Long-term follow-up of a randomized study of combination interferon and glatiramer acetate in multiple sclerosis: Efficacy and safety results up to 7 years

BACKGROUND

To report the long-term results of the blinded extension phase of the randomized, controlled study of the combined use of interferon beta-1a (IFN) 30μg IM weekly and glatiramer acetate (GA) 20mg daily compared to each agent alone in relapsing-remitting multiple sclerosis (RRMS).

METHODS

1008 RRMS patients were followed on protocol until the last participant enrolled completed 3 years, allowing some subjects to be followed for up to 7 years. The primary endpoint was reduction in annualized relapse rate. Secondary outcomes included time to confirmed disability, Multiple Sclerosis Functional Composite (MSFC) score and MRI metrics.

RESULTS

Similar to the core study, combination IFN + GA was not superior to the better of the single agents (GA) in risk of relapse. Both the combination therapy and GA were significantly better than IFN in reducing the risk of relapse. The combination was not better than either agent alone in lessening confirmed EDSS worsening or change in MSFC. Also similar to the core result, the combination was superior to either agent alone in reducing new lesion activity, but the 3 year MRI result did not presage a clinical benefit over the extended observation interval.

CONCLUSION

Combining GA & IFN did not produce a significant clinical benefit over the entire study duration. The earlier effect on reducing MRI activity did not result in a later clinical advantage. The combination showed a sustained advantage in reducing disease activity free status.

Streamlined EDSS for use in multiple sclerosis clinical practice: Development and cross-sectional comparison to EDSS

Background:

The Expanded Disability Status Scale (EDSS) is the standard measure of disability in multiple sclerosis clinical trials. The EDSS has limited application in the clinical setting due to required completion time and scoring complexity. Systematically recording an objective, simplified, less time-intensive, and neurologist-derived disability score would be beneficial for patient care.

Objective:

To develop and validate a streamlined version of the Expanded Disability Status Scale (sEDSS) for clinical monitoring.

Methods:

The EDSS was modified by eliminating maneuvers with no impact on function, consolidating redundancies, and simplifying scoring. This sEDSS was refined and preliminarily validated using a pilot cohort of 102 patients. Subsequently, the sEDSS was retrospectively validated using 968 patients from the CombiRx trial. We evaluated correlation and agreement between each functional system as well as the overall sEDSS and EDSS.

Results:

The sEDSS correlated strongly with the EDSS, both overall (Spearman’s rho = 0.93) and for each functional system (Spearman’s rho 0.65–0.97). Correlation was slightly lower for functional systems where scoring was modified for consolidation and simplification.

Conclusion:

The sEDSS had strong agreement and correlation with the existing EDSS and can provide a useful measure of disability in clinical practice.

Disability Progression After Switching from Natalizumab to Fingolimod or Interferon Beta/Glatiramer Acetate Therapies: A NARCOMS Analysis

Background: Physicians must weigh the benefits against the risk of progressive multifocal leukoencephalopathy (PML) in patients treated with natalizumab, especially beyond 2 years. However, disability progression associated with switching therapies versus continuing natalizumab therapy after 2 years has not been fully evaluated. Methods: In this retrospective analysis using the NARCOMS Registry, disability progression (Patient-Determined Disease Steps [PDDS] scale) and physical health-related quality of life (HRQOL) worsening (12-item Short Form Health Status Survey Physical Component Score [SF-12 PCS]) were compared between participants switching to fingolimod (n = 50) or interferon beta (IFNβ)/glatiramer acetate (GA) (n = 71) therapy and those continuing natalizumab (n = 406) after 2 years or more of treatment (median follow-up: natalizumab, 4 years; fingolimod, 4.5 years; IFNβ/GA, 5 years). Results: Participants continuing to take natalizumab had less disability progression (mean PDDS change: natalizumab, 0.3; fingolimod, 0.6; IFNβ/GA, 0.7; P = .0036), were less likely to report disability progression (proportion with PDDS increase: natalizumab, 31%; fingolimod, 46%; IFNβ/GA, 42%; P = .0296), and had less worsening in physical HRQOL (mean SF-12 PCS change: natalizumab, -1.4; fingolimod, -2.8; IFNβ/GA, -4.6; P = .0476) than those switching treatment. Conclusions: Although all medication groups exhibited some level of worsening, switching from natalizumab treatment after 2 years was associated with increased disability progression and worsening physical HRQOL. The risk of disability progression from disease activity and the risk of PML should be considered when making natalizumab treatment decisions.

Prevalence of multiple sclerosis symptoms across lifespan: data from the NARCOMS Registry

The North American Research Committee on Multiple Sclerosis is a voluntary patient registry with more than 38,000 registrants as of 2015. In a recent collaborative project, longitudinal data on patient-perceived impairment in 11 domains commonly affected by multiple sclerosis were examined and tabulated as a function of disease duration. The patterns of disability accumulation differed by domain. Certain symptoms (sensory, fatigue) were particularly prevalent early in the disease. Other symptoms (mobility, hand function, fatigue, bowel/bladder dysfunction, spasticity) were progressively more common with longer disease duration. Some symptoms (vision, cognition, sensory, pain, depression) were relatively common early on in multiple sclerosis, but did not appear to be more frequent with longer disease duration. Ongoing research includes studies of the impact of disease-modifying therapy and symptomatic treatment on patient-perceived impairment over the disease course.

Health insurance affects the use of disease-modifying therapy in multiple sclerosis

OBJECTIVE

To evaluate the association between health insurance coverage and disease-modifying therapy (DMT) use for multiple sclerosis (MS).

METHODS

In 2014, we surveyed participants in the North American Research Committee on MS registry regarding health insurance coverage. We investigated associations between negative insurance change and (1) the type of insurance, (2) DMT use, (3) use of free/discounted drug programs, and (4) insurance challenges using multivariable logistic regressions.

RESULTS

Of 6,662 respondents included in the analysis, 6,562 (98.5%) had health insurance, but 1,472 (22.1%) reported negative insurance change compared with 12 months earlier. Respondents with private insurance were more likely to report negative insurance change than any other insurance. Among respondents not taking DMTs, 6.1% cited insurance/financial concerns as the sole reason. Of respondents taking DMTs, 24.7% partially or completely relied on support from free/discounted drug programs. Of respondents obtaining DMTs through insurance, 3.3% experienced initial insurance denial of DMT use, 2.3% encountered insurance denial of DMT switches, and 1.6% skipped or split doses because of increased copay. For respondents with relapsing-remitting MS, negative insurance change increased their odds of not taking DMTs (odds ratio [OR] 1.50; 1.16-1.93), using free/discounted drug programs for DMTs (OR 1.89; 1.40-2.57), and encountering insurance challenges (OR 2.48; 1.64-3.76).

CONCLUSIONS

Insurance coverage affects DMT use for persons with MS, and use of free/discounted drug programs is substantial and makes economic analysis that ignores these supplements potentially inaccurate. The rising costs of drugs and changing insurance coverage adversely affect access to treatment for persons with MS.

Symptomatic Management of Multiple Sclerosis-Associated Tremor Among Participants in the NARCOMS Registry

BACKGROUND

Tremor affects 25% to 58% of patients with multiple sclerosis (MS) and is associated with poor prognosis and increased disability. MS-related tremor is difficult to treat, and data regarding patient-reported characterization and response to treatment are limited. We describe the symptomatic treatment of tremor in 508 enrollees in the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry who self-reported tremor.

METHODS

From 777 surveys sent to NARCOMS participants who indicated mild or greater tremor using the Tremor and Coordination Scale, we compiled data regarding disability, tremor severity, symptomatic medication use, and reported response to medications.

RESULTS

Symptomatic medications reported to reduce tremor were used by 238 respondents (46.9%). Symptomatic medication use was associated with increased rates of unemployment and disability, and many other characteristics were similar between groups. Symptomatic drug use was more likely in participants reporting moderate (53.9%) or severe (51.3%) tremor than in those with mild (36.6%) or totally disabling (35.0%) tremor. This disparity held true across multiple tremor severity scores. The most commonly used drug classes were anticonvulsants (50.8%) and benzodiazepines (46.2%), with gabapentin and clonazepam used most often in their respective classes.

CONCLUSIONS

Tremor in MS remains poorly treated; less than half of the participants reported benefit from symptomatic medications. Patients with moderate-to-severe tremor are more likely to report tremor benefit than are those with mild or disabling tremor. γ-Aminobutyric acid-active medications were most commonly reported as beneficial.

Improvement of multiple sclerosis-associated tremor as a treatment effect of natalizumab

BACKGROUND

Tremor is among the most physically disabling symptoms associated with MS. The effect of MS disease modifying therapies (DMTs) on the severity of MS tremor is unclear.

OBJECTIVE

To compare the change over time in scores reflecting tremor severity between subjects treated with natalizumab and other disease modifying drugs.

METHODS

Questionnaires were sent to North American Research Committee on MS registrants reporting mild or greater tremor on semiannual updates. Respondents on natalizumab and other MS therapies completed a survey which included tremor-specific scales to indicate tremor severity both currently and when the current therapy was initiated. Differences between natalizumab and non-natalizumab groups were compared using ANOVA.

RESULTS

Surveys were returned by 567 registrants, including 202 taking natalizumab. Subjects on natalizumab were more likely to report tremor improvement (29.6%) than those never (15.2%) or previously (14.8%, p=0.0002) on natalizumab. Over a mean recall period of 6.2+4.6 years, the Tremor Related Activities of Daily Living score worsened by 1.8 points among natalizumab-treated subjects, 3.3 points among those previously on natalizumab, and 5.3 points among those who never took natalizumab (p=0.009).

CONCLUSION

Respondents taking natalizumab were more likely to experience tremor improvement than those taking other MS disease modifying therapies.

Prevalence and characteristics of tremor in the NARCOMS multiple sclerosis registry: a cross-sectional survey

OBJECTIVES

(1)To describe the prevalence and severity of tremor in patients with multiple sclerosis (MS) registered within a large North American MS registry; (2) to provide detailed descriptions on the characteristics and severity of tremor in a subset of registrants and (3) to compare several measures of tremor severity for strength of agreement.

SETTING

The North American Research Committee on MS (NARCOMS) registry.

PARTICIPANTS

Registrants of NARCOMS reporting mild or greater tremor severity.

OUTCOME MEASURES

We determined the cross-sectional prevalence of tremor in the NARCOMS registry over three semiannual updates between fall 2010 and fall 2011. A subset of registrants (n=552) completed a supplemental survey providing detailed descriptions of their tremor. Outcomes included descriptive characteristics of their tremors and correlations between outcome measures to determine the strength of agreement in assessing tremor severity.

RESULTS

The estimated prevalence of tremor in NARCOMS ranged from 45% to 46.8%, with severe tremor affecting 5.5-5.9% of respondents. In the subset completing the supplemental survey, mild tremor severity was associated with younger age of MS diagnosis and tremor onset than those with moderate or severe tremor. However, tremor severity did not differ by duration of disease or tremor. Respondents provided descriptions of tremor symptoms on the Clinical Ataxia Rating Scale, which had a moderate to good (ρ=0.595) correlation with the Tremor Related Activities of Daily Living (TRADL) scale. Objectively scored Archimedes' spirals had a weaker (ρ=0.358) correlation with the TRADL. Rates of unemployment, disability and symptomatic medication use increased with tremor severity, but were high even among those with mild tremor.

CONCLUSIONS

Tremor is common among NARCOMS registrants and severely disabling for some. Both ADL-based and symptom-descriptive measures of tremor severity can be used to stratify patients.

Patient perspectives on switching disease-modifying therapies in the NARCOMS registry

INTRODUCTION

The evolving landscape of disease-modifying therapies (DMTs) for multiple sclerosis raises important questions about why patients change DMTs. Physicians and patients could benefit from a better understanding of the reasons for switching therapy.

PURPOSE

To investigate the reasons patients switch DMTs and identify characteristics associated with the decision to switch.

METHOD

The North American Research Committee on Multiple Sclerosis (NARCOMS) Registry conducted a supplemental survey among registry participants responding to the 2011 update survey. The supplemental survey investigated reasons for switching DMT, origin of the discussion of DMT change, and which factors influenced the decision. Chi-square tests, Fisher's exact tests, and logistic regression were used for the analyses.

RESULTS

Of the 691 eligible candidates, 308 responded and met the inclusion criteria (relapsing disease course, switched DMT after September 2010). The responders were 83.4% female, on average 52 years old, with a median (interquartile range) Patient-Determined Disease Steps score of 4 (2-5). The most recent prior therapy included first-line injectables (74.5%), infusions (18.1%), an oral DMT (3.4%), and other DMTs (4.0%). The discussion to switch DMT was initiated almost equally by physicians and participants. The primary reason for choosing the new DMT was based most frequently on physician's recommendation (24.5%) and patient perception of efficacy (13.7%).

CONCLUSION

Participants frequently initiated the discussion regarding changing DMT, although physician recommendations regarding the specific therapy were still weighed highly. Long-term follow-up of these participants will provide valuable information on their disease trajectory, satisfaction with, and effectiveness of their new medication.

Treatment discontinuation and disease progression with injectable disease-modifying therapies: findings from the north american research committee on multiple sclerosis database

Injectable first-line disease-modifying therapies (DMTs) for multiple sclerosis (MS) are generally prescribed for continuous use. Accordingly, the various factors that influence patient persistence with treatment and that can lead some patients to switch medications or discontinue treatment may affect clinical outcomes. Using data from the North American Research Committee on Multiple Sclerosis (NARCOMS) database, this study evaluated participants' reasons for discontinuation of injectable DMTs as well as the relationship between staying on therapy and sustained patient-reported disease progression and annualized relapse rates. Participants selected their reason(s) for discontinuation from among 16 possible options covering the categories of efficacy, safety, tolerability, and burden, with multiple responses permitted. Both unadjusted data and data adjusted for baseline age, disease duration, disability, and sex were evaluated. Discontinuation profiles varied among DMTs. Participants on intramuscular interferon beta-1a (IM IFNβ-1a) and glatiramer acetate (GA) reported the fewest discontinuations based on safety concerns, although GA was associated with reports of higher burden and lower efficacy than other therapies. Difficulties with tolerability were more often reported as a reason for discontinuing subcutaneous (SC) IFNβ-1a than as a reason for discontinuing IM IFNβ-1a, GA, or SC IFNβ-1b. In the persistent therapy cohort, less patient-reported disability progression was reported with IM IFNβ-1a treatment than with SC IFNβ-1a, IFNβ-1b, or GA. These findings have relevance to clinical decision making and medication compliance in MS patient care.

Natural history of multiple sclerosis symptoms

The North American Research Committee on Multiple Sclerosis (NARCOMS) Registry is a database that contains information from over 35,000 patient volunteers on symptom severity in 11 domains commonly affected in multiple sclerosis (MS): mobility, hand function, vision, fatigue, cognition, bowel/bladder function, sensory, spasticity, pain, depression, and tremor/coordination. The Registry affords a unique opportunity to study the frequency and severity of domain-specific impairment in a contemporary, mostly treated MS cohort over the course of the disease. The objective of this work was to calculate symptom prevalence in each of the 11 domains for years 0 to 30 from symptom onset. The resulting "symptom prevalence tables" demonstrate that a majority of participants perceive at least some degree of impairment in most domains as early as the first year of disease. The severity of impairment increases with disease duration across all domains, but the patterns of disability accumulation differ. The symptom prevalence tables illustrate the magnitude of perceived impact of the disease and highlight the extent of unmet need in symptomatic management. The tables are easy to use and allow MS patients and their clinicians to compare an individual's own impairment in any of the 11 domains to that of NARCOMS participants with the same disease duration.

Preferred sources of health information in persons with multiple sclerosis: degree of trust and information sought

Background

Effective health communication is important for informed decision-making, yet little is known about the range of information sources used by persons with multiple sclerosis (MS), the perceived trust in those information sources, or how this might vary according to patient characteristics.

Objective

We aimed to investigate the sources of health information used by persons with MS, their preferences for the source of health information, and levels of trust in those information sources. We also aimed to evaluate how these findings varied according to participant characteristics.

Methods

In 2011, participants in the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry were asked about their sources of health information using selected questions adapted from the 2007 Health Information National Trends (HINTS) survey.

Results

Of 12,974 eligible participants, 66.18% (8586/12,974) completed the questionnaire. Mass media sources, rather than interpersonal information sources, were the first sources used by 83.22% (5953/7153) of participants for general health topics and by 68.31% (5026/7357) of participants for MS concerns. Specifically, the Internet was the first source of health information for general health issues (5332/7267, 73.40%) and MS (4369/7376, 59.23%). In a logistic regression model, younger age, less disability, and higher annual income were independently associated with increased odds of use of mass media rather than interpersonal sources of information first. The most trusted information source was a physician, with 97.94% (8318/8493) reporting that they trusted a physician some or a lot. Information sought included treatment for MS (4470/5663, 78.93%), general information about MS (3378/5405, 62.50%), paying for medical care (1096/4282, 25.59%), where to get medical care (787/4282, 18.38%), and supports for coping with MS (2775/5031, 55.16%). Nearly 40% (2998/7521) of participants had concerns about the quality of the information they gathered.

Conclusions

Although physicians remain the most trusted source of health information for people with MS, the Internet is the first source of health information for most of them. This has important implications for the dissemination of health information.

Randomized study combining interferon and glatiramer acetate in multiple sclerosis

OBJECTIVE

A double-blind, randomized, controlled study was undertaken to determine whether combined use of interferon β-1a (IFN) 30 μg intramuscularly weekly and glatiramer acetate (GA) 20 mg daily is more efficacious than either agent alone in relapsing-remitting multiple sclerosis.

METHODS

A total of 1,008 participants were randomized and followed until the last participant enrolled completed 3 years. The primary endpoint was reduction in annualized relapse rate utilizing a strict definition of relapse. Secondary outcomes included time to confirmed disability, Multiple Sclerosis Functional Composite (MSFC) score, and magnetic resonance imaging (MRI) metrics.

RESULTS

Combination IFN+GA was not superior to the better of the single agents (GA) in risk of relapse. Both the combination therapy and GA were significantly better than IFN in reducing the risk of relapse. The combination was not better than either agent alone in lessening confirmed Expanded Disability Status Scale progression or change in MSFC over 36 months. The combination was superior to either agent alone in reducing new lesion activity and accumulation of total lesion volumes. In a post hoc analysis, combination therapy resulted in a higher proportion of participants attaining disease activity-free status (DAFS) compared to either single arm, driven by the MRI results.

INTERPRETATION

Combining the 2 most commonly prescribed therapies for multiple sclerosis did not produce a significant clinical benefit over 3 years. An effect was seen on some MRI metrics. In a test of comparative efficacy, GA was superior to IFN in reducing the risk of exacerbation. The extension phase for CombiRx will address whether the observed differences in MRI and DAFS findings predict later clinical differences.

Disability in multiple sclerosis: a reference for patients and clinicians

OBJECTIVE

To create a reference table of disability outcomes in multiple sclerosis (MS) that would enable patients to rank their disability relative to others' with similar disease duration and to develop a cost-effective research tool for comparing MS severity across patient populations and time periods.

METHODS

The North American Research Committee on Multiple Sclerosis (NARCOMS) Registry collects disability data from patients with MS on a validated, 9-point Patient-Determined Disease Steps (PDDS) scale. We compiled the Disability Expectancy Table, which displays cumulative frequencies of PDDS scores for each year of disease duration, from 0 to 45 years. We also tabulated disease duration-adjusted mean ranks of PDDS scores, referred to as Patient-derived MS Severity Scores (P-MSSS).

RESULTS

The cohort consisted of 27,918 NARCOMS enrollees, 72.7% of whom were female and 90.1% of whom were white. Mean age at symptom onset was 30.1 ± 10.1 years, and age at enrollment was 47.1 ± 11.0 years. The Disability Expectancy Table and P-MSSS afford a detailed overview of disability outcomes in a large MS cohort over a 45-year period. In the first year of disease, 15% of patients reported need of ambulatory aid, and 4% needed bilateral assistance or worse; after 45 years of disease, 76% of patients required ambulatory aid, and 52% bilateral assistance or worse. Proportion of patients who reported minimal or no interference in daily activities (PDDS ≤ 1) declined from 63% in the first year to 8% after 45 years of disease.

CONCLUSION

The Disability Expectancy Table allows individual patients to determine how their disability ranks relative to NARCOMS enrollees with the same disease duration. P-MSSS may be used to compare disability across patient populations and to track disease progression in patient cohorts. P-MSSS does not require a formal neurologic examination and may therefore find wide applicability as a practical and cost-effective outcome measure in epidemiologic studies.

"Seeing" in NARCOMS: a look at vision-related quality of life in the NARCOMS registry

BACKGROUND

Research on vision-related quality of life (QOL) in multiple sclerosis (MS) is still limited. Tools such as the Visual Functioning Questionnaire-25 (VFQ-25) and the Vision Performance Scale (VPS) facilitate assessments of the severity of visual impairment and its impact on daily life.

OBJECTIVE

The objective of this paper is to examine vision-related QOL, comorbid eye conditions, use of visual aids and utilization of eye-care providers in the North American Research Committee on Multiple Sclerosis (NARCOMS) population, and to explore these issues in those with a history of optic neuritis (ON) and diplopia.

METHODS

In 2008, NARCOMS registrants reported on their use of visual aids, the VFQ-25, VPS, history of ON, diplopia, refractive error conditions (REC) and comorbid eye diseases (CED). We conducted regression analyses and correlations between select variables.

RESULTS

The response rate for the survey was 60.4%. Of the 9107 responders, 66.7% reported visual disability measured by VPS. Of respondents, 43.1% had a history of ON and 38.6% reported prior diplopia. Frequencies of myopia (51.8%), hyperopia (26.6%), and uveitis (3.4%) exceeded those expected for the general population. Mean (SD) VFQ-25 composite score was 82.0 (14.2). A history of ON or diplopia accounted for 9.7% of the variance in the VFQ-25; 90.6% of respondents used glasses or contact lenses. Rates of utilizations of eye-care providers were lower than expected.

CONCLUSION

Prior ON, diplopia, REC and CED adversely impact vision-related QOL in MS. Increased utilization of eye-care providers and use of visual aids could improve vision-related QOL in people with MS.

Impact of loss of mobility on instrumental activities of daily living and socioeconomic status in patients with MS

OBJECTIVE

To assess the effects of mobility loss on instrumental activities of daily living (IADL) and socioeconomic status in multiple sclerosis (MS) patients.

METHODS

Participants were active registrants in the North American Research Committee on Multiple Sclerosis registry completing the Fall 2006 (IADL analysis, n = 10,396) or Spring 2007 (socioeconomic analysis, n = 8180) surveys. Cross-sectional correlations and linear and logistic regression were performed using sociodemographic factors, mobility scales, and Patient Determined Disease Steps as independent variables and IADLs as the response.

RESULTS

Mobility loss was significantly correlated with decreased IADL scores (r = -0.74; p < 0.0001); this correlation remained significant after adjustment for covariates. Mobility loss also negatively correlated with employment (r = -0.48 for women; r = -0.50 for men, both p < 0.0001) and annual income (r = -0.29; p < 0.0001). These correlations were all significant even with mild mobility loss. The relationships derived from the regression models suggest that the effect of mobility on employment is greater than the effect of demographic variables, and a small but direct effect on annual income that is independent of effects mediated through employment. The self-reported diagnosis of MS for study inclusion and use of single-item ordinal scales for mobility and disability can potentially be criticized as study limitations, although the diagnosis and the scales were previously validated.

CONCLUSION

Mobility loss independently correlated with IADL, and associated with reduced socioeconomic status in people with MS. These correlations were significant with mild mobility loss, supporting early treatment.

Retinal architecture predicts pupillary reflex metrics in MS

OBJECTIVE

To study the relation of retinal nerve fiber layer thinning to clinical and physiologic measures of visual function in patients with MS or neuromyelitis optica and unilateral optic neuropathy.

METHODS

We studied a cohort of control subjects (n = 64) and patients (n = 24) with evidence of unilateral thinning of their average retinal nerve fiber layer as measured by optical coherence tomography in order to characterize the relationship between ganglion cell axonal degeneration and its impact upon vision and pupillary light reflex metrics using infrared pupillometry.

RESULTS

When compared to the normal fellow eye, and with respect to normal subjects' eyes, we confirmed significant abnormalities in retinal nerve fiber layer thickness, total macular volume, low-contrast letter acuity, and pupillary reflex metrics in the eye with the thinner retinal nerve fiber layer. For each -5% change in pupil diameter, there was a corresponding 7.1 Amicrom reduction in the average retinal nerve fiber layer thickness. There was a significant difference between the pupillary metric of percent change in diameter and a decrease in low-contrast letter acuity (P < 0.001). Each -5% change in pupil diameter was associated with a substantial 3.4 line loss of low-contrast letter acuity (P < 0.001). Each -5% change in pupil diameter was associated with a 0.2 mm(2) decrease in total macular volume (P < 0.001).

CONCLUSION

These findings further corroborate the hypothesis that the retina can be utilized as a model to advance our understanding of the mechanisms of axonal and neurodegeneration, and the corresponding impact of these processes upon the pathophysiology of MS and related disorders.