Stereotyped B-cell responses are linked to IgG constant region polymorphisms in multiple sclerosis.

Clonally related B cells infiltrate the brain, meninges, and cerebrospinal fluid of MS patients, but the mechanisms driving the B-cell response and shaping the immunoglobulin repertoires remain unclear. Here, we used single-cell full-length RNA-seq and BCR reconstruction to simultaneously assess the phenotypes, isotypes, constant region polymorphisms, and the paired heavy- and light-chain repertoires in intrathecal B cells. We detected extensive clonal connections between the memory B cell and antibody-secreting cell (ASC) compartments and observed clonally related cells of different isotypes including IgM/IgG1, IgG1/IgA1, IgG1/IgG2, and IgM/IgA1. There was a strong dominance of the G1m1 allotype constant region polymorphisms in ASCs, but not in memory B cells. Tightly linked to the G1m1 allotype, we found a preferential pairing of the immunoglobulin heavy-chain variable (IGHV)4 gene family with the κ variable (IGKV)1 gene family. The IGHV4-39 gene was most used and showed the highest frequency of pairing with IGKV1-5 and IGKV1(D)-33. These results link IgG constant region polymorphisms to stereotyped B-cell responses in MS and indicate that the intrathecal B-cell response in these patients could be directed against structurally similar epitopes.

Serum neurofilament light chain concentration predicts disease worsening in multiple sclerosis.

BACKGROUND: Serum neurofilament light (sNfL) chain is a promising biomarker reflecting neuro-axonal injury in multiple sclerosis (MS). However, the ability of sNfL to predict outcomes in real-world MS cohorts requires further validation. OBJECTIVE: The aim of the study is to investigate the associations of sNfL concentration, magnetic resonance imaging (MRI) and retinal optical coherence tomography (OCT) markers with disease worsening in a longitudinal European multicentre MS cohort. METHODS: MS patients (n = 309) were prospectively enrolled at four centres and re-examined after 2 years (n = 226). NfL concentration was measured by single molecule array assay in serum. The patients' phenotypes were thoroughly characterized with clinical examination, retinal OCT and MRI brain scans. The primary outcome was disease worsening at median 2-year follow-up. RESULTS: Patients with high sNfL concentrations (⩾8 pg/mL) at baseline had increased risk of disease worsening at median 2-year follow-up (odds ratio (95% confidence interval) = 2.8 (1.5-5.3), p = 0.001). We found no significant associations of MRI or OCT measures at baseline with risk of disease worsening. CONCLUSION: Serum NfL concentration was the only factor associated with disease worsening, indicating that sNfL is a useful biomarker in MS that might be relevant in a clinical setting.

Hospitalization following influenza infection and pandemic vaccination in multiple sclerosis patients: a nationwide population-based registry study from Norway.

Patients with multiple sclerosis (MS) are at increased risk of infections and related worsening of neurological function. Influenza infection has been associated with increased risk of various neurological complications. We conducted a population-based registry study to investigate the risk of acute hospitalization of MS patients in relation to influenza infection or pandemic vaccination in Norway. The entire Norwegian population in the years 2008-2014 was defined as our study population (N = 5,219,296). Information on MS diagnosis, influenza infection and vaccination were provided by Norwegian national registries. The self-controlled case series method was used to estimate incidence rate ratios (IRRs) with 95% confidence intervals (95% CI) in defined risk periods. 6755 MS patients were identified during the study period. Average age at first registration of an MS diagnosis was 51.8 years among men and 49.9 years among females (66.9%). The IRR for emergency hospitalization among MS patients the first week after an influenza diagnosis was 3.4 (95% CI 2.4-4.8). The IRR was 5.6 (95% CI 2.7-11.3) after pandemic influenza, and 4.8 (95% CI 3.1-7.4) after seasonal influenza. Pandemic vaccination did not influence risk of hospitalization [IRR within the first week: 0.7 (95% CI 0.5-1.0)]. Among MS patients, influenza infection was associated with increased risk for acute hospitalization while no increased risk was observed after pandemic vaccination. Influenza vaccination could prevent worsening of MS-related symptoms as well as risk of hospitalization.

Quantitative proteomic analyses of CD4+ and CD8+ T cells reveal differentially expressed proteins in multiple sclerosis patients and healthy controls.

BACKGROUND: Multiple sclerosis (MS) is an autoimmune, neuroinflammatory disease, with an unclear etiology. However, T cells play a central role in the pathogenesis by crossing the blood-brain-barrier, leading to inflammation of the central nervous system and demyelination of the protective sheath surrounding the nerve fibers. MS has a complex inheritance pattern, and several studies indicate that gene interactions with environmental factors contribute to disease onset. METHODS: In the current study, we evaluated T cell dysregulation at the protein level using electrospray liquid chromatography-tandem mass spectrometry to get novel insights into immune-cell processes in MS. We have analyzed the proteomic profiles of CD4+ and CD8+ T cells purified from whole blood from 13 newly diagnosed, treatment-naive female patients with relapsing-remitting MS and 14 age- and sex-matched healthy controls. RESULTS: An overall higher protein abundance was observed in both CD4+ and CD8+ T cells from MS patients when compared to healthy controls. The differentially expressed proteins were enriched for T-cell specific activation pathways, especially CTLA4 and CD28 signaling in CD4+ T cells. When selectively analyzing proteins expressed from the genes most proximal to > 200 non-HLA MS susceptibility polymorphisms, we observed differential expression of eight proteins in T cells between MS patients and healthy controls, and there was a correlation between the genotype at three MS genetic risk loci and protein expressed from proximal genes. CONCLUSION: Our study provides evidence for proteomic differences in T cells from relapsing-remitting MS patients compared to healthy controls and also identifies dysregulation of proteins encoded from MS susceptibility genes.

Restriction spectrum imaging of white matter and its relation to neurological disability in multiple sclerosis.

BACKGROUND: Restriction spectrum imaging (RSI) is a recently introduced magnetic resonance imaging diffusion technique. The utility of RSI in multiple sclerosis (MS) is unknown. OBJECTIVE: To investigate the association between RSI-derived parameters and neurological disability in MS. METHODS: Seventy-seven relapsing-remitting MS patients were scanned with RSI on a 3-T scanner. RSI-derived parameters: fast and slow apparent diffusion coefficient (sADC), fractional anisotropy, restricted fractional anisotropy, neurite density (ND), cellularity, extracellular water fraction, and free water fraction, were obtained in white matter lesions (WML) and normal appearing white matter (NAWM). Patients were divided into three groups according to their expanded disability status scale (EDSS): with minimal, low, and substantial disability (<2.5, 2.5-3, and >3, respectively). Group comparisons and correlation analyses were performed. RESULTS: All tested RSI-derived parameters differed between WML and NAWM ( p < 0.001 for all pairwise comparisons). The sADC in WML showed largest difference across disability subgroups (analysis of variance (ANOVA): F = 5.1, η2 = 0.12, p = 0.008). ND in NAWM showed strongest correlation with disability (ϱ = -0.39, p < 0.001). CONCLUSION: The strongest correlation with EDSS of ND obtained in NAWM indicates that processes outside lesions are important for disability in MS. Our study suggests that RSI-derived parameters may help understand the "clinico-radiological paradox" and improve disease monitoring in MS.

Genetic variants are major determinants of CSF antibody levels in multiple sclerosis.

Immunological hallmarks of multiple sclerosis include the production of antibodies in the central nervous system, expressed as presence of oligoclonal bands and/or an increased immunoglobulin G index-the level of immunoglobulin G in the cerebrospinal fluid compared to serum. However, the underlying differences between oligoclonal band-positive and -negative patients with multiple sclerosis and reasons for variability in immunoglobulin G index are not known. To identify genetic factors influencing the variation in the antibody levels in the cerebrospinal fluid in multiple sclerosis, we have performed a genome-wide association screen in patients collected from nine countries for two traits, presence or absence of oligoclonal bands (n = 3026) and immunoglobulin G index levels (n = 938), followed by a replication in 3891 additional patients. We replicate previously suggested association signals for oligoclonal band status in the major histocompatibility complex region for the rs9271640*A-rs6457617*G haplotype, correlated with HLA-DRB1*1501, and rs34083746*G, correlated with HLA-DQA1*0301 (P comparing two haplotypes = 8.88 × 10(-16)). Furthermore, we identify a novel association signal of rs9807334, near the ELAC1/SMAD4 genes, for oligoclonal band status (P = 8.45 × 10(-7)). The previously reported association of the immunoglobulin heavy chain locus with immunoglobulin G index reaches strong evidence for association in this data set (P = 3.79 × 10(-37)). We identify two novel associations in the major histocompatibility complex region with immunoglobulin G index: the rs9271640*A-rs6457617*G haplotype (P = 1.59 × 10(-22)), shared with oligoclonal band status, and an additional independent effect of rs6457617*G (P = 3.68 × 10(-6)). Variants identified in this study account for up to 2-fold differences in the odds of being oligoclonal band positive and 7.75% of the variation in immunoglobulin G index. Both traits are associated with clinical features of disease such as female gender, age at onset and severity. This is the largest study population so far investigated for the genetic influence on antibody levels in the cerebrospinal fluid in multiple sclerosis, including 6950 patients. We confirm that genetic factors underlie these antibody levels and identify both the major histocompatibility complex and immunoglobulin heavy chain region as major determinants.

Prevalence of multiple sclerosis among immigrants in Norway.

BACKGROUND: Multiple sclerosis (MS) prevalence is unevenly distributed worldwide. Immigration to Norway from countries with a lower MS prevalence is increasing. The aim of this study was to investigate MS prevalence in different immigrant populations in Norway and evaluate the effect of migrating from low- to high-risk regions of MS. METHOD: First- and second-generation immigrants from the largest immigrant populations were identified from the 2012 Norwegian prevalence study. Prevalence of MS in different ethnic groups was compared using the standardized prevalence ratio (SPR). RESULTS: European and North-American immigrants had the highest prevalence of MS, whereas African and Asian immigrants had the lowest. The prevalence of first-generation Iranian immigrants was not significantly different from the total Norwegian population (SPR 0.70, 95% CI: 0.46-1.03). Second-generation immigrants from Pakistan (SPR 1.62, 95% CI: 0.88-2.76) had a strong increase in prevalence compared to the first generation (SPR 0.13, 95% CI: 0.05-0.28). CONCLUSION: MS prevalence among immigrants in Norway in general reflects the uneven distribution worldwide. The sharp increase in prevalence in immigrants seen in one generation suggests strong environmental factors affecting the MS risk in Norway.

Oligoclonal bands and age at onset correlate with genetic risk score in multiple sclerosis.

BACKGROUND: Many genetic risk variants are now well established in multiple sclerosis (MS), but the impact on clinical phenotypes is unclear. OBJECTIVE: To investigate the impact of established MS genetic risk variants on MS phenotypes, in well-characterized MS cohorts. METHODS: Norwegian MS patients (n = 639) and healthy controls (n = 530) were successfully genotyped for 61 established MS-associated single nucleotide polymorphisms (SNPs). Data including and excluding Major Histocompatibility Complex (MHC) markers were summed to a MS Genetic Burden (MSGB) score. Study replication was performed in a cohort of white American MS patients (n = 1997) and controls (n = 708). RESULTS: The total human leukocyte antigen (HLA) and the non-HLA MSGB scores were significantly higher in MS patients than in controls, in both cohorts (P << 10(-22)). MS patients, with and without cerebrospinal fluid (CSF) oligoclonal bands (OCBs), had a higher MSGB score than the controls; the OCB-positive patients had a slightly higher MSGB than the OCB-negative patients. An early age at symptom onset (AAO) also correlated with a higher MSGB score, in both cohorts. CONCLUSION: The MSGB score was associated with specific clinical MS characteristics, such as OCBs and AAO. This study underlines the need for well-characterized, large cohorts of MS patients, and the usefulness of summarizing multiple genetic risk factors of modest effect size in genotype-phenotype analyses.

Environmental exposures and the risk of multiple sclerosis investigated in a Norwegian case-control study.

BACKGROUND: Several environmental exposures, including infection with Epstein-Barr virus, low levels of vitamin D and smoking are established risk factors for multiple sclerosis (MS). Also, high hygienic standard and infection with parasites have been proposed to influence MS risk. The aim of this study was to investigate the influence of various environmental exposures on MS risk in a Norwegian cohort, focusing on factors during childhood related to the hygiene hypothesis. METHODS: A questionnaire concerning environmental exposures, lifestyle, demographics and comorbidity was administrated to 756 Norwegian MS patients and 1090 healthy controls. Logistic regression was used to calculate odds ratio (OR) with 95% confidence interval (CI) for the risk of MS associated with the variables infectious mononucleosis, severe infection during childhood, vaccination and animals in the household during childhood. Age, gender, HLA-DRB1*15:01, smoking and infectious mononucleosis were included as covariates. General environmental exposures, including tobacco use, were also evaluated. RESULTS: Infectious mononucleosis was confirmed to be significantly associated with increased MS risk, also after adjusting for the covariates (OR = 1.79, 95% CI: 1.12-2.87, p = 0.016). The controls more often reported growing up with a cat and/or a dog in the household, and this was significant for ownership of cat also after adjusting for the covariates (OR = 0.56, 95% CI: 0.40-0.78, p = 0.001). More patients than controls reported smoking and fewer patients reported snuff use. CONCLUSIONS: In this Norwegian MS case-control study of environmental exposures, we replicate that infectious mononucleosis and smoking are associated with increased MS risk. Our data also indicate a protective effect on MS of exposure to cats during childhood, in accordance with the hypothesis that risk of autoimmune diseases like MS may increase with high hygienic standard.

The instrumented single leg stance test detects early balance impairment in people with multiple sclerosis.

Balance impairment is frequent in people with multiple sclerosis (pwMS) and affects risk of falls and quality of life. By using inertial measurement units (IMUs) on the Single Leg Stance Test (SLS) we aimed to discriminate healthy controls (HC) from pwMS and detect differences in balance endurance and quality. Thirdly, we wanted to test the correlation between instrumented SLS parameters and self-reported measures of gait and balance. Fifty-five pwMS with mild (EDSS<4) and moderate disability (EDSS≥4) and 20 HC performed the SLS with 3 IMUs placed on the feet and sacrum and filled the Twelve Item Multiple Sclerosis Walking Scale (MSWS-12) questionnaire. A linear mixed model was used to compare differences in the automated balance measures. Balance duration was significantly longer in HC compared to pwMS (p < 0.001) and between the two disability groups (p < 0.001). Instrumented measures identified that trunk stability (normalized mediolateral and antero-posterior center of mass stability) had the strongest association with disability (R2 marginal 0.30, p < 0.001) and correlated well with MSWS-12 (R = 0.650, p < 0.001). PwMS tended to overestimate own balance compared to measured balance duration. The use of both self-reported and objective assessments from IMUs can secure the follow-up of balance in pwMS.

"No association between disease modifying treatment and fatigue in multiple sclerosis".

BACKGROUND: Fatigue affects 60-90% of people with multiple sclerosis (MS). It reduces quality of life and the ability to work. The cause of fatigue in MS remains unknown. Several disease-modifying treatments (DMTs) slow the disease process in relapsing MS by suppressing neuroinflammation. We aimed to investigate if treatment with a DMT is associated with lower rates of fatigue. METHODS: In this cross-sectional study of the MS population in three counties in Norway, we used the Fatigue Scale for Motor and Cognitive Functions (FSMC) and the Hospital Anxiety and Depression Scale (HADS) to assess patient-reported fatigue, anxiety and depression. Clinical data were retrieved from the electronic patient record system. We categorized DMTs as high-efficacy therapy or moderate-efficacy therapy. High-efficacy drugs included fingolimod, natalizumab, ocrelizumab, rituximab, alemtuzumab, daclizumab, and autologous hematopoietic stem cell transplantation. Moderate-efficacy drugs included interferons, glatiramer acetate, dimethyl fumarate, and teriflunomide. We included persons with relapsing MS only. RESULTS: Of 1142 patients, 80% had fatigue. Fifty-six percent of the patients were on DMTs (25% on moderate-efficacy treatment and 30% on high-efficacy treatment), 18% had discontinued treatment and 26% had never received any DMT. Sex, level of disability as measured by the Multiple Sclerosis Severity Score, anxiety and depression were independently associated with fatigue. Moderate-efficacy treatment was associated with less fatigue, but not after adjustment for other variables. There was no association between high-efficacy treatment and fatigue. CONCLUSION: We found no independent relationship between the use of disease-modifying treatment and fatigue in MS.

Immune cell subpopulations and serum neurofilament light chain are associated with increased risk of disease worsening in multiple sclerosis.

Changes is lymphocyte subpopulations in peripheral blood have been proposed as biomarkers for evaluation of disease activity in multiple sclerosis (MS). Serum neurofilament light chain (sNfL) is a biomarker reflecting neuro-axonal injury in MS that could be used to monitor disease activity, response to drugs and to prognosticate disease course. Here we show a moderate correlation between sNfL and lymphocyte cell subpopulations, and our data furthermore suggest that sNfL and specific immune cell subpopulations together could predict future disease worsening in MS.

Fatigue in multiple sclerosis is associated with socioeconomic factors.

OBJECTIVES: Fatigue is one of the leading causes of reduced quality of life and inability to work in people with multiple sclerosis (pwMS). Currently, no treatment effectively ameliorates fatigue. We still know little about what causes fatigue and which factors may contribute to fatigue. Knowledge about socioeconomic factors' role in fatigue might help us recognize strategies for the management of fatigue. Our aim was to explore whether socioeconomic factors are associated with the presence or level of perceived fatigue. METHODS: This is a cross-sectional study of the MS population in three Norwegian counties. We used the Fatigue Scale for Motor and Cognitive Functions to assess self-reported fatigue, and obtained socioeconomic data from Statistics Norway and questionnaires. To assess self-reported anxiety and depression, we employed the Hospital Anxiety and Depression Scale. Clinical data were gathered from the hospital record system. RESULTS: The response rate was 64% (1599/2512). Seventy percent of the respondents were female, and the mean age was 52 years. Higher levels of education were associated with lower levels of fatigue. Receiving a disability pension, being divorced and having children were all factors associated with higher levels of fatigue, as were low parental education, low income, current smoking, and autoimmune comorbidities. We found a higher prevalence of anxiety and depression in pwMS with fatigue compared to those without fatigue CONCLUSION: Female sex, high level of disability, anxiety, depression and socioeconomic factors were independently associated with fatigue in contemporary patients with MS. These factors should be considered when devising management strategies.

Sensor-based gait analyses of the six-minute walk test identify qualitative improvement in gait parameters of people with multiple sclerosis after rehabilitation.

The aim of this work was to determine whether wearable inertial measurement units (IMUs) could detect gait improvements across different disability groups of people with Multiple Sclerosis (pwMS) by the six-minute walk test (6MWT) during a rehabilitation stay in a specialized rehabilitation center. Forty-six pwMS and 20 healthy controls (HC) were included in the study. They performed the 6MWT with two inertial measurement units (IMUs) placed on the feet. Thirty-two of the pwMS were retested at the end of the stay. PwMS were divided in a mild-disability and a moderate-disability group. The 6MWT was divided in six sections of 1 min each for technical analysis, and linear mixed models were used for statistical analyses. The comparison between the two disability groups and HC highlighted significant differences for each gait parameter (all p < 0.001). The crossing effect between the test-retest and the two disability groups showed greater improvement for the moderate-disability group. Finally, the gait parameter with the higher effect size, allowing the best differentiation between the disability groups, was the foot flat ratio (R2 = 0.53). Gait analyses from wearable sensors identified different evolutions of gait patterns during the 6MWT in pwMS with different physical disability. The measured effect of a short-time rehabilitation on gait with 6MWT was higher for pwMS with higher degree of disability. Using IMUs in a clinical setting allowed to identify significant changes in inter-stride gait patterns. Wearable sensors and key parameters have the potential as useful clinical tools for focusing on gait in pwMS.

The influence of socioeconomic factors on access to disease modifying treatment in a Norwegian multiple sclerosis cohort.

OBJECTIVE: Several studies report an impact of socioeconomic factors on access to disease modifying treatment (DMT) in multiple sclerosis (MS), with a trend of less access to more deprived persons. We investigated the impact of socioeconomic status (SES) on access to treatment in a well-defined Norwegian MS cohort. METHODS: This is a study of a population-based Norwegian MS cohort. We collected detailed information on disease development, progression, and DMT administered. Socioeconomic data was obtained from Statistics Norway and a questionnaire. RESULTS: We included 1314 persons with relapsing remitting MS at the prevalence date 01/01/2018. The population ever treated with DMTs is younger at onset, has shorter time from onset to diagnosis and lower expanded disability status score (EDSS) at diagnosis. The persons with MS (pwMS) with the highest levels of education, and those who are married are more likely to be ever treated with DMT. In the subgroup treated with a high efficacy DMT as a first drug, the pwMS are younger at prevalence date (39.9 years (SD 12.1)) compared with those who are not treated with a high efficacy DMT as first drug (43.8 years (SD 10.3)). The subgroup treated with a high efficacy DMT as a first drug has a 0.5 point higher EDSS at diagnosis compared to those not treated with a high efficacy DMT as a first drug. The level of education, household income and marital status are inversely related to access to high efficacy DMT as a first drug. None of the above differences persist when analyzing the subgroup diagnosed within the last six years (2012-2017). CONCLUSIONS: Since 2012, the pwMS in this Norwegian cohort are treated equally with DMT in terms of different measures of socioeconomic position.

Rebaseline no evidence of disease activity (NEDA-3) as a predictor of long-term disease course in a Norwegian multiple sclerosis population.

Introduction: No evidence of disease activity with three components (NEDA-3) is achieved if the person with MS (pwMS) has no new MRI lesions, no new relapses and no change in Expanded disability status scale (EDSS) over 1 year. Whether NEDA-3 is a good tool in measuring disease activity is up for discussion, but it is superior to the individual parameters separately and user-friendly. There is disagreement on whether NEDA-3 is a good predictor of long-term disability. Methods: This is a retrospective cohort study using real-world data with limited selection bias from the complete MS population at two hospitals in the southeast of Norway. We included pwMS diagnosed between 2006 and 2017 who had enough information to determine time to failure of NEDA-3 after diagnosis. Results: Of 536 pwMS, only 38% achieved NEDA 1 year after diagnosis. PwMS achieving NEDA were more likely to be started on a high efficacy drug as the initial drug, but there were no demographic differences. Mean time to NEDA failure was 3.3 (95% CI 2.9-3.7) years. Starting a high efficiacy therapy was associated with an increased risk of sustaining NEDA as compared to those receiving moderate efficacy therapy. PwMS who achieved NEDA at year one had a mean time to EDSS 6 of 33.8 (95% CI 30.9-36.8) years vs. 30.8 (95% CI 25.0-36.6) years in pwMS who did not achieve NEDA, p < 0.001. When rebaselining NEDA 1 year after diagnosis, 52.2% achieved NEDA in the 1st year after rebaseline, mean time to NEDA failure was 3.4 (95% CI 3.0-3.7) years and mean time to EDSS 6 was 44.5 (95% CI 40.4-48.5) years in pwMS achieving NEDA vs. 29.6 (95% CI 24.2-35.0) years in pwMS not achieving NEDA, p < 0.001. After rebaseline, pwMS with a high efficacy therapy as the initial drug had a mean time from diagnosis to NEDA fail of 4.8 years (95% CI 3.9-5.8) vs. 3.1 years (95% CI 2.7-3.5) in pwMS started on a moderate efficacy therapy, p < 0.001. In pwMS with NEDA failure at year one, 70% failed one, 28% failed two and 2% failed three components. New MRI lesions were the most common cause of NEDA failure (63%), followed by new relapses (50%) and EDSS change (25%). Conclusion: NEDA-3 from rebaseline after 1 year, once treatment is stabilized, can predict the long-term disease course in MS. Starting a high efficacy DMT is associated with longer time to NEDA failure than moderate therapies. Finally, most pwMS only fail one component and new MRI lesions are the most likely cause of NEDA failure.

Exploring Retinal Blood Vessel Diameters as Biomarkers in Multiple Sclerosis.

We aimed to determine whether retinal vessel diameters and retinal oxygen saturation in newly diagnosed patients with multiple sclerosis (pwMS) are different from those of a healthy population. Retinal blood vessel diameters were measured using imaging with a spectrophotometric non-invasive retinal oximeter. Twenty-three newly diagnosed untreated relapsing-remitting MS (RRMS) patients (mean age: 32.2 ± 7.5 years, age range = 18-50 years, 56.5% female) were measured and compared to 23 age- and sex-matched healthy controls (HCs) (mean age: 34.8 ± 8.1 years). Patients with Optic Neuritis were excluded. Retinal venular diameter (143.8 µm versus 157.8 µm: mean; p = 0.0013) and retinal arteriolar diameter (112.6 µm versus 120.6 µm: mean; p = 0.0089) were smaller in pwMS when compared with HCs, respectively. There was no significant difference in the oxygen saturation in retinal venules and arterioles in pwMS (mean: 60.0% and 93.7%; p = 0.5980) compared to HCs (mean: 59.3% and 91.5%; p = 0.8934), respectively. There was a significant difference in the median low contrast visual acuity (2.5% contrast) between the pwMS and the HC groups (p = 0.0143) Retinal arteriolar and venular diameter may have potential as objective biomarkers for MS.