Our results suggest the presence of trans-synaptic degeneration as a contributor to chronic axon damage in MS.

Retinal axonal and neuronal damage develops quickly after ON onset. Assessment of ganglion cell layer thickness by OCT after ON onset can be used as an imaging marker of persistent visual disability.

Patients with multiple sclerosis (MS) almost always experience effects in the visual pathway; and thus, visual dysfunction is not only common but also highly relevant. The visual pathway represents a model of acute focal central nervous system (CNS) damage, through acute optic neuritis and retinal periphlebitis, as well as a model of chronic, diffuse CNS damage through chronic retinopathy and optic neuropathy. The optic pathway can be accurately evaluated in detail, due to the availability of highly sensitive imaging techniques (e.g. magnetic resonance imaging or optical coherent tomography) or electrophysiological tests (multifocal visual evoked potentials or electroretinography). These techniques allow the interactions between the different processes at play to be evaluated, such as inflammation, demyelination, axonal damage and neurodegeneration. Moreover, these features mean that the visual pathway can be used as a model to test new neuroprotective or regenerative therapies.

IMPORTANCE Neuroprotective and remyelinating therapies are required for multiple sclerosis (MS), and acute optic neuritis (AON) is a potential condition to evaluate such treatments.OBJECTIVE To comprehensively assess key biological and methodological aspects of AON trials for testing neuroprotection and remyelination in MS.

It is currently believed that the incidence rate of optic neuritis (ON) ranges between 0.56 and 5.1 cases per 100,000 person-years. However, since these figures were generated, they have not been updated and there are suggestions that the incidence of ON is on the rise. When designing new therapies and clinical trials for ON, and to improve the management this disease, it is important to have accurate epidemiological data. Thus, we set out to obtain the prevalence and incidence rates of ON in Barcelona (Spain) from 2008 to 2012, by a retrospective evaluation of electronic hospital records at the Hospital Clinic of Barcelona (population of 300,000 in the catchment area) matching the following ICD-9-CM codes as search terms: 377.3-optic neuritis; 377.30-optic neuritis, unspecific; 377.31-optic papillitis; 377.32-retrobulbar neuritis, acute; 377.39-other optic neuritis and "optic neuropathy". Demographic and clinical data were collected from records with a confirmed diagnosis of ON, including cases of idiopathic ON, multiple sclerosis, neuromyelitis optica and CRION. The prevalence of acute ON on 31 December 2012 was 2.75 cases per 100,000 people. The mean annual prevalence of acute ON during the 2008-2012 period was 7.87 cases per 100,000 person-year and the mean annual incidence rate was 5.36 cases per 100,000 person-years. The incidence of ON in Barcelona during 2008-2012 was higher than previously reported. This increase may reflect the evolution of diagnostic criteria, the use of a referral-center approach instead of a population-based approach, increased awareness of demyelinating diseases, latitude-related factors and possibly a true increase in its incidence.

Colour vision impairment is associated with greater MS severity.

BackgroundMultiple Sclerosis (MS) is an immune-mediated disease of the Central Nervous System with two major underlying etiopathogenic processes: inflammation and neurodegeneration. The latter determines the prognosis of this disease. MS is the main cause of non-traumatic disability in middle-aged populations.FindingsThe MS-VisualPath Cohort was set up to study the neurodegenerative component of MS using advanced imaging techniques by focusing on analysis of the visual pathway in a middle-aged MS population in Barcelona, Spain. We started the recruitment of patients in the early phase of MS in 2010 and it remains permanently open. All patients undergo a complete neurological and ophthalmological examination including measurements of physical and disability (Expanded Disability Status Scale; Multiple Sclerosis Functional Composite and neuropsychological tests), disease activity (relapses) and visual function testing (visual acuity, color vision and visual field). The MS-VisualPath protocol also assesses the presence of anxiety and depressive symptoms (Hospital Anxiety and Depression Scale), general quality of life (SF-36) and visual quality of life (25-Item National Eye Institute Visual Function Questionnaire with the 10-Item Neuro-Ophthalmic Supplement). In addition, the imaging protocol includes both retinal (Optical Coherence Tomography and Wide-Field Fundus Imaging) and brain imaging (Magnetic Resonance Imaging). Finally, multifocal Visual Evoked Potentials are used to perform neurophysiological assessment of the visual pathway.DiscussionThe analysis of the visual pathway with advance imaging and electrophysilogical tools in parallel with clinical information will provide significant and new knowledge regarding neurodegeneration in MS and provide new clinical and imaging biomarkers to help monitor disease progression in these patients.

Objectives: To assess the association of primary retinal inflammation, namely retinal periphlebitis (RP) and microcystic macular edema, with clinical, brain, and retinal imaging biomarkers of multiple sclerosis (MS) severity.Methods: One hundred patients with MS underwent a neurologic and ophthalmic examination, MRI, and optical coherence tomography. Disability was assessed using the Expanded Disability Status Scale at baseline and after a 1-year follow-up. The normalized brain volume, the normalappearing gray matter volume, and T1 lesion volume were assessed at baseline as radiologic biomarkers of disease severity. Retinal nerve fiber layer thickness and macular volume at baseline were used as surrogate markers of axonal damage. We used general linear models adjusted for sex, age, disease duration, and MS treatment to compared adjusted means of these parameters among patients with RP and patients without primary retinal inflammation.Results: Five patients showed RP, 2 showed microcystic macular edema, and the retina was normal in the remaining 93. Patients with RP had a tendency toward a higher adjusted-mean Expanded Disability Status Scale score at baseline and disability progression after a 1-year follow-up compared with patients without primary retinal inflammation. These patients also had a higher adjusted-mean T1 lesion volume (adjusted differences: 10.4, 95% confidence interval [CI]: 0.6 to 20.2; p 5 0.038) and lower T1 brain volume (adjusted differences: 268, 95% CI: 2139 to 2; p 5 0.059). Patients with RP had a lower adjusted-mean retinal nerve fiber layer thickness (adjusted differences: 213.4, 95% CI: 224.4 to 22.3; p 5 0.018) and a trend toward lower macular volume. Multiple sclerosis (MS) causes axonal degeneration, determining disease severity. Retinal periphlebitis (RP) is a vasculitis that affects the peripheral retina in approximately 10% of patients with MS. The presence of RP is associated with a higher disease activity in relapses and gadoliniumenhancing lesions. Conclusions:1 Additionally, optical coherence tomography (OCT) has identified retinal nerve fiber layer (RNFL) atrophy and a decreased macular volume (MV) as axonal damage markers in MS. 224 Moreover, OCT enabled identification of microcystic macular edema (MME) in 0.5% to 5% of patients with MS and it seems to be associated with MS activity or previous optic neuritis (ON).2 In this study, we assessed the association between primary retinal inflammation (RP and MME) and clinical (Expanded Disability Status Scale [EDSS]) and imaging (brain and retinal) biomarkers of disease severity to evaluate their suitability as biomarkers in MS.