aggressive therapy of plasma exchange (PE) should be employed instead of IVMP in the first line. To assess the visual outcomes of NMO-ON patients after IVMP by radiomics analysis of whole brain diffusion tensor imaging (DTI) data. Retrospective. In all, 57 NMO-ON patients receiving IVMP therapy for 3 days. 3.0T; DTI images acquired by a single-shot echo planar image sequence; T1 images acquired by 3D fast spoiled gradient echo (3D-FSPGR) MRI. In all, 200 DTI measures were extracted from the DTI data and employed as features to construct a radiomics assessment model for visual outcomes of NMO-ON patients after IVMP. The assessment performance was evaluated by area under the receiver operating characteristic curve (AUC), classification accuracy (ACC), sensitivity, specificity, and positive and negative predicted values (PPV and NPV). The selected DTI measures would reveal the white matter impairments related to visual recovery of NMO-ON patients. The relationship between the selected DTI measures and the clinical visual characteristics were investigated by Pearson correlation, Spearman's rank correlation, and one-way analysis of variance analysis. The radiomics model obtained an ACC of 73.68% (P = 0.002), AUC of 0.7931, sensitivity of 0.6207, specificity of 0.8571, PPV of 0.8182, and NPV of 0.6857 in assessing visual outcomes of the NMO-ON patients after IVMP treatment. The selected DTI measures revealed white matter impairments related to the visual outcomes in the white matter tracts of vision-relevant regions, motor-related regions, and corpus callosum. The white matter impairments were found significantly correlated with the disease duration and the length of lesions in the optic nerve. Radiomics analysis of DTI data has great potential in assessing visual outcomes of NMO-ON patients after IVMP therapy. 2 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;49:1365-1373.

Chloride imbalance is involved in the pathogenesis of optic neuritis in neuromyelitis optica

Chloride imbalance between the serum and the cerebrospinal fluid (CSF) has been recently shown to exist in the acute phase of neuromyelitis optica (NMO). In this report, we studied the relation between the quotient of chloride (QCl) and the severity of optic neuritis (ON) in NMO patients. There was a positive correlation (R = 0.67; p < 0.05) between QCl and the length of ON-lesion. The visual prognosis also showed a positive correlation with QCl in the acute phase (R = 0.58; p < 0.05). These results support the theory that chloride imbalance between serum and CSF may trigger the ON in NMO spectrum disorders.

Treatment strategies for neuromyelitis optica.

Neuromyelitis optica (NMO) is an autoimmune demyelinating disease with pathogenic autoantibodies that act against the astrocyte water channel protein, i.e. aquaporin-4: the disease is associated with recurrent episodes of optic neuritis (ON) and transverse myelitis, often resulting in severe disability. The main goals in treatment of NMO include acute symptomatic therapy and long-term stabilization of symptoms by preventing relapse. In recent years, ongoing randomized controlled trials in NMO patients have studied evidence for treatment. Briefly, acute-stage management (with pulse therapy using corticosteroids and/or plasmapheresis) and maintenance therapy (including rituximab, mycophenolate mofetil, and azathioprine) have been recommended in some case series and retrospective studies. Because of the high prevalence of liver disease, all NMO patients in Taiwan should be screened for hepatitis B and C before treatment is initiated. Although immunosuppression and plasma exchange are the mainstays of therapy for NMO ON, several selective and potentially therapeutic strategies targeting specific steps in NMO pathogenesis including blockers of NMO-IgG binding and inhibitors of granulocyte function have been evaluated in recent years.

Evaluation of the retinal nerve fiber layer in neuromyelitis optica spectrum disorders: A systematic review and meta-analysis

BackgroundAn increasing number of studies have investigated the value of optical coherence tomography in patients with neuromyelitis optica (NMO) spectrum disorders; however, no systematic review has been performed to date. We aimed to systematically review and investigate the possibility of differentiating NMO and multiple sclerosis (MS) via an optical coherence tomography measurement. MethodsElectronic databases, including MEDLINE, EMBASE and Web of Science, were systematically searched up to June 2017. A meta-analysis was performed to compare the retinal nerve fiber layer (RNFL) thickness between patients with NMO and MS (or healthy controls). ResultsTwenty-four studies were identified. The meta-analysis demonstrated that the RNFL loss was substantially more severe in NMO than in MS; however, subclinical axon damage was also found in eyes without optic neuritis in NMO. The intereye RNFL difference between eyes with or without optic neuritis was more prominent in NMO (−30.98μm) than in MS (−9.87μm). ConclusionThe RNFL loss was more severe in NMO than in MS, and the intereye RNFL difference between eyes with or without optic neuritis may be useful in differentiating NMO from MS.

Optic Neuritis Presenting With Altitudinal Visual Field Defect in a Neuromyelitis Optica Patient

Herein, we report a case with neuromyelitis optica (NMO) who presented with optic neuritis and visual field examination revealed superior altitudinal visual field defect. Via the presentation of this patient, we point out NMO as an alternative differential diagnosis in patients with altitudinal visual defect clinics. Based on this presentation and literature data, we discuss some hypotheses about pathogenesis of optic neuritis in NMO and underlying mechanisms of optic neuritis development presenting with altitudinal visual defect as well. J Neurol Res. 2017;7(6):112-114 doi: https://doi.org/10.14740/jnr463w

Optic Neuritis Presenting With Altitudinal Visual Field Defect in a Neuromyelitis Optica Patient

Herein, we report a case with neuromyelitis optica (NMO) who presented with optic neuritis and visual field examination revealed superior altitudinal visual field defect. Via the presentation of this patient, we point out NMO as an alternative differential diagnosis in patients with altitudinal visual defect clinics. Based on this presentation and literature data, we discuss some hypotheses about pathogenesis of optic neuritis in NMO and underlying mechanisms of optic neuritis development presenting with altitudinal visual defect as well. J Neurol Res. 2017;7(6):112-114 doi: https://doi.org/10.14740/jnr463w

Literature Commentary

Objective: To differentiate magnetic resonance imaging (MRI) characteristics of optic neuritis associated with neuromyelitis optica (NMO) and relapsing-remitting multiple sclerosis (RRMS). Background: Optic neuritis is a common presenting feature of both NMO and MS. Distinguishing between NMO and RRMS is important in guiding treatment, but biomarkers of NMO and MS can be absent early in the disease process. We looked for differences in MRI characteristics of optic neuritis associated with NMO and MS that provide an early clue in the diagnostic workup. Design/Methods: We conducted a retrospective analysis of 26 NMO and 26 RRMS patients presenting to the Johns Hopkins Hospital with MRI-confirmed acute optic neuritis. Magnetic resonance images were assessed to identify the location and longitudinal extent of each contrast enhancing lesion. For the purposes of this study, the optic nerve was divided into intraorbital, canalicular, prechiasmal, chiasmal, and optic tract. Results: There are distinct differences in MRI characteristics between NMO-associated and RRMS-associated optic neuritis. The majority of NMO lesions were longitudinally extensive measuring at least 17.6 mm in length and involving at least 3 optic nerve segments. At a cut-off of 17.6 mm of lesion length, the specificity for NMO is 76.9% with a sensitivity of 80.8% and a positive likelihood ratio of 3.50. Conversely, MS lesions were more commonly focal in 1 optic nerve segment localized anteriorly. Conclusions: Optic neuritis in NMO has a distinct pattern on MRI as compared with RRMS and can help differentiate these 2 neuroinflammatory diseases at presentation.

Should plasma exchange be offered to patients with multiple sclerosis-associated optic neuritis?

Should plasma exchange be offered to patients with multiple sclerosis-associated optic neuritis?

Experimental mouse model of optic neuritis with inflammatory demyelination produced by passive transfer of neuromyelitis optica-immunoglobulin G

BackgroundAlthough optic neuritis (ON) is a defining feature of neuromyelitis optica (NMO), appropriate animal models of NMO ON are lacking. Most NMO patients are seropositive for immunoglobulin G autoantibodies (NMO-IgG) against the astrocyte water channel aquaporin-4 (AQP4).MethodsSeveral approaches were tested to develop a robust, passive-transfer mouse model of NMO ON, including NMO-IgG and complement delivery by: (i) retrobulbar infusion; (ii) intravitreal injection; (iii) a single intracranial injection near the optic chiasm; and (iv) 3-days continuous intracranial infusion near the optic chiasm.ResultsLittle ON or retinal pathology was seen using approaches (i) to (iii). Using approach (iv), however, optic nerves showed characteristic NMO pathology, with loss of AQP4 and glial fibrillary acidic protein immunoreactivity, granulocyte and macrophage infiltration, deposition of activated complement, demyelination and axonal injury. Even more extensive pathology was created in mice lacking complement inhibitor protein CD59, or using a genetically modified NMO-IgG with enhanced complement effector function, including significant loss of retinal ganglion cells. In control studies, optic nerve pathology was absent in treated AQP4-deficient mice, or in wild-type mice receiving control (non-NMO) IgG and complement.ConclusionPassive transfer of NMO-IgG and complement by continuous infusion near the optic chiasm in mice is sufficient to produce ON with characteristic NMO pathology. The mouse model of NMO ON should be useful in further studies of NMO pathogenesis mechanisms and therapeutics.

Spectral-Domain Optical Coherence Tomography of Retinal Nerve Fiber Layer Thickness in NMO Patients

Neuromyelitis optica (NMO) is a demyelinating syndrome of the central nervous system. NMO might be underdiagnosed at early stages when patients have not yet developed the full spectrum of disease. The aim of this study was to analyze the retinal nerve fiber layer (RNFL) with optical coherence tomography (OCT) and to compare RNFL measurements between NMO patients, patients with relapsing-remitting multiple sclerosis (RRMS), and healthy controls to determine whether differences in RNFL thickness could be an early diagnostic marker for NMO. In a cross-sectional study, eyes of 25 NMO patients, 25 RRMS patients, and 50 healthy controls underwent RNFL measurements by OCT. Clinical parameters were collected by history and chart review. Pairwise Wilcoxon rank sum tests with Holm correction were used to compare means of RNFL thickness among 6 groups (NMO, RRMS, and healthy control) of patients [without or with 1 or more episode of optic neuritis (ON)]. The association between RNFL thickness and patient characteristics for NMO group was examined via linear mixed-effects models (adjusting for within-patient intereye correlations and history of ON, where appropriate). Based on the pairwise Wilcoxon rank sum tests with Holm correction, significant differences were found between NMO with 1 episode of ON and non-ON eyes (mean RNFL 63.7 vs 97.0 µm, P < 0.0001), multiple sclerosis (MS) non-ON eyes, and controls (RNFL 93.2 vs 98.4 µm, P = 0.03). No significant differences were found between NMO and MS with 1 attack of ON eyes (RNFL 63.7 vs 73.9 µm, P = 0.46), NMO non-ON eyes and healthy controls (RNFL 97.0 vs 98.4 µm, P = 0.56), and NMO non-ON and MS non-ON (RNFL 97.0 vs 93.2 µm, P = 0.56). For NMO group, RNFL thickness was associated with a history of ON (P < 0.001) but not with disability or disease duration when adjusting for the history of ON (P > 0.1). RNFL in NMO is not different enough to distinguish NMO ON from MS ON eyes, but the intereye difference in RFNL with a history of unilateral ON may be a better diagnostic marker for NMO.

Optic Neuritis, its Differential Diagnosis and Management

The aim of this review is to summarize the latest information about optic neuritis, its differential diagnosis and management. Optic Neuritis (ON) is defined as inflammation of the optic nerve, which is mostly idiopathic. However it can be associated with variable causes (demyelinating lesions, autoimmune disorders, infectious and inflammatory conditions). Out of these, multiple sclerosis (MS) is the most common cause of demyelinating ON. ON occurs due to inflammatory processes which lead to activation of T-cells that can cross the blood brain barrier and cause hypersensitivity reaction to neuronal structures. For unknown reasons, ON mostly occurs in adult women and people who live in high latitude. The clinical diagnosis of ON consists of the classic triad of visual loss, periocular pain and dyschromatopsia which requires careful ophthalmic, neurologic and systemic examinations to distinguish between typical and atypical ON. ON in neuromyelitis optica (NMO) is initially misdiagnosed as ON in MS or other conditions such as Anterior Ischemic Optic Neuropathy (AION) and Leber’s disease. Therefore, differential diagnosis is necessary to make a proper treatment plan. According to Optic Neuritis Treatment Trial (ONTT) the first line of treatment is intravenous methylprednisolone with faster recovery and less chance of recurrence of ON and conversion to MS. However oral prednisolone alone is contraindicated due to increased risk of a second episode. Controlled High-Risk Subjects Avonex® Multiple Sclerosis Prevention Study “CHAMPS”, Betaferon in Newly Emerging Multiple Sclerosis for Initial Treatment “BENEFIT” and Early Treatment of MS study “ETOMS” have reported that treatment with interferon β-1a,b results in reduced risk of MS and MRI characteristics of ON. Contrast sensitivity, color vision and visual field are the parameters which remain impaired mostly even after good recovery of visual acuity.

Role of NMO-IgG in Distinguishing the Type of Optic Neuritis

To emphasize the importance of neuromyelitis optica (NMO)-immunoglobulin G (IgG) antibodies testing in patients with typical optic neuritis (ON) refractory to steroid treatment. Two patients were evaluated with ON refractory to steroid therapy and poor visual acuity; they were tested for NMO-IgG antibodies. Brain magnetic resonance imaging was normal in both patients. The serum and cerebrospinal fluid were positive for NMO-IgG antibodies. Magnetic resonance imaging of the cervical and thoracic spine revealed lesions longer than three vertebral segments and the diagnosis of NMO was confirmed. Treatment with plasma exchange and immunosuppressive therapy resulted in marked improvement of visual acuity. This improvement was sustained. The testing for NMO-IgG antibodies is important for distinguishing ON in NMO from multiple sclerosis in cases of ON refractory to steroid treatment. These cases suggest that testing for NMO-IgG antibodies should be performed in comparative trials on a larger series.

The Use of Serum Glial Fibrillary Acidic Protein Measurements in the Diagnosis of Neuromyelitis Optica Spectrum Optic Neuritis

BackgroundGlial fibrillary acidic protein (GFAP) is a specific intermediate filament of the cytoskeleton of the astrocyte and may be used as a specific marker for astrocytic damage. It is detectable in the cerebrospinal fluid following a relapse caused by Multiple Sclerosis (MS) and Neuromyelitis Optica (NMO) spectrum disease. Higher levels are found following an NMO-related relapse. It is not known if GFAP is also detectable in the serum following such relapses. In particular, it is not known if lesions limited to the optic nerve release GFAP in sufficient quantities to be detectable within the serum. The aim of this study was to ascertain the extent to which serum GFAP levels can distinguish between an episode of optic neuritis (ON) related to NMO spectrum disease and ON from other causes.Methodology/Principal FindingsOut of 150 patients consecutively presenting to our eye hospital over the period March 2009 until July 2010, we were able to collect a serum sample from 12 patients who had presented with MS-related ON and from 10 patients who had presented with NMO spectrum disease-related ON. We also identified 8 patients with recurrent isolated ON and 8 patients with a corticosteroid-dependent optic neuropathy in the absence of any identified aetiology. GFAP was detectable in the serum of all but three patients (two patients with MS-related ON and one with recurrent optic neuritis). The median serum GFAP level in the patient group with NMO spectrum disease was 4.63 pg/mL whereas in all other cases combined together, this was 2.14 pg/mL. The difference was statistically significant (P = 0.01). A similar statistically significant difference was found when cases with pathology limited to the optic nerve were compared (P = 0.03).ConclusionsGlial pathology in NMO related optic neuritis is reflected in elevated serum GFAP levels independently of whether or not there is extra-optic nerve disease.

Bilateral and recurrent optic neuritis in multiple sclerosis

To assess the frequency of bilateral and recurrent optic neuritis (ON) in multiple sclerosis (MS) and to compare these results with epidemiological data of ON in neuromyelitis optica (NMO) and recurrent ON without other signs of disease. We identified 472 patients with diagnosis of MS from the Swedish Multiple Sclerosis Register. These patients were evaluated for the presence of ON and whether the ON was the presenting symptom of MS; unilateral or bilateral; monophasic or recurrent. Twenty-one percent presented with ON as their first manifestation of MS. The proportion of patients developing a second attack of ON before demonstration of other manifestations of MS was 5.5% and the frequency of recurrent bilateral ON as the presenting symptom was 3.8%. Only two patients presented with simultaneously appearing bilateral ON corresponding to 0.42%. Recurrent ON, whether unilateral or bilateral, is a common presentation of MS. As MS is a much more common disease than NMO, care must be taken when evaluating the work-up of patients with recurrent ON. In some cases repeated MRI and lumbar punctures are warranted to improve diagnostic accuracy, even in the presence of the serological marker NMO-IgG.

Visual field defects of optic neuritis in neuromyelitis optica compared with multiple sclerosis

BackgroundNeuromyelitis optica (NMO) is an inflammatory demyelinating disease that predominantly affects the optic nerves and the spinal cord, and is possibly mediated by an immune mechanism distinct from that of multiple sclerosis (MS). Central scotoma is recognized as a characteristic visual field defect pattern of optic neuritis (ON), however, the differing pathogenic mechanisms of NMO and MS may result in different patterns of visual field defects for ON.MethodsMedical records of 15 patients with NMO and 20 patients with MS having ON were retrospectively analyzed. A thorough systemic and neurological examination was performed for evaluating ON. The total number of relapses of ON and visual fields was investigated. Visual fields were obtained by Goldmann perimeter with each ON relapse.ResultsAll MS patients experienced central scotoma, with 90% of them showing central scotoma with every ON relapse. However, 53% of NMO patients showed central scotoma with every ON relapse (p = 0.022), and the remaining 47% of patients experienced non-central scotoma (altitudinal, quadrant, three quadrant, hemianopia, and bitemporal hemianopia). Thirteen percent of NMO patients did not experience central scotoma during their disease course. Altitudinal hemianopia was the most frequent non-central scotoma pattern in NMO.ConclusionsNMO patients showed higher incidence of non-central scotoma than MS, and altitudinal hemianopia may be characteristic of ON occurring in NMO. As altitudinal hemianopia is highly characteristic of ischemic optic neuropathy, we suggest that an ischemic mechanism mediated by anti-aquaporin-4 antibody may play a role in ON in NMO patients.

Optical coherence tomography of the retina: applications in neurology

This review summarizes the mechanisms and recent developments of optical coherence tomography and its practical uses in neurology. The application of optical coherence tomography imaging of the retina in multiple sclerosis, neuromyelitis optica, Alzheimer disease, and Parkinson disease are reviewed. Thinning of the peripapillary retinal nerve fibre layer has been detected in patients with optic neuritis, multiple sclerosis, neuromyelitis optica, Alzheimer disease, and Parkinson disease. However, the patterns of change differ in some aspects. The findings indicate loss of retinal ganglion cells and may reflect degenerative change in the brain in these conditions. The retinal nerve fibre layer thickness may be used as a biological marker and may help to distinguish between optic neuritis associated with multiple sclerosis and optic neuritis in neuromyelitis optica.

Optical coherence tomography helps differentiate neuromyelitis optica and MS optic neuropathies

To evaluate the retinal nerve fiber layer (RNFL) thickness and macular volume in neuromyelitis optica (NMO) spectrum patients using optical coherence tomography (OCT). OCT can quantify damage to retinal ganglion cell axons and can identify abnormalities in multiple sclerosis and optic neuritis (ON) eyes. OCT may also be useful in the evaluation of patients with NMO. OCT and visual function testing were performed in 26 NMO spectrum patients with a history of ON, 17 patients with isolated longitudinally extensive transverse myelitis (LETM) without ON, 378 patients with relapsing-remitting multiple sclerosis (RRMS), and 77 healthy controls at 2 centers. Substantial RNFL thinning was seen in NMO ON eyes (63.6 microm) relative to both RRMS ON eyes (88.3 microm, p < 0.0001) and control eyes (102.4 microm, p < 0.0001). A first episode of ON was estimated to cause 24 microm more loss of RNFL thickness in NMO than RRMS. Similar results were seen for macular volume. ON also was associated with more severe visual impairment in NMO spectrum patients than in RRMS patients. Eyes in the LETM group and unaffected NMO eyes were not significantly different from controls, though conclusions about these subgroups were limited by small sample sizes. Optical coherence tomography (OCT) shows more severe retinal damage after optic neuritis (ON) episodes in neuromyelitis optica (NMO) than in relapsing-remitting multiple sclerosis. Identification of substantial retinal nerve fiber layer loss (>15 microm) after ON in a non-multiple sclerosis patient should prompt consideration of an NMO spectrum condition. OCT may be a useful tool for the evaluation of patients with NMO.