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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

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

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

Evaluation of optical coherence tomography findings in patients with multiple sclerosis and glaucoma

PURPOSE

Glaucoma and multiple sclerosis (MS) can cause optic disc pathology and, in this way, affect optical coherence tomography (OCT) data. In this context, the objective of this study is to investigate the changes in the mean, quadrant, and sector data measured by OCT in glaucoma and MS patients.

METHODS

The sample of this prospective cohort study consisted of 42 MS patients (84 eyes), 34 Primary open-angle glaucomas patients (67 eyes), and 24 healthy control subjects (48 eyes). The MS group was divided into two groups according to the presence of a history of optic neuritis. Accordingly, those with a history of optic neuritis were included in the MS ON group, and those without a history of optic neuritis were included in the MS NON group. The differences between these groups in the mean, quadrant, and sector data related to the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) were evaluated.

RESULTS

Superior nasal (SN), superior temporal (ST), inferior nasal (IN), and superior quadrant (SUP) values were significantly lower in the glaucoma group than in the MS group (p < 0.05). The mean superior GCC (GCC SUP) value was significantly lower in the MS ON group than in the glaucoma group (p < 0.05). On the other hand, SN, ST, inferior temporal (IT), IN, average RNFL (AVE RNFL), semi-average superior RNFL (SUP AVE RNFL), semi-average inferior RNFL (INF AVE RNFL), SUP, and inferior quadrant RNFL (INF) values were significantly lower in the glaucoma group than in the MS NON group (p < 0.05).

CONCLUSION

RNFL and GCC parameters get thinner in MS and glaucoma patients. While the inferior and superior RNFL quadrants are more frequently affected in glaucoma patients, the affected quadrants vary according to the presence of a history of optic neuritis in MS patients. It is noteworthy that the GCC superior quadrant was thin in MS ON patients. The findings of this study indicate that OCT data may be valuable in the differential diagnosis of glaucoma and MS.

The macular retinal ganglion cell layer as a biomarker for diagnosis and prognosis in multiple sclerosis: A deep learning approach

PURPOSE

The macular ganglion cell layer (mGCL) is a strong potential biomarker of axonal degeneration in multiple sclerosis (MS). For this reason, this study aims to develop a computer-aided method to facilitate diagnosis and prognosis in MS.

METHODS

This paper combines a cross-sectional study of 72 MS patients and 30 healthy control subjects for diagnosis and a 10-year longitudinal study of the same MS patients for the prediction of disability progression, during which the mGCL was measured using optical coherence tomography (OCT). Deep neural networks were used as an automatic classifier.

RESULTS

For MS diagnosis, greatest accuracy (90.3%) was achieved using 17 features as inputs. The neural network architecture comprised the input layer, two hidden layers and the output layer with softmax activation. For the prediction of disability progression 8 years later, accuracy of 81.9% was achieved with a neural network comprising two hidden layers and 400 epochs.

CONCLUSION

We present evidence that by applying deep learning techniques to clinical and mGCL thickness data it is possible to identify MS and predict the course of the disease. This approach potentially constitutes a non-invasive, low-cost, easy-to-implement and effective method.

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.

Optical Coherence Tomography and Visual Evoked Potentials as Prognostic and Monitoring Tools in Progressive Multiple Sclerosis

Understanding the mechanisms underlying progression and developing new treatments for progressive multiple sclerosis (PMS) are among the major challenges in the field of central nervous system (CNS) demyelinating diseases. Over the last 10 years, also because of some technological advances, the visual pathways have emerged as a useful platform to study the processes of demyelination/remyelination and their relationship with axonal degeneration/protection. The wider availability and technological advances in optical coherence tomography (OCT) have allowed to add information on structural neuroretinal changes, in addition to functional information provided by visual evoked potentials (VEPs). The present review will address the role of the visual pathway as a platform to assess functional and structural damage in MS, focusing in particular on the role of VEPs and OCT, alone or in combination, in the prognosis and monitoring of PMS.

Trans-synaptic degeneration in the visual pathway: Neural connectivity, pathophysiology, and clinical implications in neurodegenerative disorders

There is a strong interrelationship between eye and brain diseases. It has been shown that neurodegenerative changes can spread bidirectionally in the visual pathway along neuronal projections. For example, damage to retinal ganglion cells in the retina leads to degeneration of the visual cortex (anterograde degeneration) and vice versa (retrograde degeneration). The underlying mechanisms of this process, known as trans-synaptic degeneration (TSD), are unknown, but TSD contributes to the progression of numerous neurodegenerative disorders, leading to clinical and functional deterioration. The hierarchical structure of the visual system comprises of a strong topographic connectivity between the retina and the visual cortex and therefore serves as an ideal model to study the cellular effect, clinical manifestations, and deterioration extent of TSD. With this review we provide comprehensive information about the neural connectivity, synapse function, molecular changes, and pathophysiology of TSD in visual pathways. We then discuss its bidirectional nature and clinical implications in neurodegenerative diseases. A thorough understanding of TSD in the visual pathway can provide insights into progression of neurodegenerative disorders and its potential as a therapeutic target.

Visual Evoked Potentials as a Biomarker in Multiple Sclerosis and Associated Optic Neuritis

: ABSTRACT:: Multiple sclerosis (MS) is an inflammatory, degenerative disease of the central nervous system (CNS) characterized by progressive neurological decline over time. The need for better "biomarkers" to more precisely capture and track the effects of demyelination, remyelination, and associated neuroaxonal injury is a well-recognized challenge in the field of MS. To this end, visual evoked potentials (VEPs) have a role in assessing the extent of demyelination along the optic nerve, as a functionally eloquent CNS region. Moreover, VEPs testing can be used to predict the extent of recovery after optic neuritis (ON) and capture disabling effects of clinical and subclinical demyelination events in the afferent visual pathway. In this review, the evolving role of VEPs in the diagnosis of patients with ON and MS and the utility of VEPs testing in determining therapeutic benefits of emerging MS treatments is discussed.

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.

Macular ganglion cell complex parameters by optical coherence tomography in cases of multiple sclerosis without optic neuritis compared to healthy eyes

Purpose:

To compare different macular thickness parameters and peripapillary retinal nerve fiber layer (RNFL) thickness between recently diagnosed cases of multiple sclerosis (MS) without optic neuropathy (ON) and healthy individuals.

Methods:

This cross-sectional study was performed between June 2014 and June 2015. All subjects underwent ocular and retinal examination. Spectral domain optical coherence tomography (SD-OCT) was used to measure the thickness of different layers of the retina at macular and peripapillary regions and at different quadrants. Between groups comparison was performed with P < 0.05 indicating statistical significance.

Results:

There were 32 eyes in the MS group and 74 eyes in the control group. The MS group was significantly younger than the control group (P < 0.001). The mean ganglion cell complex (GCL++) thickness in superior macular area was 64.1 ± 8.9 μ in the MS group and 71.1 ± 5.9 μ in the control group. The thickness of the RNFL did not statistically differ in each of the quadrants between groups. Despite controlling for age, the macular thickness parameters were significantly thinner in eyes with MS compared to healthy eyes (P < 0.01).

Conclusion:

The macular ganglion cell complex (mGCC) parameters were significantly reduced in recently diagnosed cases of MS as compared to healthy individuals.

Eyes are mirror of the brain: comparison of multiple sclerosis patients and healthy controls using OCT

Objective: To evaluate the thickness of choroid and retinal nerve fiber layer (RNFL) in multiple sclerosis (MS) patients with and without optic neuritis using enhanced depth imaging optical coherence tomography (EDI-OCT). Methods: In this cross-sectional study, both eyes of 52 MS patients [n = 104 eyes; 62 eyes of MS patients without optic neuritis (MS-NON) and 42 eyes of MS patients with optic neuritis (MS-ON)] and only one eye of 36 healthy control subjects (n = 36 eyes) were evaluated. Complete ophthalmologic examination and EDI-OCT scanning were completed for all participants. Choroidal thickness measurements were executed at three different points. Results: Choroidal thickness measurements were similar between MS patients and healthy control subjects. However, the mean subfoveal choroidal thickness was increased significantly in MS-ON group (399.13 ± 82.91 μm) compared to MS-NON group (342.71 ± 82.46 μm; p = 0.004). Mean RNFL thickness was significantly reduced in MS patients (90.42 ± 13.31 μm) compared to healthy controls (101.18 ± 10.75 μm; p < 0.001). Moreover, temporal RNFL thickness was significantly thinner in MS-ON group (54 ± 14.50 μm) than MS-NON group (62.15 ± 15.88 μm; p = 0.01). In MS patients, temporal RNFL thickness was correlated with both Expanded Disability Status Score (r = 0.383; p < 0.001) and longer disease duration (r=-0.202; p = 0.04). Conclusion: The results of the present study suggest that RNFL thickness can be used as an important parameter while following up with MS patients. However, more studies using EDI-OCT are required with larger MS patient groups and automated method.

The role of optical coherence tomography in therapeutics and conditions, which primarily have systemic manifestations: a narrative review

Optical coherence tomography is designed to evaluate in vivo qualitative and quantitative changes of the anterior segment, optic nerve and the retina. Initial applications of this technology were confined mainly to ophthalmic diseases. However recently, numerous studies have evaluated its use in systemic conditions and in therapeutics where, optic nerve and retinal architecture can be assessed to monitor progression of systemic conditions and its response to treatment. This is a narrative review aimed at evaluating the debate surrounding the role of spectral domain optical coherence tomography, in systemic conditions where optic nerve affection can be measured and be used in the diagnosis, monitoring and assessment of treatment effect as a non-invasive, quick, novel technique.

Color vision testing versus pattern visual evoked potentials and optical coherence tomography parameters in subclinical optic nerve involvement in multiple sclerosis

Acute idiopathic demyelinating optic neuritis is frequently the initial manifestation of multiple sclerosis (MS). We aimed to discuss the value of color vision testing to detect possible optic nerve involvement in patients with MS who had no history of optic neuritis. We evaluated color vision with Farnsworth-Munsell 100 (FM-100) hue test. Total error scores (TES), partial error scores for the red-green axis (RGS) and blue-yellow axis (BYS) were calculated. Topographic optic disc parameters (RNFL, RA, DA, CV, RV, and vertical C/D ratio), total macular volume (TMV), central macular thickness (CMT), and retinal ganglion cell layer (RGCL) were determined using spectral domain optical coherence tomography (SD-OCT). Choroidal thickness (CT) was measured using enhanced depth imaging optical coherence tomography (EDI-OCT). Pattern visual evoked potentials (PVEP) were also performed. Twenty-eight patients with RRMS (56 eyes) and 25 healthy controls (50 eyes) were included. P100 latencies were significantly delayed and P100 amplitudes were significantly reduced in the patient group compared with the controls (p ≤ 0.05). Statistically significant thinning was found in temporal quadrant in the patient group compared with the controls (p = 0.002). TES RGS, and BYS were all increased in the patient group but this was not statistically significant. We found no correlation between TES, RGS, BYS, and P100 latencies or OCT parameters. In our investigation as to whether color vision testing could be a simple biomarker for showing neurodegeneration of the anterior visual pathway regardless of optic neuritis, PVEP and OCT-assessed RNFL thickness seemed to be a more valuable biomarker than color vision testing.

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.

Evaluation of thickness of retinal nerve fiber layer, ganglion cell layer, and choroidal thickness in essential tremor: can eyes be a clue for neurodegeneration?

The pathology of essential tremor (ET) and underlying mechanisms of the disease are still unclear, but an increasing amount of research has been conducted on the subject. Discussions are ongoing about ET's definition as a neurodegenerative disease. Optic coherence tomography (OCT) provides a window to the brain where direct visualization of central nervous system (CNS) changes may be possible, and it can help us to develop a new point of view on ET. The goal of this study was to examine OCT parameters in ET. 40 ET patients and 40 healthy controls, i.e., a total of 160 eyes were evaluated. Retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and choroid thinning were analyzed using spectral domain OCT. The mean age was 25.77 ± 8.98 in the ET group and 27.25 ± 8.22 in the control group. We found a decreased global RNFL thickness for both eyes in ET patients. All GCL and IPL thickness parameters were lower in the patients with ET (P < 0.001, P 0.03). Choroid was significantly thicker in ET patients than the controls (P < 0.001). Our study's results suggest that the usefulness of OCT in detecting neurodegeneration in ET. RNFL, GCL, IPL measurements are highly reproduced findings of neurodegeneration. Increased choroid volume may indicate neuroinflammation. Eyes in ET may shed light on nature of the disease, and may be used as a diagnostic tool.

The Temporal Retinal Nerve Fiber Layer Thickness Is the Most Important Optical Coherence Tomography Estimate in Multiple Sclerosis

BACKGROUND

Reduced peripapillary retinal nerve fiber layer (pRNFL) and combined ganglion cell and inner plexiform layer (GCIP) thicknesses as measured by optical coherence tomography (OCT) have been observed in multiple sclerosis (MS) patients. The purpose was to determine the most associative OCT measure to level of cognitive and physical disability in MS.

METHODS

Data were collected from 546 MS patients and 175 healthy controls (HCs). We compared the average pRNFL, temporal pRNFL (T-pRNFL), overall inner ganglion cell/inner plexiform layer (GCIP), and the overall ganglion cell complex (GCC) including macular RNFL and GCIP thicknesses measurements in differentiating MS subtypes from HCs. The association between OCT measures, Expanded Disability Status Scale (EDSS), and Symbol Digit Modalities Test (SDMT) were assessed using generalized estimating equations models.

RESULTS

Both peripapillary and macular OCT measurements could differentiate all MS subtypes from HCs. The SDMT score was significantly associated with reduced thickness of all OCT measures, mostly in average pRNFL (0.14 µm, P = 0.001) and T-pRNFL (0.17 µm, P < 0.001). The EDSS score was significantly associated with reduced inner retinal layer thickness. The largest reduction was seen in T-pRNFL (-1.52 μm, P < 0.001) and inner GCC (-1.78 μm, P < 0.001).

CONCLUSION

The T-pRNFL is highly sensitive and associated with level of both cognitive and physical disability.

The Contribution of Optical Coherence Tomography in Neuromyelitis Optica Spectrum Disorders

Neuromyelitis optica spectrum disorders (NMOSD) comprises a group of central nervous system disorders of inflammatory autoimmune origin that mainly affect the optic nerves and the spinal cord and can cause severe visual and general disability. The clinical signs are similar to those of multiple sclerosis (MS), with the result that it is often difficult to differentiate between the two, thus leading to misdiagnosis. As the treatment and prognosis of NMOSD and MS are different, it is important to make an accurate and early diagnosis of NMOSD. Optical coherence tomography (OCT) is a non-invasive technique that enables a quantitative study of the changes that the optic nerve and the macula undergo in several neurodegenerative diseases. Many studies have shown that some of these changes, such as retinal nerve fiber layer thinning or microcystic macular edema, can be related to alterations in the brain due to neurodegenerative disorders. The purpose of this mini-review is to show how OCT can be useful for the diagnosis of NMOSD and follow-up of affected patients, as well as for the differential diagnosis with MS.

20/40 or Better Visual Acuity After Optic Neuritis: Not as Good as We Once Thought?

BACKGROUND

Although patients with acute optic neuritis (ON) recover high-contrast visual acuity (HCVA) to 20/40 or better in 95% of affected eyes, patients with a history of ON continue to note subjective abnormalities of vision. Furthermore, substantial and permanent thinning of the retinal nerve fiber layer (RNFL) and the ganglion cell layer (GCL) is now known to occur early in the course of ON. We measured vision-specific quality of life (QOL) in patients with a history of acute ON and recovery of VA to 20/40 or better in their affected eyes to determine how these QOL scores relate to RNFL and GCL thickness and low-contrast letter acuity (LCLA) across the spectrum of visual recovery.

METHODS

Data from an ongoing collaborative study of visual outcomes in multiple sclerosis and ON were analyzed for this cross-sectional observational cohort. Patients and disease-free control participants completed the 25-Item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25) and 10-Item Neuro-Ophthalmic Supplement to the NEI-VFQ-25, as well as VA and LCLA testing for each eye separately and binocularly. Optical coherence tomography measures for each eye included peripapillary RNFL thickness and macular GCL + inner plexiform layer (GCL + IPL) thickness.

RESULTS

Patients with a history of acute ON and recovery to 20/40 or better VA (n = 113) had significantly reduced scores for the NEI-VFQ-25 (83.7 ± 15.4) and 10-Item Neuro-Ophthalmic Supplement (74.6 ± 17.4) compared with disease-free controls (98.2 ± 2.1 and 96.4 ± 5.2, P < 0.001, linear regression models, accounting for age and within-patient, intereye correlations). Most patients with 20/40 or better visual recovery (98/112, 88%) had monocular HCVA in their affected eye of 20/20 or better. Although patients with 20/50 or worse HCVA recovery demonstrated the worst performance on low-contrast acuity, affected eye RNFL and GCL + IPL thickness, and QOL scales, these measures were also significantly reduced among those with 20/40 or better HCVA recovery compared with controls.

CONCLUSIONS

Patients with a history of ON and "good" visual recovery, defined in the literature as 20/40 or better HCVA, are left with clinically meaningful reductions in vision-specific QOL. Such patient-observed deficits reflect the underlying significant degrees of retinal axonal and neuronal loss and visual dysfunction that are now known to characterize ON even in the setting of maximal HCVA recovery. There remains an unmet therapeutic need for patients with ON.

Quantitative visual tests after poorly recovered optic neuritis due to multiple sclerosis

BACKGROUND

Visual dysfunction in MS can be quantified using a variety of tests. Many vision tests have not been formally evaluated among MS patients with existing visual dysfunction.

OBJECTIVE

Evaluate several versions of visual acuity and contrast sensitivity tests, measures of central and peripheral vision, retina structure, electrophysiologic function, and quality of life among MS patients with moderate/severe visual dysfunction.

METHODS

Cross-sectional study of 46 patients with stable, incompletely recovered optic neuritis. Testing included Snellen eye charts, several Sloan low contrast charts, Pelli Robson (PR) contrast sensitivity charts, optical coherence tomography, visual fields, Farnsworth Munsell 100-hue test, visual evoked potentials (VEP), and visual function quality of life (VFQ-25) testing.

RESULTS

98% of eyes could read two lines of the PR chart, while only 43% read the 2.5% contrast chart. Low contrast tests correlated strongly with each other and with retinal nerve fiber layer (RNFL) thickness, visual fields, and color vision but not with VEPs. For patients with RNFL <75µm, VFQ-25 scores dropped by approximately 2 points for every 1µm decrease in RNFL.

CONCLUSION

Among MS patients with visual impairment due to optic neuritis, PR contrast sensitivity could be utilized as a single chart. Visual quality of life was associated with RNFL thinning below 75µm.

Optical Coherence Tomography as a Biomarker for Diagnosis, Progression, and Prognosis of Neurodegenerative Diseases

Neurodegenerative diseases present a current challenge for accurate diagnosis and for providing precise prognostic information. Developing imaging biomarkers for multiple sclerosis (MS), Parkinson disease (PD), and Alzheimer's disease (AD) will improve the clinical management of these patients and may be useful for monitoring treatment effectiveness. Recent research using optical coherence tomography (OCT) has demonstrated that parameters provided by this technology may be used as potential biomarkers for MS, PD, and AD. Retinal thinning has been observed in these patients and new segmentation software for the analysis of the different retinal layers may provide accurate information on disease progression and prognosis. In this review we analyze the application of retinal evaluation using OCT technology to provide better understanding of the possible role of the retinal layers thickness as biomarker for the detection of these neurodegenerative pathologies. Current OCT analysis of the retinal nerve fiber layer and, specially, the ganglion cell layer thickness may be considered as a good biomarker for disease diagnosis, severity, and progression.

Retinal measures correlate with cognitive and physical disability in early multiple sclerosis

Further studies are needed to determine the role of retinal optical coherence tomography (OCT) in non-optic neuritis (ON) eyes of patients with early MS. The objective of this study is to explore the relationship between retinal layers' thickness and cognitive as well as physical disability in patients with the early RRMS. Participants in this cross-sectional study were adults with early RRMS, stable on interferon beta-1a, or fingolimod therapy, and without a history of ON in one or both eyes. Patients were evaluated clinically, underwent a battery of cognitive tests, and a retinal OCT scan which was also performed on a group of healthy age- and gender-matched controls. We studied 47 patients with RRMS, on interferon beta-1a (N = 32) or fingolimod (N = 15), and 18 healthy controls. Multivariate analyses controlling for age, disease duration, treatment, and education when exploring cognitive function, showed that pRNFL thickness correlated negatively with 9HPT (standardized Beta -0.4, p < 0.0001), and positively with SDMT (standardized Beta 0.72, p = 0.007). In patients with early RRMS without optic neuropathy, retinal thickness measures correlated with physical disability and cognitive disability, supporting their potential as biomarkers of axonal loss.

Adding Papillomacular Bundle Measurements to Standard Optical Coherence Tomography Does Not Increase Sensitivity to Detect Prior Optic Neuritis in Patients with Multiple Sclerosis

Purpose

To improve the detection of retinal nerve fiber layer (RNFL) thinning in multiple sclerosis (MS), a special peripapillary ring scanning algorithm (N-site RNFL, N-RNFL) was developed for spectral domain optical coherence tomography (SD-OCT). In contrast to the standard protocol (ST-RNFL) scanning starts nasally, not temporally, and provides an additional sector of analysis, the papillomacular bundle (PMB). We aimed to ascertain whether the temporal RNFL differs between the two techniques, whether N-RNFL is more sensitive than ST-RNFL to detect previous optic neuritis (ON), and whether analyzing the PMB adds additional sensitivity. Furthermore, we investigated whether RNFL is associated with disease severity and/or disease duration.

Methods

We conducted a cross-sectional case-control study of 38 patients with MS, of whom 24 had a history of ON, and 40 healthy controls (HC). Subjects with ON within the previous 6 months were excluded. Records included clinical characteristics, visual evoked potentials (VEP), and SD-OCT in both techniques.

Results

In a total of 73 evaluable MS eyes, temporal N-RNFL was abnormal in 17.8%, temporal ST-RNFL in 19.2%, and the PMB-RNFL in 21.9%. In ON eyes, the sensitivity of temporal N-RNFL and ST-RNFL did not differ significantly (37.0%/33.3%, p = 0.556). The sensitivity of VEP was 85.2%. RNFL thickness was associated with disease severity in all eyes, with and without a history of ON, and with disease duration.

Conclusion

The two OCT techniques detected previous ON with similar sensitivity, but the sensitivity of VEPs was superior to that of both N-RNFL and ST-RNFL. Our results indicate that the widely used ST-RNFL technique is appropriate for peripapillary RNFL measurements in MS patients.

Evaluation of the Innermost Retinal Layers and Visual Evoked Potentials in Patients with Multiple Sclerosis

PURPOSE

The present study was conducted to investigate alterations in the innermost layers of the retina using optical coherence tomography (OCT) and to assess potential associations of structural measures with functional markers in patients with Multiple Sclerosis (MS).

MATERIALS AND METHODS

Ninety-four eyes of 47 MS patients and 60 eyes of 30 healthy individuals were included in the study. All patients underwent complete ophthalmological examination and OCT imaging to analyze peripapillary retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness. Visual evoked potentials (VEPs) and expanded disability status scale (EDSS) score were assessed for MS patients.

RESULTS

The average RNFL and GCIPL thicknesses were thinner in MS patients (86.2 ± 11.9 µm and 73.6 ± 9.7 µm, respectively) when compared with those of healthy controls (96.7 ± 8.2 µm and 85.9 ± 4.6 µm, respectively, p < 0.001 for both). Within MS patients, the average RNFL and GCIPL thicknesses were lower in eyes with a prior history of optic neuritis (MS ON) than in eyes with no optic neuritis history (MS non-ON) (p = 0.012 and p < 0.001, respectively). RNFL and GCIPL thicknesses were inversely correlated with VEP latency (r = -0.40, p < 0.001 and r = -0.36, p < 0.001, respectively) in MS patient eyes. There was a correlation between GCIPL thickness and VEP amplitude in eyes with previous ON history (r = 0.34, p = 0.035). No significant correlations were found between OCT measurements and EDSS score.

CONCLUSIONS

Innermost layers of the retina are highly affected by the pathophysiologic process in MS disease, manifesting as a reduction in RNFL and GCIPL thickness. The structural retinal changes show correlation with alterations in potentials showing the optic pathway function.

How strong is the relationship between glaucoma, the retinal nerve fibre layer, and neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis?

Glaucoma is a neurodegenerative disorder with established relationships with ocular structures such as the retinal nerve fibre layer (RNFL) and the ganglion cell layer (GCL). Ocular imaging techniques such as optical coherence tomography (OCT) allow for quantitative measurement of these structures. OCT has been used in the monitoring of glaucoma, as well as investigating other neurodegenerative conditions such as Alzheimer's disease (AD) and multiple sclerosis (MS). In this review, we highlight the association between these disorders and ocular structures (RNFL and GCL), examining their usefulness as biomarkers of neurodegeneration. The average RNFL thickness loss in patients with AD is 11 μm, and 7 μm in MS patients. Most of the studies investigating these changes are cross-sectional. Further longitudinal studies are required to assess sensitivity and specificity of these potential ocular biomarkers to neurodegenerative disease progression.

Analysis of retinal nerve fibre layer, visual evoked potentials and relative afferent pupillary defect in multiple sclerosis patients

OBJECTIVE

The aim of this study was to analyse retinal nerve fibre layer (RNFL), pattern-reversal visual evoked potentials (pVEPs) and relative afferent pupillary defect (RAPD) changes in multiple sclerosis (MS) patients with the consideration of past optic neuritis (ON).

METHODS

Ophthalmological, neurological, OCT, RNFL and pVEP studies were conducted in 59 MS patients. RAPD tests were performed in 47 of them. Control group consisted of 28 healthy volunteers.

RESULTS

Abnormal RNFL was found in 59% of cases of eyes with ON and 28% of eyes without ON. In eyes with ON, significantly lower RNFL values were indicated in the temporal and lower quadrants. Elongation of pVEP latency was found in 83% of eyes with ON and 60% of eyes without ON. The average value of pVEP latency was larger and the amplitude was lower in the subgroup of eyes with RNFL at the borderline or below the norm. RAPD was observed only in eyes with ON and with RNFL thinning. No association was found between the RAPD and pVEP parameters.

CONCLUSIONS

VEPs were more frequently abnormal than RNFL in MS patients. RNFL damage in eyes without ON may indicate neurodegenerations in CNS of MS patients; it can also be the consequence of subclinical ON.

SIGNIFICANCE

An analysis of RNFL and VEP can be useful for evaluating the optic nerve in MS patients.

A comparative optical coherence tomography study in neuromyelitis optica spectrum disorder and multiple sclerosis

OBJECTIVES

The aim of this study was to find, using spectral domain-optical coherence tomography (SD-OCT), retinal imaging biomarkers differentiating neuromyelitis optica spectrum disorder (NMOSD), multiple sclerosis (MS) and healthy controls (HCs).

MATERIALS AND METHODS

The population was composed of patients with NMOSD (n=23) or MS (n=110) and of HCs (n=75). Evaluation criteria were retinal thickness/volume, visual acuity, low contrast vision acuity and Expanded Disability Status Scale score.

RESULTS

Considering all eyes and after statistical adjustments including the number of optic neuritis (ON) episodes, we found that NMOSD patients did not have significantly more retinal atrophy than MS patients; whereas MS non-optic neuritis (NON) eyes had thinner temporal (p=0.032) and temporo-superior peripapillary retinal nerve fibre layer (pRNFL; p=0.011) thicknesses than NMOSD NON eyes; in addition, NMOSD NON eyes presented significant naso-inferior pRNFL (p=0.024), temporal pRNFL (p=0.039), macular ganglion cell complex (p=0.004) and ganglion cell layer (p=0.002) atrophy vs HC eyes. We identified significant correlations between visual and clinical disability and retinal thicknesses in both diseases.

CONCLUSION

OCT may help to differentiate NMOSD and MS by focusing on the NON eyes (temporal pRNFL atrophy more severe in MS). Moreover, we discuss the possibility of a retinal degenerative process independent of ON in NMOSD.

Relationship between optical coherence tomography and electrophysiology of the visual pathway in non-optic neuritis eyes of multiple sclerosis patients

Purpose

Loss of retinal ganglion cells in in non-optic neuritis eyes of Multiple Sclerosis patients (MS-NON) has recently been demonstrated. However, the pathological basis of this loss at present is not clear. Therefore, the aim of the current study was to investigate associations of clinical (high and low contrast visual acuity) and electrophysiological (electroretinogram and multifocal Visual Evoked Potentials) measures of the visual pathway with neuronal and axonal loss of RGC in order to better understand the nature of this loss.

Methods

Sixty-two patients with relapsing remitting multiple sclerosis with no previous history of optic neuritis in at least one eye were enrolled. All patients underwent a detailed ophthalmological examination in addition to low contrast visual acuity, Optical Coherence Tomography, full field electroretinogram (ERG) and multifocal visual evoked potentials (mfVEP).

Results

There was significant reduction of ganglion cell layer thickness, and total and temporal retinal nerve fibre layer (RNFL) thickness (p<0.0001, 0.002 and 0.0002 respectively). Multifocal VEP also demonstrated significant amplitude reduction and latency delay (p<0.0001 for both). Ganglion cell layer thickness, total and temporal RNFL thickness inversely correlated with mfVEP latency (r = −0.48, p<0.0001 respectively; r = −0.53, p<0.0001 and r = −0.59, p<0.0001 respectively). Ganglion cell layer thickness, total and temporal RNFL thickness also inversely correlated with the photopic b-wave latency (r = −0.35, p = 0.01; r = −0.33, p = 0.025; r = −0.36, p = 0.008 respectively). Multivariate linear regression model demonstrated that while both factors were significantly associated with RGC axonal and neuronal loss, the estimated predictive power of the posterior visual pathway damage was considerably larger compare to retinal dysfunction.

Conclusion

The results of our study demonstrated significant association of RGC axonal and neuronal loss in NON-eyes of MS patients with both retinal dysfunction and post-chiasmal damage of the visual pathway.

Axonal loss of retinal neurons in multiple sclerosis associated with optic radiation lesions

OBJECTIVE

To investigate the potential links between thinning of retinal ganglion cell axons in eyes of patients with multiple sclerosis (MS) without past optic neuritis (ON) and MS-related inflammatory damage of the posterior visual pathway.

METHODS

Temporal retinal nerve fiber layer (tRNFL) thickness was analyzed in eyes with no history of ON (NON) from 53 patients with relapsing-remitting MS. Fifty normal age- and sex-matched controls were examined with optical coherence tomography. Low-contrast visual acuity charts were used for functional assessment of vision. The optic tract (OT) and optic radiation (OR) were identified using probabilistic tractography, and volume of T2 fluid-attenuated inversion recovery lesions and diffusion tensor imaging (DTI) indices were measured within both structures. Cross-sectional diameter of the OT was also calculated.

RESULTS

tRNFL thickness was significantly reduced in NON eyes and was associated with reduced low-contrast visual acuity. Lesions within the OR were detected in the majority of patients. There was a significant correlation between thinning of the tRNFL and OR lesion volume (adjusted for non-OR lesion volume, age, sex, and disease duration). tRNFL thickness also correlated with OR DTI indices. No OT lesions were identified in any of the patients and no relationship between retinal nerve fiber layer loss and potential markers of OT lesions was found.

CONCLUSION

The results demonstrate a strong tract-specific association between loss of tRNFL fibers and MS-related inflammation within OR.

Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

OBJECTIVES

To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness.

METHODS

3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp-Parrish-Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearman's correlation coefficient was carried out.

RESULTS

FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r=0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r=-0.360, p ≤ 0.001).

CONCLUSIONS

The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity.

Optical coherence tomography and visual evoked potentials: which is more sensitive in multiple sclerosis?

OBJECTIVE

To assess the sensitivity of optic coherence tomography (OCT) and visual evoked potentials (VEPs) to visual pathway abnormalities in multiple sclerosis (MS).

METHODS

A total of 40 MS subjects, 28 with optic neuritis (ON) at least 3 months before (bilateral in 5), underwent assessment of visual acuity, Expanded Disability Status Scale (EDSS), OCT and VEPs, the latter quantified with a 0-4 conventional score.

RESULTS

OCT and VEPs were abnormal in 36% and 56% respectively in all eyes (p=0.11), 68% and 86% in eyes with previous ON (p=0.12), and in 19% versus 40% in eyes without ON history (p=0.007). Combining VEP and OCT increased sensitivity to 89% in ON and 44% in non-ON eyes. Considering all eyes, global retinal nerve fibre layer (RNFL) thickness and VEP score were significantly correlated between them (ρ=-0.63, p<0.001) and with EDSS (RNFL: ρ=0.40, p<0.001; VEP score: ρ=0.47, p<0.001). Disease duration correlated with VEP score (ρ=0.25, p=0.025) and RNFL thickness (ρ=-0.71, p<0.001).

CONCLUSIONS

In eyes without ON, VEPs were more frequently abnormal than OCT, while the two techniques showed similar sensitivity in eyes previously affected by ON. The correlation of VEPs and OCT measures with disability prompts further exploration of the two techniques as potential markers of disease burden.

Relationship between Structural and Functional Assessment of the Visual System in Mildly Disabled Relapsing-Remitting Multiple Sclerosis Patients

Studies that explored the anterior visual pathway in the patients with multiple sclerosis (MS) have demonstrated contradictory results about the correlation between structural and functional status of optic nerve and retina. We aimed to investigate the functional and structural findings in our cohort of mildly disabled relapsing-remitting MS patients. A total of 134 eyes (80 eyes of the patients with MS and 54 eyes of the control group) were investigated. Eyes of MS patients were divided into two groups-as eyes with history of optic neuritis (ON group) and without history of optic neuritis (NON group). Ophthalmological investigation including visual evoked potentials, standard automated perimetry, and optical coherence tomography were performed for all participants. Retinal and macular thicknesses were significantly decreased in ON and NON groups compared with controls. Also, visual evoked potential latencies and visual field loss were worse in the both MS groups compared with control group. We did not find any correlation between visual evoked potentials and retinal or macular thickness values but visual field parameters were correlated between retinal and macular layer loss in the NON group. According to our results and some previous studies, although both functional and structural changes were detected in patients with MS, functional status markers do not always show parallelism (or synchrony) with structural changes, especially in eyes with history of optic neuritis.

Electropysiologic evaluation of the visual pathway in patients with multiple sclerosis

PURPOSE

To evaluate the ability of visual evoked potentials and pattern electroretinograms (PERG) to detect subclinical axonal damage in patients during the early diagnostic stage of multiple sclerosis (MS). The authors also compared the ability of optical coherence tomography (OCT), PERG, and visual evoked potentials to detect axonal loss in MS patients and correlated the functional and structural properties of the retinal nerve fiber layer.

METHODS

Two hundred twenty-eight eyes of 114 subjects (57 MS patients and 57 age- and sex-matched healthy controls) were included. The visual pathway was evaluated based on functional and structural assessments. All patients underwent a complete ophthalmic examination that included assessment of visual acuity, ocular motility, intraocular pressure, visual field, papillary morphology, OCT, visual evoked potentials, and PERG.

RESULTS

Visual evoked potentials (P100 latency and amplitude), PERG (N95 amplitude and N95/P50 ratio), and OCT parameters differed significantly between MS patients and healthy subjects. Moderate significant correlations were found between visual evoked potentials or PERG parameters and OCT measurements.

CONCLUSIONS

Axonal damage in ganglion cells of the visual pathway can be detected based on structural measures provided by OCT in MS patients and by the N95 component and N95/P50 index of PERG, thus providing good correlation between function and structure.

Evaluation of changes in retinal nerve fiber layer thickness and visual functions in cases of optic neuritis and multiple sclerosis

CONTEXT

Retinal nerve fiber layer (RNFL) thinning has been demonstrated in cases of optic neuritis (ON) and multiple sclerosis (MS) in Caucasian eyes, but no definite RNFL loss pattern or association with visual functions is known in Indian eyes.

AIM

To evaluate RNFL thickness in cases of ON and MS, and to correlate it with visual function changes in Indian patients.

SETTINGS AND DESIGN

Cross-sectional case-control study at a tertiary level institution.

MATERIALS AND METHODS

Cases consisted of patients of (i) typical ON without a recent episode (n = 30:39 ON eyes and 21 fellow eyes), (ii) MS without ON (n = 15;30 eyes) while the controls were age-matched (n = 15; 30 eyes). RNFL thickness was measured using the Stratus 3 °CT. The visual functions tested included the best-corrected visual acuity (BCVA), contrast sensitivity, stereopsis, visual evoked responses, and visual fields.

STATISTICAL ANALYSIS USED

Intergroup analysis was done using ANOVA and Pearson's correlation coefficient used for associations.

RESULTS

RNFL thickness was reduced significantly in the ON and MS patients compared to the controls (P-0.001). Maximum loss is in the temporal quadrant. Lower visual function scores are associated with reduced average overall RNFL thickness. In ON group, RNFL thinning is associated with severe visual field defects while contrast sensitivity has strongest correlation with RNFL in the MS group.

CONCLUSIONS

RNFL thickness is reduced in ON and MS cases in a pattern similar to Caucasians and is associated with the magnitude of impairment of other visual parameters. Contrast sensitivity and stereoacuity are useful tests to identify subclinical optic nerve involvement in multiple sclerosis.

Optical coherence tomography in Susac's syndrome

Susac's syndrome is an autoimmune endotheliopathy with predilection for brain, retina and cochlea (Susac, 1994). Optical coherence tomography (OCT) is a non-invasive method, which is increasingly used in the diagnosis of retinal as well as primary central nervous system diseases. OCT is suggested as a useful diagnostic tool in differentiating Susac's syndrome from multiple sclerosis (MS) (Brandt et al., 2012). This report demonstrates the OCT findings in 3 patients with Susac's syndrome in different stages of the disease. The OCT demonstrated decreased retinal nerve fiber layer (RNFL) thickness, which was patchy in nature and more prominent in the nasal quadrants. We also observed loss of the normal foveal contour, which is uncharacteristic for MS. The extent and degree of the OCT abnormalities in our patients correlated with the stage and severity of the disease and correlated with the findings on the visual field studies. We confirm that OCT is a useful diagnostic tool in Susac's syndrome and helps to differentiate it from MS. Furthermore, OCT may be a non-invasive alternative to fluorescein angiography in longitudinal follow up of these patients.

Quantitative 3-T diffusion tensor imaging in detecting optic nerve degeneration in patients with glaucoma: association with retinal nerve fiber layer thickness and clinical severity

INTRODUCTION

To investigate the association of quantitative 3-T diffusion tensor imaging (DTI) with retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and clinical severity in detecting optic nerve degeneration in patients with primary closed-angle glaucoma.

METHODS

Twenty three patients (42 eyes; 9 men, 14 women) with primary closed-angle glaucoma and 20 healthy controls were enrolled in this study. Both DTI and OCT were performed on the optic nerves of all subjects. The mean diffusivity (MD), fractional anisotropy (FA), and eigenvalue maps were obtained for quantitative analysis. RNFL thickness and quantitative electrophysiology were also performed on all subjects. The association of quantitative DTI with RNFL thickness and glaucoma stage was analyzed.

RESULTS

Compared with control nerves, the FA, λ[parallel], and λ[perpendicular] values, and RNFL thickness in affected nerves decreased, while MD increased in patients with primary glaucoma (p < 0.05). There was a significant correlation between FA, MD, λ[parallel], and λ[perpendicular] and the mean RNFL thickness (P < 0.01). The mean FA and λ[perpendicular] values derived with DT MR imaging correlated well with glaucoma stage (P < 0.05), but the mean MD and λ[parallel] values did not correlate with glaucoma stage (P > 0.05).

CONCLUSION

DTI measurement could detect abnormality of the optic nerve in patients with glaucoma and may serve as a biomarker of disease severity.

Interpretation of RNFLT values in multiple sclerosis-associated acute optic neuritis using high-resolution SD-OCT device

PURPOSE

Optical coherence tomography (OCT) has emerged as the technique of choice in measuring the retinal nerve fibre layer (RNFL) quantitatively. It is suggested that RNFL reduction may correlate with lesion burden and diffuse axonal degeneration in the whole CNS of patients with multiple sclerosis (MS). However, RNFL changes because of optic neuritis (ON) must be taken into account.

METHODS

Twenty-three patients with acute ON (46 eyes) associated with clinical definite MS (23 ON eyes, 23 fellow eyes) and 23 sex- and age-matched healthy controls were studied. Retinal nerve fibre layer thickness (RNFLT) was measured at baseline, using a high-resolution spectral domain OCT (SD-OCT) applying circular, peripapillary OCT scans with a novel eye-tracking mechanism.

RESULTS

The internal OCT software was able to identify RNFL atrophy in three out of five of the acute ON eyes and one out of four of the fellow eyes with previous ON episodes. Retinal nerve fibre layer thickness of two ON (8.7%) and five fellow eyes (21.7%) was overestimated, thus located within the 95% and 5% confidence interval of the company standard values (not marked pathologic). In contrast, our comparison with age- and sex-matched controls revealed RNFL atrophy suggestive of prior, clinically silent RNFL loss in ON and fellow eyes (30.4%).

CONCLUSION

Retinal nerve fibre layer thickness measurements at a single time-point seem to have a limited role in detecting prior clinically silent optic nerve injury. Our data suggest that affected eyes should be compared with the fellow eyes and a sufficient number of age- and sex-matched controls to allow the detection of even subtle RNFL changes at baseline. The role of OCT for disease monitoring of MS must be evaluated in detail, as ON is often the initial symptom of MS.

Retinal damage in multiple sclerosis disease subtypes measured by high-resolution optical coherence tomography

Background. Optical coherence tomography (OCT) has facilitated characterisation of retinal alterations in MS patients. Only scarce and in part conflicting data exists on different MS subtypes. Objective. To analyse patterns of retinal changes in different subtypes of MS with latest spectral-domain technology. Methods. In a three-centre cross-sectional study 414 MS patients and 94 healthy controls underwent spectral-domain OCT examination. Results. Eyes of MS patients without a previous optic neuritis showed a significant reduction of both retinal nerve fibre layer (RNFL) thickness and total macular volume (TMV) compared to healthy controls independent of the MS subtype (P < 0.001 for all subtypes). RNFL thickness was lower in secondary progressive MS (SPMS) eyes compared to relapsing-remitting MS (RRMS) eyes (P = 0.007), and TMV was reduced in SPMS and primary progressive MS (PPMS) eyes compared to RRMS eyes (SPMS: P = 0.039, PPMS: P = 0.005). Independent of the subtype a more pronounced RNFL thinning and TMV reduction were found in eyes with a previous optic neuritis compared to unaffected eyes. Conclusion. Analysis of this large-scale cross-sectional dataset of MS patients studied with spectral-domain OCT confirmed and allows to generalize previous findings. Furthermore it carves out distinct patterns in different MS subtypes.

Recent advances in optic neuritis related to multiple sclerosis

More advanced methods of detecting and quantifying optic neuritis (ON) in multiple sclerosis have been developed in the past 15 years. This review focuses on developments in optical coherence tomography (OCT) measurement of the retinal nerve fibre layer (RNFL) and its role in monitoring axonal loss in the course of the disease. New clinical trial methods of measuring visual acuity (VA) include high-contrast VA testing with Early Treatment Diabetic Retinopathy Study charts, low-contrast letter acuity and contrast sensitivity testing. Multi-focal visual evoked potentials have been used to detect early, subtle visual impairment in ON and early recovery of visual function. New technical developments in OCT may help advance our knowledge in studying the relationship between optic nerve/retinal atrophy and brain atrophy in clinically isolated syndrome (CIS), relapsing remitting multiple sclerosis, secondary progressive multiple sclerosis and primary progressive multiple sclerosis. The treatment of CIS patients is still debatable.

Early diagnosis, monitoring, and treatment of optic neuritis

BACKGROUND

About half of multiple sclerosis patients present with optic neuritis (ON) as a clinically isolated syndrome (CIS). In the Optic Neuritis Treatment Trial study, 28% of patients with ON and an abnormal brain magnetic resonance imaging (MRI) did not have a relapse at the end of 15 years. It is still difficult to predict which CIS patients will go on to develop clinically definite multiple sclerosis and which will have a benign course.

REVIEW SUMMARY

This review focuses on more advanced methods of detecting and quantifying ON in multiple sclerosis that have been developed in the past 15 years, especially on recent developments in optical coherence tomography measurement of the retinal nerve fiber layer and its role in monitoring axonal loss in the course of the disease. New clinical trial methods of measuring visual acuity include high-contrast visual acuity testing with the Early Treatment Diabetic Retinopathy Study charts, low-contrast letter acuity, and contrast sensitivity testing. More advanced neuroimaging techniques include magnetization transfer imaging and diffusion tensor imaging to quantify visual pathway lesions. Other tests of visual function, such as multifocal visual-evoked potentials and functional MRI, have been shown to be more sensitive than conventional visual-evoked potentials or MRI in detecting early, subtle visual impairment in ON and early recovery of visual function related to cortical plasticity. Newer agents are currently being investigated for CIS in ongoing clinical trials.

CONCLUSIONS

Better methods are being developed for the earlier diagnosis, monitoring, and treatment of ON. In the future, CIS patients may be stratified according to their risk of development of clinically definite multiple sclerosis and therefore, receive the appropriate treatment.

Clinically isolated syndromes suggestive of multiple sclerosis: an optical coherence tomography study

BACKGROUND

Optical coherence tomography (OCT) is a simple, high-resolution technique to quantify the thickness of retinal nerve fiber layer (RNFL), which provides an indirect measurement of axonal damage in multiple sclerosis (MS). This study aimed to evaluate RNFL thickness in patients at presentation with clinically isolated syndromes (CIS) suggestive of MS.

METHODOLOGY

This was a cross-sectional study. Twenty-four patients with CIS suggestive of MS (8 optic neuritis [ON], 6 spinal cord syndromes, 5 brainstem symptoms and 5 with sensory and other syndromes) were prospectively studied. The main outcome evaluated was RNFL thickness at CIS onset. Secondary objectives were to study the relationship between RNFL thickness and MRI criteria for disease dissemination in space (DIS) as well as the presence of oligoclonal bands in the cerebrospinal fluid.

PRINCIPAL FINDINGS

Thirteen patients had decreased RNFL thickness in at least one quadrant. Mean RNFL thickness was 101.67±10.72 µm in retrobulbar ON eyes and 96.93±10.54 in unaffected eyes. Three of the 6 patients with myelitis had at least one abnormal quadrant in one of the two eyes. Eight CIS patients fulfilled DIS MRI criteria. The presence of at least one quadrant of an optic nerve with a RNFL thickness at a P<5% cut-off value had a sensitivity of 75% and a specificity of 56% for predicting DIS MRI.

CONCLUSIONS

The findings from this study show that axonal damage measured by OCT is present in any type of CIS; even in myelitis forms, not only in ON as seen up to now. OCT can detect axonal damage in very early stages of disease and seems to have high sensitivity and moderate specificity for predicting DIS MRI. Studies with prospective long-term follow-up would be needed to establish the prognostic value of baseline OCT findings.

Degeneration of retinal layers in multiple sclerosis subtypes quantified by optical coherence tomography

BACKGROUND

Optical coherence tomography can be used to assess retinal degeneration in multiple sclerosis (MS). Thinning of the retinal nerve fibre layer and macular thickness have been well characterized, but newer devices allow quantification of all retinal layers.

OBJECTIVES

The objective of this study was to evaluate the thickness of the paramacular retina, peripapillary retinal nerve fibre layer, and deeper paramacular layers in MS patient subgroups, using state-of-the-art optical coherence tomography.

METHODS

Using a Heidelberg Engineering Spectralis device, we performed paramacular volumetric retinal scans and circular peripapillary fibre-layer scans, manually segmenting different retinal layers into single horizontal foveal scans in 95 patients with definite MS (42 relapsing-remitting, 41 secondary progressive, 12 primary progressive), plus 91 age- and sex-matched controls.

RESULTS

Even without a history of optic neuritis, all MS subgroups had significant thinning of the peripapillary retinal nerve fibre layer, the paramacular retinal thickness and the retinal ganglion cell- and inner plexiform layer. Only in primary progressive MS was the inner nuclear layer significantly reduced.

CONCLUSIONS

Our findings indicate a primary retinal pathology involving the inner nuclear layer in primary progressive MS. Results in eyes without history of optic neuritis suggest possible subclinical episodes of optic neuritis or retrograde trans-synaptic degeneration of retinal ganglion cells and their axons.