[Retinal atrophy using optical coherence tomography (OCT) in 15 patients with multiple sclerosis and comparison with healthy subjects]

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Establishing Optic Nerve Diameter Threshold Sensitive and Specific for Optic Atrophy Diagnosis

PURPOSE

To determine a potential threshold optic nerve diameter (OND) that could reliably differentiate healthy nerves from those affected by optic atrophy (OA) and to determine correlations of OND in OA with retinal nerve fiber layer (RNFL) thickness, visual acuity (VA), and visual field mean deviation (VFMD).

METHODS

This was a retrospective case control study. Magnetic resonance (MR) images were reviewed from individuals with OA aged 18 years or older with vision loss for more than 6 months and an OA diagnosis established by a neuro-ophthalmologist. Individuals without OA who underwent MR imaging of the orbit for other purposes were also collected. OND was measured on coronal T2-weighted images in the midorbital section, 1cm posterior to the optic disc. Measurements of mean RNFL thickness, VA and VFMD were also collected.

RESULTS

In this study 47 OA subjects (63% women, 78 eyes) and 75 normal subjects (42.7% women, 127 eyes) were assessed. Healthy ONDs (mean 2.73 ± 0.24 mm) were significantly greater than OA nerve diameters (mean 1.94 ± 0.32 mm; P < 0.001). A threshold OND of ≤2.3 mm had a sensitivity of 0.92 and a specificity of 0.93 in predicting OA. Mean RNFL (r = 0.05, p = 0.68), VA (r = 0.17, p = 0.14), and VFMD (r = 0.18, p = 0.16) were not significantly associated with OND.

CONCLUSION

ONDs are significantly reduced in patients with OA compared with healthy nerves. A threshold OND of ≤2.3 mm is highly sensitive and specific for a diagnosis of OA. OND was not significantly correlated with RNFL thickness, VA, or VFMD.

Macular volume and fovea thickness as OCT-criteria for multiple sclerosis. Preliminary results

Background. The characteristic optical coherence tomography (OCT) changes in the optic nerve head in patients with multiple sclerosis are known and have been described many times, however, the state of the macular area is described in a small number of publications.The aim: to analyze the changes in the macular area of the retina in patients with multiple sclerosis, to identify the OCT signs pathognomonic for this disease and to trace their changes over time as the disease progresses.Material and methods. In addition to the standard ophthalmological examination, 28 patients (55 eyes) diagnosed with multiple sclerosis underwent OCT of the macular zone to determine the thickness of the fovea and the volume of the macula in the 6 mm zone. The follow-up period was 6–12 years. The endpoints were the primary treatment and the most recent inspection.Results. At the initial examination, the visual acuity was 0.96 ± 0.24 (95% CI: 0.9–1.03), fovea thickness – 253.0 μm (Q1–Q3: 233.0–264.0), macular volume – 5.471 mm3 (Q1–Q3: 5.281–5.625). In 37 cases (67.3 %), the macular volume was below normal. The initial fovea thickness was below normal in 9 cases (16.4 %). At the end of the study, visual acuity did not change statistically (p = 0.824) and amounted to 0.96 ± 0.25 (95% CI: 0.90–1.04). The fi nal thickness of the fovea was 247.5 μm (Q1–Q3: 233.0–260.0), changes are statistically significant (p = 0.02). Number of cases with a thickness below normal in the fi nal study was 11 (20 %), change of frequency of cases was not statistically signifi cant (p = 0.5). The fi nal macular volume was 5.393 mm3 (Q1–Q3: 5.197–5.565), the changes are statistically significant (p = 0.023). The final number of cases with a volume below the norm was 42 (76.4 %), the change in the frequency of cases is close to statistically signifi cant (p = 0.063). At all stages of the study, there was no case of an isolated decrease in the thickness of the fovea without a decrease in the volume of the macula.Conclusion. The decrease in the volume of the macula with time while maintaining the thickness of the fovea within the normal range can be attributed to the pathognomonic OCT signs of multiple sclerosis. This criterion can be used for a comprehensive assessment of the course and therapy of this disease.

Outcome Measures in Clinical Trials for Multiple Sclerosis

Due to the heterogeneous nature of the disease, it is a challenge to capture disease activity of multiple sclerosis (MS) in a reliable and valid way. Therefore, it can be difficult to assess the true efficacy of interventions in clinical trials. In phase III trials in MS, the traditionally used primary clinical outcome measures are the Expanded Disability Status Scale and the relapse rate. Secondary outcome measures in these trials are the number or volume of T2 hyperintense lesions and gadolinium-enhancing T1 lesions on magnetic resonance imaging (MRI) of the brain. These secondary outcome measures are often primary outcome measures in phase II trials in MS. Despite several limitations, the traditional clinical measures are still the mainstay for assessing treatment efficacy. Newer and potentially valuable outcome measures increasingly used or explored in MS trials are, clinically, the MS Functional Composite and patient-reported outcome measures, and on MRI, brain atrophy and the formation of persisting black holes. Several limitations of these measures have been addressed and further improvements will probably be proposed. Major improvements are the coverage of additional functional domains such as cognitive functioning and assessment of the ability to carry out activities of daily living. The development of multidimensional measures is promising because these measures have the potential to cover the full extent of MS activity and progression. In this review, we provide an overview of the historical background and recent developments of outcome measures in MS trials. We discuss the advantages and limitations of various measures, including newer assessments such as optical coherence tomography, biomarkers in body fluids and the concept of 'no evidence of disease activity'.

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.

Challenges to clinical trials in multiple sclerosis: outcome measures in the era of disease-modifying drugs

PURPOSE OF REVIEW

This review summarizes standard and evolving outcome measures in multiple sclerosis (MS) clinical trials.

RECENT FINDINGS

Progress in the development of MS treatments has led to an increasing number of clinical trials and a need for sensitive, timely, and clinically relevant outcome measures. Relapse rate and the Expanded Disability Status Scale remain the standard clinical outcome measures, but the MS Functional Composite continues to gain additional validation as a meaningful outcome measure. The uncertain relationship between MRI outcome measures and clinical disability has been a persistent challenge in MS clinical trials, but there is increasing evidence supporting a correlation between MRI changes and disability in relapsing-remitting MS patients. Additionally, new imaging techniques are being developed to further increase the sensitivity of MRI as a tool in MS clinical trials. Optical coherence tomography is another outcome measure gaining influence in clinical trials. Some of the greatest challenges remain in the subset of primary progressive MS clinical trials in which brain atrophy appears to be the most promising imaging outcome measure, but the optimal clinical measures and study durations are still uncertain.

SUMMARY

Progress in MS clinical trials requires critical evaluation of existing and future outcome measures and their relationships to one another.

RNFL thickness in MS-associated acute optic neuritis using SD-OCT: critical interpretation and limitations

PURPOSE

Axonal loss is considered a key prognostic factor in diagnosing and monitoring the progress of multiple sclerosis (MS). The purpose of our research was to determine whether the measurement of retinal nerve fibre layer thickness (RNFLT) as measured with high-resolution spectral-domain optical coherence tomography (SD-OCT) differs between optic nerve injury following acute optic neuritis (ON) or following unregistered subclinical axonal damage in patients with MS.

METHODS

High-resolution SD-OCT measurements of RNFLT were initially carried out in the acute phase of ON and again after 3 months, in 25 patients with clinical definite MS and 25 sex- and age-matched healthy controls, all at the University Eye Hospital, Vienna.

RESULTS

Conventional OCT-based RNFLT analysis correctly identified all three patients with initial RNFL swelling. However, only two of three acute ON eyes with a history of ON were registered with RNFLT decrease in seven peripapillary sectors (PPs). The remaining have only been revealed using RNFLT symmetry comparison. Two of 22 (9%) first-episode ON eyes were labelled as pathologic. The number and metric RNFL values of pathologically labelled PPs remained unchanged after 3 months. Our age- and sex-match-based measurement model, with patients with MS being plotted individually and towards the fellow eye, identified all acute ON eyes (with a history of prior ON) with RNFLT reduction in 11 PPs. A global RNFL loss was registered in 36.4% (eight of 22 eyes). However, in 72%, or 16 of 22 ON eyes presenting with first episode of acute ON, a segmental RNFL loss was initially registered in 39 PPs upon baseline examination. The number of PPs with identified axonal decrease increased to a total of 48 PPs within the observational period.

CONCLUSIONS

Spectral-domain optical coherence tomography imaging of identical scanning locations, combined with an optimized scan centring around the optic disc, offers the technological potential of detecting prior, subtle, clinically unregistered optic nerve injury within MS individuals. Significant discrepancy in RNFLT to the potential ON eye may be achieved by comparing OCT metrics with the fellow eye and a sufficient number of age and sex-matched controls.

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

Optical coherence tomography (OCT) is a new method that could aid analysis of neurodegeneration in multiple sclerosis (MS) by capturing thinning of the retinal nerve fibre layer (RNFL). Meta-analyses of data for time domain OCT show RNFL thinning of 20.38 microm (95% CI 17.91-22.86, n=2063, p<0.0001) after optic neuritis in MS, and of 7.08 microm (5.52-8.65, n=3154, p<0.0001) in MS without optic neuritis. The estimated RNFL thinning in patients with MS is greater than the extent expected in normal ageing, probably because of retrograde trans-synaptic degeneration and progressive loss of retinal ganglion cells, in addition to the more pronounced thinning caused by optic neuritis if present. RNFL thickness correlates with visual and neurological functioning as well as with paraclinical data. Developments that could improve understanding of the relation between structure and function in MS pathophysiology include spectral or Fourier domain OCT technology, polarisation-sensitive OCT, fluorescence labelling, structural assessment of action-potential propagation, and segmentation algorithms allowing quantitative assessment of retinal layers.

Optical coherence tomography (OCT) in optic neuritis and multiple sclerosis

Optical coherence tomography (OCT) is a non-invasive imaging technique routinely used in ophthalmology to visualize and quantify the layers of the retina. It also provides information on optic nerve head topography, peripapillary retinal nerve fiber layer thickness, and macular volume, which correlate with axonal loss. These measurements are of particular interest in optic neuropathies and in multiple sclerosis, and OCT parameters are now used as endpoints in neurologic clinical trials.