Optical coherence tomography as a biomarker in multiple sclerosis

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Early Diagnosis of Multiple Sclerosis Using Swept-Source Optical Coherence Tomography and Convolutional Neural Networks Trained with Data Augmentation

BACKGROUND

The aim of this paper is to implement a system to facilitate the diagnosis of multiple sclerosis (MS) in its initial stages. It does so using a convolutional neural network (CNN) to classify images captured with swept-source optical coherence tomography (SS-OCT).

METHODS

SS-OCT images from 48 control subjects and 48 recently diagnosed MS patients have been used. These images show the thicknesses (45 × 60 points) of the following structures: complete retina, retinal nerve fiber layer, two ganglion cell layers (GCL+, GCL++) and choroid. The Cohen distance is used to identify the structures and the regions within them with greatest discriminant capacity. The original database of OCT images is augmented by a deep convolutional generative adversarial network to expand the CNN's training set.

RESULTS

The retinal structures with greatest discriminant capacity are the GCL++ (44.99% of image points), complete retina (26.71%) and GCL+ (22.93%). Thresholding these images and using them as inputs to a CNN comprising two convolution modules and one classification module obtains sensitivity = specificity = 1.0.

CONCLUSIONS

Feature pre-selection and the use of a convolutional neural network may be a promising, nonharmful, low-cost, easy-to-perform and effective means of assisting the early diagnosis of MS based on SS-OCT thickness data.

Retinal thickness as a marker of disease progression in longitudinal observation of patients with Wolfram syndrome

AIMS

Wolfram syndrome (WFS) is a recessively inherited monogenic form of diabetes coexisting with optic atrophy and neurodegenerative disorders with no currently recognized markers of disease progression. The aim of the study was to evaluate retinal parameters by using optical coherence tomography (OCT) in WFS patients after 2 years of follow-up and analysis of the parameters in relation to visual acuity.

METHODS

OCT parameters and visual acuity were measured in 12 WFS patients and 31 individuals with type 1 diabetes.

RESULTS

Total thickness of the retinal nerve fiber layer (RNFL), average retinal thickness and total retinal volume decreased in comparison with previous OCT examination. Significant decreases were noted for RNFL (average difference -17.92 µm 95% CI -30.74 to -0.10; p = 0.0157), macular average thickness (average difference -5.38 µm 95% CI -10.63 to -2.36; p = 0.0067) and total retinal volume (average difference -0.15 mm³ 95% CI -0.30 to -0.07; p = 0.0070). Central thickness remained unchanged (average difference 1.5 µm 95% CI -7.61 to 10.61; p = 0.71). Visual acuity of WFS patients showed a strong negative correlation with diabetes duration (R = -0.82; p = 0.0010). After division of WFS patients into two groups (with low-vision and blind patients), all OCT parameters except for the RNFL value were lower in blind WFS patients.

CONCLUSIONS

OCT measures structural parameters and can precede visual acuity loss. The OCT study in WFS patients should be performed longitudinally, and serial retinal examinations may be helpful as a potential end point for future clinical trials.

Assessment of the retinal nerve fiber layer in individuals with obstructive sleep apnea

Background

The effect of obstructive sleep apnea (OSA) syndrome in the peripapillary retinal nerve fiber layer (RNFL) thicknesses remains unclear. The purpose of this study was to assess RNFL measurements acquired using scanning laser polarimetry (SLP) and optical coherence tomography (OCT) in patients with OSA.

Methods

The sample of this cross-sectional study included 40 OSA patients and 45 age-matched controls, consecutively and prospectively selected. All participants underwent at least one reliable standard automated perimetry (SAP) test, while RNFL measurements were obtained using the SLP and OCT. The OSA group was divided into 3 sub-groups based on the apnea/hypopnea index (AHI): mild, moderate, or severe OSA. SAP, SLP, and OCT outcomes were compared between the control and OSA groups. The relationship between AHI and RNFL parameters was also evaluated.

Results

Age was not different between both groups. Mean deviation of SAP was −0.47 ± 0.9 dB and −1.43 ± 2.3 dB in the control and OSA groups, respectively (p = 0.01). RNFL thickness measured with OCT was similar between groups. OSA patients showed increased nerve fiber indicator (NFI; 20.9 ± 7.9 versus 16.42 ± 7.82; p = 0.01) and decreased superior average (59.74 ± 10.35 versus 63.73 ± 6.58; p = 0.03) obtained with SLP compared with healthy individuals. In the total sample, NFI and AHI were moderately correlated (r = 0.358; p = 0.001). In severe OSA subjects (n = 22), NFI and AHI had a Spearman correlation coefficient of 0.44 (p = 0.04).

Conclusion

RNFL thickness measured with OCT did not differ significantly between groups. Severe OSA was related to a reduction of the RNFL thickness assessed by SLP.

CROP - The Clinico-Radiologico-Ophthalmological Paradox in Multiple Sclerosis: Are Patterns of Retinal and MRI Changes Heterogeneous and Thus Not Predictable?

BACKGROUND

To date, no direct scientific evidence has been found linking tissue changes in multiple sclerosis (MS) patients, such as demyelination, axonal destruction or gliosis, with either steady progression and/or stepwise accumulation of focal CNS lesions. Tissue changes such as reduction of the retinal nerve fiber layer (RNFL) and the total macular volume (TMV), or brain- and spinal cord atrophy indicates an irreversible stage of tissue destruction. Whether these changes are found in all MS patients, and if there is a correlation with clinical disease state, remains controversial. The objective of our study was to determine, whether there was any correlation between the RNFL or TMV of patients with MS, and: (1) the lesion load along the visual pathways, (2) the ratios and absolute concentrations of metabolites in the normal-appearing white matter (NAWM), (3) standard brain atrophy indices, (4) disease activity or (5) disease duration.

METHODS

28 MS patients (RRMS, n = 23; secondary progressive MS (SPMS), n = 5) with moderately-high disease activity or long disease course were included in the study. We utilised: (1) magnetic resonance imaging (MRI) and (2) -spectroscopy (MRS), both operating at 3 Tesla, and (3) high-resolution spectral domain-OCT with locked reference images and eye tracking mode) to undertake the study.

RESULTS

There was no consistency in the pattern of CNS metabolites, brain atrophy indices and the RNFL/TMV between individuals, which ranged from normal to markedly-reduced levels. Furthermore, there was no strict correlation between CNS metabolites, lesions along the visual pathways, atrophy indices, RNFL, TMV, disease duration or disability.

CONCLUSIONS

Based on the findings of this study, we recommend that the concept of 'clinico-radiologico paradox' in multiple sclerosis be extended to CROP-'clinico-radiologico-ophthalmological paradox'. Furthermore, OCT data of MS patients should be interpreted with caution.

Retinal nerve fiber layer sector-specific compromise in relapsing and remitting multiple sclerosis

Objective

To evaluate quadrant and sector retinal nerve fiber layer (RNFL) thickness and total macular volume (TMV) in relapsing–remitting multiple sclerosis (RR-MS) patients.

Methods

Optical coherence tomography measures of RNFL and TMV were studied in 321 eyes without prior optic neuritis (ON) (MS unaffected), 151 eyes with prior ON (MS affected), and 148 healthy control eyes.

Results

Mean RNFL thickness was significantly lower in the MS affected and MS unaffected groups relative to the control group (p < 0.0001). RNFL thicknesses in the superior, inferior, and temporal quadrants were significantly reduced in MS unaffected (113 ± 15 μm, 119 ± 17 μm, 63 ± 13 μm) (p < 0.001) and MS affected groups (99 ± 19 μm, 103 ± 21 μm, 51 ± 13 μm) (p < 0.0001) compared with that in controls (120 ± 14 μm, 128 ± 15 μm, 69 ± 8 μm, respectively). TMV was significantly reduced in both the MS affected and MS unaffected groups compared with that in the controls (p < 0.0001).

Conclusion

Quadrant, sector, and PMB RNFL thicknesses are significant individual measures in RR-MS for both affected and unaffected eyes and may prove valuable in future investigations including biomarker and outcomes research.

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We detailed RNFL quadrant and sector segmentation analysis in multiple sclerosis.

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RNFL sector thicknesses were lower in 2 affected eyes relative to 1 affected eye.

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PMB thickness distinguishes MS affected and MS unaffected groups from controls.

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TMV thickness distinguishes MS affected and MS unaffected groups from controls.

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EDSS correlated with RNFL for unaffected group and TMV for affected group.

Association of vitamin D deficiency with RNFL thickness in MS individuals without history of optic neuritis

Vitamin D deficiency has been associated with both increased risk and severity of Multiple Sclerosis (MS) as it has a modulating effect on the immune process that causes inflammation/demyelination and axonal damage. Optical Coherence Tomography (OCT) offers a quick, reliable and non-invasive way to assess the Retinal Nerve Fiber Layer (RNFL) and identifies axonal loss generated by either direct inflammation or from neurodegeneration.

OBJECTIVE

To determine the association of vitamin D and RNFL in MS patients without a history of Optic Neuritis (ON) by comparing RNFL thickness in patients that are vitamin D deficient with those having normal serum levels.

METHOD

The cohort of 76 MS patients underwent OCT testing to assess the RNFL thickness and macular volume, and measurement of serum 25-OH Vitamin D level. Vitamin D deficiency was defined as <30ng/ml and sufficiency as ≥30ng/ml.

RESULTS

A total of 131 eyes were divided in two groups: vitamin D deficient (n=86 eyes, mean=17.7ng/ml) and vitamin D sufficient (n=45 eyes, mean=40.3ng/ml). Twenty one eyes had previous ON and were excluded from this analysis. Vitamin D deficiency was identified in 66% of the participants. RNFL thickness was similar for the vitamin D deficient and sufficient groups (85.5 vs 86μm respectively, p=0.89). Significant differences were present for age with the deficient group being younger (42 years vs 51 years, p=0.005) and having shorter disease duration (7.5 years vs 11.4 years, p=0.006).

CONCLUSION

Vitamin D deficiency is not associated with thinning of RNFL or macular volume in MS eyes unaffected by ON. This finding suggests the role of vitamin D in modulating the severity of MS is not exerted through an influence on neurodegeneration.

Evaluation of Retinal Nerve Fiber Layer in Patients with Idiopathic Optic Perineuritis using Optical Coherence Tomography

The aim of this study was to assess the effect of idiopathic Optic perineuritis on the retinal nerve fiber layer, and determine the ability of optical coherence tomography to evaluate retinal nerve fiber loss after idiopathic Optic perineuritis. Four patients were assessed in this study. In all cases, average retinal nerve fiber layer was significantly thinner in the affected eye in comparison with the normal reference value and with the value for the contralateral normal eye at 12 months after the onset of optic perineuritis. Our study revealed that retinal nerve fiber layer loss occurs in idiopathic optic nerve sheath inflammation.

There is still a role for the blink reflex in the diagnosis and follow-up of multiple sclerosis

OBJECTIVE

The evolution of the diagnostic criteria for multiple sclerosis (MS) has essentially evolved to clinical manifestations and magnetic resonance imaging. Inexpensive, quick to apply, non-invasive, quantitative and reliable neurophysiological tests are rare in daily practice and absent in clinical trials.

METHOD

The blink reflex was assessed in 50 patients with remitting-relapsing MS (RRMS) and 100 matched controls.

RESULTS

Patients with RRMS had abnormalities in the blink reflex waves in relation to controls. If only RRMS patients were considered, these abnormalities were more pronounced in patients with longer disease duration, higher disability and for those with clinical or image lesions in the brainstem.

CONCLUSION

Neurophysiological tests, such as the blink reflex, can be used for helping the diagnosis and follow-up of patients with RRMS, since the reflex can identify dissemination in time and in space in a clear and quantitative manner.

SIGNIFICANCE

Potential good methods for diagnosis and follow-up of MS should be considered for clinical trials and daily practice.

Evaluation of optic nerve development in preterm and term infants using handheld spectral-domain optical coherence tomography

PURPOSE

To evaluate effects of prematurity on early optic nerve (ON) development and the usefulness of ON parameters as indicators of central nervous system (CNS) development and pathology.

DESIGN

Prospective, cross-sectional, longitudinal study.

PARTICIPANTS

Forty-four preterm infants undergoing retinopathy of prematurity (ROP) screening and 52 term infants.

METHODS

We analyzed ON from portable handheld spectral-domain optical coherence tomography (SD-OCT) images (Bioptigen, Inc, Research Triangle Park, NC) of 44 preterm and 52 term infants. The highest-quality ON scan from either eye was selected for quantitative analysis. Longitudinal analysis was performed at 31-36 weeks and 37-42 weeks postmenstrual age (PMA). Preterm ON parameters also were assessed for correlation with indicators of cognitive, language, and motor development and CNS pathology.

MAIN OUTCOME MEASURES

Vertical cup diameter (vCD), vertical disc diameter (vDD), vertical cup-to-disc ratio (vCDR), cup depth, and indicators of neurocognitive development and CNS pathology.

RESULTS

At 37-42 weeks PMA, preterm infants had larger vCD and vCDR than term infants (908 vs. 700 μm [P<0.001] and 0.68 vs. 0.53 μm [P<0.001], respectively), whereas cup depth and vDD were not significantly different. Longitudinal changes (n = 26 preterm eyes; mean interval, 4.7 weeks) in vDD and in vCDR were an increase of 74 μm (P = 0.008) and decrease of 0.05 (P = 0.015), respectively. In preterm infants (n = 44), periventricular leukomalacia was associated with larger vCD (1084 vs. 828 μm; P = 0.005) and vCDR (0.85 vs. 0.63; P<0.001), posthemorrhagic hydrocephalus was associated with shallower cup (331 vs. 456 μm; P = 0.030), and clinical magnetic resonance imaging was associated with larger vCDR (0.73 vs. 0.64; P = 0.023). In 23 preterm infants with Bayley Scales of Infant Development scores, larger vCDR was associated with lower cognitive scores (P = 0.049).

CONCLUSIONS

This is the first analysis of ON parameters in premature infants using SD-OCT. It demonstrated that by age of term birth, vCD and vCDR are larger in preterm infants who were screened for ROP than in term infants. In this prospective pilot study, ON parameters in these preterm infants associate weakly with CNS pathology and future cognitive development. Future prospective studies with larger numbers are necessary before further conclusions can be made.

Retinal layer segmentation in patients with multiple sclerosis using spectral domain optical coherence tomography

PURPOSE

To evaluate the thickness of the 10 retinal layers in the paramacular area of patients with multiple sclerosis (MS) compared with healthy subjects using the new segmentation technology of spectral domain optical coherence tomography (OCT). To examine which layer has better sensitivity for detecting neurodegeneration in patients with MS.

DESIGN

Observational, cross-sectional study.

PARTICIPANTS

Patients with MS (n = 204) and age-matched healthy subjects (n = 138).

METHODS

The Spectralis OCT system (Heidelberg Engineering, Inc., Heidelberg, Germany) was used to obtain automated segmentation of all retinal layers in a parafoveal scan in 1 randomly selected eye of each participant, using the new segmentation application prototype.

MAIN OUTCOME MEASURES

The thicknesses of 512 parafoveal points in the 10 retinal layers were obtained in each eye, and the mean thickness of each layer was calculated and compared between patients with MS and healthy subjects. The analysis was repeated, comparing patients with MS with and without previous optic neuritis. Correlation analysis was performed to evaluate the association between each retinal layer mean thickness, duration of disease, and functional disability in patients with MS. A logistic regression analysis was performed to determine which layer provided better sensitivity for detecting neurodegeneration in patients with MS.

RESULTS

All retinal layers, except the inner limiting membrane, were thinner in patients with MS compared with healthy subjects (P < 0.05). Greater effects were observed in the inner retinal layers (nerve fiber, ganglion cells, inner plexiform, and inner nuclear layers) of eyes with previous optic neuritis (P < 0.05). The retinal nerve fiber layer and ganglion cell layer thicknesses were inversely correlated with the functional disability score in patients with MS. The ganglion cell layer and inner plexiform layer thicknesses could predict axonal damage in patients with MS.

CONCLUSIONS

Analysis based on the segmentation technology of the Spectralis OCT revealed retinal layer atrophy in patients with MS, especially of the inner layers. Reduction of the ganglion cell and inner plexiform layers predicted greater axonal damage in patients with MS.