Retinal thickness measured with optical coherence tomography and risk of disability worsening in multiple sclerosis: a cohort study

Retinal Optical Coherence Tomography Longitudinal Measures as Prognostic Biomarkers in Multiple Sclerosis: Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Optical coherence tomography (OCT) has emerged as a valuable marker for assessing inflammation and neuroaxonal degeneration in multiple sclerosis (MS). Although traditional markers such as brain atrophy and axonal loss are crucial for monitoring MS progression, their clinical application can be limited by various factors. This meta-analysis of longitudinal studies aims to assess the predictive value of OCT-derived retinal layer thickness thresholds for monitoring and predicting MS disease progression and cognitive decline.

METHODS

Our systematic review and meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A comprehensive systematic search was performed using electronic databases (PubMed, Embase, Web of Science, and Google Scholar) for longitudinal studies using Spectral Domain-OCT (SD-OCT) to assess retinal layer thickness and its predictive value for MS progression. Data were extracted on study design, OCT measurements, disability progression definitions, and clinical outcomes. We analyzed hazard ratios (HR) and odds ratios (OR) for associations between OCT-measured thresholds and disability progression, including physical and cognitive deterioration.

RESULTS

Our study included 14 longitudinal studies that met our inclusion criteria, 13 studies were included in our quantitative analysis, with a total of 3,683 participants. Baseline peripapillary retinal nerve fiber layer (pRNFL) thickness below 88 μm was significantly associated with increased risk of future disease progression and physical worsening measured by Expanded Disability Status Scale progression (HR = 2.376, p < 0.001; HR = 2.258, p < 0.001, respectively). The same was noted for ganglion cell-inner plexiform layer (GCIPL) thickness below 77 μm (HR = 2.751, p < 0.001 and HR = 2.66, p < 0.001, respectively). In addition, annualized rates of pRNFL thinning above 1.5 μm/y and GCIPL thinning above 1 μm/y also significantly predicted disease worsening (HR = 3.019, p = 0.005 and HR = 3.535, p < 0.001, respectively).

DISCUSSION

OCT-derived retinal layer thresholds, specifically a pRNFL thickness of ≤88 μm and a GCIPL thickness of ≤77 μm, are significantly associated with an increased risk of future MS disability progression. Furthermore, annual thinning rates of pRNFL >1.5 μm/y and GCIPL >1 μm/y demonstrate greater predictive power and are more clinically relevant for identifying individuals at high risk of both physical and cognitive disability progression outcomes. Further research is needed to standardize OCT thresholds and improve clinical use in treatment planning.

Optical coherence tomography in secondary progressive multiple sclerosis: cross-sectional and longitudinal exploratory analysis from the MS-SMART randomised controlled trial

BACKGROUND

Optical coherence tomography (OCT) inner retinal metrics reflect neurodegeneration in multiple sclerosis (MS). We explored OCT measures as biomarkers of disease severity in secondary progressive MS (SPMS).

METHODS

We investigated people with SPMS from the Multiple Sclerosis-Secondary Progressive Multi-Arm Randomisation Trial OCT substudy, analysing brain MRIs, clinical assessments and OCT at baseline and 96 weeks. We measured peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell-inner plexiform layer (GCIPL) thicknesses. Statistical analysis included correlations, multivariable linear regressions and mixed-effects models.

RESULTS

Of the 212 participants recruited at baseline, 192 attended at 96 weeks follow-up. Baseline pRNFL and GCIPL thickness correlated with Symbol Digit Modalities Test (SDMT) (respectively, r=0.33 (95% CI 0.20 to 0.47); r=0.39 (0.26 to 0.51)) and deep grey matter volume (respectively, r=0.21 (0.07 to 0.35); r=0.28 (0.14 to 0.41)).pRNFL was associated with Expanded Disability Status Scale (EDSS) score change (normalised beta (B)=-0.12 (-0.23 to -0.01)). Baseline pRNFL and GCIPL were associated with Timed 25-Foot Walk change (T25FW) (respectively, B=-0.14 (-0.25 to -0.03); B=-0.20 (-0.31 to -0.10)) and 96-week percentage brain volume change (respectively, B=0.14 (0.03 to 0.25); B=0.23 (0.12 to 0.34)). There were significant annualised thinning rates: pRNFL (-0.83 µm/year) and GCIPL (-0.37 µm/year).

CONCLUSIONS

In our cohort of people with SPMS and long disease duration, OCT measures correlated with SDMT and deep grey matter volume at baseline; EDSS, T25FW and whole brain volume change at follow-up.

Slower retinal thinning over a year predicts continuous NEDA status at follow-up in multiple sclerosis: A longitudinal OCT study

INTRODUCTION

Retinal layer thickness measured by optical coherence tomography (OCT) correlates with disability and disease activity in multiple sclerosis (MS), yet there is scarce data on the ability of retinal OCT rates of change to predict subsequent continuous disease stability.

AIMS

To investigate whether the rate of change in retinal OCT measures during the first year of monitoring can predict maintenance of continuous "No evidence of disease activity" (c-NEDA) status in MS.

METHODS

We conducted a longitudinal study of people with MS (PwMS) from our observational cohort (AMIR) at the American University of Beirut. Cases included had at least three spectral-domain OCT scans at baseline, 12 months, and at the last visit. Mixed effects regression (controlling for age, sex, disease duration, EDSS, gap time from initiation of current DMT to first OCT scan, type of DMT, and history of optic neuritis per eye) was performed to explore the differences between the annualized changes in retinal layer thicknesses (microns/year) during the first year in the c-NEDA group compared to those with evidence of disease activity (EDA) at any point during follow-up.

RESULTS

In total, 222 eyes of 111 RRMS cases (67 females, 60.4%) were included and followed up clinically for a median (min-max) of 5.24 (3-8.64) years. During the study period, 51 (45.9%) cases maintained c-NEDA, and 60 (54.1%) had EDA. In regression models, EDA cases had greater mean retinal thinning rates during the first year of observation compared to c-NEDA cases with an annualized loss (microns/year) in pRNFL of -1.84 versus 0.03 (p < 0.0001); in macular RNFL -1.86 versus -0.76 (p < 0.0001); in GCIPL -0.13 versus 0.53 (p = 0.008); and in retinal thickness -3.81 versus -1.06 (p < 0.0001).

CONCLUSION

Our data support the potential value of retinal OCT in prospectively identifying PwMS likely to maintain c-NEDA status versus EDA during follow-up, guiding proactive treatment strategies.

Cognitive test performance and disease progression in primary and secondary progressive MS: An analysis of the SPRINT-MS study

BACKGROUND

Clinical trials of disease-modifying therapies (DMTs) for multiple sclerosis (MS) increasingly incorporate cognitive outcomes, although effects of DMTs on cognition remain unknown.

METHODS

In this secondary analysis of data from SPRINT-MS, a phase 2 randomized, placebo-controlled trial of ibudilast for progressive MS, we evaluated performance on Symbol Digit Modalities Test (SDMT) and Selective Reminding Test (SRT) in relation to physical disability, brain volume assessed with magnetic resonance imaging, and retinal nerve fiber layer (RNFL) thickness over 96-week follow-up. We hypothesize that trial participants would show a decline in cognitive test scores over 96 weeks of follow-up, with a possible between-group difference in favor of ibudilast.

RESULTS

Data from 255 participants were analyzed. On average, physical outcome measures, brain parenchymal fraction, and RNFL thickness worsened; average SDMT and SRT scores remained largely unchanged. There were no differences between treatment groups in cognitive outcomes at 96-week follow-up. Practice effects likely contributed to results.

CONCLUSIONS

Observed stability of cognitive scores in individuals with progressive MS over 96-week follow-up may reflect true cognitive stability. However, the possibility that current cognitive measurement instruments are psychometrically flawed remains, warranting further research.

Interventions promoting remyelination in multiple sclerosis: a systematic review of clinical trials

OBJECTIVES

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) characterized by demyelination and axonal damage. Current therapies primarily manage symptoms and slow disease progression but do not achieve remyelination. This systematic review evaluates the efficacy and safety of remyelination-promoting interventions in MS, focusing on clinical trials utilizing outcome measures validated in prior studies as indicators of remyelination.

METHODS

A comprehensive search of PubMed, Embase, Web of Science, and Cochrane Library was conducted in May 2024. Clinical trials assessing interventions with potential remyelinating properties were included. Data extraction followed standardized forms, and study quality was evaluated using ROBINS-I for non-randomized trials and RoB 2.0 for RCTs. Remyelination was assessed using Magnetization Transfer Ratio (MTR), Visual Evoked Potentials (VEPs), Myelin Water Fraction (MWF), Diffusion Tensor Imaging (DTI), and Optical Coherence Tomography (OCT).

RESULTS

From 1,615 screened records, 25 studies met the inclusion criteria and were analyzed. Across the 3341 participants, 17 interventions were evaluated. Most studies demonstrated a moderate risk of bias, yet all interventions, except one, were generally safe and well tolerated. Notably, rHIgM22, L-T3, opicinumab, clemastine fumarate, phenonytoin, domperidone, GSK239512, human fetal neural precursor cells (hfNPCs), and low-intensity repetitive transcranial magnetic stimulation (LI-rTMS) exhibited remyelination potential. Additionally, disease-modifying therapies (DMTs) such as Ocrelizumab, Fingolimod, and Natalizumab showed promising effects.

DISCUSSION

Although several interventions demonstrated remyelination potential, limitations such as small sample sizes, short follow-up periods, and lack of standardized clinical endpoints validating remyelination's functional impact, highlight the need for robust clinical trial designs, advanced biomarkers, and combination therapies integrating remyelination, neuroprotection, and immunomodulation to improve MS treatment outcomes.

An update on the evaluation of treatment switching criteria in multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a complex disorder driven by both inflammatory and neurodegenerative processes. While disease-modifying therapies (DMTs) have significantly improved prognosis, robust treatment switching criteria remain essential to balance efficacy and safety over the disease course.

AREAS COVERED

This review examines historical and current criteria for escalating DMTs from moderate- to high-efficacy therapies (HET). The authors summarize emerging clinical, imaging, and biological markers that inform decision-making and explore strategies for de-escalation, including DMT discontinuation and innovative approaches such as exit and bridge therapies.

EXPERT OPINION

Recent advances in MS management emphasize earlier initiation of HET and more stringent switching criteria. Although innovative monitoring tools - including clinical evaluations, imaging, biological markers, and patient-reported outcomes (PROs) - enhance disease assessment, they require further validation, standardization, and broader accessibility. Similarly, de-escalation criteria need additional research to optimize patient selection.

Biomarkers of Progression Independent of Relapse Activity-Can We Actually Measure It Yet?

Progression independent of relapse activity (PIRA) is increasingly recognized as a key driver of disability in multiple sclerosis (MS). However, the concept of PIRA remains elusive, with uncertainty surrounding its definition, underlying mechanisms, and methods of quantification. This review examines the current landscape of biomarkers used to predict and measure PIRA, focusing on clinical, imaging, and body fluid biomarkers. Clinical disability scores such as the Expanded Disability Status Scale (EDSS) are widely used, but may lack sensitivity in capturing subtle relapse-independent progression. Imaging biomarkers, including MRI-derived metrics (brain and spinal cord volume loss, chronic active lesions) and optical coherence tomography (OCT) parameters (retinal nerve fiber layer and ganglion cell-inner plexiform layer thinning), offer valuable insights, but often reflect both inflammatory and neurodegenerative processes. Body fluid biomarkers, such as neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP), are promising indicators of axonal damage and glial activation, but their specificity for PIRA remains limited. This review emphasizes the distinction between predicting PIRA-identifying individuals at risk of future progression-and measuring ongoing PIRA-related disability in real time. We highlight the limitations of current biomarkers in differentiating PIRA from relapse-associated activity and call for a clearer conceptual framework to guide future research. Advancing the precision and utility of PIRA biomarkers will require multimodal approaches, longitudinal studies, and standardized protocols to enable their clinical integration and to improve personalized MS management.

Macular inner retinal layers in multiple sclerosis

Aim

To evaluate the structural changes of individual inner retinal layers in the macular area and identify the most affected layer in subgroups of multiple sclerosis (MS) patients compared to healthy controls (HC).

Methods

In total, Optical coherence tomography (OCT) data from 507 MS patients and 183 HC were exported retrospectively. The MS patients were grouped according to MS sub-types, primary progressive (PP), Relapsing-Remitting (RR) and Secondary progressive (SP). Thickness of four inner retinal layers, the macula nerve fiber layer (NFL), ganglion cell layer (GCL), inner plexiform layer (IPL) and the inner nuclear layer (INL) were evaluated in nine sectors based on the Early Treatment Diabetic Retinopathy Study (ETDRS) map. The individual layer thickness measurements were compared between each MS subtype and HC while controlling for the potential confounding effects of age, sex, and previous history of ON.

Results

The NFL was thinner in all inferior, superior, and nasal sectors in all MS subgroups. The thinning was more pronounced in the PP and SP groups. The thinning varied between 3 to 20% compared to HC. The GCL was also thinner, especially in the inner sectors of the ETDRS grid. The SP subgroup had the largest reduction (27.8%) in the inner nasal sector. The IPL was also reduced in all MS subgroups. In contrast to PP and SP groups, the RR group showed an increased INL thickness compared to HC in the inner sectors.

Conclusion

Macular region is suitable for monitoring the neurodegeneration in MS. The macular NFL seems to have the strongest association with MS disease and may serve as a marker for global atrophy. The pattern of IPL reduction tends to follow the GCL, so these layers can be measured combined.

Optical coherence tomography and angiography in multiple sclerosis: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Anterior visual pathway involvement is common in multiple sclerosis (MS) and optical coherence tomography (OCT) can be utilized to examine the integrity of the ganglion cell axons (peri-papillary retinal nerve fiber layer; pRNFL) and cell bodies (ganglion cell & inner plexiform layer; GCIPL). OCT angiography (OCTA) can be used to investigate the retinal microvasculature. In this systematic review and meta-analysis, we synthesized OCT and OCTA findings in MS.

METHODS

We identified studies that performed OCT and OCTA in people with MS and included data permitting at least one of the following comparisons: 1) MS optic neuritis (MS-ON) vs healthy-control (HC) eyes; 2) MS non-ON (MS-NON) vs HC eyes; and 3) MS-ON vs MS-NON eyes.

RESULTS

The OCT meta-analysis included 170 studies and 8542 HC, 5529 MS-ON, and 14,822 MS-NON eyes. MS-ON and MS-NON eyes had lower pRNFL and GCIPL thickness compared to HC. There was no difference in inner nuclear layer (INL) thickness between HC and MS; INL was thicker in MS-ON compared to MS-NON eyes. The OCTA meta-analysis included 24 studies and 1344 HC, 505 MS-ON, and 1168 MS-NON eyes. MS-ON and MS-NON eyes had lower peripapillary vessel density and macular superficial vessel density compared to HC. We also summarized 12 studies evaluating the diagnostic yield of inter-eye differences in OCT measurements for detecting unilateral optic nerve involvement.

CONCLUSIONS

OCT allows for reliable quantification of retinal neuro-axonal damage in MS. In our review, we highlight studies demonstrating that OCT can establish robust thresholds for detecting unilateral optic nerve involvement.

Effect of siponimod on retinal thickness, a marker of neurodegeneration, in participants with SPMS: Findings from the EXPAND OCT substudy

BACKGROUND

People with MS show abnormal thinning of the retinal layers, which is associated with clinical disability and brain atrophy, and is a potential surrogate marker of neurodegeneration and treatment effects.

OBJECTIVE

To evaluate the utility of retinal thickness as a surrogate marker of neurodegeneration and treatment effect in participants with secondary progressive MS (SPMS) from the optical coherence tomography (OCT) substudy of the EXPAND Phase 3 clinical trial (siponimod versus placebo).

METHODS

In the OCT substudy population (n = 159), treatment effects on change in the average thickness of the retinal layer, peripapillary retinal nerve fiber layer (pRNFL), and combined macular ganglion cell and inner plexiform layers (GCIPL) were analyzed by high-definition spectral domain OCT at months 3, 12, and 24.

RESULTS

Thinning from baseline was observed across all retinal layers and time points in the placebo group. Siponimod significantly reduced GCIPL thinning versus placebo at month 24 (adjusted mean [SE] [µm]: -0.47 [0.81] vs. -4.29 [1.23]; p = 0.01), and overall retinal thinning at months 12 (+0.66 [0.54] vs. -1.86 [0.75]; p = 0.006) and 24 (-0.05 [0.59] vs. -2.30 [0.88]; p = 0.033). Although not significant, results for pRNFL consistently followed the same trends.

CONCLUSION

This exploratory substudy supports further investigation of OCT measurement of retinal atrophy as a non-invasive potential biomarker of treatment effects on neurodegeneration in SPMS.

Association of peripapillary retinal nerve fiber layer atrophy with cognitive impairment in patients with neuromyelitis optica spectrum disorder

BACKGROUND

We aimed to explore the association between peripapillary retinal nerve fiber layer thickness (pRNFL), macular ganglion cell-inner plexiform layer (mGCIPL), and cognitive impairment (CI) in patients with neuromyelitis optica spectrum disorder (NMOSD).

METHOD

In this cross-sectional study, 38 (28 aquaporin-4 (AQP4) IgG-seropositive) NMOSD patients and 20 healthy controls (HC) underwent cognitive assessment using Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS) battery. Spectral-domain optical coherence tomography (OCT) was performed for both eyes of all NMOSD patients. First, we examined the association of pRNFL and mGCIPL with cognitive function in all patients, regardless of the history of previous optic neuritis (ON). We then included only eyes without a prior history of ON, incorporating non-ON eyes in patients with unilateral ON and the average of OCT measures for both non-ON eyes in patients without a history of ON.

RESULTS

Sixteen (42.1%) NMOSD patients exhibited global CI. There was a significant decrease in pRNFL (Δ: 24.33 μm, p = 0.002) and mGCIPL (Δ: 9.20 μm, p = 0.009) in NMOSD patients with CI compared to those without. The atrophy of pRNFL showed an inverse association with CI before (OR = 1.059, 95% CI: 1.015, 1.105) and after adjustment for age, sex, and disease duration (OR = 1.072, 95%CI: 1.009, 1.139). An inverse significant association was observed between mGCIPL atrophy and CI before adjustment (OR = 1.102, 95% CI: 1.017, 1.194), but not after adjustment (OR = 1.106, 95%CI: 0.999, 1.224). After narrowing our analysis to non-ON eyes, the same results for pRNFL and CI were observed (unadjusted: OR = 1.054, 95% CI: 1.004, 1.106; adjusted: OR = 1.081, 95%CI: 1.000, 1.168). There was no significant association found between mGCIPL thickness and CI in both unadjusted and adjusted models. In sensitivity analyses, we observed no significant association between pRNFL and mGCIPL with CI in AQP-IgG-seropositive NMOSD patients.

CONCLUSION

This study, for the first time, provide a preliminary evidence for a possible relation between pRNFL atrophy and occurrence of cognitive impairment in NMOSD patients. Further studies are required to explore the possible association of OCT parameters with cognition function in NMOSD patients.

Biomarker combinations from different modalities predict early disability accumulation in multiple sclerosis

Objective

Establishing biomarkers to predict multiple sclerosis (MS) disability accrual has been challenging using a single biomarker approach, likely due to the complex interplay of neuroinflammation and neurodegeneration. Here, we aimed to investigate the prognostic value of single and multimodal biomarker combinations to predict four-year disability progression in patients with MS.

Methods

In total, 111 MS patients were followed up for four years to track disability accumulation based on the Expanded Disability Status Scale (EDSS). Three clinically relevant modalities (MRI, OCT and blood serum) served as sources of potential predictors for disease worsening. Two key measures from each modality were determined and related to subsequent disability progression: lesion volume (LV), gray matter volume (GMV), retinal nerve fiber layer, ganglion cell-inner plexiform layer, serum neurofilament light chain (sNfL) and serum glial fibrillary acidic protein. First, receiver operator characteristic (ROC) analyses were performed to identify the discriminative power of individual biomarkers and their combinations. Second, we applied structural equation modeling (SEM) to the single biomarkers in order to determine their causal inter-relationships.

Results

Baseline GMV on its own allowed identification of subsequent EDSS progression based on ROC analysis. All other individual baseline biomarkers were unable to discriminate between progressive and non-progressive patients on their own. When comparing all possible biomarker combinations, the tripartite combination of MRI, OCT and blood biomarkers achieved the highest discriminative accuracy. Finally, predictive causal modeling identified that LV mediates significant parts of the effect of GMV and sNfL on disability progression.

Conclusion

Multimodal biomarkers, i.e. different major surrogates for pathology derived from MRI, OCT and blood, inform about different parts of the disease pathology leading to clinical progression.

Anatomy-driven segmentation of parafoveal optical coherence tomography (OCT) measures may improve associations with clinical outcomes in multiple sclerosis

BACKGROUND

Previous investigations on optical coherence tomography (OCT) in multiple sclerosis (MS) focused on generalizable macular and peri-papillary regions without considering the anatomic variations of the retinal layer thickness.

OBJECTIVE

This study aimed to assess the utility of parafoveal retinal layer thickness measured by OCT, underscoring its relationships with clinical outcomes in MS.

METHODS

In this cross-sectional study, 214 people with MS (pwMS) and 57 age- and sex-matched healthy controls (HCs) were enrolled. Spectral domain OCT evaluation using 1, 3, 6 mm Early Treatment Diabetic Retinopathy Study grid were conducted. The macular and parafoveal thickness (excluding the 1 mm foveal/umbo contribution) of the retinal nerve fiber layer (RNFL), ganglion cell-inner plexiform layer (GCIPL), ganglion cell layer (GCL), inner plexiform layer (IPL), and the peri-papillary RNFL (pRNFL) were measured. Multivariable step-wise logistic, linear and generalized estimating equation (GEE) regression models were used to assess the association between the OCT parameters and clinical MS outcomes.

RESULTS

The parafoveal RNFL thickness (d = 0.27, p = 0.023), GCL (d = 0.87, p < 0.001), IPL (d = 0.82, p < 0.001), and GCIPL (d = 0.85, p < 0.001) were all significantly lower in pwMS than HCs. Optic neuritis history [odds ratio (OR) = 0.84, p < 0.001] and progressive MS (PMS) status (OR = 0.92, p < 0.001) were both best predicted by parafoveal GCL. The Expanded Disability Status Scale (EDSS) was associated with the parafoveal thickness of GCL (standardized β = -0.472, p < 0.001) and pRNFL (standardized β = 0.187, p = 0.021). The parafoveal GCL thickness as predictor of MS disability was also confirmed by the GEE models.

CONCLUSION

This investigation supports the potential use of parafoveal OCT segmentation as an alternative assessment method in detecting neuroinflammatory and neurodegenerative processes in MS. Averaging of the parafoveal retinal layer thickness into the OCT measures may increase the sensitivity of the standard macular OCT segmentation outcomes. Further studies should aim at exploring the reproducibility of this OCT outcome and its longitudinal responsiveness.

A bibliometric analysis of optic atrophy from 2003 to 2023: research trends and hot spots

Background

Optic atrophy (OA) is primarily caused by damage to the retinal pathway system, including widespread degeneration of retinal ganglion cells and axons, leading to visual impairment and blindness. Despite its clinical significance and diverse etiological factors, there is currently a lack of comprehensive bibliometric analyses exploring research trends and hotspots within this field.

Method

This study retrieved relevant literature on OA published between 2003 and 2023 from the Web of Science Core Collection database. We conducted a bibliometric analysis using tools such as CiteSpace, VOSviewer, and SCImago Graphica to examine annual publication trends, co-occurrence patterns, collaborative networks among countries and institutions, and the evolution of research hotspots of OA.

Results

A total of 5,274 publications were included in the bibliometric analysis, comprising 4,561 research articles and 713 review articles. The United States emerged as the leading country in OA research, followed by Germany and China. Over the past two decades, the primary research hotspots focused on "mitochondrial dysfunction," "hereditary optic neuropathy," "ocular hypertension" and "diagnostic techniques." Future research trends are likely to revolve around "molecular mechanisms" and "therapeutic targets."

Conclusion

This bibliometric analysis provides an overview of research developments in OA over the past 20 years, highlighting the emphasis on the pathological basis of OA and advancements in diagnostic and therapeutic approaches. Future studies should continue to explore the molecular basis of mitochondrial dysfunction to identify potential gene therapy targets for treating OA.

Effect of Different Treatments on Retinal Thickness Changes in Patients With Multiple Sclerosis: A Review

BACKGROUND

Multiple sclerosis (MS) is an autoimmune disorder affecting the central nervous system, with varying clinical manifestations such as optic neuritis, sensory disturbances, and brainstem syndromes. Disease progression is monitored through methods like MRI scans, disability scales, and optical coherence tomography (OCT), which can detect retinal thinning, even in the absence of optic neuritis. MS progression involves neurodegeneration, particularly trans-synaptic degeneration, which extends beyond the initial injury site. This review focuses on the impact of different MS treatments on retinal thickness as assessed by OCT.

RESULTS

Injectable drugs, such as interferon beta and glatiramer acetate (GA), have a relatively modest impact on retinal atrophy. Oral medications like Fingolimod, Teriflunomide, and Dimethyl fumarate also have different impacts on retinal thickness. Fingolimod has been shown to protect against retinal thinning but may lead to macular edema. DMF-treated patients had less ganglion cell-inner plexiform layer thinning than GA-treated patients but more thinning compared to natalizumab-treated patients and healthy controls. Teriflunomide's impact on retinal layers remains unexplored in human studies. Monoclonal antibodies, including Alemtuzumab, Rituximab, Ocrelizumab, and Natalizumab, had protective effects on retinal layer atrophy. Alemtuzumab-treated patients showed significantly less atrophy compared to interferon- and GA-treated patients. Rituximab initially increased atrophy rates in the first months but subsequently demonstrated potential neuroprotective effects. Ocrelizumab slowed the rate of inner nuclear layer thinning in progressive forms of the disease. Natalizumab is considered the most effective in reducing retinal layer atrophy, particularly the peripapillary retinal nerve fiber layer.

CONCLUSIONS

It's important to note that the effectiveness of these treatments may vary depending on MS subtype and individual factors. Future research should explore the long-term effects of these treatments on retinal layers and their correlations with overall disease progression and disability in MS patients.

Multimodal Longitudinal Optical Imaging Reveals Optic Neuritis Preceding Retinal Pathology in Experimental Autoimmune Encephalomyelitis

BACKGROUND AND OBJECTIVES

Inflammatory demyelinating diseases of the CNS, chief among them multiple sclerosis (MS), are a major cause of disability in young adults. Early manifestations of MS commonly involve visual dysfunction, which is often caused by optic neuritis and is accompanied by quantifiable structural changes of the anterior visual pathway. Retinal optical coherence tomography (OCT) has emerged as an important tool for clinical assessment of these structural alterations, but the underlying pathobiological mechanisms and temporal dynamics are yet poorly understood at a cellular level.

METHODS

Using the experimental autoimmune encephalomyelitis (EAE) model of MS in fluorescent reporter mouse strains for neuronal function and innate immune cells, we use a unique combination of retinal intravital 2-photon microscopy (2PM) and OCT. In this fashion, we elucidate the spatiotemporal interplay of functional and structural retinal changes over the course of 1 month after EAE induction, with histopathologic imaging validating main results.

RESULTS

While all mice display histologic signs of optic neuritis early after EAE induction and independently of motor symptom severity, retinal signs of neuronal stress and parenchymal immune activation spike well after clinical peak of disease, with no signs of lasting structural damage appearing within 1 month after EAE induction. Thus, local retinal endpoints appear to be functions of downstream axonal damage rather than of immediate immune activation directed at the retina. However, as early as 1 week after EAE induction, retinal 2PM can detect recruitment of perivascular immune cells towards the optic nerve (ON), providing the earliest sign of disease activity in otherwise clinically inconspicuous mice.

DISCUSSION

Our work identifies the recruitment of CX3CR1+ cells to the ON as an early sign of disease underlining the importance of combined structural and functional retinal imaging for the spatiotemporal characterization of neuroinflammatory and neurodegenerative processes. It further proposes retinal phagocyte orientation, morphology, and abundance as potential surrogate markers for neurodegenerative activity.

Measuring Disease Progression in Multiple Sclerosis Clinical Drug Trials and Impact on Future Patient Care

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system characterised by inflammation, demyelination and neurodegeneration. Although several drugs are approved for MS, their efficacy in progressive disease is modest. Addressing disease progression as a treatment goal in MS is challenging due to several factors. These include a lack of complete understanding of the pathophysiological mechanisms driving MS and the absence of sensitive markers of disease progression in the short-term of clinical trials. MS usually begins at a young age and lasts for decades, whereas clinical research often spans only 1-3 years. Additionally, there is no unifying definition of disease progression. Several drugs are currently being investigated for progressive MS. In addition to new medications, the rise of new technologies and of adaptive trial designs is enabling larger and more integrated data collection. Remote assessments and decentralised clinical trials are becoming feasible. These will allow more efficient and large studies at a lower cost and with less burden on study participants. As new drugs are developed and research evolves, we anticipate a concurrent change in patient care at various levels in the foreseeable future. We conducted a narrative review to discuss the challenges of accurately measuring disease progression in contemporary MS drug trials, some new research trends and their implications for patient care.

Early reduction of retinal thickness predicts physical and cognitive disability in newly diagnosed multiple sclerosis patients: results from a cross-sectional study

INTRODUCTION

Retinal nerve fiber layer (RNFL) thickness is a promising biomarker of axonal loss and a potential outcome predictor in Multiple Sclerosis (MS). Cognitive impairment (CoI) exhibits a high prevalence in patients with MS (pwMS), even in the early phases of the disease. Our aim was to explore the role of RNFL thickness as a predictor of physical and cognitive disability in pwMS.

METHODS

All newly diagnosed pwMS referred to the MS centre of the University-Hospital "Policlinico-San Marco" between 2015-2019 were evaluated at baseline and at 3 years. RNFL and ganglion cell layer (GCL) thickness for right (r.e.) and left eyes (l.e.) were measured with Optical Coherence Tomography (OCT). Disability level and cognitive profile were assessed, using the Expanded Disability Status Scale (EDSS) and the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) battery, respectively.

RESULTS

We consecutively enrolled 487 pwMS, including 68 (14.0%) with primary progressive MS (PPMS). At baseline, RNFL and GCL were bilaterally thinner in PPMS (r.e. 90.4 ± 12.7; l.e. 90.2 ± 13.5, and r.e. 80.1 ± 11.2; l.e. 80.3 ± 12.6, respectively) compared to relapsing-remitting MS (RRMS) (r.e. 94.6 ± 13.1; l.e. 94.3 ± 14.8, and r.e. 85.1 ± 9.5; l.e. 84.9 ± 9.3, respectively) (p < 0.01). Both groups exhibited reduced RNFL and GCL thickness, worse cognitive performance and higher EDSS scores at 3-years follow-up compared with baseline. RNFL thickness ≤ 88.0 μm was an independent predictor of CoI (OR = 5.32; 95% CI = 1.84-9.12; p = 0.02) and disability worsening (OR = 3.18; 95% CI = 1.21-10.33; p = 0.05).

DISCUSSION

RNFL thickness, as a biomarker of neurodegeneration, could be considered a predictive biomarker of cognitive degeneration and physical disability in MS.

Beyond lines of treatment: embracing early high-efficacy disease-modifying treatments for multiple sclerosis management

Recent advances in multiple sclerosis (MS) management have shifted perspectives on treatment strategies, advocating for the early initiation of high-efficacy disease-modifying therapies (heDMTs). This perspective review discusses the rationale, benefits, and challenges associated with early heDMT initiation, reflecting on the obsolescence of the traditional "first-line" and "second-line" treatment classifications. The article emerges from the last update of the consensus document of the Spanish Society of Neurology on the treatment of MS. During its development, there was a recognized need to further discuss the concept of treatment lines and the early use of heDMTs. Evidence from randomized controlled trials and real-world studies suggests that early heDMT initiation leads to improved clinical outcomes, including reduced relapse rates, slowed disease progression, and decreased radiological activity, especially in younger patients or those in early disease stages. Despite the historical belief that heDMTs involve more risks and adverse events compared to moderate-efficacy DMTs (meDMTs), some studies have reported comparable safety profiles between early heDMTs and meDMTs, though long-term safety data are still lacking. The review also addresses the need for a personalized approach based on patient characteristics, prognostic factors, and preferences, explores the importance of therapeutic inertia, and highlights the evolving landscape of international and national guidelines that increasingly advocate for early intensive treatment approaches. The article also addresses the challenges of ensuring access to these therapies and the importance of further research to establish long-term safety and effectiveness of DMTs in MS.

Assessing disease progression and treatment response in progressive multiple sclerosis

Progressive multiple sclerosis poses a considerable challenge in the evaluation of disease progression and treatment response owing to its multifaceted pathophysiology. Traditional clinical measures such as the Expanded Disability Status Scale are limited in capturing the full scope of disease and treatment effects. Advanced imaging techniques, including MRI and PET scans, have emerged as valuable tools for the assessment of neurodegenerative processes, including the respective role of adaptive and innate immunity, detailed insights into brain and spinal cord atrophy, lesion dynamics and grey matter damage. The potential of cerebrospinal fluid and blood biomarkers is increasingly recognized, with neurofilament light chain levels being a notable indicator of neuro-axonal damage. Moreover, patient-reported outcomes are crucial for reflecting the subjective experience of disease progression and treatment efficacy, covering aspects such as fatigue, cognitive function and overall quality of life. The future incorporation of digital technologies and wearable devices in research and clinical practice promises to enhance our understanding of functional impairments and disease progression. This Review offers a comprehensive examination of these diverse evaluation tools, highlighting their combined use in accurately assessing disease progression and treatment efficacy in progressive multiple sclerosis, thereby guiding more effective therapeutic strategies.

Oculomic stratification of COVID-19 patients' intensive therapy unit admission status and mortality by retinal morphological findings

To investigate if retinal thickness has predictive utility in COVID-19 outcomes by evaluating the statistical association between retinal thickness using OCT and of COVID-19-related mortality. Secondary outcomes included associations between retinal thickness and length of stay (LoS) in hospital. In this retrospective cohort study, OCT scans from 230 COVID-19 patients admitted to the Intensive Care Unit (ITU) were compared with age and gender-matched patients with pneumonia from before March 2020. Total retinal, GCL + IPL, and RNFL thicknesses were recorded, and analysed with systemic measures collected at the time of admission and mortality outcomes, using linear regression models, Pearson's R correlation, and Principal Component Analysis. Retinal thickness was significantly associated with all-time mortality on follow up in the COVID-19 group (p = 0.015), but not 28-day mortality (p = 0.151). Retinal and GCL + IPL layer thicknesses were both significantly associated with LoS in hospital for COVID-19 patients (p = 0.006 for both), but not for patients with pneumonia (p = 0.706 and 0.989 respectively). RNFL thickness was not associated with LoS in either group (COVID-19 p = 0.097, pneumonia p = 0.692). Retinal thickness associated with LoS in hospital and long-term mortality in COVID-19 patients, suggesting that retinal structure could be a surrogate marker for frailty and predictor of disease severity in this group of patients, but not in patients with pneumonia from other causes.

Retinal changes in multiple sclerosis: An optical coherence tomography and angiography study

BACKGROUND

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system with neuroaxonal damage. It is the principal driver of non-traumatic disability in young adults. Visual symptoms are common and optic neuritis (ON) may be the revealing feature in up to 30% of cases. Structural optical coherence tomography (OCT) represents a biomarker of central nervous system neurodegeneration in MS. OCT-angiography (OCT-A) is a noninvasive tool allowing the study of retinal vasculature and the detection of microvascular damage in neuro-retinal diseases. In this study, we aimed to assess structural and microvascular retinal changes in patients with MS with and without ON and to correlate the findings with visual function and MS disability.

METHODS

We conducted a cross-sectional study including patients diagnosed with MS according to the 2017 McDonald criteria. All patients underwent complete neurological examination with evaluation of the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Severity Score (MSSS) and an ophthalmological examination including OCT and OCT-A. Patients were compared with age- and sex-matched healthy subjects. The primary endpoints were assessment of retinal nerve fiber layer (RNFL) thickness, ganglion cell layer (GCL+), and ganglion cell complex (GCL++) thicknesses on OCT. Vascular densities in the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) were assessed on OCT-A, as well as central avascular zone (CAZ) parameters, lacunarity and fractal dimension.

RESULTS

A total of 160 MS eyes with and without a previous history of ON and 64 age- and gender-matched healthy eyes were analyzed. Among 160 eyes with MS, 69 had a history of ON. We observed a decrease in RNFL and GCL++ thickness in all 12 quadrants in MS patients when compared to healthy controls. Multivariate analysis by linear regression noted a significant correlation for temporal GCL++ and inferonasal RNFL thickness that were decreased in the MS group. A greater decrease in retinal layers thickness was identified in MS patients with a history of ON. On OCT-A, vascular density in (SCP) was significantly reduced in the MS group (P<0.002). A significant correlation between RNFL thickness and retinal vascular density was found but only in less than half of the hourly quadrants. A significant correlation was noted between visual acuity and CC density (P<0.0001). We also noted an inverse correlation between EDSS scores and CC density (P=0.02 and r=-0.275) and between MSSS and RNFL/GCL++ thicknesses.

CONCLUSIONS

RNFL and GCL++ layers were thinner in MS patients with a history of ON and were reversely correlated with disease severity. Moreover, retinal vascular changes were observed in MS even in eyes without ON, and CC was reversely correlated with visual function and current disability. Thus, structural OCT coupled with OCT-A could represent a noninvasive and dynamic biomarker of MS severity and progression.

Individual Prognostication of Disease Activity and Disability Worsening in Multiple Sclerosis With Retinal Layer Thickness z Scores

BACKGROUND AND OBJECTIVES

Retinal optical coherence tomography (OCT) provides promising prognostic imaging biomarkers for future disease activity in multiple sclerosis (MS). However, raw OCT-derived measures have multiple dependencies, supporting the need for establishing reference values adjusted for possible confounders. The purpose of this study was to investigate the capacity for age-adjusted z scores of OCT-derived measures to prognosticate future disease activity and disability worsening in people with MS (PwMS).

METHODS

We established age-adjusted OCT reference data using generalized additive models for location, scale, and shape for peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell-inner plexiform layer (GCIP) thicknesses, involving 910 and 423 healthy eyes, respectively. Next, we transformed the retinal layer thickness of PwMS from 3 published studies into age-adjusted z scores (pRNFL-z and GCIP-z) based on the reference data. Finally, we investigated the association of pRNFL-z or GCIP-z as predictors with future confirmed disability worsening (Expanded Disability Status Scale score increase) or disease activity (failing of the no evidence of disease activity [NEDA-3] criteria) as outcomes. Cox proportional hazards models or logistic regression analyses were applied according to the original studies. Optimal cutoffs were identified using the Akaike information criterion as well as location with the log-rank and likelihood-ratio tests.

RESULTS

In the first cohort (n = 863), 172 PwMS (24%) had disability worsening over a median observational period of 2.0 (interquartile range [IQR]:1.0-3.0) years. Low pRNFL-z (≤-2.04) were associated with an increased risk of disability worsening (adjusted hazard ratio (aHR) [95% CI] = 2.08 [1.47-2.95], p = 3.82e-5). In the second cohort (n = 170), logistic regression analyses revealed that lower pRNFL-z showed a higher likelihood for disability accumulation at the two-year follow-up (reciprocal odds ratio [95% CI] = 1.51[1.06-2.15], p = 0.03). In the third cohort (n = 78), 46 PwMS (59%) did not maintain the NEDA-3 status over a median follow-up of 2.0 (IQR: 1.9-2.1) years. PwMS with low GCIP-z (≤-1.03) had a higher risk of showing disease activity (aHR [95% CI] = 2.14 [1.03-4.43], p = 0.04). Compared with raw values with arbitrary cutoffs, applying the z score approach with optimal cutoffs showed better performance in discrimination and calibration (higher Harrell's concordance index and lower integrated Brier score).

DISCUSSION

In conclusion, our work demonstrated reference cohort-based z scores that account for age, a major driver for disease progression in MS, to be a promising approach for creating OCT-derived measures useable across devices and toward individualized prognostication.

Heterophoria in multiple sclerosis patients: a proof of principle cross-sectional study

Objectives

The pathophysiology of multiple sclerosis (MS) involves inflammatory neurodegeneration in the brainstem, cerebellum, and retina. The clinical relevance of oculomotor involvement in MS, however, remains uncertain.

Methods

In this cross-sectional study, we evaluated heterophoria as a (sub)clinical tool in 54 MS patients and 55 age-matched healthy controls (HCs). We quantified heterophoria in prism diopters for distance and near range with orthoptic examination. Our primary outcome was high degrees of horizontal heterophoria (HDHH) defined as measurements beyond ±2 standard deviations from the mean prism diopter of heterophoria of our HCs.

Results

More than one-third (37%, n=20/54) of MS patients but only 11% (n=6/55) of HCs were classified as HDHH [distance, MS=9% (n=5/54) versus HC=6% (n=3/55); near, MS=19% (n=10/54) versus HC=5% (n=3/55)]. Our MS patients presented more combined vertical and horizontal deviations at near range [MS 19% (n=10/54) versus for HC 7% (n=4/55)]. We observed the combination of HDHH both at distance and at near testing in 9% (n=5/54) of MS patients but not at all in HCs (n=0/55).

Discussion

Despite the high prevalence of heterophoria, HDHH may be an additional (sub)clinical tool of subclinical involvement in MS. Thus, orthoptic examination may be an additional tool to improve MS diagnostic procedures.

De-escalation of Disease-Modifying Therapy for People with Multiple Sclerosis Due to Safety Considerations: Characterizing 1-Year Outcomes in 25 People Who Switched from Ocrelizumab to Diroximel Fumarate

INTRODUCTION

Switching disease-modifying therapy (DMT) may be considered for relapsing-remitting multiple sclerosis (RRMS) if a patient's current therapy is no longer optimal. This was particularly important during the recent COVID-19 pandemic because of considerations around immune deficiency and impaired vaccine response associated with B cell-depleting DMTs. This real-world, single-center study aimed to evaluate change or decline in functional ability and overall disease stability in people with RRMS who were switched from B cell-depleting ocrelizumab (OCRE) to diroximel fumarate (DRF) because of safety concern related to the COVID-19 pandemic.

METHODS

Adults with RRMS were included if they had been clinically stable for ≥ 1 year on OCRE. Data collected at baseline and 1 year post switch included relapse rate, magnetic resonance imaging (MRI), blood work for assessment of peripheral immune parameters, the Cognitive Assessment Battery (CAB), optical coherence tomography (OCT), and patient-reported outcomes (PROs).

RESULTS

Participants (N = 25) had a mean (SD) age of 52 (9) years, and a mean (SD) duration of 26 (8) months' treatment with OCRE before the switch to DRF. Median washout duration since the last OCRE infusion was 7 months (range 4-18 months). No participants relapsed on DRF during follow-up, and all remained persistent on DRF after 1 year. There were no significant changes in peripheral immune parameters, other than an increase in the percentage of CD19+ cells 1 year after switching (p < 0.05). Similarly, there were no significant changes in CAB, OCT, and PROs.

CONCLUSION

These preliminary findings suggest that transition to DRF from OCRE may be an effective treatment option for people with RRMS who are clinically stable but may need to switch for reasons unrelated to effectiveness. Longer follow-up times on larger samples are needed to confirm these observations.

Polarization-resolved analysis of outer retinal bands: investigating ballistic and multiply scattered photons using full-field swept-source optical coherence tomography

Precise interpretation of the anatomical origins of outer retinal optical coherence tomography (OCT) presents technical challenges owing to the delicate nature of the retina. To address this challenge, our study introduces a novel polarization-sensitive full-field swept-source OCT (FF-SS-OCT) that provides parallel-polarization and cross-polarization OCT measurements, predominantly capturing ballistically reflected photons and multiply scattered photons, respectively. Notably, parallel-polarization OCT unveils layer-like structures more effectively, including the inner plexiform layer (IPL) sub-layers, outer plexiform layer (OPL) sub-layers (in rod-dominant regions), and rod/cone outer segment (OS) tips, compared to cross-polarization OCT, where such sub-layers are not visible. Through a comparative analysis of parallel-polarization and cross-polarization OCT images of the outer retina, we discovered that the 2nd outer retinal OCT band results from contributions from both the ellipsoid zone (EZ) and the inner segment/outer segment (IS/OS) junction. Similarly, the 3rd outer retinal OCT band appears to reflect contributions from both the interdigitation zone (IZ) and photoreceptor OS tips. This polarization-sensitive approach advances our understanding of the origins of outer retinal OCT signals and proposes potential new biomarkers for assessing retinal health and diseases.

Correlation of Visual System Biomarkers With Motor Deficits in Experimental Autoimmune Encephalomyelitis-Optic Neuritis

Purpose

Experimental autoimmune encephalomyelitis (EAE) scoring, the most commonly used primary outcome metric for an in vivo model of multiple sclerosis (MS), is highly variable and subjective. Here we explored the use of visual biomarkers in EAE as more objective and clinically relevant primary outcomes.

Methods

Motor impairment in myelin oligodendrocyte glycoprotein-immunized C57BL/6J mice was quantified using a five-point EAE grading scale. Pattern electroretinography (pERG) and retinal ganglion cell/inner plexiform layer (RGC/IPL) complex thickness were measured 60 days after induction. Optic nerve histopathology was analyzed at endpoint.

Results

EAE mice displayed motor impairments ranging from mild to severe. Significant correlations were seen between pERG amplitude and last EAE score, mean EAE score, and cumulative EAE score. Optical coherence tomography (OCT) analysis demonstrated a significant correlation between thinning of the RGC/IPL complex and both EAE score and pERG amplitude. Optic nerve histopathology showed significant correlations between demyelination and cumulative EAE score, pERG amplitude, and RGC/IPL complex thickness, as well as between immune cell infiltration and cumulative EAE score, pERG amplitude, and RGC/IPL complex thickness in EAE mice.

Conclusions

Unlike EAE scoring, pERG and OCT show direct measurement of retinal structure and function. Therefore we conclude that visual outcomes are well suited as a direct assessment of optic nerve involvement in this EAE model of MS while also being indicative of motor impairment.

Translational Relevance

Standardizing directly translatable measurements as primary outcome parameters in the murine EAE model could lead to more rapid and relevant testing of new therapeutic approaches for mitigating MS.

Evolution of retinal degeneration and prediction of disease activity in relapsing and progressive multiple sclerosis

Retinal optical coherence tomography has been identified as biomarker for disease progression in relapsing-remitting multiple sclerosis (RRMS), while the dynamics of retinal atrophy in progressive MS are less clear. We investigated retinal layer thickness changes in RRMS, primary and secondary progressive MS (PPMS, SPMS), and their prognostic value for disease activity. Here, we analyzed 2651 OCT measurements of 195 RRMS, 87 SPMS, 125 PPMS patients, and 98 controls from five German MS centers after quality control. Peripapillary and macular retinal nerve fiber layer (pRNFL, mRNFL) thickness predicted future relapses in all MS and RRMS patients while mRNFL and ganglion cell-inner plexiform layer (GCIPL) thickness predicted future MRI activity in RRMS (mRNFL, GCIPL) and PPMS (GCIPL). mRNFL thickness predicted future disability progression in PPMS. However, thickness change rates were subject to considerable amounts of measurement variability. In conclusion, retinal degeneration, most pronounced of pRNFL and GCIPL, occurs in all subtypes. Using the current state of technology, longitudinal assessments of retinal thickness may not be suitable on a single patient level.

Macular OCT's Proficiency in Identifying Retrochiasmal Visual Pathway Lesions in Multiple Sclerosis-A Pilot Study

Optical coherence tomography (OCT) is a non-invasive imaging technique based on the principle of low-coherence interferometry that captures detailed images of ocular structures. Multiple sclerosis (MS) is a neurodegenerative disease that can lead to damage of the optic nerve and retina, which can be depicted by OCT. The purpose of this pilot study is to determine whether macular OCT can be used as a biomarker in the detection of retrochiasmal lesions of the visual pathway in MS patients. We conducted a prospective study in which we included 52 MS patients and 27 healthy controls. All participants underwent brain MRI, visual field testing, and OCT evaluation of the thicknesses of the peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell layer (GCL), and macular inner plexiform layer (IPL). OCT measurements were adjusted for optic neuritis (ON). VF demonstrated poor capability to depict a retrochiasmal lesion identified by brain MRI (PPV 0.50). In conclusion, the OCT analysis of the macula appears to excel in identifying retrochiasmal MS lesions compared to VF changes. The alterations in the GCL and IPL demonstrate the most accurate detection of retrochiasmal visual pathway changes in MS patients.

Hybrid deep learning and optimal graph search method for optical coherence tomography layer segmentation in diseases affecting the optic nerve

Accurate segmentation of retinal layers in optical coherence tomography (OCT) images is critical for assessing diseases that affect the optic nerve, but existing automated algorithms often fail when pathology causes irregular layer topology, such as extreme thinning of the ganglion cell-inner plexiform layer (GCIPL). Deep LOGISMOS, a hybrid approach that combines the strengths of deep learning and 3D graph search to overcome their limitations, was developed to improve the accuracy, robustness and generalizability of retinal layer segmentation. The method was trained on 124 OCT volumes from both eyes of 31 non-arteritic anterior ischemic optic neuropathy (NAION) patients and tested on three cross-sectional datasets with available reference tracings: Test-NAION (40 volumes from both eyes of 20 NAION subjects), Test-G (29 volumes from 29 glaucoma subjects/eyes), and Test-JHU (35 volumes from 21 multiple sclerosis and 14 control subjects/eyes) and one longitudinal dataset without reference tracings: Test-G-L (155 volumes from 15 glaucoma patients/eyes). In the three test datasets with reference tracings (Test-NAION, Test-G, and Test-JHU), Deep LOGISMOS achieved very high Dice similarity coefficients (%) on GCIPL: 89.97±3.59, 90.63±2.56, and 94.06±1.76, respectively. In the same context, Deep LOGISMOS outperformed the Iowa reference algorithms by improving the Dice score by 17.5, 5.4, and 7.5, and also surpassed the deep learning framework nnU-Net with improvements of 4.4, 3.7, and 1.0. For the 15 severe glaucoma eyes with marked GCIPL thinning (Test-G-L), it demonstrated reliable regional GCIPL thickness measurement over five years. The proposed Deep LOGISMOS approach has potential to enhance precise quantification of retinal structures, aiding diagnosis and treatment management of optic nerve diseases.

Diagnosis of multiple sclerosis using optical coherence tomography supported by explainable artificial intelligence

BACKGROUND/OBJECTIVES

Study of retinal structure based on optical coherence tomography (OCT) data can facilitate early diagnosis of relapsing-remitting multiple sclerosis (RRMS). Although artificial intelligence can provide highly reliable diagnoses, the results obtained must be explainable.

SUBJECTS/METHODS

The study included 79 recently diagnosed RRMS patients and 69 age matched healthy control subjects. Thickness (Avg) and inter-eye difference (Diff) features are obtained in 4 retinal layers using the posterior pole protocol. Each layer is divided into six analysis zones. The Support Vector Machine plus Recursive Feature Elimination with Leave-One-Out Cross Validation (SVM-RFE-LOOCV) approach is used to find the subset of features that reduces dimensionality and optimises the performance of the classifier.

RESULTS

SVM-RFE-LOOCV was used to identify OCT features with greatest capacity for early diagnosis, determining the area of the papillomacular bundle to be the most influential. A correlation was observed between loss of layer thickness and increase in functional disability. There was also greater functional deterioration in patients with greater asymmetry between left and right eyes. The classifier based on the top-ranked features obtained sensitivity = 0.86 and specificity = 0.90.

CONCLUSIONS

There was consistency between the features identified as relevant by the SVM-RFE-LOOCV approach and the retinotopic distribution of the retinal nerve fibres and the optic nerve head. This simple method contributes to implementation of an assisted diagnosis system and its accuracy exceeds that achieved with magnetic resonance imaging of the central nervous system, the current gold standard. This paper provides novel insights into RRMS affectation of the neuroretina.

Synaptic injury in the inner plexiform layer of the retina is associated with progression in multiple sclerosis

While neurodegeneration underlies the pathological basis for permanent disability in multiple sclerosis (MS), predictive biomarkers for progression are lacking. Using an animal model of chronic MS, we find that synaptic injury precedes neuronal loss and identify thinning of the inner plexiform layer (IPL) as an early feature of inflammatory demyelination-prior to symptom onset. As neuronal domains are anatomically segregated in the retina and can be monitored longitudinally, we hypothesize that thinning of the IPL could represent a biomarker for progression in MS. Leveraging our dataset with over 800 participants enrolled for more than 12 years, we find that IPL atrophy directly precedes progression and propose that synaptic loss is predictive of functional decline. Using a blood proteome-wide analysis, we demonstrate a strong correlation between demyelination, glial activation, and synapse loss independent of neuroaxonal injury. In summary, monitoring synaptic injury is a biologically relevant approach that reflects a potential driver of progression.

Predictive value of retinal atrophy for cognitive decline across disease duration in multiple sclerosis

BACKGROUND

We investigated the association between changes in retinal thickness and cognition in people with MS (PwMS), exploring the predictive value of optical coherence tomography (OCT) markers of neuroaxonal damage for global cognitive decline at different periods of disease.

METHOD

We quantified the peripapillary retinal nerve fibre (pRFNL) and ganglion cell-inner plexiform (GCIPL) layers thicknesses of 207 PwMS and performed neuropsychological evaluations. The cohort was divided based on disease duration (≤5 years or >5 years). We studied associations between changes in OCT and cognition over time, and assessed the risk of cognitive decline of a pRFNL≤88 µm or GCIPL≤77 µm and its predictive value.

RESULTS

Changes in pRFNL and GCIPL thickness over 3.2 years were associated with evolution of cognitive scores, in the entire cohort and in patients with more than 5 years of disease (p<0.01). Changes in cognition were related to less use of disease-modifying drugs, but not OCT metrics in PwMS within 5 years of onset. A pRFNL≤88 µm was associated with earlier cognitive disability (3.7 vs 9.9 years) and higher risk of cognitive deterioration (HR=1.64, p=0.022). A GCIPL≤77 µm was not associated with a higher risk of cognitive decline, but a trend was observed at ≤91.5 µm in PwMS with longer disease (HR=1.81, p=0.061).

CONCLUSIONS

The progressive retinal thinning is related to cognitive decline, indicating that cognitive dysfunction is a late manifestation of accumulated neuroaxonal damage. Quantifying the pRFNL aids in identifying individuals at risk of cognitive dysfunction.

Trans-Synaptic Degeneration in the Visual Pathway in Patients With Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

BACKGROUND AND OBJECTIVES

We aimed to assess the presence of retinal neurodegeneration independent of optic neuritis (ON) in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and to investigate the development of trans-synaptic anterograde degeneration in these patients after ON.

METHODS

Cross-sectional, retrospective study of 34 adult patients with MOGAD and 23 healthy controls (HC). Clinical, optical coherence tomography (OCT), and MRI data were collected. Peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell inner plexiform layer (GCIPL) were obtained using Heidelberg Spectralis. FreeSurfer7 was used to obtain the lateral geniculate nucleus (LGN), occipital volume fractions (to total estimated intracranial volume), and occipital cortical thickness. For the anterior visual pathway, the analysis was conducted using eyes, classified based on the history of ON (Eye-ON and Eye-NON) and compared with Eye-HC. The analysis of OCT and brain volumetric measures was conducted comparing MOGAD-ON, MOGAD-NON, and HC groups. The analysis of covariance with a Bonferroni-adjusted post hoc test was used to test differences between groups and linear regression analysis to evaluate OCT/MRI associations; age and sex were considered as covariates.

RESULTS

24 (70.5%) patients had a prior ON. Median pRNFL and GCIPL thickness (um) was significantly reduced in Eye-ON vs EyeNON and HC (pRNFL: 69.4 (17.3), 89.6 (13.7), 98.2 (11.7), p < 0.001; GCIPL: 55.8 (8.7), 67.39 (8.7), 72.6 (4.5), p < 0.001). pRNFL and GCIPL thickness had a negative correlation with the number of ON episodes (p = 0.025 and p = 0.031, respectively). LGN volume fraction was significantly lower in patients with MOGAD-ON than in HC (0.33 (0.05) vs 0.39 (0.04), p = 0.002). The occipital cortical thickness was lower in MOGAD-ON compared with MOGAD-NON and HC (p = 0.010). In patients with MOGAD-ON, pRNFL correlated with LGN volume (p = 0.006), occipital thickness (p = 0.002), and the medial occipital cortex (p = 0.002), but not the lateral occipital lobe.

DISCUSSION

Compared with HC, MOGAD-ON exhibits reduced retinal thickness, primarily influenced by the presence and the number of prior ON episodes. Moreover, MOGAD-ON demonstrates significant atrophy in the retinal, subcortical, and cortical regions of the visual pathway, distinguishing them from MOGAD-NON and HC. These findings suggest that in patients with MOGAD neurodegeneration is tightly correlated with damage to the involved pathway.

Predicting disease severity in multiple sclerosis using multimodal data and machine learning

BACKGROUND

Multiple sclerosis patients would benefit from machine learning algorithms that integrates clinical, imaging and multimodal biomarkers to define the risk of disease activity.

METHODS

We have analysed a prospective multi-centric cohort of 322 MS patients and 98 healthy controls from four MS centres, collecting disability scales at baseline and 2 years later. Imaging data included brain MRI and optical coherence tomography, and omics included genotyping, cytomics and phosphoproteomic data from peripheral blood mononuclear cells. Predictors of clinical outcomes were searched using Random Forest algorithms. Assessment of the algorithm performance was conducted in an independent prospective cohort of 271 MS patients from a single centre.

RESULTS

We found algorithms for predicting confirmed disability accumulation for the different scales, no evidence of disease activity (NEDA), onset of immunotherapy and the escalation from low- to high-efficacy therapy with intermediate to high-accuracy. This accuracy was achieved for most of the predictors using clinical data alone or in combination with imaging data. Still, in some cases, the addition of omics data slightly increased algorithm performance. Accuracies were comparable in both cohorts.

CONCLUSION

Combining clinical, imaging and omics data with machine learning helps identify MS patients at risk of disability worsening.

Recent advances in the use of optical coherence tomography in neuro-ophthalmology: A review

Optical coherence tomography (OCT) is an in vivo imaging modality that provides non-invasive, high resolution and fast cross-sectional images of the optic nerve head, retina and choroid. OCT angiography (OCTA) is an emerging tool. It is a non-invasive, dye-free imaging approach of visualising the microvasculature of the retina and choroid by employing motion contrast imaging for blood flow detection and is gradually receiving attention for its potential roles in various neuro-ophthalmic and retinal conditions. We will review the clinical utility of the OCT in the management of various common neuro-ophthalmic and neurological disorders. We also review some of the OCTA research findings in these conditions. Finally, we will discuss the limitations of OCT as well as introduce other emerging technologies.

Associations between cortical lesions, optic nerve damage, and disability at the onset of multiple sclerosis: insights into neurodegenerative processes

BACKGROUND

Multiple sclerosis cortical lesions are areas of demyelination and neuroaxonal loss. Retinal layer thickness, measured with optical coherence tomography (OCT), is an emerging biomarker of neuroaxonal loss. Studies have reported correlations between cortical lesions and retinal layer thinning in established multiple sclerosis, suggesting a shared pathophysiological process. Here, we assessed the correlation between cortical lesions and OCT metrics at the onset of multiple sclerosis, examining, for the first time, associations with physical or cognitive disability.

OBJECTIVE

To examine the relationship between cortical lesions, optic nerve and retinal layer thicknesses, and physical and cognitive disability at the first demyelinating event.

METHODS

Thirty-nine patients and 22 controls underwent 3T-MRI, optical coherence tomography, and clinical tests. We identified cortical lesions on phase-sensitive inversion recovery sequences, including occipital cortex lesions. We measured the estimated total intracranial volume and the white matter lesion volume. OCT metrics included peripapillary retinal nerve fibre layer (pRNFL), ganglion cell and inner plexiform layer (GCIPL) and inner nuclear layer (INL) thicknesses.

RESULTS

Higher total cortical and leukocortical lesion volumes correlated with thinner pRNFL (B = -0.0005, 95 % CI -0.0008 to -0.0001, p = 0.01; B = -0.0005, 95 % CI -0.0008 to -0.0001, p = 0.01, respectively). Leukocortical lesion number correlated with colour vision deficits (B = 0.58, 95 %CI 0.039 to 1,11, p = 0.036). Thinner GCIPL correlated with a higher Expanded Disability Status Scale (B = -0.06, 95 % CI -1.1 to -0.008, p = 0.026). MS diagnosis (n = 18) correlated with higher cortical and leukocortical lesion numbers (p = 0.004 and p = 0.003), thinner GCIPL (p = 0.029) and INL (p = 0.041).

CONCLUSION

The association between cortical lesions and axonal damage in the optic nerve reinforces the role of neurodegenerative processes in MS pathogenesis at onset.

Plasma Lipidomic Profiling Using Mass Spectrometry for Multiple Sclerosis Diagnosis and Disease Activity Stratification (LipidMS)

This investigation explores the potential of plasma lipidomic signatures for aiding in the diagnosis of Multiple Sclerosis (MS) and evaluating the clinical course and disease activity of diseased patients. Plasma samples from 60 patients with MS (PwMS) were clinically stratified to either a relapsing-remitting (RRMS) or a chronic progressive MS course and 60 age-matched controls were analyzed using state-of-the-art direct infusion quantitative shotgun lipidomics. To account for potential confounders, data were filtered for age and BMI correlations. The statistical analysis employed supervised and unsupervised multivariate data analysis techniques, including a principal component analysis (PCA), a partial least squares discriminant analysis (oPLS-DA) and a random forest (RF). To determine whether the significant absolute differences in the lipid subspecies have a relevant effect on the overall composition of the respective lipid classes, we introduce a class composition visualization (CCV). We identified 670 lipids across 16 classes. PwMS showed a significant increase in diacylglycerols (DAG), with DAG 16:0;0_18:1;0 being proven to be the lipid with the highest predictive ability for MS as determined by RF. The alterations in the phosphatidylethanolamines (PE) were mainly linked to RRMS while the alterations in the ether-bound PEs (PE O-) were found in chronic progressive MS. The amount of CE species was reduced in the CPMS cohort whereas TAG species were reduced in the RRMS patients, both lipid classes being relevant in lipid storage. Combining the above mentioned data analyses, distinct lipidomic signatures were isolated and shown to be correlated with clinical phenotypes. Our study suggests that specific plasma lipid profiles are not merely associated with the diagnosis of MS but instead point toward distinct clinical features in the individual patient paving the way for personalized therapy and an enhanced understanding of MS pathology.

Visual outcome measures in clinical trials of remyelinating drugs

One of the most promising approaches to delay, prevent or reverse disability progression in multiple sclerosis (MS) is to enhance endogenous remyelination and limit axonal degeneration. In clinical trials of remyelinating drugs, there is a need for reliable, sensitive and clinically relevant outcome measures. The visual pathway, which is frequently affected by MS, provides a unique model system to evaluate remyelination of acute and chronic MS lesions in vivo and non-invasively. In this review, we discuss the different measures that have been used and scrutinise visual outcome measure selection in current and future remyelination trials.

Choroid plexus volume as a marker of retinal atrophy in relapsing remitting multiple sclerosis

OBJECTIVE

To evaluate choroid plexus (CP) volume as a biomarker for predicting clinical disability and retinal layer atrophy in relapsing remitting multiple sclerosis (RRMS).

METHODS

Ninety-five RRMS patients and 26 healthy controls (HCs) underwent 3 T whole brain MRI, expanded disability status scale (EDSS) and optical coherence tomography (OCT). Fully automated intra-retinal segmentation was performed to obtain the volumes of the retinal nerve fiber layer (RNFL), combined ganglion cell layer -inner plexiform layer (GCIPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), retinal pigment epithelium (RPE), total macular volume (TMV) and papillomacular bundle (PMB). Automated segmentation of the CP within the lateral ventricles was performed and the choroid plexus volume (CPV) was normalized by total intracranial volume (TIV). Linear regression analysis and generalized estimating equation (GEE) models were applied to evaluate relationships between nCPV and EDSS, T2 lesion volume, disease duration, and retinal layer volumes, followed by Bonferroni correction analysis for multiple comparisons.

RESULTS

RRMS patients had larger tChPV compared to HCs (p < 0.001). After Bonferroni correction, there was a significant positive correlation between tChPV and EDSS (r2 = 0.25, p = 0.0002), disease duration (r2 = 0.30, p = 0.01), and T2 lesion volume (r2 = 0.39, p = 0.0000). A robust negative correlation was found between tChPV and RNFL (p < 0.001), GCIPL (p = 0.003), TMV (p = 0.0185), PMB (p < 0.0001), G (p = 0.04), T(p = 0.0001).

CONCLUSIONS

Our findings support the association of tChPV with disability and altered retinal integrity in RRMS.

Development of a predictive model for predicting disability after optic neuritis: a secondary analysis of the Optic Neuritis Treatment Trial

Objective

The present study aimed to develop a prediction model for predicting developing debilities after optic neuritis.

Methods

The data for this research was obtained from the Optic Neuritis Treatment Trial (ONTT). The predictive model was built based on a Cox proportional hazards regression model. Model performance was assessed using Harrell's C-index for discrimination, calibration plots for calibration, and stratification of patients into low-risk and high-risk groups for utility evaluation.

Results

A total of 416 patients participated. Among them, 101 patients (24.3%) experienced disability, which was defined as achieving or surpassing a score of 3 on the expanded disability status scale. The median follow-up duration was 15.5 years (interquartile range, 7.0 to 16.8). Two predictors in the final predictive model included the classification of multiple sclerosis at baseline and the condition of the optic disk in the affected eye at baseline. Upon incorporating these two factors into the model, the model's C-index stood at 0.71 (95% CI, 0.66-0.76, with an optimism of 0.005) with a favorable alignment with the calibration curve. By utilizing this model, the ONTT cohort can be categorized into two risk categories, each having distinct rates of disability development within a 15-year timeframe (high-risk group, 41% [95% CI, 31-49%] and low-risk group, 13% [95% CI, 8.4-17%]; log-rank p-value of <0.001).

Conclusion

This predictive model has the potential to assist physicians in identifying individuals at a heightened risk of experiencing disability following optic neuritis, enabling timely intervention and treatment.

Delimiting MOGAD as a disease entity using translational imaging

The first formal consensus diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) were recently proposed. Yet, the distinction of MOGAD-defining characteristics from characteristics of its important differential diagnoses such as multiple sclerosis (MS) and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (NMOSD) is still obstructed. In preclinical research, MOG antibody-based animal models were used for decades to derive knowledge about MS. In clinical research, people with MOGAD have been combined into cohorts with other diagnoses. Thus, it remains unclear to which extent the generated knowledge is specifically applicable to MOGAD. Translational research can contribute to identifying MOGAD characteristic features by establishing imaging methods and outcome parameters on proven pathophysiological grounds. This article reviews suitable animal models for translational MOGAD research and the current state and prospect of translational imaging in MOGAD.

Differential Study of Retinal Thicknesses in the Eyes of Alzheimer's Patients, Multiple Sclerosis Patients and Healthy Subjects

Multiple sclerosis (MS) and Alzheimer's disease (AD) cause retinal thinning that is detectable in vivo using optical coherence tomography (OCT). To date, no papers have compared the two diseases in terms of the structural differences they produce in the retina. The purpose of this study is to analyse and compare the neuroretinal structure in MS patients, AD patients and healthy subjects using OCT. Spectral domain OCT was performed on 21 AD patients, 33 MS patients and 19 control subjects using the Posterior Pole protocol. The area under the receiver operating characteristic (AUROC) curve was used to analyse the differences between the cohorts in nine regions of the retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL) and outer nuclear layer (ONL). The main differences between MS and AD are found in the ONL, in practically all the regions analysed (AUROCFOVEAL = 0.80, AUROCPARAFOVEAL = 0.85, AUROCPERIFOVEAL = 0.80, AUROC_PMB = 0.77, AUROCPARAMACULAR = 0.85, AUROCINFERO_NASAL = 0.75, AUROCINFERO_TEMPORAL = 0.83), and in the paramacular zone (AUROCPARAMACULAR = 0.75) and infero-temporal quadrant (AUROCINFERO_TEMPORAL = 0.80) of the GCL. In conclusion, our findings suggest that OCT data analysis could facilitate the differential diagnosis of MS and AD.

Optical coherence tomography (OCT) measurements and disability in multiple sclerosis (MS): A systematic review and meta-analysis

BACKGROUND

Studies have demonstrated that people with multiple sclerosis (pwMS) experience visual impairments and neurodegenerative retinal processes. The disability progression in pwMS may be associated with retinal changes assessed with optical coherence tomography (OCT). This meta-analysis aims at synthesizing the correlations between OCT measurements of disability in pwMS.

METHODS

We systematically searched four databases (PubMed/MEDLINE, Embase, Scopus, and Web of Science) from inception to November 2022, then conducted a meta-analysis using a random effects model to determine the pooled correlation coefficient(r) between OCT measurements and disability scales by R version 4.2.3 with the meta version 6.2-1 package.

RESULTS

From 3129 studies, 100 studies were included. Among 9051 pwMS, the female-to-male ratio was 3.15:1, with a mean age of 39.57 ± 6.07 years. The mean disease duration and Expanded Disability Status Scale (EDSS) were 8.5 ± 3.7 and 2.7 ± 1.1, respectively. Among the pooled subgroup analyses, macular ganglion cell inner plexiform layer (mGCIPL) in patients with relapsing-remitting (pwRRMS) and peripapillary retinal nerve fiber layer (pRNFL) in patients with progressive MS (pwPMS) had strong correlations with EDSS, r = -0.33 (95% CI: -0.45 to -0.20, I2 = 45%, z-score = -4.86, p < 0.001) and r = -0.20 (95% CI:-0.58 to 0.26, I2 = 76%, z-score = -0.85, p = 0.395), respectively. According to subgroup analysis on pwMS without optic neuritis (ON) history, the largest correlation was seen between EDSS and macular ganglion cell complex (mGCC): r = -0.39 (95% CI: -0.70 to 0.04, I2 = 79%, z-score = -1.79, p = 0.073).

CONCLUSION

OCT measurements are correlated with disability in pwMS, and they can complement the comprehensive neurological visit as an additional paraclinical test.

Optical coherence tomography versus other biomarkers: Associations with physical and cognitive disability in multiple sclerosis

BACKGROUND

Optical coherence tomography (OCT) is a biomarker of neuroaxonal loss in multiple sclerosis (MS).

OBJECTIVE

The objective was to assess the relative role of OCT, next to magnetic resonance imaging (MRI) and serum markers of disability in MS.

METHODS

A total of 100 patients and 52 controls underwent OCT to determine peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell-inner plexiform layers (GCIPL). Serum neurofilament light chain (sNfL), total lesion volume (TLV), and brain parenchymal fraction (BPF) were also assessed. The associations of OCT with disability were examined in linear regression models with correction for age, vision, and education.

RESULTS

In patients, pRNFL was associated with the Symbol Digit Modalities Test (SDMT; p = 0.030). In the multivariate analysis including sNfL and MRI measures, pRNFL (β = 0.19, p = 0.044) and TLV (β = -0.24, p = 0.023) were the only markers associated with the SDMT. pRNFL (p < 0.001) and GCIPL (p < 0.001) showed associations with the Expanded Disability Status Scale (EDSS). In the multivariate analysis, GCIPL showed the strongest association with the EDSS (β = -0.32, p < 0.001) followed by sNfL (β = 0.18, p = 0.024).

CONCLUSION

The associations of OCT measures with cognitive and physical disability were independent of serum and brain MRI markers of neuroaxonal loss. OCT can be an important tool for stratification in MS, while longitudinal studies using combinations of biomarkers are warranted.

Visual function resists early neurodegeneration in the visual system in primary progressive multiple sclerosis

BACKGROUND

Neurodegeneration in multiple sclerosis (MS) affects the visual system but dynamics and pathomechanisms over several years especially in primary progressive MS (PPMS) are not fully understood.

METHODS

We assessed longitudinal changes in visual function, retinal neurodegeneration using optical coherence tomography, MRI and serum NfL (sNfL) levels in a prospective PPMS cohort and matched healthy controls. We investigated the changes over time, correlations between outcomes and with loss of visual function.

RESULTS

We followed 81 patients with PPMS (mean disease duration 5.9 years) over 2.7 years on average. Retinal nerve fibre layer thickness (RNFL) was reduced in comparison with controls (90.1 vs 97.8 µm; p<0.001). Visual function quantified by the area under the log contrast sensitivity function (AULCSF) remained stable over a continuous loss of RNFL (0.46 µm/year, 95% CI 0.10 to 0.82; p=0.015) up until a mean turning point of 91 µm from which the AULCSF deteriorated. Intereye RNFL asymmetry above 6 µm, suggestive of subclinical optic neuritis, occurred in 15 patients and was related to lower AULCSF but occurred also in 5 out of 44 controls. Patients with an AULCSF progression had a faster increase in Expanded Disability Status Scale (beta=0.17/year, p=0.043). sNfL levels were elevated in patients (12.2 pg/mL vs 8.0 pg/mL, p<0.001), but remained stable during follow-up (beta=-0.14 pg/mL/year, p=0.291) and were not associated with other outcomes.

CONCLUSION

Whereas neurodegeneration in the anterior visual system is already present at onset, visual function is not impaired until a certain turning point. sNfL is not correlated with structural or functional impairment in the visual system.

Progression events defined by home-based assessment of motor function in multiple sclerosis: protocol of a prospective study

Background

This study relates to emerging concepts of appropriate trial designs to evaluate effects of intervention on the accumulation of irreversible disability in multiple sclerosis (MS). Major starting points of our study are the known limitations of current definitions of disability progression by rater-based clinical assessment and the high relevance of gait and balance dysfunctions in MS. The study aims to explore a novel definition of disease progression using repeated instrumental assessment of relevant motor functions performed by patients in their home setting.

Methods

The study is a prospective single-center observational cohort study with the primary outcome acquired by participants themselves, a home-based assessment of motor functions based on an RGB-Depth (RGB-D) camera, a camera that provides both depth (D) and color (RGB) data. Participants are instructed to perform and record a set of simple motor tasks twice a day over a one-week period every 6 months. Assessments are complemented by a set of questionnaires. Annual research grade assessments are acquired at dedicated study visits and include clinical ratings as well as structural imaging (MRI and optical coherence tomography). In addition, clinical data from routine visits is provided semiannually by treating neurologists. The observation period is 24 months for the primary endpoint with an additional clinical assessment at 27 month to confirm progression defined by the Expanded Disability Status Scale (EDSS). Secondary analyses aim to explore the time course of changes in motor parameters and performance of the novel definition against different alternative definitions of progression in MS. The study was registered at Deutsches Register für Klinische Studien (DRKS00027042).

Discussion

The study design presented here investigates disease progression defined by marker-less home-based assessment of motor functions against 3-month confirmed disease progression (3 m-CDP) defined by the EDSS. The technical approach was chosen due to previous experience in lab-based settings. The observation time per participant of 24, respectively, 27 months is commonly conceived as the lower limit needed to study disability progression. Defining a valid digital motor outcome for disease progression in MS may help to reduce observation times in clinical trials and add confidence to the detection of progression events in MS.

Optical coherence tomography with voxel-based morphometry: a new tool to unveil focal retinal neurodegeneration in multiple sclerosis

Neurodegeneration is the main contributor to disability accumulation in multiple sclerosis. Previous studies in neuro-ophthalmology have revealed that neurodegeneration in multiple sclerosis also affects the neuro-retina. Optical coherence tomography has been used to measure thinning of retinal layers, which correlates with several other markers for axonal/neuronal loss in multiple sclerosis. However, the existing analytical tools have limitations in terms of sensitivity and do not provide topographical information. In this study, we aim to evaluate whether voxel-based morphometry can increase sensitivity in detecting neuroaxonal degeneration in the retina and offer topographical information. A total of 131 people with multiple sclerosis (41 clinically isolated syndrome, 53 relapsing-remitting and 37 progressive multiple sclerosis) and 50 healthy subjects were included. Only eyes with normal global peripapillary retinal nerve fibre layer thickness and no history of optic neuritis were considered. Voxel-based morphometry and voxel-wise statistical comparisons were performed on the following: (i) patients at different disease stages and 2) patients who experienced the first demyelination attack without subclinical optic neuritis, assessed by visual evoked potentials. Standard parameters failed to discern any differences; however, voxel-based morphometry-optical coherence tomography successfully detected focal macular atrophy of retinal nerve fibre layer and ganglion cell/inner plexiform layer, along with thickening of inner nuclear layer in patients who experienced the first demyelination attack (disease duration = 4.2 months). Notably, the atrophy pattern of the ganglion cell/inner plexiform layer was comparable across disease phenotypes. In contrast, the retinal nerve fibre layer atrophy spread from the optic nerve head to the fovea as the disease evolved towards the progressive phase. Furthermore, for patients who experienced the first neurological episode, the severity of retinal nerve fibre layer atrophy at entry could predict a second attack. Our results demonstrate that voxel-based morphometry-optical coherence tomography exhibits greater sensitivity than standard parameters in detecting focal retinal atrophy, even at clinical presentation, in eyes with no history of optic neuritis and with normal latency of visual evoked potentials. Thinning of the ganglion cell/inner plexiform layer primarily concentrated in nasal perifovea in all disease phenotypes, indicating selective vulnerability of retinal ganglion cells and their perifoveal axons. Conversely, the degree of retinal nerve fibre layer thinning seems to be related to the clinical course of multiple sclerosis. The findings suggest bidirectional neurodegeneration in the visual pathway. Voxel-based morphometry-optical coherence tomography shows potential as a valuable tool for monitoring neurodegeneration on a patient level and evaluating the efficacy of novel neuroprotective treatments.

Explainable artificial intelligence toward usable and trustworthy computer-aided diagnosis of multiple sclerosis from Optical Coherence Tomography

BACKGROUND

Several studies indicate that the anterior visual pathway provides information about the dynamics of axonal degeneration in Multiple Sclerosis (MS). Current research in the field is focused on the quest for the most discriminative features among patients and controls and the development of machine learning models that yield computer-aided solutions widely usable in clinical practice. However, most studies are conducted with small samples and the models are used as black boxes. Clinicians should not trust machine learning decisions unless they come with comprehensive and easily understandable explanations.

MATERIALS AND METHODS

A total of 216 eyes from 111 healthy controls and 100 eyes from 59 patients with relapsing-remitting MS were enrolled. The feature set was obtained from the thickness of the ganglion cell layer (GCL) and the retinal nerve fiber layer (RNFL). Measurements were acquired by the novel Posterior Pole protocol from Spectralis Optical Coherence Tomography (OCT) device. We compared two black-box methods (gradient boosting and random forests) with a glass-box method (explainable boosting machine). Explainability was studied using SHAP for the black-box methods and the scores of the glass-box method.

RESULTS

The best-performing models were obtained for the GCL layer. Explainability pointed out to the temporal location of the GCL layer that is usually broken or thinning in MS and the relationship between low thickness values and high probability of MS, which is coherent with clinical knowledge.

CONCLUSIONS

The insights on how to use explainability shown in this work represent a first important step toward a trustworthy computer-aided solution for the diagnosis of MS with OCT.

Risk of retinal disease in patients with autism spectrum disorder

BACKGROUND

Ocular abnormalities and visual dysfunction have been associated with autism spectrum disorder (ASD). Our study assessed the risks of developing retinal diseases in individuals with ASD.

METHODS

In all, 18 874 patients with ASD and 188 740 controls were selected from the Taiwan National Health Insurance Research Database between 2001 and 2009. The control group was matched based on demographic characteristics and medical and ophthalmological comorbidities. The hazard ratios (HRs) with 95% confidence intervals were calculated with Cox-regression analyses adjusted for selected confounders.

RESULTS

Individuals with ASD had a higher incidence of developing retinal diseases (1.48‰ vs 0.73‰, P < .001), and the diagnosis of retinal diseases occurred earlier than the controls (3.73 vs 6.28 years, P < .001). When compared to the control group, the HR of developing retinal diseases in the ASD group was 1.75 (95%: 1.04-2.94) and 7.84 (95%: 3.51-17.47) for retinal detachment. There was no association between the cumulative daily dose of atypical antipsychotics and the incidence of retinal diseases in the ASD group.

CONCLUSION

Individuals with ASD have a higher risk of developing retinal detachment and are diagnosed with retinal diseases earlier than controls. Future research is needed to elucidate the mechanisms mediating the progression of retinal diseases in the ASD population.