Optical coherence tomography is highly sensitive in detecting prior optic neuritis

MOG35 - 55-induced EAE model of optic nerve inflammation compared to MS, MOGAD and NMOSD related subtypes of human optic neuritis

Optic neuritis (ON), or inflammation of the optic nerve, is a common presenting symptom of demyelinating neuroinflammatory conditions that result in significant, subacute vision loss. Given its association with visual impairment and varying extent of visual recovery, ON has been recognized as a significant health burden with a need for new therapeutic strategies to improve long-term visual outcomes. Among the resources utilized to study ON, animal models have emerged as powerful tools to examine the underlying pathophysiology and the effectiveness of proposed therapies. In the current review, we discuss the functional and structural phenotypes related to ON in currently used mouse models, and summarize how the pathophysiology and visual phenotype of the myelin oligodendrocyte glycoprotein 35-55 (MOG35 - 55) experimental autoimmune encephalomyelitis (EAE) mouse model recapitulates clinical features of multiple sclerosis (MS), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and neuromyelitis optica spectrum disorder (NMOSD). The location of ON and the amount of visual recovery in the EAE model most closely resembles MS and NMOSD. However, we propose that the MOG35 - 55-induced EAE model of ON is primarily a MOGAD model given its similarity in pathophysiology, spinal cord demyelination pattern, and the degree of vision loss, retinal nerve fiber layer (RNFL) swelling, and disc edema. Overall, the MOG35 - 55-induced EAE animal model demonstrates overlapping features of autoimmune demyelinating conditions and serves as a comprehensive tool to further our understanding of visual impairment in all three conditions.

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

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Increased retinal thickness in sarcoidosis patients with ocular system involvement visualized with optical coherence tomography: a cross-sectional study

This study investigates the thickness of retinal structures in patients with neurosarcoidosis (NS) and ocular sarcoidosis (OS). We compared the central macular thickness (CMT), retinal thickness (RT), central nerve fiber layer (RNFL) thickness, and ganglion cell layer (GCL) thickness using optical coherence tomography. In a cross-sectional study, we categorized 97 sarcoidosis patients (185 eyes) into four groups: patients without ocular or central nervous system sarcoidosis (Non-Ocular/Non-CNS, n = 53), patients with OS (Ocular, n = 13), patients with NS (CNS, n = 16), and patients with combined OS and NS (Ocular/CNS, n = 15). The mean age was 51 (14) years. We found no overall difference between the groups in the CMT (p = 0.3), RT (p = 0.9), RNFL (p = 0.3), and GCL measurements (p = 0.9). Only in patients with a disease duration of more than five years, the CMT was significantly thicker in the Ocular group (278 μm, p < 0.001), the CNS group (267 μm, p = 0.04), and the Ocular/CNS group (268 μm, p = 0.04), compared to the Non-Ocular/Non-CNS group (249 μm). The RT was significantly thicker in the Ocular group (296 μm, p = 0.008) and the Ocular/CNS group (291 μm, p = 0.03) compared to the Non-Ocular/Non-CNS group (283 μm). In the RNFL measurements, the Ocular group (33.7 μm, p = 0.002) was thicker than the Non-ocular/Non-CNS group (29.1 μm). We found an increased retinal thickness in patients with ocular sarcoidosis and long disease duration.

Macular patterns of neuronal and visual field loss in recovered optic neuritis identified by machine learning

We used machine learning to investigate the residual visual field (VF) deficits and macula retinal ganglion cell (RGC) thickness loss patterns in recovered optic neuritis (ON). We applied archetypal analysis (AA) to 377 same-day pairings of 10-2 VF and optical coherence tomography (OCT) macula images from 93 ON eyes and 70 normal fellow eyes ≥ 90 days after acute ON. We correlated archetype (AT) weights (total weight = 100%) of VFs and total retinal thickness (TRT), inner retinal thickness (IRT), and macular ganglion cell-inner plexiform layer (GCIPL) thickness. AA showed most ON eyes had a 10-2 VF pattern like the normal fellow eye VF, despite having markedly thinner GCIPL patterns. AA identified 7 VF and 11 retinal thickness ATs for each OCT model. The normal VF AT constituted 80% of ON eyes and 90% of normal fellow eyes. The most common GCIPL AT consisted of diffuse thinning. We identified significant correlations for the normal AT weights using OCT AT weights of five GCIPL ATs (r = 0.45), four TRT ATs (0.53) and two IRT ATs (0.42). Following acute ON, most eyes had complete 10-2 VF recovery despite significant GCIPL thinning, suggesting compensatory mechanisms for vision.

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.

Myelin Oligodendrocyte Glycoprotein Antibody Disease Optic Neuritis: A Structure-Function Paradox?

BACKGROUND

Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) is a demyelinating disorder that most commonly presents with optic neuritis (ON) and affects children more often than adults. We report 8 pediatric patients with MOG-associated ON and characterize focal optical coherence tomography (OCT) abnormalities over time that help distinguish this condition from the trajectories of other demyelinating disorders. These OCT findings are examined in the context of longitudinal visual function testing.

METHODS

This is a retrospective case series of 8 pediatric patients with MOG-associated ON who were referred for neuro-ophthalmic evaluation. Longitudinal data for demographics, clinical history, physical examination, and OCT obtained in the course of clinical evaluations were collected through retrospective medical record review.

RESULTS

Patients demonstrated acute peripapillary retinal nerve fiber layer (RNFL) thickening in one or both eyes, consistent with optic disc swelling. This was followed by steady patterns of average RNFL thinning, with 9 of 16 eyes reaching significantly low RNFL thickness using OCT platform reference databases ( P < 0.01), accompanied by paradoxical recovery of high-contrast visual acuity (HCVA) in every patient. There was no correlation between HCVA and any OCT measures, although contrast sensitivity (CS) was associated with global thickness, PMB thickness, and nasal/temporal (N/T) ratio, and color vision was associated with PMB thickness. There was a lower global and papillomacular bundle (PMB) thickness ( P < 0.01) in clinically affected eyes compared with unaffected eyes. There was also a significantly higher N:T ratio in clinically affected eyes compared with unaffected eyes in the acute MOG-ON setting ( P = 0.03), but not in the long-term setting.

CONCLUSIONS

MOG shows a pattern of prominent retinal atrophy, as demonstrated by global RNFL thinning, with remarkable preservation of HCVA but remaining deficits in CS and color vision. These tests may be better clinical markers of vision changes secondary to MOG-ON. Of the OCT parameters measured, PMB thickness demonstrated the most consistent correlation between structural and functional measures. Thus, it may be a more sensitive marker of clinically significant retinal atrophy in MOG-ON. The N:T ratio in acute clinically affected MOG-ON eyes in our study was higher than the N:T ratio of neuromyelitis optica (NMO)-ON eyes and similar to the N:T ratio in multiple sclerosis (MS)-ON eyes as presented in the prior literature. Therefore, MOG may share a more similar pathophysiology to MS compared with NMO.

Retinal clues for selective neuronal loss in multiple sclerosis

OBJECTIVE

The relationship between the cell body layer and the dendritic network layer of the retina and cognitive performance (CP) in MS patients has not been examined separately. The objective of this study is to predict cognitive impairment (CI) in RRMS patients and to examine the relationship between CP and ganglion cell layer (GCL), inner plexiform layer (IPL), and GCL divided by IPL (GCL/IPL).

METHODS

Ophthalmological evaluation, retinal segmentation, and Symbol Digit Modalities Test (SDMT) were performed on 102 RRMS patients and 54 healthy subjects. The relationships of GCL, IPL, and GCL/IPL with CP in eyes without a history of optic neuritis were investigated using Spearman's correlation. Models were created by accepting 1 standard deviation less of the SDMT mean of the control group as the limit for CI. The cutoff value of the GCL/IPL variable that could predict CI was calculated by ROC analysis, and the ability to accurately predict CI was tested with binary logistic regression.

RESULTS

No correlation was found between OCT parameters and CP in healthy subjects. Correlation was found between GCL thickness and GCL/IPL variable and CP in RRMS patients (r=0.235, r=0.667 respectively). A GCL/IPL value of 1.255 was able to identify CI with 81.8% sensitivity and 75.9% specificity (AUC=0.844, LR=3.38) and predicted CI with 74.5% accuracy (Nagelkerke R2=0.439).

CONCLUSION

In RRMS patients, the IPL thickness is unrelated to CP. Therewithal, the GCL/IPL-CP relationship is stronger than the GCL-CP relationship and GCL/IPL can predict CI.

A comprehensive review of the advances in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is a rare relapsing neuroinflammatory autoimmune astrocytopathy, with a predilection for the optic nerves and spinal cord. Most cases are characterised by aquaporin-4-antibody positivity and have a relapsing disease course, which is associated with accrual of disability. Although the prognosis in NMOSD has improved markedly over the past few years owing to advances in diagnosis and therapeutics, it remains a severe disease. In this article, we review the evolution of our understanding of NMOSD, its pathogenesis, clinical features, disease course, treatment options and associated symptoms. We also address the gaps in knowledge and areas for future research focus.

Diagnostic Performance of Adding the Optic Nerve Region Assessed by Optical Coherence Tomography to the Diagnostic Criteria for Multiple Sclerosis

BACKGROUND AND OBJECTIVES

The optic nerve has been recommended as an additional region for demonstrating dissemination in space (DIS) in diagnostic criteria for multiple sclerosis (MS). The aim of this study was to investigate whether adding the optic nerve region as determined by optical coherence tomography (OCT) as part of the DIS criteria improves the 2017 diagnostic criteria.

METHODS

From a prospective observational study, we included patients with a first demyelinating event who had complete information to assess DIS and a spectral domain OCT scan obtained within 180 days. Modified DIS criteria (DIS + OCT) were constructed by adding the optic nerve to the current DIS regions based on validated thresholds for OCT intereye differences. Time to second clinical attack was the primary endpoint.

RESULTS

We analyzed 267 patients with MS (mean age 31.3 years [SD 8.1], 69% female) during a median observation period of 59 months (range: 13-98). Adding the optic nerve as a fifth region improved the diagnostic performance by increasing accuracy (DIS + OCT 81.2% vs DIS 65.6%) and sensitivity (DIS + OCT 84.2% vs DIS 77.9%) without lowering specificity (DIS + OCT 52.2% vs DIS 52.2%). Fulfilling DIS + OCT criteria (≥2 of 5 DIS + OCT regions involved) indicated a similar risk of a second clinical attack (hazard ratio [HR] 3.6, CI 1.4-14.5) compared with a 2.5-fold increased risk when fulfilling DIS criteria (HR 2.5, CI 1.2-11.8). When the analysis was conducted according to topography of the first demyelinating event, DIS + OCT criteria performed similarly in both optic neuritis and nonoptic neuritis.

DISCUSSION

Addition of the optic nerve, assessed by OCT, as a fifth region in the current DIS criteria improves diagnostic performance by increasing sensitivity without lowering specificity.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that adding the optic nerve as determined by OCT as a fifth DIS criterion to the 2017 McDonald criteria improves diagnostic accuracy.

Retinal Vascular Density Using Optical Coherence Tomography-Angiography in Optic Neuritis

The aim of this study is to access the perifoveolar and peripapillary vascular density (VD) using optical coherence tomography-angiography (OCT-A) in eyes with optic neuritis (ON) and in fellow eyes, then compare that to healthy controls.

METHOD

This is a cross-sectional study including 22 patients with unilateral ON and 20 control eyes of healthy subjects. A complete clinical examination and OCT-A were performed at least 6 months after the acute episode of optic neuritis. Vascular plexuses of the peripapillary and perifoveolar images obtained from OCT-A were used to calculate the VD in each plexus: superficial, deep, and peripapillary capillaries for each group (ON eyes, fellow eyes, healthy eyes).

RESULTS

Compared to healthy control eyes, in the peripapillary area, we found a significant decrease in VD not only in ON eyes but also in fellow eyes in average (p ≤ 0.05) and in the temporal sector (p < 0.001). In the perifoveolar area, the VD of the superficial capillary plexus is decreased in all sectors (p < 0.001) in ON eyes and only in the upper sector (p = 0.037) of fellow eyes compared to control eyes. VD correlates with ganglion cell layer (GCL) thickness in ON and in fellow eyes.

CONCLUSION

Peripapillary vascular density is decreased in both affected eyes and fellow eyes after a unilateral episode of optic neuritis, suggesting a subclinical involvement of the disease. Further studies are needed to clarify the mechanism and clinical implications of these data.

Subclinical optic neuritis in pediatric myelin oligodendrocyte glycoprotein antibody-associated disease

BACKGROUND AND OBJECTIVES

The clinical spectrum of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is heterogenous and has evolved over time since the commercial availability of the anti-MOG antibody assay. Subclinical disease activity has been previously reported in the visual pathway, but prevalence data remains limited. We investigated subclinical optic neuritis (ON) based on changes on retinal nerve fiber layer (RNFL) thickness on optic coherence tomography (OCT) in pediatric patients who tested positive for the anti-MOG antibody.

METHODS

In this retrospective, single-center cohort study, we examined children with MOGAD with at least one complete assessment of the anterior visual pathway. Subclinical ON was defined by structural visual system disease in the absence of a subjective complaint of vision loss, pain (particularly with eye movement), or color desaturation.

RESULTS

Records were reviewed from 85 children with MOGAD, 67 of whom (78.8%) had complete records for review. Eleven children (16.4%) had subclinical ON on OCT. Ten had significant reductions in RNFL, of which one had two distinct episodes of decreased RNFL, and one had significant elevations in RNFL. Of the eleven children with subclinical ON, six (54.5%) had a relapsing disease course. We also highlighted the clinical course of three children with subclinical ON detected on longitudinal OCT, including two who had subclinical ON outside of clinical relapses.

CONCLUSION

Children with MOGAD can have subclinical ON events that can manifest as significant reductions or elevations in RNFL on OCT. OCT should be used routinely in the management and monitoring of MOGAD patients.

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.

A prospective study of disease modifying therapy and retinal atrophy in relapsing-remitting multiple sclerosis

BACKGROUND

To compare the rate of retinal atrophy over time in patients with relapsing-remitting multiple sclerosis (RRMS) treated with various disease-modifying therapies (DMT).

METHODS

Patients with RRMS on various DMT and those observed without treatment were prospectively enrolled into the study between September 2015 and June 2018. All subjects with follow-up of 1-4 years were included and categorized into groups as "no drug", "low efficacy drug", "high efficacy drug", or "dimethyl fumarate" (DMF), based on treatment modality used for the longest duration of their follow-up. Ocular coherence tomography (OCT) was used to measure peripapillary retinal nerve fiber layer thickness (RNFL) and ganglion cell/inner plexiform layer (GC-IPL) thickness at baseline and every 6 months. A linear mixed effects regression model was performed to compare rates of retinal atrophy across treatment groups.

RESULTS

Out of 67 participants who met inclusion criteria (mean age = 37; 76% female), 13 were untreated, 12 on low efficacy therapy, 18 on DMF, and 24 on high efficacy therapy. History of optic neuritis was associated with lower baseline GC-IPL thickness (p = 0.003). Higher baseline GC-IPL thickness was associated with increased rate of GC-IPL thinning (p = 0.009). Age, disease duration, and ethnicity were not predictors of baseline RNFL or GC-IPL thickness, or rate of atrophy of these layers.

CONCLUSIONS

There were no differences in rate of GC-IPL atrophy between patients with RRMS on different treatments in this cohort. Age, disease duration, and ethnicity also did not predict retinal atrophy. History of ON was associated with reduced GC-IPL thickness at baseline, consistent with previous research. Rate of GC-IPL thinning was higher for subjects with higher baseline GC-IPL thickness, suggesting a plateau effect.

Imaging of Central Nervous System Demyelinating Disorders

OBJECTIVE

This article summarizes neuroimaging findings in demyelinating disease, the most common being multiple sclerosis. Revisions to criteria and treatment options have been ongoing, and MRI plays a pivotal role in diagnosis and disease monitoring. The common antibody-mediated demyelinating disorders with their respective classic imaging features are reviewed, as well as the differential diagnostic considerations on imaging.

LATEST DEVELOPMENTS

The clinical criteria of demyelinating disease rely heavily on imaging with MRI. With novel antibody detection, the range of clinical demyelinating syndromes has expanded, most recently with myelin oligodendrocyte glycoprotein-IgG antibodies. Imaging has improved our understanding of the pathophysiology of multiple sclerosis and disease progression, and further research is underway. The importance of increased detection of pathology outside of the classic lesions will have an important role as therapeutic options are expanding.

ESSENTIAL POINTS

MRI has a crucial role in the diagnostic criteria and differentiation among common demyelinating disorders and syndromes. This article reviews the typical imaging features and clinical scenarios that assist in accurate diagnosis, differentiation between demyelinating diseases and other white matter diseases, the importance of standardized MRI protocols in clinical practice, and novel imaging techniques.

The Acute Optic Neuritis Network (ACON): Study protocol of a non-interventional prospective multicenter study on diagnosis and treatment of acute optic neuritis

Optic neuritis (ON) often occurs at the presentation of multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD). The recommended treatment of high-dose corticosteroids for ON is based on a North American study population, which did not address treatment timing or antibody serostatus. The Acute Optic Neuritis Network (ACON) presents a global, prospective, observational study protocol primarily designed to investigate the effect of time to high-dose corticosteroid treatment on 6-month visual outcomes in ON. Patients presenting within 30 days of the inaugural ON will be enrolled. For the primary analysis, patients will subsequently be assigned into the MS-ON group, the aquapotin-4-IgG positive ON (AQP4-IgG+ON) group or the MOG-IgG positive ON (MOG-IgG+ON) group and then further sub-stratified according to the number of days from the onset of visual loss to high-dose corticosteroids (days-to-Rx). The primary outcome measure will be high-contrast best-corrected visual acuity (HC-BCVA) at 6 months. In addition, multimodal data will be collected in subjects with any ON (CIS-ON, MS-ON, AQP4-IgG+ON or MOG-IgG+ON, and seronegative non-MS-ON), excluding infectious and granulomatous ON. Secondary outcomes include low-contrast best-corrected visual acuity (LC-BCVA), optical coherence tomography (OCT), magnetic resonance imaging (MRI) measurements, serum and cerebrospinal fluid (CSF) biomarkers (AQP4-IgG and MOG-IgG levels, neurofilament, and glial fibrillary protein), and patient reported outcome measures (headache, visual function in daily routine, depression, and quality of life questionnaires) at presentation at 6-month and 12-month follow-up visits. Data will be collected from 28 academic hospitals from Africa, Asia, the Middle East, Europe, North America, South America, and Australia. Planned recruitment consists of 100 MS-ON, 50 AQP4-IgG+ON, and 50 MOG-IgG+ON. This prospective, multimodal data collection will assess the potential value of early high-dose corticosteroid treatment, investigate the interrelations between functional impairments and structural changes, and evaluate the diagnostic yield of laboratory biomarkers. This analysis has the ability to substantially improve treatment strategies and the accuracy of diagnostic stratification in acute demyelinating ON.

Trial registration

ClinicalTrials.gov, identifier: NCT05605951.

Ophthalmologic Involvement in Adults with Histiocytic Disorders: Clinical Presentation and Treatment Outcomes

PURPOSE

To evaluate the clinical presentation, treatment, and outcomes in adult patients with histiocytic disorders with ocular, orbital, optic nerve, or cavernous sinus involvement.

DESIGN

Observational, retrospective chart review.

PARTICIPANTS

Adult patients (age ≥ 18 years) at Mayo Clinic from January 1, 1996, to July 1, 2021, with histiocytic disorders. Inclusion criteria were (1) histiocytic disorder by biopsy and appropriate clinical phenotype; (2) available medical records; and (3) ocular, orbital, optic nerve, or cavernous sinus involvement.

METHODS

Retrospective chart review.

MAIN OUTCOME MEASURES

Response to therapy, measured in clinical and radiographic impact.

RESULTS

Thirty-two patients were identified: 7 with Langerhans cell histiocytosis (LCH); 15 with Erdheim-Chester disease (ECD); 1 with mixed LCH/ECD phenotype; 8 with Rosai-Dorfman disease (RDD); and 1 with mixed RDD/ECD phenotype. Ophthalmologic involvement was part of the initial presentation in 69% of patients (22/32). Eyelid edema (13/32, 41%) and proptosis (12/32, 38%) were the most frequent presentations. Isolated orbital or cavernous sinus involvement was present in 3 of 7 patients with LCH and 1 of 8 patients with RDD. Optic nerve sheath involvement was present in 2 of 7 LCH patients, 14 of 15 ECD patients, and 1 RDD/ECD patient. Diffuse (> 75%) orbital involvement was seen in 12 of 15 ECD patients and 1 of 7 LCH patients. Ocular involvement was seen in 1 of 15 ECD patients, 6 of 8 RDD patients, and 1 of 1 mixed RDD/ECD patient. The cavernous sinuses were involved in 1 of 7 LCH patients, 5 of 15 ECD patients, and both mixed phenotype patients. Visual acuity was affected in 14 patients (14/24, 58%) with a median logarithm of the minimum angle of resolution visual acuity of 0.1 (range, -0.12 to 3). BRAF V600E mutations were found in 75% (3/4) of LCH patients and 91% (10/11) of ECD patients. Patients received a variety of treatment, and response was variable across disease types.

CONCLUSIONS

Orbital involvement was more commonly seen in LCH and ECD, whereas ocular involvement was more common in RDD. Visual acuity may be impacted from ocular involvement or compression of the optic nerve with diffuse orbital involvement.

Application of the International Interocular Difference Thresholds into Practice: Localising the Patient Experience

Demyelinating diseases of the central nervous system (CNS) often have neuro-ophthalmological manifestations, and retinal examination can be helpful in making the diagnosis. The latest iteration of optical coherence tomography (OCT)-based criteria for optic neuritis in multiple sclerosis has been developed in the research realm, but its application to clinical practice, and to the more uncommon demyelinating diseases requires further study. The ability to use OCT data to distinguish between various CNS demyelinating disorders could provide additional paraclinical tools to accurately diagnose patients. Furthermore, neuro-ophthalmological testing can define the extent of inflammatory damage in the CNS, independent of patient-reported history. New referrals for OCT at a tertiary multiple sclerosis and neuro-immunology referral centre (n = 167) were analysed retrospectively for the self-reporting of optic neuritis, serological test results, and diagnosis. Only approximately 30% of patients with a clinical history of unilateral optic neuritis solely had a unilateral optic neuropathy, nearly 40% of those subjects actually having evidence of bilateral optic neuropathies. Roughly 30% of patients reporting a history of bilateral optic neuritis did not have any evidence of structural disease, with 20% of these patients having a separate, intervenable diagnosis noted on macular scans. OCT is a useful adjunct diagnostic tool in the evaluation of demyelinating disease and has the ability to aid in a more accurate diagnosis for patients. Application of the international interocular difference thresholds to a clinical patient population generally reproduces the original results, emphasising their appropriateness. The analysis distinguishing the demyelinating diseases needs to be replicated in a blinded, multi-centre setting.

Diagnosis and classification of optic neuritis

There is no consensus regarding the classification of optic neuritis, and precise diagnostic criteria are not available. This reality means that the diagnosis of disorders that have optic neuritis as the first manifestation can be challenging. Accurate diagnosis of optic neuritis at presentation can facilitate the timely treatment of individuals with multiple sclerosis, neuromyelitis optica spectrum disorder, or myelin oligodendrocyte glycoprotein antibody-associated disease. Epidemiological data show that, cumulatively, optic neuritis is most frequently caused by many conditions other than multiple sclerosis. Worldwide, the cause and management of optic neuritis varies with geographical location, treatment availability, and ethnic background. We have developed diagnostic criteria for optic neuritis and a classification of optic neuritis subgroups. Our diagnostic criteria are based on clinical features that permit a diagnosis of possible optic neuritis; further paraclinical tests, utilising brain, orbital, and retinal imaging, together with antibody and other protein biomarker data, can lead to a diagnosis of definite optic neuritis. Paraclinical tests can also be applied retrospectively on stored samples and historical brain or retinal scans, which will be useful for future validation studies. Our criteria have the potential to reduce the risk of misdiagnosis, provide information on optic neuritis disease course that can guide future treatment trial design, and enable physicians to judge the likelihood of a need for long-term pharmacological management, which might differ according to optic neuritis subgroups.

Agreement of different OCT scan directions for individual retinal-layer thickness measurements in multiple sclerosis subjects with prior unilateral optic neuritis

The similarities between horizontal and vertical Optical Coherence Tomography (OCT) scans for the individual retinal layer thickness measurements in the macula was evaluated. Two volumetric scans (B-scans oriented horizontally and vertically) were performed in 64 multiple sclerosis subjects with history of unilateral optic neuritis and 64 healthy controls. The agreement between the thickness measurements with horizontal and vertical OCT scans was evaluated in 3 groups of eyes: healthy controls, eyes with history of optic neuritis and the fellow eyes. The mean difference in individual layer thickness between the scans was smaller than the instrument’s axial resolution in all 3 groups. The limit of agreement (LoA) varied among the different layers and sectors analyzed and this trend was similar in all the groups. For the inner retinal layers (retinal nerve fiber layer to inner nuclear layer), the inner macular sectors had a larger LoA compared to the corresponding outer sectors. In the outer plexiform and nuclear layers, the central and inner sectors (except inner temporal) had LoA larger than the other sectors and layers. The larger LoA seen for different layers and sectors suggests that the scan direction must be same for the follow-up OCT measurements and in clinical studies.

Acute optic neuritis: What do complementary tests add to diagnosis?

INTRODUCTION

Optic neuritis (ON) is the inflammation of the optic nerve due in many cases, to a pathological immune response. Since its symptoms can be subtle, diagnosis is sometimes challenging. The value of complementary tests for diagnosis and prognosis of ON was demonstrated in retrospective analysis, but their utility in the acute period of ON has been scarcely studied. The aim of this study is to determine the usefulness of clinical assessment, optical coherence tomography (OCT), visual evoked potentials (VEP) and orbit magnetic resonance imaging (MRI) for making diagnosis and prognosis of acute ON (AON).

MATERIALS AND METHODS

A cross-sectional study was conducted including patients with ON within 90 days of symptom onset. A complete neuro-ophthalmological evaluation, OCT, VEP and MRI were carried out, determining in each case its sensitivity, specificity and predictive values in the diagnosis of ON and the assessment of its severity.

RESULTS

75 eyes of 34 patients with ON were included. Regarding diagnosis, low contrast visual acuity (LCVA) displayed the highest sensitivity (100%), being superior than the sensitivity of all complementary tools, always below 80%. Orbit MRI abnormal findings has a Specificity of 100% to confirm diagnosis. Regarding severity assessment and prognosis, Ganglion cell +inner plexiform layer (GCIP) thickness, but not retinal nerve fibre layer (RNFL), correlates significantly with patients' visual acuity (VA) (p < 0.05). Furthermore, both P100latency and VEP's amplitude showed to be significantly associated with VA (p < 0.05) in the acute period. The combination of two predictors (measurement of RNFL and GCIP) are capable of explaining 60% of the variation of the patient's visual acuity, with statistical significance (p = 0.02) CONCLUSIONS: In depth neuro-ophthalmological assessment during the acute phase of ON, including contrast sensitivity measurement, proved to be superior to complementary tests for diagnosis, surpassing the performance of OCT and VEP. However, these tools can add to prognosis, as GCIP thickness and VEP's amplitude correlate with disease severity and its findings could encourage prompt aggressive treatments in AON.

Optical coherence tomography in multiple sclerosis: A 3-year prospective multicenter study

Objective

To evaluate changes over 3 years in the thickness of inner retinal layers including the peripapillary retinal nerve fiber layer (pRNFL), and combined macular ganglion cell and inner plexiform layers (mGCIPL), in individuals with relapsing‐remitting multiple sclerosis (RRMS) versus healthy controls; to determine whether optical coherence tomography (OCT) is sufficiently sensitive and reproducible to detect small degrees of neuroaxonal loss over time that correlate with changes in brain volume and disability progression as measured by the Expanded Disability Status Scale (EDSS).

Methods

Individuals with RRMS from 28 centers (n = 333) were matched with 64 healthy participants. OCT scans were performed on Heidelberg Spectralis machines (at baseline; 1 month; 6 months; 6‐monthly thereafter).

Results

OCT measurements were highly reproducible between baseline and 1 month (intraclass correlation coefficient >0.98). Significant inner retinal layer thinning was observed in individuals with multiple sclerosis (MS) compared with controls regardless of previous MS‐associated optic neuritis––group differences (95% CI) over 3 years: pRNFL: −1.86 (−2.54, −1.17) µm; mGCIPL: −2.03 (−2.78, −1.28) µm (both p < 0.0001; effect sizes 0.39 and 0.34). Greater inner retinal layer atrophy was observed in individuals diagnosed with RRMS <3 years versus >5 years (pRNFL: p < 0.05; mGCIPL: p < 0.01). Brain volume decreased by 1.3% in individuals with MS over 3 years compared to 0.5% in control subjects (effect size 0.76). mGCIPL atrophy correlated with brain atrophy (p < 0.0001). There was no correlation of OCT data with disability progression.

Interpretation

OCT has potential to estimate rates of neurodegeneration in the retina and brain. The effect size for OCT, smaller than for magnetic resonance imaging based on Heidelberg Spectralis data acquired in this study, was increased in early disease.

Retinal nerve fiber layer characteristics in patients with spontaneous intracranial hypotension: a retrospective case series

OBJECTIVE

To evaluate changes in retinal nerve fiber layer (RNFL) and macular thicknesses, included ganglion cell-inner plexiform layer (GCIPL) thickness, in patients with spontaneous intracranial hypotension (SIH).

METHODS

This was a retrospective, nonrandom, observational case series study. Comprehensive ophthalmic examinations and systemic examinations were performed. Spectral domain optical coherence tomography angiography scanning was used to measure peripapillary RNFL thickness and macular volume.

RESULTS

In total, 108 eyes in 54 patients with SIH were evaluated; these were compared with 108 eyes in 54 healthy controls. The mean ages were 38.2 ± 9.4 years (patients with SIH) and 38.9 ± 9.4 years (healthy controls). In both groups, 33 patients were women (61.1%). The peripapillary RNFL and GCIPL were thinner in patients with SIH than in healthy controls (100.08 ± 9.94 µm vs 104.83 ± 8.35 µm and 81.46 ± 5.67 µm vs 85.67 ± 4.57 µm, respectively). Among patients with SIH, the GCIPL was thinner in patients with visual field defects (79.81 ± 5.62 µm vs 82.39 ± 5.12 µm).

CONCLUSIONS

The RNFL and GCIPL were thinner in patients with SIH than in healthy controls. The GCIPL was thinner in eyes with visual field defects among patients with SIH.

Visual fields and optical coherence tomography (OCT) in neuro-ophthalmology: Structure-function correlation

Visual field (VF) testing is an essential component of the neurological examination. The differential diagnosis of VF defects depends on relating this measure of afferent visual function to the structure of the visual pathway and optical coherence tomography (OCT) is an invaluable tool for detailed structural evaluation of the optic nerve and retina. This review describes the ways in which interpretation of VF and OCT can be used together to increase the accuracy of the localization of lesions along the visual pathway. Lesions of the anterior visual pathway (originating in ganglion cells or nerve fibre layer of the retina or optic nerve) will typically produce defects that respect the horizontal midline, reflecting the arcuate path of the ganglion cell axons as they travel to the optic nerve. OCT of peripapillary retinal nerve fibre layer and ganglion cell complex (GCC) will typically demonstrate irreversible thinning in compressive and demyelinating lesions affecting anterior visual pathway. Chiasmal lesions produce highly localizable VF defects (junctional scotoma and bitemporal hemianopia) which correspond to the thinning of nasal portion of GCC. Lesions of the optic tract result in incongruous homonymous hemianopia on VF with corresponding hemianopic thinning on GCC developing within months. Lesions affecting optic radiations usually produce more congruous homonymous VF defects and can also produce homonymous thinning on GCC, however, this takes much longer to develop as trans-synaptic degeneration at the lateral geniculate body must occur.

Three "Red Lines" for Pattern Recognition-Based Differential Diagnosis Using Optical Coherence Tomography in Clinical Practice

BACKGROUND

Optical coherence tomography (OCT) devices for imaging of the eye are broadly available. The test is noninvasive, rapid, and well-tolerated by patients. This creates a large number of OCT images and patient referrals. Interpretation of OCT findings at the interface between neurological and ophthalmologic conditions has become a key skill in the neuro-ophthalmology service. Similar to the interpretation of visual fields, recogntion of the vertical and horizontal medians are helpful. A third "red line" is added, which will be reviewed here.

EVIDENCE

Levels 1a to 5 evidence.

ACQUISITION

Literature research.

RESULTS

There is level 1a evidence that neurodegeneration of the brain is associated with inner retinal layer atrophy. Predominantly, this is driven by retrograde (trans-synaptic) axonal degeneration from the brain to the eye. This process typically stops at the level of the inner nuclear layer (INL). Anterograde (Wallerian) axonal degeneration from the eye to the brain can trespass the INL. The geography of atrophy and swelling of individual macular retinal layers distinguishes prechiasmal from postchiasmal pathology. The emerging patterns are a front-back "red line" at the INL; a vertical "red line" through the macula for chiasmal/postchiasmal pathology; and a horizontal "red line" through the macular for pathology pointing to the optic disc. This is summarized by illustrative case vignettes.

CONCLUSIONS

The interpretation of patterns of individual retinal layer atrophy (3 "red lines") needs to be combined with recognition of localized layer thickening (edema, structural) at the macula. Certain macular patterns point to pathology at the level of the optic disc. This requires revision of the optic disc OCT and will guide need for further investigations. The 3 "red lines" proposed here may be found useful in clinical practice and the related mnemonics ("half moon," "sunset," "rainbow") for teaching.

Subclinical anterior optic pathway involvement in early multiple sclerosis and clinically isolated syndromes

Optical coherence tomography (OCT) is gaining increasing relevance in the assessment of patients with multiple sclerosis. Converging evidence point to the view that neuro-retinal changes, in eyes without acute optic neuritis, reflect inflammatory and neurodegenerative processes taking place throughout the CNS. The present study aims at exploring the usefulness of OCT as a marker of inflammation and disease burden in the earliest phases of the disease. Thus, a cohort of 150 consecutive patients underwent clinical, neurophysiological and brain MRI assessment as well as lumbar puncture as part of their diagnostic workup for a neurological episode suggestive of inflammatory CNS disorder; among those 32 patients had another previous misdiagnosed episode. For the present study, patients also received a visual pathway assessment (OCT, visual evoked potentials, visual acuity), measurement of CSF inflammatory markers (17 cytokines-chemokines, extracellular vesicles of myeloid origin), and dosage of plasma neurofilaments. Subclinical optic nerve involvement is frequently found in clinically isolated syndromes by visual evoked potentials (19.2%). OCT reveals ganglion cell layer asymmetries in 6.8% of patients; retinal fibre layer asymmetries, despite being more frequent (17.8%), display poor specificity. The presence of subclinical involvement is associated with a greater disease burden. Second, ganglion cell layer thinning reflects the severity of disease involvement even beyond the anterior optic pathway. In fact, the ganglion cell layer in eyes without evidence of subclinical optic involvement is correlated with Expanded Disability Status Scale, low contrast visual acuity, disease duration, brain lesion load, presence of gadolinium enhancing lesions, abnormalities along motor and somatosensory evoked potentials, and frequency of CSF-specific oligoclonal bands. Third, the inner nuclear layer thickens in a post-acute (1.1-3.7 months) phase after a relapse, and this phenomenon is counteracted by steroid treatment. Likewise, a longitudinal analysis on 65 patients shows that this swelling is transient and returns to normal values after 1 year follow-up. Notwithstanding, the clinical, MRI, serological and CSF markers of disease activity considered in the study are strictly associated with one another, but none of them are associated with the inner nuclear layer. Our findings challenge the current hypothesis that the inner nuclear layer is an acute phase marker of inflammatory activity. The present study suggests that instrumental evidence of subclinical optic nerve involvement is associated with a greater disease burden in clinically isolated syndrome. Neuro-retinal changes are present since the earliest phases of the disease and yield important information regarding the neurodegenerative and inflammatory processes occurring in the CNS.

Artificial intelligence extension of the OSCAR-IB criteria

Artificial intelligence (AI)-based diagnostic algorithms have achieved ambitious aims through automated image pattern recognition. For neurological disorders, this includes neurodegeneration and inflammation. Scalable imaging technology for big data in neurology is optical coherence tomography (OCT). We highlight that OCT changes observed in the retina, as a window to the brain, are small, requiring rigorous quality control pipelines. There are existing tools for this purpose. Firstly, there are human-led validated consensus quality control criteria (OSCAR-IB) for OCT. Secondly, these criteria are embedded into OCT reporting guidelines (APOSTEL). The use of the described annotation of failed OCT scans advances machine learning. This is illustrated through the present review of the advantages and disadvantages of AI-based applications to OCT data. The neurological conditions reviewed here for the use of big data include Alzheimer disease, stroke, multiple sclerosis (MS), Parkinson disease, and epilepsy. It is noted that while big data is relevant for AI, ownership is complex. For this reason, we also reached out to involve representatives from patient organizations and the public domain in addition to clinical and research centers. The evidence reviewed can be grouped in a five-point expansion of the OSCAR-IB criteria to embrace AI (OSCAR-AI). The review concludes by specific recommendations on how this can be achieved practically and in compliance with existing guidelines.

Peripapillary and parafoveal microvascular changes in eyes with optic neuritis and their fellow eyes measured by optical coherence tomography angiography: an Exploratory Study

PURPOSE

This study aimed to evaluate parafoveal and peripapillary microvascular alterations in eyes with optic neuritis (ON) along with their fellow eyes compared to healthy control eyes using optical coherence tomography angiography (OCT-A).

METHODS

We included 31 ON-affected eyes and 31 fellow eyes of 31 patients who had experienced unilateral ON and 33 eyes of 33 healthy controls in this exploratory retrospective cross-sectional study. Optical coherence tomography angiography (OCT-A) was used to generate microvascular structural images and quantify the vessel density of the superficial retinal capillary plexus (SRCP), the deep retinal capillary plexus (DRCP) and radial peripapillary capillary (RPC) segments. We used the Kruskal-Wallis test for the comparison of OCT-A results between the three groups and generalized estimating equation models for the pairwise comparisons.

RESULTS

There were significant differences of SRCP (p = 0.0003) and RPC segment (p < 0.0001) vessel densities between the three groups. Specifically, there was a reduction in parafoveal and peripapillary vessel density in the ON-affected eyes compared to fellow eyes (SRCP, estimates, -1.97, 95% confidence interval [CI], -3.07, -0.87; RPC, -6.95, 95% CI, -8.70, -5.19) and controls (SRCP, -3.15, 95% CI, -4.61, -1.69; RPC, -8.66, 95% CI, -10.55, -6.76). The superior sector of the RPC segments vessel density in the fellow eyes was decreased compared to the controls (-4.93, 95% CI, -8.07, -1.80).

CONCLUSIONS

The results of this study suggest that microvascular changes occur in both the affected eye and unaffected fellow eye after a unilateral ON episode. Future studies are needed to clarify the clinical implications of these findings.

Retinal asymmetry in multiple sclerosis

The diagnosis of multiple sclerosis is based on a combination of clinical and paraclinical tests. The potential contribution of retinal optical coherence tomography (OCT) has been recognized. We tested the feasibility of OCT measures of retinal asymmetry as a diagnostic test for multiple sclerosis at the community level. In this community-based study of 72 120 subjects, we examined the diagnostic potential of the inter-eye difference of inner retinal OCT data for multiple sclerosis using the UK Biobank data collected at 22 sites between 2007 and 2010. OCT reporting and quality control guidelines were followed. The inter-eye percentage difference (IEPD) and inter-eye absolute difference (IEAD) were calculated for the macular retinal nerve fibre layer (RNFL), ganglion cell inner plexiform layer (GCIPL) complex and ganglion cell complex. Area under the receiver operating characteristic curve (AUROC) comparisons were followed by univariate and multivariable comparisons accounting for a large range of diseases and co-morbidities. Cut-off levels were optimized by ROC and the Youden index. The prevalence of multiple sclerosis was 0.0023 [95% confidence interval (CI) 0.00229–0.00231]. Overall the discriminatory power of diagnosing multiple sclerosis with the IEPD AUROC curve (0.71, 95% CI 0.67–0.76) and IEAD (0.71, 95% CI 0.67–0.75) for the macular GCIPL complex were significantly higher if compared to the macular ganglion cell complex IEPD AUROC curve (0.64, 95% CI 0.59–0.69, P = 0.0017); IEAD AUROC curve (0.63, 95% CI 0.58–0.68, P < 0.0001) and macular RNFL IEPD AUROC curve (0.59, 95% CI 0.54–0.63, P < 0.0001); IEAD AUROC curve (0.55, 95% CI 0.50–0.59, P < 0.0001). Screening sensitivity levels for the macular GCIPL complex IEPD (4% cut-off) were 51.7% and for the IEAD (4 μm cut-off) 43.5%. Specificity levels were 82.8% and 86.8%, respectively. The number of co-morbidities was important. There was a stepwise decrease of the AUROC curve from 0.72 in control subjects to 0.66 in more than nine co-morbidities or presence of neuromyelitis optica spectrum disease. In the multivariable analyses greater age, diabetes mellitus, other eye disease and a non-white ethnic background were relevant confounders. For most interactions, the effect sizes were large (partial ω² > 0.14) with narrow confidence intervals. In conclusion, the OCT macular GCIPL complex IEPD and IEAD may be considered as supportive measurements for multiple sclerosis diagnostic criteria in a young patient without relevant co-morbidity. The metric does not allow separation of multiple sclerosis from neuromyelitis optica. Retinal OCT imaging is accurate, rapid, non-invasive, widely available and may therefore help to reduce need for invasive and more costly procedures. To be viable, higher sensitivity and specificity levels are needed.

The role of optical coherence tomography in the diagnosis of afferent visual pathway problems: A neuroophthalmic perspective

Optical coherence tomography (OCT) is a noninvasive ocular imaging technique that has become a standard tool in neuroophthalmic practice. Specifically, OCT captures retinal manifestations of neuroaxonal injury caused by lesions along anterior and posterior regions of the afferent visual pathway, in patients presenting with vision loss. More recently, the advent of OCT angiography (OCTA) has enabled evaluation of the choroidal and retinal microvasculature, thus informing our understanding regarding vascular mechanisms associated with optic nerve and retinal injuries. Much of our longitudinal experience with OCT in the field of neuroophthalmology has been acquired from the study of optic neuritis (ON) caused by inflammatory disorders of the central nervous system (CNS). Over the past two decades, OCT has emerged as a surrogate endpoint for CNS neuroaxonal injury in multiple sclerosis (MS) research trials. On a more pragmatic level, OCT is used in the clinical arena to diagnose ON associated with: MS, neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody associated disease (MOGAD). Subsequent advancements in swept-source (SS) and enhanced depth imaging (EDI) have established OCT as the new "gold standard" in the diagnosis of optic disc drusen. Recent studies have highlighted pathognomonic OCT features that distinguish cases of true papilledema from pseudopapilledema, in patients presenting with undifferentiated optic disc elevation. Preoperative OCT measures of neuroaxonal integrity have shown prognostic value in predicting postoperative visual outcomes for patients with compressive anterior visual pathway lesions. Finally, OCT is indispensable in differentiating optic neuropathies from retinal diseases in patients with visual loss and a nondiagnostic fundus examination. An in-depth discussion regarding the technical aspects of OCT is beyond the scope of this chapter. Instead, we wish to highlight the value OCT brings to the diagnosis and management of common neuroophthalmic conditions, with emphasis on optic neuropathies and retinal disorders.

Recent advances and future directions on the use of optical coherence tomography in neuro-ophthalmology

Optical coherence tomography (OCT) is a noninvasive imaging technique used to qualitatively and quantitatively analyze various layers of the retina. OCT of the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) is particularly useful in neuro-ophthalmology for the evaluation of patients with optic neuropathies and retrochiasmal visual pathway disorders. OCT allows for an objective quantification of edema and atrophy of the RNFL and GCIPL, which may be evident before obvious clinical signs and visual dysfunction develop. Enhanced depth imaging OCT allows for visualization of deep structures of the optic nerve and has emerged as the gold standard for the detection of optic disc drusen. In the evaluation of compressive optic neuropathies, OCT RNFL and GCIPL thicknesses have been established as the most important visual prognostic factor. There is increasing evidence that inclusion of OCT as part of the diagnostic criteria for multiple sclerosis (MS) increases its sensitivity. Moreover, OCT of the RNFL and GCIPL may be helpful in the early detection and monitoring the treatment of conditions such as MS and Alzheimer's disease. OCT is an important aspect of the neuro-ophthalmologic assessment and its use is likely to increase moving forward.

State of the Art and Future Challenges in Multiple Sclerosis Research and Medical Management: An Insight into the 5th International Porto Congress of Multiple Sclerosis

The 5th International Porto Congress of Multiple Sclerosis took place between the 14th and 16th of February 2019 in Porto, Portugal. Its intensive programme covered a wide-range of themes-including many of the hot topics, challenges, pitfalls and yet unmet needs in the field of multiple sclerosis (MS)-led by a number of well-acknowledged world experts. This meeting review summarizes the talks that took place during the congress, which focussed on issues in MS as diverse as the development and challenges of progressive MS, epidemiology, differential diagnosis, medical management, molecular research and imaging tools.

Rodent Models of Optic Neuritis

Optic neuritis (ON) is an inflammatory attack of the optic nerve that leads to visual disability. It is the most common optic neuropathy affecting healthy young adults, most commonly women aged 20-45 years. It can be idiopathic and monophasic or as part of a neurologic disease such as multiple sclerosis with recurrence and cumulative damage. Currently, there is no therapy to repair the damage from optic neuritis. Animal models are an essential tool for the understanding of the pathogenesis of optic neuritis and for the development of potential treatment strategies. Experimental autoimmune encephalomyelitis (EAE) is the most commonly used experimental rodent model for human autoimmune inflammatory demyelinating diseases of the central nervous system (CNS). In this review, we discuss the latest rodent models regarding optic neuritis, focusing on EAE model, and on its recent achievements and developments.

Differences in morphology and visual function of myelin oligodendrocyte glycoprotein antibody and multiple sclerosis associated optic neuritis

Background

Myelin oligodendrocyte glycoprotein immunoglobulin G associated optic neuritis (MOG-ON) is a recently described entity. Recent studies have shown that MOG-ON has a more severe clinical presentation than classic optic neuritis (ON).

Objective

This study aimed to define morphological characteristics of MOG-ON, correlate these with clinical characteristics and compare them with multiple sclerosis associated ON (MS-ON) and healthy controls (CTRL).

Methods

In a retrospective study, we included MOG-ON and MS-ON patients seen between 2011 and 2018 at the University Hospital Bern. Data from clinical examination, perimetry, and optical coherence tomography (OCT) were analyzed.

Results

A total of 66 eyes of 43 patients were included; 22 MS-ON and 33 CTRL eyes were sex- and age-matched to 11 MOG-ON eyes. We found significantly worse visual acuity at nadir, but better recovery and thinner global peripapillary retinal nerve fiber layer thickness in MOG-ON patients compared to MS-ON patients. Both groups exhibited irregular thinning of the macular ganglion cell layer. Furthermore, the visual acuity and visual field parameters correlated to retinal layer thickness only in MOG-ON eyes.

Conclusion

In comparison to MS-ON, MOG-ON is associated with more prominent acute vision loss and more pronounced global thinning of the pRNFL. Both entities result in similar final visual acuity and atrophy of the macular ganglion cell layer.

Optical coherence tomography for detection of asymptomatic optic nerve lesions in clinically isolated syndrome

Objective

To evaluate the ability of intereye retinal thickness difference (IETD) measured by optical coherence tomography (OCT) to detect asymptomatic optic nerve involvement in clinically isolated syndrome (CIS).

Methods

We conducted a cross-sectional study of patients who recently presented a CIS (≤4.5 months). All patients underwent OCT and brain/optic nerve MRI. Optic nerve involvement was defined clinically (episode of optic neuritis [ON] or not) and radiologically (optic nerve hypersignal on 3D double inversion recovery [3D-DIR]). We evaluated the sensitivity and specificity of previously published IETD thresholds and report the observed optimal thresholds for identifying symptomatic optic nerve involvement but also for identifying asymptomatic optic nerve involvement (optic nerve hypersignal without ON history). Primary outcomes were ganglion cell–inner plexiform layer (GC-IPL) and peripapillary retinal nerve fiber layer IETD.

Results

The study group consisted of 130 patients. In the CIS with ON group, 3D-DIR showed a hypersignal in all 41 symptomatic optic nerves and in 11 asymptomatic optic nerves. In the CIS without ON group, 3D-DIR showed a unilateral optic nerve hypersignal in 22 patients and a bilateral optic nerve hypersignal in 7 patients. For the detection of symptomatic and asymptomatic optic nerve lesion, GC-IPL IETD had better performance. We found an optimal GC-IPL IETD threshold ≥2.83 µm (sensitivity 88.2, specificity 83.3%) for the detection of symptomatic lesions and an optimal GC-IPL IETD ≥1.42 µm (sensitivity 89.3%, specificity 72.6%) for the detection of asymptomatic lesions.

Conclusions

Detection of asymptomatic optic nerve lesions in CIS requires lower IETD thresholds than previously reported. GC-IPL IETD represents an alternative biomarker to MRI for the detection of asymptomatic optic nerve lesions.

Classification of evidence

This study provides Class I evidence that OCT accurately identifies asymptomatic optic nerve involvement in patients with CIS.

Validation of inter-eye difference thresholds in optical coherence tomography for identification of optic neuritis in multiple sclerosis

OBJECTIVE

To examine and validate thresholds for inter-eye differences in peripapillary retinal nerve fibre (pRNFL) and ganglion cell + inner plexiform layer (GCIPL) thicknesses for identifying unilateral optic neuritis in MS.

METHODS

In this two-centre, cross-sectional study, optical coherence tomography was performed in 340 patients with clinically isolated syndrome (CIS) and MS. Cut-off values of inter-eye difference for identification of eyes with a history of unilateral ON were evaluated by receiver-operating characteristics analysis.

RESULTS

For pRNFL ≥5 µm, sensitivity was 69% and specificity 68%, while for GCIPL ≥4 µm sensitivity was 67% and specificity 78%. The areas under the curve (AUC) were 0.72 (95% confidence interval: 0.64 - 0.79) for pRNFL and 0.78 (95%CI: 0.72 - 0.85) for GCIPL, indicating GCIPL as the superior model (p<0.001). When analysing only CIS patients, GCIPL inter-eye difference ≥4 µm also remained significant, while pRNFL inter-eye difference did not.

INTERPRETATIONS

Inter-eye differences of ≥4 μm for GCIPL and to a lesser degree ≥5 μm for RNFL are robust thresholds for identifying unilateral optic nerve lesions. These thresholds could be used to demonstrate previous symptomatic and possibly asymptomatic ON and might be included into a new version of the diagnostic criteria.

Macular ganglion cell-inner plexiform layer thinning as a biomarker of disability progression in relapsing multiple sclerosis

BACKGROUND

Macular ganglion cell-inner plexiform layer (mGCIPL) is an emerging biomarker of neuroaxonal degeneration in multiple sclerosis (MS).

OBJECTIVE

We aimed to determine cut-off values of mGCIPL thinning for discriminating between progressing and stable patients in relapsing multiple sclerosis (RMS).

METHODS

This is a 3-year prospective longitudinal study on 183 RMS patients with annual optical coherence tomography. Best possible cut-off values of baseline mGCIPL and annual loss of macular ganglion cell-inner plexiform layer (aLmGCIPL) for discriminating clinically progressing (physical progression or cognitive decline) from stable patients were defined by receiver operating characteristics analysis and tested using multivariate regression models.

RESULTS

Baseline mGCIPL thickness <77 µm was associated with an increased risk (hazard ratio: 2.7, 95% confidence interval (CI): 1.5-4.7, p < 0.001) of disability progression. An aLmGCIPL cut-off ⩾1 µm accurately identified clinically progressing patients (87% sensitivity at 90% specificity) and was a strong predictor of clinical progression (odds ratio: 18.3, 95% CI: 8.8-50.3).

CONCLUSION

We present evidence that cross-sectionally measured mGCIPL thickness and annualized thinning rates of mGCIPL are able to identify clinically progressing RMS with high accuracy.

Vitamin D Levels and Visual System Measurements in Progressive Multiple Sclerosis: A Cross-sectional Study

Background

Vitamin D deficiency is associated with increased disease activity in multiple sclerosis (MS), but its role in progressive MS has not been elucidated. The objective was to determine the correlation between vitamin D levels and visual parameters in primary progressive MS (PPMS) and secondary progressive MS (SPMS).

Methods

Serum 25-hydroxyvitamin D (25[OH]D) and 25-hydroxyvitamin D₃ (25[OH]D₃) levels were obtained from the Secondary and Primary Progressive Ibudilast NeuroNEXT Trial in MS (SPRINT-MS). Visual function measurements and vitamin D associations were determined using the Pearson correlation and the generalized linear mixed model.

Results

The analysis included 258 patients (mean ± SD age of 55.6 ± 7.3 years, 52.7% female, and 52.3% PPMS). Mean vitamin D values were above sufficiency and were similar between PPMS and SPMS (P = .47 and P = .31). There was no association between 25(OH)D₃ levels and any visual markers, including peripapillary retinal nerve fiber layer thickness (Spearman r = -0.08), macular volume (r = -0.03), ganglion cell-inner plexiform layer (r = -0.07), and 2.5% low-contrast visual acuity test (r = -0.10). No statistically significant associations between vitamin D levels and visual system measurements were detected in the PPMS and SPMS subgroups.

Conclusions

Vitamin D levels were not associated with optical coherence tomography findings or low-contrast letter acuity in this group of patients with progressive MS.

Focal alteration of the intraretinal layers in neurodegenerative disorders

Focal intraretinal alterations have been studied to advance our understanding of the pathology of neurodegenerative diseases. The current literature involving focal alterations in the intraretinal layers was reviewed through PubMed using the search terms "focal alteration", "region of interest", "optical coherence tomography", "glaucoma", "multiple sclerosis", "Alzheimer's disease", "Parkinson disease", "neurodegenerative diseases" and other related items. It was found that focal alterations of intraretinal layers were different in various neurodegenerative diseases. The typical focal thinning might help differentiate various ocular and cerebral diseases, track disease progression, and evaluate the outcome of clinical trials. Advanced exploration of focal intraretinal alterations will help to further validate their clinical and research utility.

Optimization of spectral domain optical coherence tomography and visual evoked potentials to identify unilateral optic neuritis

BACKGROUND

Optic neuritis is a common manifestation of multiple sclerosis and frequently the presenting sign. The diagnosis of MS is heavily based on MRI findings but the latter is relatively insensitive in detecting optic nerve lesions. Identification of optic nerve lesion using ancillary tools such spectral-domain optical coherence tomography (SDOCT) by measuring the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL), and visual-evoked potentials latencies (VEP) may facilitate early diagnosis and treatment of multiple sclerosis.

OBJECTIVE

To determine the optimal of SDOCT measures in RFNL and GCIPL and the VEP latency value for the identification of a prior symptomatic optic nerve lesion.

METHODS

Thirty patients with diagnosed clinically with optic neuritis and fifty healthy control subjects were tested with SDOCT and VEP and the sensitivity, specificity, negative and positive predictive values of optimal values from healthy controls and optic neuritis patients were determined of for the identification unilateral optic nerve lesion.

RESULTS

The inter-eye GCIPL difference of 3.5 µm is highly sensitive (100%) and specific (98%) in identifying unilateral optic nerve lesion, while lowest 5th percentile normal GCIPL threshold values of 71 µm was highly sensitive (100%) but less specific (83.3%). The inter-eye RNFL difference of 5.5 µm had a sensitivity of 70% and specificity of 90% in identifying optic nerve lesion while the lower 5th percentile normal RNFL value of 92.3 µm was poorly sensitive (40%). Finally, the 95th percentile normal VEP latency of 104.50 milliseconds had sensitivity of 80% and specificity of 76% in identifying optic nerve lesion.

CONCLUSIONS

The inter-eye GCIPL difference is a powerful index for identifying unilateral optic nerve lesion, while the inter-eye RNFL difference and 95th percentile normal VEP latency had very good sensitivity and specificity. These measures can be useful in the evaluation of the first demyelinating event of MS and therefor can facilitate early diagnosis and therapy.

Focal Thickness Reduction of the Ganglion Cell-Inner Plexiform Layer Best Discriminates Prior Optic Neuritis in Patients With Multiple Sclerosis

Purpose

The goal was to visualize topographic thickness maps of the intraretinal layers and evaluate their discrimination abilities and relationships with clinical manifestations in patients with multiple sclerosis (MS) and a history of optic neuritis (ON).

Methods

Thirty patients with relapsing-remitting MS (34 eyes with a history of ON [MSON] and 26 non-ON fellow eyes [MSFE]) were recruited together with 63 age- and sex-matched controls (HC). Ultrahigh resolution optical coherence tomography was used to image the macula and the volumetric data set was segmented to yield six intraretinal layers. Topographic thickness maps were aligned and averaged for the visualization. The thickness maps were partitioned using the Early Treatment Diabetic Retinopathy Study (ETDRS) and related to Sloan low-contrast letter acuity (LCLA), Expanded Disability Status Scale (EDSS), and disease duration.

Results

Focal thickness reduction occurred in the macular retinal nerve fiber layer (mRNFL) and ganglion cell-inner plexiform layer (GCIPL), with the most profound reduction occurring in MSON eyes (P < 0.05). A horseshoe-like thickness reduction pattern (U Zone) in the GCIPL appeared in MSON. The thickness of the U Zone had better discrimination power than the ETDRS partitions (area under the curve = 0.97) and differentiated 96% of MSON from HC. The thickness of the U Zone was positively correlated to 2.5% LCLA (r = 0.38, P < 0.05) and 1.25% LCLA (r = 0.57, P < 0.05).

Conclusions

The horseshoe-like thickness reduction of the GCIPL appeared to be an ON-specific focal thickness alteration with the highest discrimination power of prior ON.

Optical coherence tomography and multiple sclerosis: Update on clinical application and role in clinical trials

Optical coherence tomography (OCT) has emerged as a fast, non-invasive, inexpensive, high-resolution imaging technique in multiple sclerosis (MS). Retinal layer quantification by OCT facilitates a 'window' into not only local retinal pathology but also global neurodegenerative processes, recognised to be the principal substrates of disability accumulation in MS. While OCT measures in MS have been demonstrated to reflect visual function, inflammatory activity outside of the visual pathways, disability measures including the prediction of disability progression, whole brain atrophy, and the differential neuroprotective effects of disease-modifying therapies, debate continues regarding the clinical utility of OCT in everyday practice. This review presents an overview of the evidence supporting OCT, with particular focus on its application in the MS clinic. We will also discuss the role of OCT in MS clinical trials to develop novel neuroprotective and potential remyelinating therapies.

Critical review: Typical and atypical optic neuritis

Typical optic neuritis is an idiopathic demyelinating condition that is often associated with multiple sclerosis. This has been well characterized and has an excellent prognosis. Atypical optic neuritis can result from an inflammatory, infectious, or autoimmune disorder. Differentiating the two types of optic neuritis is paramount and may be challenging early on in the clinical course. This review describes the recent literature describing the pathophysiology, clinical presentation, neuroimaging, and management of these disorders.