Retinal nerve fiber layer is associated with brain atrophy in multiple sclerosis

Microperimetry as a diagnostic tool for the detection of early, subclinical retinal damage and visual impairment in multiple sclerosis

BACKGROUND

A majority of multiple sclerosis patients experience visual impairment, often as the initial presenting symptom of the disease. While structural changes in the retinal nerve fiber layer and optic nerve have demonstrated correlations with brain atrophy in multiple sclerosis using magnetic resonance imaging, a non-invasive, cost-effective, and clinically efficacious modality to identify early damage and facilitate prompt therapeutic intervention to slow the progression of multiple sclerosis and its ocular manifestations, is still urgently needed. In this study, we sought to determine the role of macular sensitivity measured by microperimetry in the detection of subclinical multiple sclerosis-related retinal damage and visual dysfunction.

METHODS

This cross-sectional observational case-control study involved population-based samples of multiple sclerosis patients and age-, race-, and gender-matched healthy control subjects. Among the key criteria for the multiple sclerosis patients were diagnosis by the McDonald criteria, visual acuity greater than 20/25, and no history of optic neuritis. Macular sensitivity and average macular thickness were measured in all subjects using microperimetry and spectral-domain optical coherence tomography, respectively. Pearson correlation coefficients were measured using bivariate correlations. Sample means, mean differences, and 95% confidence intervals were calculated using independent sample t-tests.

RESULTS

Twenty-eight eyes from 14 MS patients and 18 eyes from 9 control subjects were included. Mean macular sensitivity of control subjects and multiple sclerosis patients in decibels was 18.2 ± 0.4 and 16.5 ± 0.4, respectively, corresponding to a mean difference of 1.7 (95% CI, 1.1-2.4; P < 0.001). Macular sensitivity was positively correlated with macular thickness in multiple sclerosis patients (r = 0.49, P = 0.01) but not control subjects (r = 0.15, P = 0.55).

CONCLUSIONS

Macular sensitivity as measured by microperimetry was decreased in multiple sclerosis patients with normal visual acuity and no history of optic neuritis. Furthermore, macular sensitivity demonstrated a positive correlation with macular thickness as measured by optical coherence tomography. As such, microperimetry may represent a non-invasive and efficient method to identify signs of subclinical visual dysfunction that correspond with early macular architectural changes characteristic of multiple sclerosis.

Correlation between brain volume and retinal photoreceptor outer segment volume in normal aging and neurodegenerative diseases

PURPOSE

To investigate the association between outer retinal layer metrics, including photoreceptor outer segment volume, on spectral-domain optical coherence tomography (OCT) and brain volume on MRI in normal aging, Alzheimer's disease and Parkinson's disease.

METHODS

This was an exploratory analysis of a cross-sectional cohort study that was approved by the Cleveland Clinic Institutional Review Board to evaluate neurodegenerative disorders. Subjects aged ≥ 50 were recruited. A comprehensive neurological exam, brain MRI with volumetric evaluation, and OCT were performed for each subject. Outer retinal layer parameters, including ellipsoid zone (EZ) to retinal pigment epithelium (RPE) volume (i.e., surrogate for panmacular photoreceptor outer segment volume), were evaluated with a novel OCT analysis platform.

RESULTS

Of 85 subjects, 64 eyes of 64 subjects met MRI and OCT quality control criteria. Total brain volume (%ICV) significantly correlated with EZ-RPE volume in the normal cognition control group (n = 31, Pearson correlation coefficient 0.514, P < .01), the Parkinson's disease group (n = 19, Pearson correlation coefficient 0.482, P = .04), and the Alzheimer's dementia group (n = 14, Pearson correlation coefficient 0.526, P = .05). Multiple linear regression analysis revealed that photoreceptor outer segment (i.e., EZ-RPE) volume was an independent, influential factor on total brain volume in all study subjects (Coefficient 15.2, 95% confidence interval 7.8-22.6, P < .001).

CONCLUSION

Outer retinal parameters on OCT may serve as a novel biomarker related to brain volume. This correlation was noted in control subjects suggesting a possible developmental link between retina and brain volume. This relationship was also maintained with atrophic neurodegenerative disorders. Further research is needed to explore possible threshold differences for underlying neurodegenerative disorders.

Visual Function and Disability Are Associated with Increased Retinal Volumetric Vessel Density in Patients with Multiple Sclerosis

PURPOSE

The goal of this study was to determine the volumetric vessel density (VVD) in the intraretinal layers and its relationship with visual function and disability in patients with multiple sclerosis (MS).

DESIGN

Cross-sectional study.

METHODS

A total of 80 patients with relapsing-remitting MS and 99 age- and sex-matched healthy controls (HC) were recruited. The retinal microvascular network in the macular area was imaged using optical coherence tomography angiography in 123 eyes without a history of optic neuritis (ON) (MSNON) and 36 eyes with a history of ON (MSON). The VVD was calculated as the vessel densities in the retinal vascular network (RVN), superficial vascular plexus (SVP), or deep vascular plexus (DVP) of an annulus (0.6-2.5 mm in diameter), divided by the corresponding tissue volume of the intraretinal layers respectively.

RESULTS

The VVD of RVN and DVP in MSNON were significantly higher than in HC (P < .05). The VVD of RVN, SVP, and DVP in MSON were significantly higher than in MSNON and HC (P < .05). The VVD in both RVN and SVP were positively related to EDSS and disease duration, but negatively related to low-contrast letter acuity (P < .05). The VVD measurements were also negatively and strongly related to the corresponding tissue volumes (P < .05).

CONCLUSIONS

This is the first study to reveal increased retinal VVD in patients with relapsing-remitting MS. The measurements of VVD in the RVN and SVP were related to disability and visual function, which may be developed as image markers for tracking disease progression.

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.

An investigation of retinal layer thicknesses in unaffected first-degree relatives of schizophrenia patients

INTRODUCTION

A large number of studies using different neuroimaging methods showed various structural changes both in patients and their unaffected first-degree relatives (FDRs) over the past years. Optical coherence tomography (OCT) is a relatively new, non-invasive imaging method used to obtain high-resolution cross-sectional images of the retina. A growing body of evidence reports thinning of retinal layers in patients with schizophrenia which is considered as a proxy for CNS alterations. We hypothesized that retinal layer changes would be observed in FDRs, in parallel with those seen in patients, as a potential endophenotype candidate.

METHODS

Thirty-eight schizophrenia patients, 38 FDRs of schizophrenia and 38 age and gender-matched healthy subjects with no family history (HCs) were recruited to this study. OCT measurements were performed and peripapillary retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL) and macular thicknesses were measured.

RESULTS

The groups did not differ on RNFL, macular or GCL thickness. However, IPL thickness was significantly lower in both patients and FDRs than HCs (p = .025 and p = .041, respectively). The difference between groups remained significant after controlling for confounders such as age, gender, smoking status, comorbid medical diseases and BMI (p = .016 patients vs HCs and p = .014 FDRs vs HCs).

CONCLUSION

Our findings suggest that IPL thinning may hold promise as a useful endophenotype for genetic and early detection studies. The evaluation of this area could provide an important avenue for elucidating some of the neurodevelopmental aberrations in the disorder.

Insomnia Might Influence the Thickness of Choroid, Retinal Nerve Fiber and Inner Plexiform Layer

Sleep may play a fundamental role in retinal regulation and the degree of retinal variables. However, no clinical study has investigated optical coherence tomography (OCT) parameters in patients with primary insomnia. All participants were evaluated with the insomnia severity index (ISI) and the Pittsburgh sleep quality index (PSQI). The retinal nerve fiber layer (RNFL), ganglion cell layer (GC), inner plexiform layer (IPL), macula and choroidal (CH) thickness were compared between 52 drug-naïve patients with primary insomnia and 45 age-gender-BMI-smoke status matched healthy controls (HC). The patients with primary insomnia differed from the HC regarding RNFL-Global (p = 0.024) and RNFL-Nasal inferior (p = 0.010); IPL-Temporal (p < 0.001), IPL-Nasal (p < 0.001); CH-Global (p < 0.001), CH-Temporal (p = 0.004), CH-Nasal (p < 0.001), and CH-Fovea (p = 0.019). ISI correlated with RNFL-Global and RNFL-Nasal inferior. The regression analysis revealed that ISI was the significant predictor for the thickness of RNFL- Nasal inferior (p = 0.020), RNFL-Global (p = 0.031), and CH-Nasal (p = 0.035) in patients with primary insomnia. Sleep disorders are seen commonly in patients with psychiatric, including ocular diseases. Adjusting the effect of insomnia can help to clarify the consistency in findings of OCT.

Retinal Nerve Fiber Layer in Patients with Alcohol Use Disorder

The objectives of the present study are to determine the effects of alcohol use on the retinal nerve fiber layer (RNFL) thickness and macular thickness of abstinent patients with alcohol use disorders (AUD) and to assess whether it correlates with alcohol consumption and/or cognitive impairment. This was a prospective, observational study that included 21 patients (42 eyes) and 21 controls (42 eyes). Patients met the criteria for early remission AUD at the moment of inclusion. We used optical coherence tomography to assess retinal thickness. Macular thickness in the group of AUD patients was lower in all quadrants (p < 0.05), with the exception of the peripheral and central. Regarding the nerve fiber layer in the macular and papilla areas, we found no significant differences. At the retina ganglion cell layer and in the nerve fiber of the macula, we found significant differences in all quadrants (p < 0.05), with the exception of the superior and superior nasal area, for the right eye. For the left eye, the only differences were found in the lower quadrant. Finally, when comparing the AUD patients to the controls, we found significant reductions in the ganglion cell layer of the macula in all quadrants in the former. There was a significant correlation between these findings and cognitive impairment (measured with the Test de Detección de Deterioro Cognitivo en Alcoholismo (TEDCA)), but not with alcohol consumption. Alcohol consumption is correlated with retinal harm and related cognitive decline.

Retinal correlates of neurological disorders

Considering the retina as an extension of the brain provides a platform from which to study diseases of the nervous system. Taking advantage of the clear optical media of the eye and ever-increasing resolution of modern imaging techniques, retinal morphology can now be visualized at a cellular level in vivo. This has provided a multitude of possible biomarkers and investigative surrogates that may be used to identify, monitor and study diseases until now limited to the brain. In many neurodegenerative conditions, early diagnosis is often very challenging due to the lack of tests with high sensitivity and specificity, but, once made, opens the door to patients accessing the correct treatment that can potentially improve functional outcomes. Using retinal biomarkers in vivo as an additional diagnostic tool may help overcome the need for invasive tests and histological specimens, and offers the opportunity to longitudinally monitor individuals over time. This review aims to summarise retinal biomarkers associated with a range of neurological conditions including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and prion diseases from a clinical perspective. By comparing their similarities and differences according to primary pathological processes, we hope to show how retinal correlates can aid clinical decisions, and accelerate the study of this rapidly developing area of research.

Examination of retinal vascular trajectory in schizophrenia and bipolar disorder

AIM

Evidence suggests microvascular dysfunction (wider retinal venules and narrower arterioles) in schizophrenia (SCZ) and bipolar disorder (BD). The vascular development is synchronous with neuronal development in the retina and brain. The retinal vessel trajectory is related to retinal nerve fiber layer thinning and cerebrovascular abnormalities in SCZ and BD and has not yet been examined. Hence, in this study we examined the retinal vascular trajectory in SCZ and BD in comparison with healthy volunteers (HV).

METHODS

Retinal images were acquired from 100 HV, SCZ patients, and BD patients, respectively, with a non-mydriatic fundus camera. Images were quantified to obtain the retinal arterial and venous trajectories using a validated, semiautomated algorithm. Analysis of covariance and regression analyses were conducted to examine group differences. A supervised machine-learning ensemble of bagged-trees method was used for automated classification of trajectory values.

RESULTS

There was a significant difference among groups in both the retinal venous trajectory (HV: 0.17 ± 0.08; SCZ: 0.25 ± 0.17; BD: 0.27 ± 0.20; P < 0.001) and the arterial trajectory (HV: 0.34 ± 0.15; SCZ: 0.29 ± 0.10; BD: 0.29 ± 0.11; P = 0.003) even after adjusting for age and sex (P < 0.001). On post-hoc analysis, the SCZ and BD groups differed from the HV on retinal venous and arterial trajectories, but there was no difference between SCZ and BD patients. The machine learning showed an accuracy of 86% and 73% for classifying HV versus SCZ and BD, respectively.

CONCLUSION

Smaller trajectories of retinal arteries indicate wider and flatter curves in SCZ and BD. Considering the relation between retinal/cerebral vasculatures and retinal nerve fiber layer thinness, the retinal vascular trajectory is a potential marker for SCZ and BD. As a relatively affordable investigation, retinal fundus photography should be further explored in SCZ and BD as a potential screening measure.

A multimodal approach to assess the validity of atrophied T2-lesion volume as an MRI marker of disease progression in multiple sclerosis

BACKGROUND

Atrophied T2-lesion volume (LV) is a novel MRI marker representing brain-lesion loss due to atrophy, able to predict long-term disability progression and conversion to secondary-progressive multiple sclerosis (MS).

OBJECTIVE

To better characterize atrophied T2-LV via comparison with other multidisciplinary markers of MS progression.

METHODS

We studied 127 MS patients (85 relapsing-remitting, RRMS and 42 progressive, PMS) and 20 clinically isolated syndrome (CIS) utilizing MRI, optical coherence tomography, and serum neurofilament light chain (sNfL) at baseline and at 5-year follow-up. Symbol Digit Modalities Test (SDMT) was obtained at follow-up. Atrophied T2-LV was calculated by combining baseline lesion masks with follow-up CSF partial-volume maps. Measures were compared between MS patients who developed or not disease progression (DP). Partial correlations between atrophied T2-LV and other biomarkers were performed, and corrected for multiple comparisons.

RESULTS

Atrophied T2-LV was the only biomarker that significantly differentiated DP from non-DP patients over the follow-up (p = 0.007). In both DP and non-DP groups, atrophied T2-LV was associated with baseline T2-LV and T1-LV (both p = 0.003), absolute change of T1-LV (DP p = 0.038; non-DP p = 0.003) and percentage of brain volume change (both p = 0.003). Furthermore, in the DP group, atrophied T2-LV was related to baseline brain parenchymal (p = 0.017) and thalamic (p = 0.003) volumes, thalamic volume change and follow-up SDMT (both p = 0.003). In non-DP patients, atrophied T2-LV was significantly related to baseline sNfL (p = 0.008), contrast-enhancing LV (p = 0.02) and percentage ventricular volume change (p = 0.003).

CONCLUSION

Atrophied T2-LV is associated with disability accrual in MS, and to several multimodal markers of disease evolution.

Changes in Retinal OCT and Their Correlations with Neurological Disability in Early ALS Patients, a Follow-Up Study

BACKGROUND

To compare early visual changes in amyotrophic lateral sclerosis (ALS) patients with healthy controls in a baseline exploration, to follow-up the patients after 6 months, and to correlate these visual changes with neurological disability.

METHODS

All patients underwent a comprehensive neurological and ophthalmological examination. A linear mixed analysis and Bonferroni p-value correction were performed, testing four comparisons as follows: Control baseline vs. control follow-up, control baseline vs. ALS baseline, control follow-up vs. ALS follow-up, and ALS baseline vs. ALS follow-up.

RESULTS

The mean time from the diagnosis was 10.80 ± 5.5 months. The analysis of the optical coherence tomography (OCT) showed: (1) In ALS baseline vs. control baseline, a macular significantly increased thickness of the inner macular ring temporal and inferior areas; (2) in ALS follow-up vs. ALS baseline, a significant macular thinning in the inner and outer macular ring inferior areas; (3) in ALS follow-up vs. ALS baseline, a significant peripapillary retinal nerve fiber layer (pRNFL) thinning in the superior and inferior quadrants; and (4) ALS patients showed a moderate correlation between some OCT pRNFL parameters and Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) score.

CONCLUSION

The OCT showed retinal changes in patients with motoneuron disease and could serve as a complementary tool for studying ALS.

Functional Evaluation of the Visual Pathway in Patients with Multiple Sclerosis Using a Multifunction Stimulator Monitor

Objectives

To assess the capability of the vision monitor unit Monpack One of detecting visual function alterations in patients with multiple sclerosis (MS) and to evaluate the correlation between structural retinal parameters and functional measurements obtained with this device.

Methods

Forty-eight patients with MS and 46 healthy controls were included in a cross-sectional study. All participants underwent a complete functional evaluation of the visual pathway, which included low-contrast visual acuity (LCVA), contrast sensitivity vision (CSV), automated perimetry, multifocal visual evoked potentials (mfVEPs), and pattern electroretinogram (ERG). All tests were performed using the vision monitor unit Monpack One (Metrovision, France), a multifunction stimulator device. Retinal structural measurements were obtained in all subjects using Triton swept source optical coherence tomography (Topcon, Japan).

Results

Patients with MS presented reduced low-contrast VA (p < 0.001) and reduced CSV at medium (p=0.001, p=0.013) and low (p=0.001, p=0.002) spatial frequencies. All visual field parameters were found to be altered in MS patients compared with controls (≤0.001). Patients with MS presented lower amplitude of the P100 waveform of the mfVEP in areas corresponding to central (p < 0.001), inferonasal (p=0.001), and inferotemporal (p=0.003) retina. The pattern ERG did not show significant differences. Significant correlations were observed between structural retinal measurements and functional parameters, especially between the inner macular areas and measurements corresponding to contrast sensitivity and perimetry indexes.

Conclusions

Patients with MS present visual dysfunction detectable with the vision monitor unit Monpack One. This device may be a fast and useful tool to provide a full evaluation of axonal damage in patients with multiple sclerosis.

Retinal Degeneration After First-Ever Optic Neuritis Helps Differentiate Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Objective: Differentiation between neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) in the early phase is challenging but crucial for treatment and prognosis.

Methods: We performed a prospective cross-sectional study to discriminate NMOSD from MS by evaluating retinal degeneration in optical coherence tomography (OCT) after a first-ever optic neuritis (ON) episode. Seventy-three NMOSD patients and 38 MS patients with ON at least 3 months prior were assessed by OCT, best-corrected visual acuity (VA), and 2.5% low-contrast VA. Multivariate linear regression models were used for comparisons. Receiver operating characteristic curves and Youden index were used for determining the discriminative value of retinal nerve fiber layer thickness (RNFL) and VA in distinguishing NMOSD from MS.

Results: Among eyes with retinal degeneration after a first-ever ON episode (n = 93), NMOSD eyes (n = 60) presented thinner RNFL (p < 0.001) and worsened VA (p < 0.001) relative to MS eyes (n = 33). Furthermore, a RNFL thinner than 78.9 μm had a specificity of 93.9% for NMOSD; combined with a VA of <0.4 decimal, these characteristics provided 100% specificity for NMOSD.

Conclusions: The first-ever ON eyes showed more severe retina degeneration in patients with NMOSD than MS, which could establish a cut-off of RNFL thickness and VA to distinguish NMOSD from MS in the early phase.

Retinal nerve fiber layer thickness associates with cognitive impairment and physical disability in multiple sclerosis

BACKGROUND

Reductions of the peripapillary retinal nerve fiber layer (pRNFL) thickness has been indicated even in early-stages of multiple sclerosis (MS). The aim was to investigate the association between pRNFL thickness, measured with optical coherence tomography (OCT), and physical disability and cognitive impairment in MS.

METHODS

465 MS patients and 168 healthy controls (HCs) were included. MS subjects were divided into subgroups according to disease subtype. All subjects underwent OCT examination of all pRNFL quadrants using Canon OCT-HS100. Associations were tested using linear mixed effect models. Physical disability was assessed with the Expanded Disability Status Scale (EDSS) and cognitive function with the Symbol Digit Modalities Test (SDMT).

RESULTS

The average pRNFL, inferior pRNFL and temporal pRNFL thicknesses were significantly correlated to both EDSS (-1.0 µm, p < 0.01; -1.2 µm, p < 0.05; -1.2 µm, p < 0.01) and SDMT (0.1 µm, p < 0.05; 0.2 µm, p < 0.05; 0.2 µm, p < 0.01). A significant thickness loss compared with HCs was seen in the average pRNFL and in all quadrants except for the superior quadrant of primary progressive MS. The largest reduction compared with HCs was seen in the temporal pRNFL of PPMS eyes (-15.8 µm; p < 0.001).

CONCLUSION

The reduction of average pRNFL, inferior pRNFL and temporal pRNFL thickness is associated with physical and cognitive disability in MS. We suggest the use of temporal pRNFL as a more sensitive outcome as it showed the strongest association to both EDSS and SDMT.

Retinal inner nuclear layer volume reflects inflammatory disease activity in multiple sclerosis; a longitudinal OCT study

Background

The association of peripapillary retinal nerve fibre layer (pRNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness with neurodegeneration in multiple sclerosis (MS) is well established. The relationship of the adjoining inner nuclear layer (INL) with inflammatory disease activity is less well understood.

Objective

The objective of this paper is to investigate the relationship of INL volume changes with inflammatory disease activity in MS.

Methods In this longitudinal, multi-centre study, optical coherence tomography (OCT) and clinical data (disability status, relapses and MS optic neuritis (MSON)) were collected in 785 patients with MS (68.3% female) and 92 healthy controls (63.4% female) from 11 MS centres between 2010 and 2017 and pooled retrospectively. Data on pRNFL, GCIPL and INL were obtained at each centre.

Results

There was a significant increase in INL volume in eyes with new MSON during the study (N = 61/1562, β = 0.01 mm³, p < .001). Clinical relapses (other than MSON) were significantly associated with increased INL volume (β = 0.005, p = .025). INL volume was independent of disease progression (β = 0.002 mm³, p = .474).

Conclusion

Our data demonstrate that an increase in INL volume is associated with MSON and the occurrence of clinical relapses. Therefore, INL volume changes may be useful as an outcome marker for inflammatory disease activity in MSON and MS treatment trials.

Relationship between retinal vessel diameter with both retinal nerve fibre layer thickness and optic nerve head parameters in middle-aged Caucasians: the Northern Finland Birth Cohort Eye study

Purpose

To study the normal relationship between retinal vessel diameter (RVD) with retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) parameters in a cohort of middle‐aged Caucasians.

Methods

We investigated 3070 individuals (6140 eyes). Central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were measured in the right eye using a semi‐automated computer‐assisted program. Retinal nerve fibre layer (RNFL) thickness and ONH parameters were assessed with Heidelberg retinal tomography (HRT).

Results

Data from 2217 persons were analysed including RNFL, CRAE, CRVE, sex, body mass index, mean arterial pressure, diabetes status, smoking status, optic disc area, rim area, spherical refraction and intraocular pressure. A larger RVD was associated with a thicker mean global RNFL thickness especially in global and inferior segments of the retina and with larger optic discs. Each 10 μm increase in the retinal arteriolar calibre was associated with a 5.58 μm increase in mean global RNFL thickness; the corresponding value for a 10 μm increase in venular calibre was 3.79 μm (p < 0.001 for both). Retinal venular calibre displayed consistent associations with RNFL thickness in both genders (p < 0.001 for all), whereas the association of arteriolar calibre and RNFL was more prominent in men (p < 0.001).

Conclusion

We found strong associations between larger RVD and thicker RNFL in all subjects. This study helps to clarify the association between RVD, RNFL thickness and ONH parameters and provides normal values for middle‐aged Caucasians that will help in future studies investigating the role of vascular aetiology in systemic and eye diseases.

Evolution of Visual Outcomes in Clinical Trials for Multiple Sclerosis Disease-Modifying Therapies

: BACKGROUND:: The visual pathways are increasingly recognized as an ideal model to study neurodegeneration in multiple sclerosis (MS). Low-contrast letter acuity (LCLA) and optical coherence tomography (OCT) are validated measures of function and structure in MS. In fact, LCLA was the topic of a recent review by the Multiple Sclerosis Outcome Assessments Consortium (MSOAC) to qualify this visual measure as a primary or secondary clinical trial endpoint with the Food and Drug Administration (FDA) and other regulatory agencies. This review focuses on the use of LCLA and OCT measures as outcomes in clinical trials to date of MS disease-modifying therapies.

METHODS

A Pubmed search using the specific key words "optical coherence tomography," "low-contrast letter acuity," "multiple sclerosis," and "clinical trials" was performed. An additional search on the clinicaltrials.gov website with the same key words was used to find registered clinical trials of MS therapies that included these visual outcome measures.

RESULTS

As demonstrated by multiple clinical trials, LCLA and OCT measures are sensitive to treatment effects in MS. LCLA has been used in many clinical trials to date, and findings suggest that 7 letters of LCLA at the 2.5% contrast level are meaningful change. Few clinical trials using the benefits of OCT have been performed, although results of observational studies have solidified the ability of OCT to assess change in retinal structure. Continued accrual of clinical trial and observational data is needed to validate the use of OCT in clinical trials, but preliminary work suggests that an intereye difference in retinal nerve fiber layer thickness of 5-6 μm is a clinically meaningful threshold that identifies an optic nerve lesion in MS.

CONCLUSIONS

Visual impairment represents a significant component of overall disability in MS. LCLA and OCT enhance the detection of visual pathway injury and can be used as measures of axonal and neuronal integrity. Continued investigation is ongoing to further incorporate these vision-based assessments into clinical trials of MS therapies.

Early auto-immune targeting of photoreceptor ribbon synapses in mouse models of multiple sclerosis

Optic neuritis is one of the first manifestations of multiple sclerosis. Its pathogenesis is incompletely understood, but considered to be initiated by an auto‐immune response directed against myelin sheaths of the optic nerve. Here, we demonstrate in two frequently used and well‐validated mouse models of optic neuritis that ribbon synapses in the myelin‐free retina are targeted by an auto‐reactive immune system even before alterations in the optic nerve have developed. The auto‐immune response is directed against two adhesion proteins (CASPR1/CNTN1) that are present both in the paranodal region of myelinated nerves as well as at retinal ribbon synapses. This occurs in parallel with altered synaptic vesicle cycling in retinal ribbon synapses and altered visual behavior before the onset of optic nerve demyelination. These findings indicate that early synaptic dysfunctions in the retina contribute to the pathology of optic neuritis in multiple sclerosis.

Retinal Tissue Perfusion in Patients with Multiple Sclerosis

Purpose: The goal of this work was to determine whether the retinal tissue perfusion (RTP) is impaired in patients with multiple sclerosis (MS). Methods: Seventy-four patients [66 relapsing-remitting MS (RRMS) and 8 clinically isolated syndrome (CIS)] and 74 age- and gender-matched healthy controls were recruited. RTP was calculated as the retinal blood flow (measured using retinal function imager) supplying the macular area divided by the corresponding tissue volume of the inner retina from the inner limiting membrane to the outer plexiform layer, as measured by ultrahigh-resolution optical coherence tomography. Results: The RTP in the MS group was 2.37 ± 0.59 nl/s/mm³ (mean ± standard deviation), which was significantly lower than the control group (4.06 ± 0.89 nl/s/mm³, P < .001), reflecting a decrease of 42%. The blood flow volume was 2.50 ± 0.50 nl/s in MS, which was 45% lower than in the control group (4.56 ± 0.91 nl/s, P < .001). In addition, the tissue volume of the inner retina was significantly lower than in the control group (P < .05). The RTP in patients with MS was significantly correlated with the retinal blood flow volume (r = 0.84, P < .001) and retinal tissue volume (r = -0.56, P < .001). However, the retinal blood flow in patients with MS was not related to the tissue volume (r = -0.06, P = .59). Conclusions: Impaired retinal tissue perfusion occurred in patients with MS, which could be developed as a possible biomarker in monitoring disease progression in MS.

Optical coherence tomography as a means to characterize visual pathway involvement in multiple sclerosis

PURPOSE OF REVIEW

Optical coherence tomography (OCT) is a noninvasive in-vivo imaging tool that enables the quantification of the various retinal layer thicknesses. Given the frequent involvement of the visual pathway in multiple sclerosis, OCT has become an important tool in clinical practice, research and clinical trials. In this review, the role of OCT as a means to investigate visual pathway damage in multiple sclerosis is discussed.

RECENT FINDINGS

Evidence from recent OCT studies suggests that the peripapillary retinal nerve fibre layer (pRNFL) appears to be an ideal marker of axonal integrity, whereas the macular ganglion cell and inner plexiform layer (GCIP) thickness enables early detection of neuronal degeneration in multiple sclerosis. The thickness of the macular inner nuclear layer (INL) has been suggested as a biomarker for inflammatory disease activity and treatment response in multiple sclerosis. OCT parameters may also be used as an outcome measure in clinical trials evaluating the neuroprotective or regenerative potential of new treatments.

SUMMARY

OCT provides insights into multiple sclerosis beyond the visual pathway. It is capable of quantifying the major pathological hallmarks of the disease, specifically inflammation and neuroaxonal degeneration. OCT, therefore, has the potential to become another mainstay in the monitoring of multiple sclerosis patients.

Damage of the lateral geniculate nucleus in MS: Assessing the missing node of the visual pathway

OBJECTIVE

To study if the thalamic lateral geniculate nucleus (LGN) is affected in multiple sclerosis (MS) due to anterograde degeneration from optic neuritis (ON) or retrograde degeneration from optic radiation (OR) pathology, and if this is relevant for visual function.

METHODS

In this cross-sectional study, LGN volume of 34 patients with relapsing-remitting MS and 33 matched healthy controls (HC) was assessed on MRI using atlas-based automated segmentation (MAGeT). ON history, thickness of the ganglion cell-inner plexiform layer (GC-IPL), OR lesion volume, and fractional anisotropy (FA) of normal-appearing OR (NAOR-FA) were assessed as measures of afferent visual pathway damage. Visual function was tested, including low-contrast letter acuity (LCLA) and Hardy-Rand-Rittler (HRR) plates for color vision.

RESULTS

LGN volume was reduced in patients vs HC (165.5 ± 45.5 vs 191.4 ± 47.7 mm³, B = -25.89, SE = 5.83, p < 0.001). It was associated with GC-IPL thickness (B = 0.95, SE = 0.33, p = 0.006) and correlated with OR lesion volume (Spearman ρ = -0.53, p = 0.001), and these relationships remained after adjustment for normalized brain volume. There was no association between NAOR-FA and LGN volume (B = -133.28, SE = 88.47, p = 0.137). LGN volume was not associated with LCLA (B = 5.5 × 10^-5, SE = 0.03, p = 0.998), but it correlated with HRR color vision (ρ = 0.39, p = 0.032).

CONCLUSIONS

LGN volume loss in MS indicates structural damage with potential functional relevance. Our results suggest both anterograde degeneration from the retina and retrograde degeneration from the OR lesions as underlying causes. LGN volume is a promising marker reflecting damage of the visual pathway in MS, with the advantage of individual measurement per patient on conventional MRI.

Optimal intereye difference thresholds by optical coherence tomography in multiple sclerosis: An international study

OBJECTIVE

To determine the optimal thresholds for intereye differences in retinal nerve fiber and ganglion cell + inner plexiform layer thicknesses for identifying unilateral optic nerve lesions in multiple sclerosis. Current international diagnostic criteria for multiple sclerosis do not include the optic nerve as a lesion site despite frequent involvement. Optical coherence tomography detects retinal thinning associated with optic nerve lesions.

METHODS

In this multicenter international study at 11 sites, optical coherence tomography was measured for patients and healthy controls as part of the International Multiple Sclerosis Visual System Consortium. High- and low-contrast acuity were also collected in a subset of participants. Presence of an optic nerve lesion for this study was defined as history of acute unilateral optic neuritis.

RESULTS

Among patients (n = 1,530), receiver operating characteristic curve analysis demonstrated an optimal peripapillary retinal nerve fiber layer intereye difference threshold of 5μm and ganglion cell + inner plexiform layer threshold of 4μm for identifying unilateral optic neuritis (n = 477). Greater intereye differences in acuities were associated with greater intereye retinal layer thickness differences (p ≤ 0.001).

INTERPRETATION

Intereye differences of 5μm for retinal nerve fiber layer and 4μm for macular ganglion cell + inner plexiform layer are robust thresholds for identifying unilateral optic nerve lesions. These thresholds may be useful in establishing the presence of asymptomatic and symptomatic optic nerve lesions in multiple sclerosis and could be useful in a new version of the diagnostic criteria. Our findings lend further validation for utilizing the visual system in a multiple sclerosis clinical trial setting. Ann Neurol 2019;85:618-629.

Cross-sectional study of smoking exposure: no differential effect on OCT metrics in a cohort of MS patients

Background

Optical coherence tomography (OCT) provides quantitative measures of retinal layer thickness. Cigarette smoking is a risk factor for multiple sclerosis (MS) onset and disease severity: its effects on OCT metrics have not been assessed.

Objective

The objective of this study was to assess the effect of smoking history on retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform (GCIP) of MS patients by OCT.

Methods

112 MS patients were recruited from the Brigham and Women’s Hospital. Spectralis OCT scans were acquired to measure GCIP, peripapillary RNFL, and total macular volume. Multivariable linear mixed effects regression model assessed RNFL and GCIP change with fixed effects for smoking history while adjusting for optic neuritis eye status, age, disease duration, sex, baseline EDSS, and disease modifying therapies (DMTs).

Results

Smoking histories were available for 102 patients: 46 (45.10%) had a history of smoking cigarettes and 56 (54.90%) never smoked. No statistically significant differences were found between ever-smokers and never-smokers with respect to GCIP, RNFL, and macular volume.

Conclusion

Our study shows no significant difference in retinal thickness between ever-smokers and never-smokers. If confirmed, this result suggests mechanistic differences between the retina and other central nervous system (CNS) compartments in response to smoking and should be noted when considering OCT as a surrogate measure of CNS activity.

Changes in peripapillary choroidal thickness in patients with multiple sclerosis

PURPOSE

To study peripapillary choroidal thickness (PPCT) around the optic disc and establish zones using a new swept source optical coherence tomography (SS-OCT) device. To evaluate PPCT differences between patients with multiple sclerosis (MS) and age- and sex-matched healthy controls.

METHODS

A total of 102 healthy subjects and 51 patients with MS were consecutively recruited. Healthy subjects were divided into teaching (n = 51, used to establish choroidal zones) and validating (n = 51, used to compare measurements with MS patients) populations. An optic disc 6.0 × 6.0-mm three-dimensional scan was obtained using SS-OCT Triton. A 26 × 26 cube-grid centred on the optic disc was generated automatically to measure PPCT. Four choroidal zones were established and used to compare PPCT between healthy controls and patients with MS.

RESULTS

Peripapillary choroidal thickness (PPCT) was significantly thinner in patients in all concentric zones (p ≤ 0.0001): 134.02 ± 16.59 μm in MS group versus 171.56 ± 12.43 μm in the control group in zone 2; 182.23 ± 20.52 versus 219.03 ± 17.99 μm, respectively, in zone 3; and 223.52 ± 10.70 versus 259.99 ± 10.29 μm, respectively, in zone 4. The choroidal thinning in the MS group tended to decrease as we distanced from the optic nerve head. Peripapillary choroidal thickness (PPCT) had a similar pattern in controls and MS; it was thicker in the superior region, followed by temporal, nasal and inferior regions.

CONCLUSION

Patients with MS showed peripapillary choroidal thinning when compared with healthy subjects in all zones around the optic disc. Peripapillary choroidal tissue shows a concentric pattern, increasing in thickness when increasing the distance from the optic nerve. The new SS-OCT could be useful for evaluating choroidal thinning in clinical practice.

Longitudinal optical coherence tomography study of optic atrophy in secondary progressive multiple sclerosis: Results from a clinical trial cohort

BACKGROUND

Limited prospective information exists regarding spectral-domain optical coherence tomography (SD-OCT) in secondary progressive multiple sclerosis (SPMS).

OBJECTIVE

Document cross-sectional and longitudinal retinal nerve fiber layer (RNFL) and macular ganglion cell plus inner plexiform layer (GCIPL) features of an SPMS clinical trial cohort.

METHODS

Prospective, observational study using a 2-year randomized placebo-controlled SPMS trial cohort with yearly SD-OCT testing. Post hoc analysis determined influences of optic neuritis (ON), disease duration, and baseline SD-OCT on annualized atrophy rates and on correlations between OCT and brain atrophy.

RESULTS

Mean RNFL and GCIPL values of patients ( n = 47, mean age = 59 years, mean disease duration = 30 years) were significantly lower among eyes with prior ON than those without (no history of ON (NON)). Annualized RNFL (-0.31 µm/year) and GCIPL (-0.29 µm/year) atrophy rates did not differ between ON and NON eyes. Baseline RNFL thickness >75 µm was associated with greater annualized RNFL atrophy (-0.85 µm/year). Neither RNFL nor GCIPL atrophy correlated with whole-brain atrophy.

CONCLUSION

This study suggests that eyes with and without ON history may be pooled for atrophy analysis in SPMS clinical trials using SD-OCT. Low baseline RNFL, small retinal atrophy rates, and lack of correlation with whole-brain atrophy in this population are important trial design considerations.

Effects of prenatal exposure to alcohol, tobacco and other drugs of abuse on retinal development

PURPOSE

To assess structural changes in the retina using optical coherence tomography (OCT) in children prenatally exposed to toxic substances.

METHODS

The study included a total of 49 infants, aged between 5 and 18years, exposed to toxic substances during pregnancy. Among the exposed children, 25 were exposed to tobacco, 20 were exposed to alcohol, and 4 children were exposed to other drugs of abuse. All children underwent a complete ophthalmology examination, including an OCT. The results were compared against a control group composed of 25 infants, age matched with controlled pregnancy, and not exposed to toxic substances.

RESULTS

Children prenatally exposed to toxic substances showed significantly thinner average retinal nerve fibre layer (RNFL) compared with control children (81.5 vs. 99.7μm; P<.005), as well as RNFL thinning in its four quadrants (superior RNFL: 97.5 vs. 127.5μm; P<.005; nasal RNFL: 61.5 vs. 72.3μm; P<.005; inferior RNFL: 99.8 vs. 128.6μm; P<.005, temporal RNFL: 58.3 vs. 68.2μm; P<.005). Exposed children also exhibited a thinner ganglion cell layer (72.9 vs. 85.9; P<.005). Greater RNFL thinning was observed in children exposed to drugs of abuse (RNFL thinner average=72), followed by children exposed to alcohol (RNFL thinner average=72.9), and finally the least affected were those children exposed to tobacco during pregnancy (RNFL=94.6).

CONCLUSION

Toxic substances during pregnancy interfere in retinal development. These results strengthen the evidence about the avoidance of any toxic substance during pregnancy.

Novel uses of retinal imaging with optical coherence tomography in multiple sclerosis

Introduction: Multiple Sclerosis (MS) is the most common chronic autoimmune neuroinflammatory condition in young adults. It is often accompanied by optic neuritis (ON) and retinal neuro-axonal damage causing visual disturbances. Optical coherence tomography (OCT) is a sensitive non-invasive method for quantifying intraretinal layer volumes. Recently, OCT not only showed to be a reliable marker for ON-associated damage, but also proved its high prognostic value for functional outcome and disability accrual in patients with MS. Consequently, OCT is discussed as a potential marker for monitoring disease severity and therapeutic response in individual patients. Areas covered: This article summarizes our current understanding of structural retinal changes in MS and describes the future potential of OCT for differential diagnosis, monitoring of the disease course and for clinical trials. Expert commentary: Today, OCT is used in clinical practice in specialized MS centers. Standardized parameters across devices are urgently needed for supporting clinical utility. Novel parameters are desirable to increase sensitivity and specificity in terms of MS.

Sequential phases of RGC axonal and somatic injury in EAE mice examined using DTI and OCT

BACKGROUND

Clinical imaging modalities including optical coherence tomography (OCT) and diffusion tensor imaging (DTI) are vital in Multiple Sclerosis (MS), but their relationships during the different phases of Retinal ganglion cell (RGC) degeneration are not clear. We hypothesize that initial injury in optic nerve causes axonal degeneration leading to RGC loss in retina, which can be characterized by a combination of DTI and OCT. Our objective was to examine the correlation between noninvasive and histological data to chronicle the degeneration profile of RGCs in the retina and optic nerve in a mouse model of MS.

MATERIALS AND METHODS

Experimental Autoimmune Encephalomyelitis (EAE) was induced in 11 C57Bl/6 mice, with 8 mice reserved as controls. OCT and DTI was conducted 2-8 weeks after induction of EAE. The thickness of the retinal ganglion cell complex (GCC) was measured using OCT and compared to DTI indices measured in optic nerves. End-stage histology was used to quantify axon/myelin loss in the optic nerve and retinal thinning/RGC loss in the retina.

RESULTS

Significant changes in DTI-derived Axial Diffusivity (AD, -17.2%) and Trace Diffusivity (TR, -18.3%) began after 2 weeks of EAE. Later significant reductions in Fractional Anisotropy (FA) and AD, with increases in Radial Diffusion (RD) were apparent after 4 and 8 weeks. OCT-derived measures of GCC thickness were reduced after 4 weeks, and reached significant reduction after 8 weeks. Among EAE mice, DTI (FA, AD and RD measures) and OCT measures were all significantly correlated after 4 and 8 weeks. Among histology measures, RGC density (-23%), RGC size (-27%), and the number of SMI31+ axons (-54%) were reduced significantly. DTI measures of FA and AD along with GCC thinning were the best independent predictors of axon loss.

CONCLUSIONS

DTI and OCT measures are tightly correlated during the chronic phase of axonal degeneration (4-8 weeks) in EAE mice. After 8 weeks of EAE, both OCT and DTI measures are strong predictors of axon loss in the Optic Nerve.

Ability of Swept-Source Optical Coherence Tomography to Detect Retinal and Choroidal Changes in Patients with Multiple Sclerosis

Purpose

To evaluate the ability of new swept-source (SS) optical coherence tomography (OCT) technology to detect changes in retinal and choroidal thickness in patients with multiple sclerosis (MS).

Methods

A total of 101 healthy and 97 MS eyes underwent retinal and choroidal assessment using SS Triton OCT (Topcon). Macular thickness and peripapillary data (retinal, ganglion cell layer (GCL+, GCL++) and retinal nerve fiber layer (RNFL) thickness) were analyzed, including choroidal thickness evaluation.

Results

Significant macular thinning was observed in all ETDRS areas (p < 0.001) in MS patients. Peripapillary retinal, RNFL, and GCL ++ thickness showed a significant reduction in patients in all sectors (p < 0.001) except in the nasal quadrant/sector (p > 0.05). GCL+ measurements were found to be reduced in the nasal (p=0.003), inferonasal (p=0.045), and temporal (p=0.001) sectors and total thickness (p < 0.001). Choroidal thickness was reduced in the outer macular ring in MS patients compared with controls (p=0.038).

Conclusion

New swept-source technology for OCT devices detects retinal thinning in MS patients, providing increased depth analysis of the choroid in these patients. MS patients present reduced retinal and choroidal thickness in the macular area and reduced peripapillary retinal, RNFL, and GCL thickness.

Multiple sclerosis

Multiple sclerosis (MS) is the most common chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system in young adults. This disorder is a heterogeneous, multifactorial, immune-mediated disease that is influenced by both genetic and environmental factors. In most patients, reversible episodes of neurological dysfunction lasting several days or weeks characterize the initial stages of the disease (that is, clinically isolated syndrome and relapsing-remitting MS). Over time, irreversible clinical and cognitive deficits develop. A minority of patients have a progressive disease course from the onset. The pathological hallmark of MS is the formation of demyelinating lesions in the brain and spinal cord, which can be associated with neuro-axonal damage. Focal lesions are thought to be caused by the infiltration of immune cells, including T cells, B cells and myeloid cells, into the central nervous system parenchyma, with associated injury. MS is associated with a substantial burden on society owing to the high cost of the available treatments and poorer employment prospects and job retention for patients and their caregivers.

Association of Retinal Nerve Fiber Layer Thickness With Brain Alterations in the Visual and Limbic Networks in Elderly Adults Without Dementia

IMPORTANCE

The eye is a sensory organ that is easily accessible for imaging techniques, allowing the measurement of the retinal nerve fiber layer (RNFL) thickness. The eye is part of the central nervous system, and its neurons may be susceptible to degeneration; therefore, changes in the RNFL thickness may reflect microstructural and volume alterations in the brain.

OBJECTIVE

To explore the association between the peripapillary RNFL thickness and brain alterations in the visual and limbic networks in elderly people without dementia.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional analysis of the Three-City/Antioxydants, Lipides Essentiels, Nutrition et Maladies Oculaires (Alienor) Study cohort (April 2009 to December 2010). The dates of analysis were July 2017 to August 2018. The setting was a population-based study in France. The brain volume analysis included 104 participants, and the diffusion tensor imaging analysis included 79 participants.

MAIN OUTCOMES AND MEASURES

Global RNFL was assessed by spectral-domain optical coherence tomography. Brain volumes were assessed via T1-weighted magnetic resonance imaging by measurement of the global white and gray matter fractions and the hippocampal fraction. Brain microstructural alterations were assessed with diffusion tensor imaging at the level of the posterior thalamic radiations, the limbic system tracts (the fornix and cingulum bundles), and the posterior limb of the internal capsule (control region). Linear regression models adjusted for several confounders were performed.

RESULTS

Among a total of 104 participants, the mean (SD) age was 80.8 (3.9) years, and the cohort was 56.7% women (n = 59). The mean (SD) global RNFL thickness was 89.3 (12.9) µm. A thicker RNFL was associated with a greater hippocampal fraction (quantity of increase β = 0.013; 95% CI, 0.001-0.025 per 10-μm increase in the RNFL thickness) and better diffusion tensor imaging variables in the global cingulum (mean diffusivity β = -0.007; 95% CI, -0.015 to -0.000) and the hippocampal part of the cingulum (mean diffusivity β = -0.009; 95% CI, -0.016 to -0.002 and radial diffusivity β = -0.010; 95% CI, -0.018 to -0.002) and the posterior thalamic radiations (fractional anisotropy β = 0.008; 95% CI, 0.000-0.017). No significant associations were found with other magnetic resonance imaging volumes or with other diffusion tensor imaging variables. In particular, there was no significant association with the control region of interest.

CONCLUSIONS AND RELEVANCE

Results of this study suggest that in elderly individuals without dementia, a thicker RNFL was associated with better magnetic resonance imaging variables both in a region that included the visual pathways and in regions particularly involved in the neurodegenerative processes of Alzheimer disease.

Transorbital ultrasonography for measuring optic nerve atrophy in multiple sclerosis

OBJECTIVE

we aimed to evaluate the utility of transorbital ultrasonography (TOS) in optic nerve assessment and quantification of ON atrophy in MS patients, and to determine whether ON atrophy correlates with the disease duration and disability measured on the Kurtzke Expanded Disability Status Scale (EDSS).

MATERIALS AND METHODS

Prospective, multicentre, blinded cohort study of 59 patients diagnosed with relapsing-remitting MS and 36 controls.

RESULTS

When measured with TOS, the diameter of both the right (2.69 ± 0.30 mm in cases; 3.20 ± 0.19 mm in controls, P < .0001) and left (2.71 ± 0.26 mm in cases; 3.24 ± 0.15 mm controls, P < .0001) ON of study patients was smaller than controls. We observed a negative correlation between EDSS and both right (ρ = .524) and left (ρ = .469) ON diameter. We also observed a negative correlation between disease duration and both right (r = .602) and left (r = .538) ON diameter. No difference was observed in the diameter of both ON among patients with a history of optic neuritis (right OND 2.68 ± 0.29 mm; left OND 2.69 ± 0.25 mm) and patients with no history of optic neuritis (right OND 2.70 ± 0.30 mm; left OND 2.73 ± 0.27 mm) (P = .805; P = .651).

CONCLUSIONS

The thickness of ON measured with TOS is correlated with EDSS and the duration of the disease without being interfered by the previous history of optic neuritis. TOS could be a reliable technique for measuring ON atrophy in MS.

Intraretinal fluid identification via enhanced maps using optical coherence tomography images

Nowadays, among the main causes of blindness in developed countries are age-related macular degeneration (AMD) and the diabetic macular edema (DME). Both diseases present, as a common symptom, the appearance of cystoid fluid regions inside the retinal layers. Optical coherence tomography (OCT) image modality was one of the main medical imaging techniques for the early diagnosis and monitoring of AMD and DME via this intraretinal fluid detection and characterization. We present a novel methodology to identify these fluid accumulations by means of generating binary maps (offering a direct representation of these areas) and heat maps (containing the region confidence). To achieve this, a set of 312 intensity and texture-based features were studied. The most relevant features were selected using the sequential forward selection (SFS) strategy and tested with three archetypal classifiers: LDC, SVM and Parzen window. Finally, the most proficient classifier is used to create the proposed maps. All of the tested classifiers returned satisfactory results, the best classifier achieving a mean test accuracy higher than 94% in all of the experiments. The suitability of the maps was evaluated in a context of a screening issue with three different datasets obtained with two different devices, testing the capabilities of the system to work independently of the used OCT device. The experiments with the map creation were performed using 323 OCT images. Using only the binary maps, more than 91.33% of the images were correctly classified. With only the heat maps, the proposed methodology correctly separated 93.50% of the images.

Optical coherence tomography indices of structural retinal pathology in schizophrenia

BACKGROUND

Prior optical coherence tomography (OCT) studies of schizophrenia have identified thinning of retinal layers. However, findings have varied across reports, and most studies have had serious methodological limitations. To address unresolved issues, we determined whether: (1) retinal thinning in schizophrenia occurs independently of comorbid medical conditions that affect the retina; (2) thinning is independent of antipsychotic medication dose; (3) optic nerve parameters are abnormal in schizophrenia; and (4) OCT indices are related to visual and cognitive impairments common in schizophrenia.

METHODS

A total of 32 people with schizophrenia and 32 matched controls participated. Spectral domain OCT generated data on retinal nerve fiber layer (RNFL), macula, and ganglion cell-inner plexiform layer (GCL-IPL) thickness, in addition to cup volume and the cup-to-disc ratio at the optic nerve head. Subjects with schizophrenia also completed measures of symptoms, visual processing, and IQ.

RESULTS

The groups did not differ on RNFL, macula, or GCL-IPL thickness. However, thinning of these layers was related to the presence of diabetes or hypertension across the sample as a whole. The schizophrenia group demonstrated enlarged cup volume and an enlarged cup-to-disc ratio in both eyes, which were unrelated to medical comorbidity, but were related to increased cognitive symptoms.

CONCLUSIONS

Past reports of retinal thinning may be artifacts of medical comorbidity that is over-represented in schizophrenia, or other confounds. However, optic nerve head abnormalities may hold promise as biomarkers of central nervous system abnormality, including cognitive decline, in schizophrenia.

HANDHELD SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY IMAGING THROUGH THE UNDILATED PUPIL IN INFANTS BORN PRETERM OR WITH HYPOXIC INJURY OR HYDROCEPHALUS

PURPOSE

The authors investigated feasibility of undilated handheld spectral domain optical coherence tomography (SDOCT) retinal imaging in preterm infants and children with neurologic abnormalities.

METHODS

Under an institutional review board-approved protocol, the authors attempted handheld SDOCT imaging of the retina, choroid, and optic nerve in infants and young children without pupil dilation. Scans were analyzed for quality and successful capture of foveal, optic nerve, and retinal structural parameters and abnormalities.

RESULTS

The authors obtained images through an undilated pupil of 11 infants/children over 28 eye imaging sessions, 27 at the bedside without sedation, and one under anesthesia. Infants had retinopathy of prematurity (n = 8), hypoxic ischemic encephalopathy (n = 2), or obstructive hydrocephalus (n = 1 child). Pupil sizes ranged from 1.0 mm to 3.5 mm. The authors captured fovea and optic nerve scans in 25/28 eye imaging sessions, with scans of adequate quality to discern prespecified foveal and optic nerve morphology, and of the 25 sessions, the choroidal-scleral junction was visible in all but 6 sessions.

CONCLUSION

Undilated, handheld SDOCT imaging is a potential alternative method to evaluate the retina and optic nerve in patients with relative contraindication to pharmacological pupil dilation. This approach will enable the study of the eye-brain connection and ocular manifestations of neurologic diseases.

Discriminative power of intra-retinal layers in early multiple sclerosis using 3D OCT imaging

OBJECTIVE

To evaluate volumetric changes and discriminative power of intra-retinal layers in early-stage multiple sclerosis (MS) using a 3D optical coherence tomography (OCT) imaging method based on an in-house segmentation algorithm.

METHODS

3D analysis of intra-retinal layers was performed in 71 patients with early-stage MS (mean disease duration 2.2 ± 3.5 years) at baseline and 40 healthy controls (HCs). All patients underwent a follow-up OCT scan within 23 ± 9 months. Patients with a clinical episode of optic neuritis (ON) more than 6 months prior to study entrance were compared with patients who never experienced clinical symptoms of an ON episode (NON).

RESULTS

Significantly decreased total retinal volume (TRV), macular retinal nerve fiber layer (mRNFL) and ganglion cell-inner plexiform layer (GCIPL) volumes were detected in ON patients compared to NON patients (all p values < 0.05) at baseline. Each parameter on its own allowed identification of prior clinical ON based on a discriminative model (ROC analysis). Over time, TRV decreased in both ON (p = 0.013) and NON patients (p = 0.002), whereas mRNFL volume (p = 0.028) decreased only in ON and GCIPL volume (p = 0.003) decreased only in NON patients.

CONCLUSION

Our 3D-OCT data demonstrated that TRV, mRNFL and GCIPL allow discrimination between ON and NON patients in a cross-sectional analysis. However, the subsequent retinal atrophy pattern diverges in the initial phase of MS: Prior ON promotes sustained axonal thinning over time indicated by mRNFL loss, whereas longitudinal measurement of GCIPL volume better depicts continuous retrograde neurodegeneration in NON patients in early-stage MS.

The Effect of Glatiramer Acetate on Retinal Nerve Fiber Layer Thickness in Patients with Relapsing-Remitting Multiple Sclerosis: A Longitudinal Optical Coherence Tomography Study

BACKGROUND

Optical coherence tomography (OCT) is a technique that allows for the assessment of retinal nerve fiber layer thickness (RNFLT) and total macular volume (TMV), which reflect neuroaxonal integrity within the retina. As such it has been used in multiple sclerosis (MS) to study neurodegeneration. Glatiramer acetate (GA) is a widely used treatment for MS, which is suggested to have a possible neuroprotective role.

OBJECTIVE

The aim of this study was to assess RFNLT and TMV changes in relapsing-remitting MS (RRMS) patients who started treatment with GA and were followed for a 24-month period.

METHODS

A cohort of 60 RRMS patients and 40 healthy controls (HCs) were imaged with OCT at baseline and follow-up. All subjects also underwent clinical and neurological examination. Measurements were compared between the RRMS patients and HCs as well as between optic neuritis (ON)-affected and ON-unaffected eyes.

RESULTS

At baseline, MS patients showed lower average RNFLT (p = 0.046) and TMV (p = 0.013) when compared with HCs. No significant differences in the evolution of OCT measures were detected over the follow-up between MS patients and HCs. MS patients with both affected and unaffected eyes showed significantly lower average RNFLT, temporal inferior RNFLT, and TMV at baseline, compared with HCs. No significant differences between ON-affected and ON-unaffected eyes in MS patients were detected over the follow-up, except for the nasal superior RNFLT (p = 0.019).

CONCLUSIONS

This study suggests a beneficial role of GA on retinal axonal degeneration in MS, and further confirms the utility of OCT to monitor the neuroprotective effect of disease-modifying treatment.

Retinal imaging with optical coherence tomography: a biomarker in multiple sclerosis?

Multiple sclerosis (MS) is a progressive neurological disorder characterized by both inflammatory and degenerative components that affect genetically susceptible individuals. Currently, the cause of MS remains unclear, and there is no known cure. Commonly used therapies tend to target inflammatory aspects of MS, but may not halt disease progression, which may be governed by the slow, subclinical accumulation of injury to neuroaxonal structures in the central nervous system (CNS). A recognized challenge in the field of MS relates to the need for better methods of detecting, quantifying, and ameliorating the effects of subclinical disease. Simply stated, better biomarkers are required. To this end, optical coherence tomography (OCT) provides highly reliable, reproducible measures of axonal damage and neuronal loss in MS patients. OCT-detected decrements in retinal nerve fiber layer thickness and ganglion-cell layer-inner plexiform layer thickness, which represent markers of axonal damage and neuronal injury, respectively, have been shown to correlate with worse visual outcomes, increased clinical disability, and magnetic resonance imaging-measured burden of disease in MS patients. Recent reports have also suggested that OCT-measured microcystic macular edema and associated thickening of the retinal inner nuclear layer represent markers of active CNS inflammatory activity. Using the visual system as a putative clinical model in MS, OCT measures of neuroaxonal structure can be correlated with functional outcomes to help us elucidate mechanisms of CNS injury and repair. In this review, we evaluate evidence from the published literature and ongoing clinical trials that support the emerging role of OCT in diagnosing, staging, and determining response to therapy in MS patients.

Chlorogenic acids inhibit glutamate dehydrogenase and decrease intracellular ATP levels in cultures of chick embryo retina cells

Chlorogenic acids (CGAs) are a group of phenolic compounds found in worldwide consumed beverages such as coffee and green tea. They are synthesized from an esterification reaction between cinnamic acids, including caffeic (CFA), ferulic and p-coumaric acids with quinic acid (QA), forming several mono- and di-esterified isomers. The most prevalent and studied compounds are 3-O-caffeoylquinic acid (3-CQA), 4-O-caffeoylquinic acid (4-CQA) and 5-O-caffeoylquinic acid (5-CQA), widely described as having antioxidant and cell protection effects. CGAs can also modulate glutamate release from microglia by a mechanism involving a decrease of reactive oxygen species (ROS). Increased energy metabolism is highly associated with enhancement of ROS production and cellular damage. Glutamate can also be used as an energy source by glutamate dehydrogenase (GDH) enzyme, providing α-ketoglutarate to the tricarboxylic acid (TCA) cycle for ATP synthesis. High GDH activity is associated with some disorders, such as schizophrenia and hyperinsulinemia/hyperammonemia syndrome. In line with this, our objective was to investigate the effect of CGAs on GDH activity. We show that CGAs and CFA inhibits GDH activity in dose-dependent manner, reaching complete inhibition at high concentration with IC50 of 52 μM for 3-CQA and 158.2 μM for CFA. Using live imaging confocal microscopy and microplate reader, we observed that 3-CQA and CFA can be transported into neuronal cells by an Na⁺-dependent mechanism. Moreover, neuronal cells treated with CGAs presented lower intracellular ATP levels. Overall, these data suggest that CGAs have therapeutic potential for treatment of disorders associated with high GDH activity.

Using the Anterior Visual System to Assess Neuroprotection and Remyelination in Multiple Sclerosis Trials

PURPOSE OF REVIEW

Clinical trials using agents directed at neuroprotection and remyelination in multiple sclerosis (MS) are needed. As optic neuritis (ON) is common in people with MS and the pathology of ON is similar to other MS lesions in the brain, measurements of the anterior visual system are frequently utilized in neuroprotection and remyelination trials. Understanding the strengths and weaknesses of the measurements is vital when interpreting the results of this research.

RECENT FINDINGS

Techniques such as visual evoked potentials (VEP) and optical coherence tomography (OCT) are well established in MS and are thought to measure axonal integrity and myelination. Novel imaging techniques can also be used in conjunction with these measurements to provide better insight into optic nerve structure and function. Magnetization transfer imaging (MTR) together with optic nerve area and volume measures neurodegeneration; diffusion tensor imaging (DTI) measures myelination status and neurodegeneration. However, these techniques require various levels of experience to interpret, and all can be confounded by ocular motion and surrounding fat and bone. This article provides a review of established and novel techniques to measure the anterior visual system in multiple sclerosis with a focus on the evidence to support their use as outcome measures in clinical trials focused on neuroprotection and remyelination therapies.

Macular and Retinal Nerve Fibre Layer Thinning in Xeroderma Pigmentosum: A Cross-sectional Study

The purpose of this study was to evaluate retinal thickness in different Xeroderma Pigmentosum (XP) complementation groups using spectral-domain optical coherence tomography (SD-OCT). This was a cross-sectional pilot study of 40 patients with XP. All patients had healthy-looking retinae and optic nerves on slit lamp biomicroscopy, and subtle or no neurological deficits. Patients were divided into two groups based on the known tendency for neurodegeneration associated with certain XP complementation groups. A third control group was obtained from a normative database. Using SD-OCT, we compared peripapillary retinal nerve fibre layer (pRNFL) and macular thickness between the groups. XP patients with a known tendency for neurodegeneration were found to have a statistically significant reduction in both pRNFL (p < 0.01) and macular thickness (p < 0.001) compared with healthy controls. In contrast, there was no statistically significant difference between pRNFL and macular thickness in XP patients not expected to develop neurodegeneration compared to the same control group. When both XP groups were compared, a statistically significant reduction in total pRNFL (p = 0.02) and macular thickness (p = 0.002) was found in XP patients predisposed to neurodegeneration. Our results suggest that pRNFL and macular thickness are reduced in XP patients with a known tendency for neurodegeneration, even before any marked neurological deficits become manifest. These findings demonstrate the potential role of retinal thickness as an anatomic biomarker and prognostic indicator for XP neurodegeneration.