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

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.

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.

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.

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.

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.

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.

Radiologically Isolated Syndrome and the Multiple Sclerosis Prodrome in Pediatrics: Early Features of the Spectrum of Demyelination

Radiologically isolated syndrome refers to the clinical scenario in which individuals have imaging concerning for multiple sclerosis and would otherwise satisfy radiographic dissemination in space criteria, but do not have any attributable signs or symptoms. Radiologically isolated syndrome has been increasingly recognized in the pediatric population and it is understood certain individuals will transition to a formal diagnosis of multiple sclerosis over time. This review aims to outline the available data within this unique population including the diagnostic criteria, epidemiology, risk factors associated with transitioning to multiple sclerosis, and the current therapeutic landscape. Radiologically isolated syndrome will also be positioned within a broader spectrum of demyelinating disease as recent data has pointed towards a likely prodromal phase that precedes a first clinical event and diagnosis of multiple sclerosis. Characterizing the radiographic features, clinical symptoms, and biomarkers that constitute this prodromal phase of multiple sclerosis would help identify patients who may most benefit from early intervention in the future.

Longitudinal stability of inter-eye differences in optical coherence tomography measures for identifying unilateral optic nerve lesions in multiple sclerosis

INTRODUCTION

Optical coherence tomography (OCT)-derived peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell+inner plexiform layer (GCIPL) thickness inter-eye differences (IEDs) are robust measurements for identifying clinical history acute ON in people with MS (PwMS). This study investigated the utility and durability of these measures as longitudinal markers to identify optic nerve lesions.

METHODS

Prospective, multi-center international study of PwMS (with/without clinical history of ON) and healthy controls. Data from two sites in the International MS Visual System Consortium (IMSVISUAL) were analyzed. Mixed-effects models were used to compare inter-eye differences based on MS and acute ON history.

RESULTS

Average age of those with MS (n = 210) was 39.1 ± 10.8 and 190 (91%) were relapsing-remitting. Fifty-nine (28.1%) had a history of acute unilateral ON, while 9/210 (4.3%) had >1 IB episode. Median follow-up between OCT scans was 9 months. By mixed-effects modeling, IEDs were stable between first and last visits within groups for GCIPL for controls (p = 0.18), all PwMS (p = 0.74), PwMs without ON (p = 0.22), and PwMS with ON (p = 0.48). For pRNFL, IEDs were within controls (p = 0.10), all PwMS (p = 0.53), PwMS without ON history (p = 0.98), and PwMS with history of ON (p = 0.81).

CONCLUSION

We demonstrated longitudinal stability of pRNFL and GCIPL IEDs as markers for optic nerve lesions in PwMS, thus reinforcing the role for OCT in demonstrating optic nerve lesions.

Advanced central nervous system imaging biomarkers in radiologically isolated syndrome: a mini review

Radiologically isolated syndrome is characterised by central nervous system white-matter hyperintensities highly suggestive of multiple sclerosis in individuals without a neurological history of clinical demyelinating episodes. It probably represents the pre-symptomatic phase of clinical multiple sclerosis but is poorly understood. This mini review summarises our current knowledge regarding advanced imaging techniques in radiologically isolated syndrome that provide insights into its pathobiology and prognosis. The imaging covered will include magnetic resonance imaging-derived markers of central nervous system volumetrics, connectivity, and the central vein sign, alongside optical coherence tomography-related metrics.

Retinal layer thickness predicts disability accumulation in early relapsing multiple sclerosis

BACKGROUND AND PURPOSE

This study was undertaken to investigate baseline peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell and inner plexiform layer (GCIPL) thickness for prediction of disability accumulation in early relapsing multiple sclerosis (RMS).

METHODS

From a prospective observational study, we included patients with newly diagnosed RMS and obtained spectral-domain optical coherence tomography scan within 90 days after RMS diagnosis. Impact of pRNFL and GCIPL thickness for prediction of disability accumulation (confirmed Expanded Disability Status Scale [EDSS] score ≥ 3.0) was tested by multivariate (adjusted hazard ratio [HR] with 95% confidence interval [CI]) Cox regression models.

RESULTS

We analyzed 231 MS patients (mean age = 30.3 years, SD = 8.1, 74% female) during a median observation period of 61 months (range = 12-93). Mean pRNFL thickness was 92.6 μm (SD = 12.1), and mean GCIPL thickness was 81.4 μm (SD = 11.8). EDSS ≥ 3 was reached by 28 patients (12.1%) after a median 49 months (range = 9-92). EDSS ≥ 3 was predicted with GCIPL < 77 μm (HR = 2.7, 95% CI = 1.6-4.2, p < 0.001) and pRNFL thickness ≤ 88 μm (HR = 2.0, 95% CI = 1.4-3.3, p < 0.001). Higher age (HR = 1.4 per 10 years, p < 0.001), incomplete remission of first clinical attack (HR = 2.2, p < 0.001), ≥10 magnetic resonance imaging (MRI) lesions (HR = 2.0, p < 0.001), and infratentorial MRI lesions (HR = 1.9, p < 0.001) were associated with increased risk of disability accumulation, whereas highly effective disease-modifying treatment was protective (HR = 0.6, p < 0.001). Type of first clinical attack and presence of oligoclonal bands were not significantly associated.

CONCLUSIONS

Retinal layer thickness (GCIPL more than pRNFL) is a useful predictor of future disability accumulation in RMS, independently adding to established markers.

Retinal ganglion cell loss is associated with future disability worsening in early relapsing-remitting multiple sclerosis

BACKGROUND AND PURPOSE

Thinning of the retinal combined ganglion cell and inner plexiform layer (GCIP) as measured by optical coherence tomography (OCT) is a common finding in patients with multiple sclerosis. This study aimed to investigate whether a single retinal OCT analysis allows prediction of future disease activity after a first demyelinating event.

METHODS

This observational cohort study included 201 patients with recently diagnosed clinically isolated syndrome or relapsing-remitting multiple sclerosis from two German tertiary referral centers. Individuals underwent neurological examination, magnetic resonance imaging, and OCT at baseline and at yearly follow-up visits.

RESULTS

Patients were included at a median disease duration of 2.0 months. During a median follow-up of 59 (interquartile range = 43-71) months, 82% of patients had ongoing disease activity as demonstrated by failing the no evidence of disease activity 3 (NEDA-3) criteria, and 19% presented with confirmed disability worsening. A GCIP threshold of ≤77 μm at baseline identified patients with a high risk for NEDA-3 failure (hazard ratio [HR] = 1.7, 95% confidence interval [CI] = 1.1-2.8, p = 0.04), and GCIP measures of ≤69 μm predicted disability worsening (HR = 2.2, 95% CI = 1.2-4.3, p = 0.01). Higher rates of annualized GCIP loss increased the risk for disability worsening (HR = 2.5 per 1 μm/year increase of GCIP loss, p = 0.03).

CONCLUSIONS

Ganglion cell thickness as measured by OCT after the initial manifestation of multiple sclerosis may allow early risk stratification as to future disease activity and progression.

Swept-Source Optical Coherence Tomography Thresholds in Differentiating Clinical Outcomes in a Real-World Cohort of Treatment-Naïve Multiple Sclerosis Patients

This study aimed to determine whether peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell–inner plexiform layer (GCIPL) thickness thresholds for single-time-point swept-source optical coherence tomography (SS-OCT) measures can differentiate the clinical outcomes of treatment-naïve people with multiple sclerosis (pwMS). A total of 275 patients with the clinically isolated syndrome (n = 23), benign MS (n = 8), relapsing–remitting MS (n = 185), secondary progressive MS (n = 28), primary progressive MS (n = 31), and with no history of optic neuritis were included. The mean Expanded Disability Status Scale (EDSS) score was 3.0 ± 1.6. The cut-off values of pRNFL (87 µm and 88 µm) and GCIPL (70 µm) thicknesses have been adopted from previous studies using spectral-domain OCT. PwMS with pRNFL ≤87 µm and ≤88 µm had a longer disease duration, more advanced disability, and more frequently progressive MS variants compared to those with greater pRNFL thicknesses. In distinguishing pwMS with disability greater than or equal to the mean EDSS score (EDSS ≥ 3) from those with less severe disability, GCIPL thickness <70 µm had the highest sensitivity, while pRNFL thickness ≤87 µm had the greatest specificity. The optimal cut-off values differentiating patients with EDSS ≥ 3 from those with less severe disability was 63 µm for GCIPL thickness and 93.5 µm for pRNFL thickness. In conclusion, pRNFL and GCIPL thickness thresholds for single-time-point SS-OCT measurements may be helpful in differentiating the disability status of treatment-naïve pwMS.

Changes in Retinal Thickness and Brain Volume during 6.8-Year Escalating Therapy for Multiple Sclerosis

Background. Different disease-modifying therapies (DMT) for multiple sclerosis (MS) have disparate effects on disability outcomes. Sweden has a leading position globally in initiating high-efficacy DMT instead of escalating DMT from 1st-line to high-efficacy DMT. With optical coherence tomography (OCT), retinal changes can be measured at a few micrometer level. OCT has been increasingly applied in diagnosing MS and monitoring disease course and therapeutic effect. Objective. We investigate the effects of 1st-line versus high-efficacy DMT for MS on retinal and brain atrophy and on functional outcomes during 6.8 years of escalating DMT. Materials and Methods. In this prospective longitudinal observational study, 18 MS patients were followed up for 6.8 years. Twelve of the patients were untreated at baseline. All patients underwent 1st-line DMT for median duration of 2.4 years and then switched to high-efficacy DMT for a median duration of 2.9 years. Findings from neurological examinations, MRI, and OCT measures were registered 2-4 times per year. Results. Ganglion cell-inner plexiform layer (GCIPL) thickness was significantly reduced during 1st-line DMT (73.75 μm, $p<0.01$ ) compared to baseline (76.38 μm). During high-efficacy DMT, thickness reduction was slower (73.27 μm, $p<0.05$ ), and MRI contrast-loading lesions vanished ( $p<0.01$ ). However, brain parenchymal fraction (BPF) decreased during high-efficacy DMT compared to 1st-line DMT. Estimated models showed similar results. Conclusion. GCIPL decline was most profound during 1st-line DMT and diminished during high-efficacy DMT. MRI contrast lesions vanished during high-efficacy DMT. However, brain atrophy continued regardless of high-efficacy DMT.

Recent Progress in the Identification of Early Transition Biomarkers from Relapsing-Remitting to Progressive Multiple Sclerosis

Despite extensive research into the pathophysiology of multiple sclerosis (MS) and recent developments in potent disease-modifying therapies (DMTs), two-thirds of relapsing-remitting MS patients transition to progressive MS (PMS). The main pathogenic mechanism in PMS is represented not by inflammation but by neurodegeneration, which leads to irreversible neurological disability. For this reason, this transition represents a critical factor for the long-term prognosis. Currently, the diagnosis of PMS can only be established retrospectively based on the progressive worsening of the disability over a period of at least 6 months. In some cases, the diagnosis of PMS is delayed for up to 3 years. With the approval of highly effective DMTs, some with proven effects on neurodegeneration, there is an urgent need for reliable biomarkers to identify this transition phase early and to select patients at a high risk of conversion to PMS. The purpose of this review is to discuss the progress made in the last decade in an attempt to find such a biomarker in the molecular field (serum and cerebrospinal fluid) between the magnetic resonance imaging parameters and optical coherence tomography measures.

Serum Neurofilaments and OCT Metrics Predict EDSS-Plus Score Progression in Early Relapse-Remitting Multiple Sclerosis

(1) Background: Early disability accrual in RRMS patients is frequent and is associated with worse long-term prognosis. Correctly identifying the patients that present a high risk of early disability progression is of utmost importance, and may be aided by the use of predictive biomarkers. (2) Methods: We performed a prospective cohort study that included newly diagnosed RRMS patients, with a minimum follow-up period of one year. Biomarker samples were collected at baseline, 3-, 6- and 12-month follow-ups. Disability progression was measured using the EDSS-plus score. (3) Results: A logistic regression model based on baseline and 6-month follow-up sNfL z-scores, RNFL and GCL-IPL thickness and BREMSO score was statistically significant, with χ2(4) = 19.542, p < 0.0001, R2 = 0.791. The model correctly classified 89.1% of cases, with a sensitivity of 80%, a specificity of 93.5%, a positive predictive value of 85.7% and a negative predictive value of 90.62%. (4) Conclusions: Serum biomarkers (adjusted sNfL z-scores at baseline and 6 months) combined with OCT metrics (RNFL and GCL-IPL layer thickness) and the clinical score BREMSO can accurately predict early disability progression using the EDSS-plus score for newly diagnosed RRMS patients.

Corneal axonal loss as an imaging biomarker of neurodegeneration in multiple sclerosis: a longitudinal study

Background

Resourceful endpoints of axonal loss are needed to predict the course of multiple sclerosis (MS). Corneal confocal microscopy (CCM) can detect axonal loss in patients with clinically isolated syndrome and established MS, which relates to neurological disability.

Objective

To assess corneal axonal loss over time in relation to retinal atrophy, and neurological and radiological abnormalities in MS.

Methods

Patients with relapsing-remitting (RRMS) (n = 68) or secondary progressive MS (SPMS) (n = 15) underwent CCM and optical coherence tomography. Corneal nerve fibre density (CNFD-fibres/mm²), corneal nerve branch density (CNBD-branches/mm²), corneal nerve fibre length (CNFL-mm/mm²) and retinal nerve fibre layer (RNFL-μm) thickness were quantified along with neurological and radiological assessments at baseline and after 2 years of follow-up. Age-matched, healthy controls (n = 20) were also assessed.

Results

In patients with RRMS compared with controls at baseline, CNFD (p = 0.004) and RNFL thickness (p < 0.001) were lower, and CNBD (p = 0.003) was higher. In patients with SPMS compared with controls, CNFD (p < 0.001), CNFL (p = 0.04) and RNFL thickness (p < 0.001) were lower. For identifying RRMS, CNBD had the highest area under the receiver operating characteristic (AUROC) curve (0.99); and for SPMS, CNFD had the highest AUROC (0.95). At follow-up, there was a further significant decrease in CNFD (p = 0.04), CNBD (p = 0.001), CNFL (p = 0.008) and RNFL (p = 0.002) in RRMS; in CNFD (p = 0.04) and CNBD (p = 0.002) in SPMS; and in CNBD (p = 0.01) in SPMS compared with RRMS. Follow-up corneal nerve loss was greater in patients with new enhancing lesions and optic neuritis history.

Conclusion

Progressive corneal and retinal axonal loss was identified in patients with MS, especially those with more active disease. CCM may serve as an imaging biomarker of axonal loss in MS.

Baseline retinal nerve fiber layer thickness as a predictor of multiple sclerosis progression: New insights from the FREEDOMS II study

BACKGROUND AND PURPOSE

The aim was to evaluate the potential of retinal nerve fiber layer thickness (RNFLT) measured with optical coherence tomography in predicting disease progression in relapsing-remitting multiple sclerosis (RRMS).

METHODS

Analyses were conducted post hoc of this 24-month, phase III, double-blind study, in which RRMS patients were randomized (1:1:1) to once daily oral fingolimod 0.5 mg, 1.25 mg or placebo. The key outcomes were the association between baseline RNFLT and baseline clinical characteristics and clinical/imaging outcomes up to 24 months. Change of RNFLT with fingolimod versus placebo within 24 months and time to retinal nerve fiber layer (RNFL) thinning were evaluated.

RESULTS

Altogether 885 patients were included. At baseline, lower RNFLT was correlated with higher Expanded Disability Status Scale score (r = -1.085, p = 0.018), lower brain volume (r = 0.025, p = 0.006) and deep gray matter volume (r = 0.731, p < 0.0001), worse visual acuity (r = -19.846, p < 0.0001) and longer duration since diagnosis (r = -0.258, p = 0.018). At month 12, low baseline RNFLT (<86 μm) versus high baseline RNFLT (≥99 μm) was associated with a greater brain volume loss (percentage change -0.605% vs. -0.315%, p = 0.035) in patients without optic neuritis history. At month 24, low baseline RNFLT versus high baseline RNFLT was associated with a higher number of new or newly enlarged T2 lesions (mean number 4.0 vs. 2.8, p = 0.014) and a higher risk of subsequent RNFL thinning (hazard ratio 2.55; 95% confidence interval 1.84-3.53; p < 0.001). The atrophy of the RNFL in the inferior quadrant was alleviated with fingolimod 0.5 mg versus placebo at month 24 (Δ(least squares mean) = 1.8, p = 0.047).

CONCLUSION

Retinal nerve fiber layer thickness could predict disease progression in RRMS.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT00355134, https://clinicaltrials.gov/ct2/show/NCT00355134.

Optical coherence tomography as a prognostic tool for disability progression in MS: a systematic review

Since multiple sclerosis (MS) is characterized by an unpredictable disease course, accurate prognosis and personalized treatment constitute an important challenge in clinical practice. We performed a qualitative systematic review to assess the predictive value of retinal layer measurement by spectral-domain optical coherence tomography (SD-OCT) in MS patients. Longitudinal MS cohort studies that determined the risk of clinical deterioration based on peripapillary retinal nerve fiber layer (pRNFL) and/or macular ganglion cell-inner plexiform layer (mGCIPL) atrophy were included. Our search strategy and selection process yielded eight articles in total. Of those, five studies only focused on patients with a relapsing-remitting disease pattern (RRMS). After correction for confounders such as disease duration, we found that (1) cross-sectional measurement of pRNFL thickness ≤ 88 µm; (2) cross-sectional measurement of mGCIPL thickness < 77 µm; (3) longitudinal measurement of pRNFL thinning > 1.5 µm/year; and (4) longitudinal measurement of mGCIPL thinning ≥ 1.0 µm/year is associated with an increased risk for disability progression in subsequent years. Longitudinal mGCIPL assessment consistently resulted in the highest risk estimates in our analysis. Within these studies, inclusion and exclusion criteria accounted for the retinal degeneration inherent to (acute) optic neuritis (ON). This small systematic review provides additional evidence that OCT-measured pRNFL and/or mGCIPL atrophy can predict disability progression in RRMS patients. We therefore recommend close clinical follow-up or initiation/change of treatment in RRMS patients with increased risk for clinical deterioration based on retinal layer thresholds, in particular when other poor prognostic signs co-occur.

Serum neurofilament-light and glial fibrillary acidic protein levels in hydroxychloroquine-treated primary progressive multiple sclerosis

BACKGROUND

In a recent trial, hydroxychloroquine (HCQ) treatment reduced the expected rate of disability worsening at 18 months in primary progressive multiple sclerosis (PPMS). Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) are emerging biomarkers in multiple sclerosis.

METHODS

We measured NfL and GFAP levels in serum samples from 39 patients with inactive PPMS included in a phase II clinical trial of HCQ treatment in PPMS at multiple time points over 18 months, and investigated the association of these biomarkers with clinical disability at screening and during follow-up. Screening and 12-month retinal nerve fiber layer (RNFL) thickness was also recorded and analyzed.

RESULTS

NfL and GFAP levels increased over time, but only significantly from screening to month 6. NfL and GFAP levels did not significantly increase from month 6 up to month 18. At screening, NfL and GFAP levels did not correlate with the Expanded Disability Status Scale (EDSS), and GFAP but not NfL modestly correlated with Timed 25-Foot Walk test (T25FW). Screening NfL and GFAP levels did not predict disability worsening (≥20% worsening on the T25FW) at month 18. RNFL thickness decreased significantly from screening to month 12 and independently predicted disability worsening.

CONCLUSIONS

In this cohort of people with inactive PPMS, HCQ treatment attenuated the increase of NfL and GFAP after 6 months of treatment and up to 18 months of follow-up, suggesting a treatment effect of HCQ over these biomarkers. RNFL thickness, a marker of neuroaxonal atrophy, was associated with disability worsening, and should be explored further as a prognostic marker in this population.

Association of Vitamin D Polygenic Risk Scores and Disease Outcome in People With Multiple Sclerosis

Background and Objectives

Observational studies suggest low levels of 25-hydroxyvitamin D (25[OH]D) may be associated with increased disease activity in people with multiple sclerosis (PwMS). Large-scale genome-wide association studies (GWAS) suggest 25(OH)D levels are partly genetically determined. The resultant polygenic scores (PGSs) could serve as a proxy for 25(OH)D levels, minimizing potential confounding and reverse causation in analyses with outcomes. Herein, we assess the association of genetically determined 25(OH)D and disease outcomes in MS.

Methods

We generated 25(OH)D PGS for 1,924 PwMS with available genotyping data pooled from 3 studies: the CombiRx trial (n = 575), Johns Hopkins MS Center (n = 1,152), and Immune-Mediated Inflammatory Diseases study (n = 197). 25(OH)D-PGS were derived using summary statistics (p < 5 × 10−8) from a large GWAS including 485,762 individuals with circulating 25(OH)D levels measured. We included clinical and imaging outcomes: Expanded disability status scale (EDSS), timed 25-foot walk (T25FW), nine-hole peg test (9HPT), radiologic activity, and optical coherence tomography-derived ganglion cell inner plexiform layer (GCIPL) thickness. A subset (n = 935) had measured circulating 25(OH)D levels. We fitted multivariable models based on the outcome of interest and pooled results across studies using random effects meta-analysis. Sensitivity analyses included a modifiedpvalue threshold for inclusion in the PGS (5 × 10−5) and applying Mendelian randomization (MR) rather than using PGS.

Results

Initial analyses demonstrated a positive association between generated 25(OH)D-PGS and circulating 25(OH)D levels (per 1SD increase in 25[OH]D PGS: 3.08%, 95% CI: 1.77%, 4.42%;p= 4.33e-06; R2= 2.24%). In analyses with outcomes, we did not observe an association between 25(OH)D-PGS and relapse rate (per 1SD increase in 25[OH]D-PGS: 0.98; 95% CI: 0.87–1.10), EDSS worsening (per 1SD: 1.05; 95% CI: 0.87–1.28), change in T25FW (per 1SD: 0.07%; 95% CI: −0.34 to 0.49), or change in 9HPT (per 1SD: 0.09%; 95% CI: −0.15 to 0.33). 25(OH)D-PGS was not associated with new lesion accrual, lesion volume or other imaging-based outcomes (whole brain, gray, white matter volume loss or GCIPL thinning). The results were similarly null in analyses using otherpvalue thresholds or those applying MR.

Discussion

Genetically determined lower 25(OH)D levels were not associated with worse disease outcomes in PwMS and raises questions about the plausibility of a treatment effect of vitamin D in established MS.

Treatment of Patients with Multiple Sclerosis Transitioning Between Relapsing and Progressive Disease

Multiple sclerosis (MS) is a chronic autoimmune demyelinating and neurodegenerative disease of the central nervous system with a wide variety of clinical phenotypes. In spite of the phenotypic classification of MS patients, current data provide evidence that diffuse neuroinflammation and neurodegeneration coexist in all MS forms, the latter gaining increasing clinical relevance in progressive phases. Given that the transition phase of relapsing-remitting MS (RRMS) to secondary progressive MS (SPMS) is not well defined, and widely accepted criteria for SPMS are lacking, randomised controlled trials (RCTs) specifically designed for the transition phase have not been conducted. This review summarizes primary and secondary analyses and reports derived from phase III prospective clinical RCTs listed in PubMed of compounds authorised through the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) for the treatment of MS. The best data are available for interferon beta-1a (IFNb-1a) subcutaneous (s.c.), IFNb-1b s.c., mitoxantrone and siponimod, the latter being the most modern compound with likely the best risk-to-effect ratio. Moreover, there is a labels discrepancy for many disease-modifying treatments (DMTs) between the FDA and EMA, which have to be taken into consideration when opting for a specific DMT.

The Usefulness of Optical Coherence Tomography in Disease Progression Monitoring in Younger Patients with Relapsing-Remitting Multiple Sclerosis: A Single-Centre Study

The purpose of the study was to assess the usefulness of optical coherence tomography (OCT) in the detection of the neurodegenerative process in younger patients with multiple sclerosis (MS). The study group consisted of 61 patients with a relapsing remitting course of MS (mean age 36.4 ± 6.7 years) divided into two groups: short (≤5 years) and long (>10 years) disease duration. OCT, P300 evoked potential, Montreal Cognitive Assessment, and performance subtests (Picture Completion and Digit Symbol) of the Wechsler Adult Intelligence Scale were performed in all patients. Mean values of most parameters assessed in OCT (pRNFL Total, pRNFL Inferior, pRNFL Superior, pRNFL Temporalis, mRNFL, GCIPL, mRNFL+GCIPL) were significantly lower in MS patients in comparison to controls. And in patients with longer disease duration in comparison to those with shorter. Most OCT parameters negatively correlated with the EDSS score (p < 0.05). No significant correlation was found between OCT results and both P300 latency and the results of psychometric tests. OCT, as a simple, non-invasive, quick, and inexpensive method, could be useful for monitoring the progression of disease in MS patients.

Retinal Examinations Provides Early Warning of Alzheimer's Disease

Patients with Alzheimer's disease have difficulty maintaining independent living abilities as the disease progresses, causing an increased burden of care on family caregivers and the healthcare system and related financial strain. This patient group is expected to continue to expand as life expectancy climbs. Current diagnostics for Alzheimer's disease are complex, unaffordable, and invasive without regard to diagnosis quality at early stages, which urgently calls for more technical improvements for diagnosis specificity. Optical coherence tomography or tomographic angiography has been shown to identify retinal thickness loss and lower vascular density present earlier than symptom onset in these patients. The retina is an extension of the central nervous system and shares anatomic and functional similarities with the brain. Ophthalmological examinations can be an efficient tool to offer a window into cerebral pathology with the merit of easy operation. In this review, we summarized the latest observations on retinal pathology in Alzheimer's disease and discussed the feasibility of retinal imaging in diagnostic prediction, as well as limitations in current retinal examinations for Alzheimer's disease diagnosis.

Normative Data and Conversion Equation for Spectral-Domain Optical Coherence Tomography in an International Healthy Control Cohort

BACKGROUND

Spectral-domain (SD-) optical coherence tomography (OCT) can reliably measure axonal (peripapillary retinal nerve fiber layer [pRNFL]) and neuronal (macular ganglion cell + inner plexiform layer [GCIPL]) thinning in the retina. Measurements from 2 commonly used SD-OCT devices are often pooled together in multiple sclerosis (MS) studies and clinical trials despite software and segmentation algorithm differences; however, individual pRNFL and GCIPL thickness measurements are not interchangeable between devices. In some circumstances, such as in the absence of a consistent OCT segmentation algorithm across platforms, a conversion equation to transform measurements between devices may be useful to facilitate pooling of data. The availability of normative data for SD-OCT measurements is limited by the lack of a large representative world-wide sample across various ages and ethnicities. Larger international studies that evaluate the effects of age, sex, and race/ethnicity on SD-OCT measurements in healthy control participants are needed to provide normative values that reflect these demographic subgroups to provide comparisons to MS retinal degeneration.

METHODS

Participants were part of an 11-site collaboration within the International Multiple Sclerosis Visual System (IMSVISUAL) consortium. SD-OCT was performed by a trained technician for healthy control subjects using Spectralis or Cirrus SD-OCT devices. Peripapillary pRNFL and GCIPL thicknesses were measured on one or both devices. Automated segmentation protocols, in conjunction with manual inspection and correction of lines delineating retinal layers, were used. A conversion equation was developed using structural equation modeling, accounting for clustering, with healthy control data from one site where participants were scanned on both devices on the same day. Normative values were evaluated, with the entire cohort, for pRNFL and GCIPL thicknesses for each decade of age, by sex, and across racial groups using generalized estimating equation (GEE) models, accounting for clustering and adjusting for within-patient, intereye correlations. Change-point analyses were performed to determine at what age pRNFL and GCIPL thicknesses exhibit accelerated rates of decline.

RESULTS

The healthy control cohort (n = 546) was 54% male and had a wide distribution of ages, ranging from 18 to 87 years, with a mean (SD) age of 39.3 (14.6) years. Based on 346 control participants at a single site, the conversion equation for pRNFL was Cirrus = -5.0 + (1.0 × Spectralis global value). Based on 228 controls, the equation for GCIPL was Cirrus = -4.5 + (0.9 × Spectralis global value). Standard error was 0.02 for both equations. After the age of 40 years, there was a decline of -2.4 μm per decade in pRNFL thickness ( P < 0.001, GEE models adjusting for sex, race, and country) and -1.4 μm per decade in GCIPL thickness ( P < 0.001). There was a small difference in pRNFL thickness based on sex, with female participants having slightly higher thickness (2.6 μm, P = 0.003). There was no association between GCIPL thickness and sex. Likewise, there was no association between race/ethnicity and pRNFL or GCIPL thicknesses.

CONCLUSIONS

A conversion factor may be required when using data that are derived between different SD-OCT platforms in clinical trials and observational studies; this is particularly true for smaller cross-sectional studies or when a consistent segmentation algorithm is not available. The above conversion equations can be used when pooling data from Spectralis and Cirrus SD-OCT devices for pRNFL and GCIPL thicknesses. A faster decline in retinal thickness may occur after the age of 40 years, even in the absence of significant differences across racial groups.

Association of the retinal vasculature, intrathecal immunity, and disability in multiple sclerosis

BACKGROUND

Optical coherence tomography angiography (OCT-A) is a novel technique allowing non-invasive assessment of the retinal vasculature. During relapsing remitting multiple sclerosis (RRMS), retinal vessel loss occurs in eyes suffering from acute optic neuritis and recent data suggest that retinal vessel loss might also be evident in non-affected eyes. We investigated whether alterations of the retinal vasculature are linked to the intrathecal immunity and whether they allow prognostication of the future disease course.

MATERIAL AND METHODS

This study includes two different patient cohorts recruited at a tertiary German academic multiple sclerosis center between 2018 and 2020 and a cohort of 40 healthy controls. A total of 90 patients with RRMS undergoing lumbar puncture and OCT-A analysis were enrolled into a cross-sectional cohort study to search for associations between the retinal vasculature and the intrathecal immune compartment. We recruited another 86 RRMS patients into a prospective observational cohort study who underwent clinical examination, OCT-A and cerebral magnetic resonance imaging at baseline and during annual follow-up visits to clarify whether alterations of the retinal vessels are linked to RRMS disease activity. Eyes with a history of optic neuritis were excluded from the analysis.

RESULTS

Rarefication of the superficial vascular complex occured during RRMS and was linked to higher frequencies of activated B cells and higher levels of the pro-inflammatory cytokines interferon-γ, tumor necrosis factor α and interleukin-17 in the cerebrospinal fluid. During a median follow-up of 23 (interquartile range 14 - 25) months, vessel loss within the superficial (hazard ratio [HR] 1.6 for a 1%-point decrease in vessel density, p=0.01) and deep vascular complex (HR 1.6 for a 1%-point decrease, p=0.05) was associated with future disability worsening.

DISCUSSION

Optic neuritis independent rarefication of the retinal vasculature might be linked to neuroinflammatory processes during RRMS and might predict a worse disease course. Thus, OCT-A might be a novel biomarker to monitor disease activity and predict future disability.

Rate of Retinal Layer Thinning as a Biomarker for Conversion to Progressive Disease in Multiple Sclerosis

Background and Objectives

The diagnosis of secondary progressive multiple sclerosis (SPMS) is often delayed because of the lack of objective clinical tools, which increases the diagnostic uncertainty and hampers the therapeutic development in progressive multiple sclerosis (MS). Optical coherence tomography (OCT) has been proposed as a promising biomarker of progressive neurodegeneration. To explore longitudinal changes in the thicknesses of retinal layers on OCT in individuals with relapsing-remitting MS (RRMS) who converted to SPMS vs matched patients with RRMS who did not convert to SPMS. Our hypothesis is that the 2 cohorts exhibit different rates of retinal thinning.

Methods

From our prospective observational cohort of patients with MS at the American University of Beirut, we selected patients with RRMS who converted to SPMS during the observation period and patients with RRMS, matched by age, disease duration, and Expanded Disability Status Scale (EDSS) at the first visit. Baseline retinal measurements were obtained using spectral domain OCT, and all patients underwent clinical and OCT evaluation every 6–12 months on average throughout the study period (mean = 4 years). Mixed-effect regression models were used to assess the annualized rates of retinal changes and the differences between the 2 groups and between converters to SPMS before and after their conversion.

Results

A total of 61 participants were selected (21 SPMS and 40 RRMS). There were no differences in baseline characteristics and retinal measurements between the 2 groups. The annualized rates of thinning of all retinal layers, except for macular volume, were greater in converters before conversion compared with nonconverters by 112% for peripapillary retinal nerve fiber layer (p = 0.008), 344% for tRNFL (p < 0.0001), and 82% for cell-inner plexiform layer (GCIPL) (p = 0.002). When comparing the annualized rate of thinning for the same patients with SPMS before and after conversion, no significant differences were found except for tRNFL and GCIPL with slower thinning rates postconversion (46% and 68%, respectively).

Discussion

Patients who converted to SPMS exhibited faster retinal thinning as reflected on OCT. Longitudinal assessment of retinal thinning could confirm the transition to SPMS and help with the therapeutic decision making for patients with MS with clinical suspicion of disease progression.