Optical Coherence Tomography Angiography (OCTA) in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Optociliary shunt vessels in multiple sclerosis

BACKGROUND/INTRODUCTION

Optociliary shunt vessels develop as a result of chronic retinal venous obstruction. Optic neuritis has never been reported as a causative influence.

OBJECTIVE

To determine whether optic neuritis predisposes to the development of optociliary shunts in patients with multiple sclerosis.

CASES

This case series follows two patients with multiple sclerosis from August 1st, 2019 to April 24th, 2024, who developed optociliary shunt vessels after attacks of optic neuritis. A 43-year-old female presented with left visual loss and bilateral superior optociliary shunt vessels. Perimetry showed bilateral peripheral visual field loss. Optical coherence tomography showed bilateral retinal thinning and ganglion cell complex loss. Optical coherence tomography angiography showed reduced capillary density bilaterally. We investigated her and eventually diagnosed her with multiple sclerosis. The second, a 49-year-old female, developed right-sided optociliary shunt vessels after an episode of neuroretinitis. Perimetry revealed bilateral central scotomata; optical coherence tomography showed disc and retinal nerve fiber layer edema, and serous retinal detachment; later, ganglion cell complex loss; and reduced capillary density on optical coherence tomography angiography. Neuroimaging revealed demyelination in both, leading to a diagnosis of multiple sclerosis, and therapy was instituted.

CONCLUSIONS

We hypothesize, that demyelinating optic neuritis due to multiple sclerosis causes chronic retinal hypoperfusion, leading to subsequent optociliary shunt development in affected eyes. Our case series reveals that eyes with optic neuritis, both previous episodes and fresh cases, can contribute to sufficient retinal vein hypoperfusion to cause the development of optociliary shunts, which should be reported in the literature.

Associations between the retinal/choroidal microvasculature and carotid plaque in patients with CAD: An OCTA study

Background

To investigate the associations between retinal/choroidal microvasculature and carotid plaque in patients with CAD assessed by optical coherence tomography angiography (OCTA).

Methods

This study included 127 CAD patients with and 79 without carotid plaque. Each patient had both OCTA taken and digitized to determine retinal/choroidal thickness, vessel density and flow area and carotid ultrasound for carotid plaque size and stability measurement. The superficial capillary plexus (SCP), deep capillary plexus (DCP), out retina and choriocapillaris vessel density, out retina and choriocapillaris flow area, and full retina thickness were analyzed in the fovea centered 6 × 6 mm area. The association between OCTA measurements and carotid plaque characteristics in patients with CAD were evaluated.

Results

The duration of hypertension and diabetes mellitus (DM) was significantly longer in CAD patients with carotid plaque than that without (p < 0.001). The mean values for vessel density SCP and DCP (except fovea zone), and choriocapillaris nasal zone were significantly lower in plaque group (p < 0.05). Negative correlations between the carotid plaque width and vessel density SCP and DCP (except fovea zone) (p < 0.05) were also found in this study.

Conclusions

In patients with CAD, carotid plaque, a risk factor and marker of atherosclerosis and stenosis, is significantly and independently associated with retinal and choroidal microvascular changes by OCTA.

OCTA characteristics in non-arteritic central retinal artery occlusion and correlation with visual acuity

AIM

To observe the retinal and choroidal circulations in patients with non-arteritic permanent central retinal artery occlusion (NA-CRAO) via optical coherence tomography angiography (OCTA) and analyze their correlation with visual acuity.

METHODS

Sixty-two eyes with clinically confirmed acute NA-CRAO were included in the study and divided into: A type (mild n=29), B type (moderate n=27) and C type (severe n=6) based on the degree of visual loss, retinal edema, and arterial blood flow delay in fundus fluorescence angiography (FFA). Contralateral healthy eyes were used as the control group. Best-corrected visual acuity (BCVA), slit lamp microscopy, indirect ophthalmoscopy, fundus color photography, OCTA, and FFA were performed. Spearman's correlation analysis was used to determine the correlations between retinal and choroidal vessels and visual acuity.

RESULTS

There were no statistically significant differences in age, gender, and intraocular pressure among the three types and the control group (P>0.05). Vessel density in deep capillary plexus (VD-DCP) significantly decreased (P<0.05) in all three types of NA-CRAO patients compared to the control group. Vessel density in superficial vascular plexus (VD-SVP) significantly decreased (P<0.05) in type A patients and choriocapillaris flow area significantly decreased (P<0.05) in type B and type C patients compared to the control group; while outer retinal flow areas significantly increased in the type A (P<0.05) and decreased in type C patients (P<0.05). The retinal thickness significantly increased in type C group (P<0.05). The VD-SVP at fovea in the type A was significantly lower than both of type B and C. The VD-SVP at nasal parafovea in type A and B was significantly lower than type C (P<0.05). The logMAR BCVA of type A was significantly better than that of type B and C groups (P<0.05). Spearman's correlation analysis showed that the logMAR BCVA was positively correlated with VD-SVP at fovea (r=0.679, P=0.031) and nasal parafovea (r=0.826, P=0.013).

CONCLUSION

OCTA is valuable for assessing retinal ischemia, and evaluating visual impairment. Deep retinal vasculature is commonly affected in all NA-CRAO types. VD-SVPs at fovea and nasal parafovea can serve as reliable markers of visual impairment in NA-CRAO.

New insights in the pathogenic mechanism of multiple sclerosis: Is Epstein-Barr virus associated with optic nerve involvement?

INTRODUCTION

There are no reports in the literature studying the possible relationship between Epstein-Barr virus (EBV) and optic nerve involvement in multiple sclerosis (MS). The aim of our study was to analyze the association between EBV antibodies titres and optical coherence tomography (OCT) and OCT angiography (OCTA) quantitative parameters.

METHODS

We conducted a retrospective study. The study included 98 eyes of 49 patients with MS. Years of MS duration, relapse count, history of optic neuritis (ON), and immunoglobulin (Ig) G antibodies to the EBV viral capsid antigen (VCA) were recorded from each patient. Also, OCT analysis (including retinal nerve fibre layer (RNFL) thickness and ganglion cell-inner plexiform layer (GCIPL) thickness) and OCTA analysis (including perfusion density (PD) and flux index (FI) of the radial peripapillary capillary plexus) were performed in each participant.

RESULTS

No significant associations were observed between anti-EBV antibody levels and OCT or OCTA parameters (p > 0,05). Correlation analysis between OCT and OCTA measurements showed a significant positive correlation between RNFL thickness and GCIPL thickness with peripapillary PD and FI (p < 0,035). Subgroup analysis revealed a significant diminution of RNFL thickness, GCIPL thickness and peripapillary PD and FI (p < 0,05) in the ON group.

CONCLUSION

We were unable to demonstrate a significant association between anti-EBV VCA IgG antibody titres and OCT or OCTA parameters. Nonetheless, further longitudinal studies are needed to explore the possible association of EBV with optic nerve involvement in MS.

Characterizing differences in retinal and choroidal microvasculature and structure in individuals with Huntington's Disease compared to healthy controls: A cross-sectional prospective study

OBJECTIVE

To characterize retinal and choroidal microvascular and structural changes in patients who are gene positive for mutant huntingtin protein (mHtt) with symptoms of Huntington's Disease (HD).

METHODS

This study is a cross-sectional comparison of patients who are gene positive for mHtt and exhibit symptoms of HD, either motor manifest or prodromal (HD group), and cognitively normal individuals without a family history of HD (control group). HD patients were diagnosed by Duke movement disorder neurologists based on the Unified Huntington's Disease Rating Scale (UHDRS). Fovea and optic nerve centered OCT and OCTA images were captured using Zeiss Cirrus HD-5000 with AngioPlex. Outcome metrics included central subfield thickness (CST), peripapillary retinal nerve fiber layer (pRNFL) thickness, ganglion cell-inner plexiform layer (GCIPL) thickness, and choroidal vascularity index (CVI) on OCT, and foveal avascular zone (FAZ) area, vessel density (VD), perfusion density (PD), capillary perfusion density (CPD), and capillary flux index (CFI) on OCTA. Generalized estimating equation (GEE) models were used to account for inter-eye correlation.

RESULTS

Forty-four eyes of 23 patients in the HD group and 77 eyes of 39 patients in the control group were analyzed. Average GCIPL thickness and FAZ area were decreased in the HD group compared to controls (p = 0.001, p < 0.001). No other imaging metrics were significantly different between groups.

CONCLUSIONS

Patients in the HD group had decreased GCIPL thickness and smaller FAZ area, highlighting the potential use of retinal biomarkers in detecting neurodegenerative changes in HD.

Optical Coherence Tomography (OCT): A Brief Look at the Uses and Technological Evolution of Ophthalmology

Medical imaging is the mainstay of clinical diagnosis and management. Optical coherence tomography (OCT) is a non-invasive imaging technology that has revolutionized the field of ophthalmology. Since its introduction, OCT has undergone significant improvements in image quality, speed, and resolution, making it an essential diagnostic tool for various ocular pathologies. OCT has not only improved the diagnosis and management of ocular diseases but has also found applications in other fields of medicine. In this manuscript, we provide a brief overview of the history of OCT, its current uses and diagnostic capabilities to assess the posterior segment of the eye, and the evolution of this technology from time-domain (TD) to spectral-domain (SD) and swept-source (SS). This brief review will also discuss the limitations, advantages, disadvantages, and future perspectives of this technology in the field of ophthalmology.

Evaluation of retinal microvascular network in patients with systemic sclerosis: An optical cohorence tomography angiography study

PURPOSE

To investigate the long-term effect of systemic sclerosis on the optic disk and retinal capillary network and to see whether the drugs used in the treatment of SSc affected optical coherence tomography angiography (OCTA) parameters.

MATERIALS AND METHODS

This cross-sectional case-control study included 40 systemic sclerosis patients and 40 healthy individuals. We included only one eye of each patient in the study. Macular layers and angiography scanning were performed with a Zeiss Cirrus 5000 OCTA system. Such values as macular thickness, retinal nerve fiber layer (RNFL), ganglion cell inner plexiform layer (GC-IPL) were obtained. For central vessel and perfusion density (VD, PD), central 6 mm were obtained and were evaluated by dividing it into 3 groups as inner, outer, and full. The FAZ was evaluated through 3 parameters: area, perimeter, circularity index.

RESULTS

Statistically significant difference was found between the groups in terms of the mean and foveal macular thickness values (p=0.008, p=0.033). Significant differences were also found between the two groups in terms of the VD and PD parameters in all regions except for 1 mm center (p<0.05). There were no significant differences in RNFL and GC-IPL values between two groups. Also, a positive correlation was observed between parapapillary perfusion density values and RNFL and GC-IPL thicknesses in SSc group. When the subgroups were compared in terms of vasodilator drug use, the subgroup using vasodilators was seen to have higher mean RNFL and inferior RNFL thicknesses (p=0.045 and p=0.035, respectively). In addition, there was a significant positive correlation between parapapillary VD and RNFL values in the SSc subgroup treated with vasodilators.

CONCLUSIONS

The results of this study demonstrate microvascular loss in individuals with systemic sclerosis, compared with healthy subjects. Also, it has been determined that OCTA is an important test for screening retinal and optic disk microvascular changes over time in cases of systemic sclerosis and may be used to evaluate the response to vasodilator drugs used in the treatment of SSc disease.

Non-Invasive Evaluation of Retinal Vascular Alterations in a Mouse Model of Optic Neuritis Using Laser Speckle Flowgraphy and Optical Coherence Tomography Angiography

Optic neuritis, a characteristic feature of multiple sclerosis (MS), involves the inflammation of the optic nerve and the degeneration of retinal ganglion cells (RGCs). Although previous studies suggest that retinal blood flow alterations occur during optic neuritis, the precise location, the degree of impairment, and the underlying mechanisms remain unclear. In this study, we utilized two emerging non-invasive imaging techniques, laser speckle flowgraphy (LSFG) and optical coherence tomography angiography (OCTA), to investigate retinal vascular changes in a mouse model of MS, known as experimental autoimmune encephalomyelitis (EAE). We associated these changes with leukostasis, RGC injury, and the overall progression of EAE. LSFG imaging revealed a progressive reduction in retinal blood flow velocity and increased vascular resistance near the optic nerve head in the EAE model, indicating impaired ocular blood flow. OCTA imaging demonstrated significant decreases in vessel density, number of junctions, and total vessel length in the intermediate and deep capillary plexus of the EAE mice. Furthermore, our analysis of leukostasis revealed a significant increase in adherent leukocytes in the retinal vasculature of the EAE mice, suggesting the occurrence of vascular inflammation in the early development of EAE pathology. The abovechanges preceded or were accompanied by the characteristic hallmarks of optic neuritis, such as RGC loss and reduced visual acuity. Overall, our study sheds light on the intricate relationship between retinal vascular alterations and the progression of optic neuritis as well as MS clinical score. It also highlights the potential for the development of image-based biomarkers for the diagnosis and monitoring of optic neuritis as well as MS, particularly in response to emerging treatments.

The Evolvement of OCT and OCT-A in Identifying Multiple Sclerosis Biomarkers

The prevalence of multiple sclerosis (MS) has been increasing among young people in developing countries over the last years. With the continuous development of new technology, the diagnosis and follow-up of these patients has received new parameters that physicians may use in their practice. This paper reviews the main biomarkers identified through Optical Coherence Tomography Angiography (OCT-A) involved in the development and progression of MS and investigates the role it may have in detecting changes to the central nervous system (CNS).

Synthetic OCT-A blood vessel maps using fundus images and generative adversarial networks

Vessel segmentation in fundus images permits understanding retinal diseases and computing image-based biomarkers. However, manual vessel segmentation is a time-consuming process. Optical coherence tomography angiography (OCT-A) allows direct, non-invasive estimation of retinal vessels. Unfortunately, compared to fundus images, OCT-A cameras are more expensive, less portable, and have a reduced field of view. We present an automated strategy relying on generative adversarial networks to create vascular maps from fundus images without training using manual vessel segmentation maps. Further post-processing used for standard en face OCT-A allows obtaining a vessel segmentation map. We compare our approach to state-of-the-art vessel segmentation algorithms trained on manual vessel segmentation maps and vessel segmentations derived from OCT-A. We evaluate them from an automatic vascular segmentation perspective and as vessel density estimators, i.e., the most common imaging biomarker for OCT-A used in studies. Using OCT-A as a training target over manual vessel delineations yields improved vascular maps for the optic disc area and compares to the best-performing vessel segmentation algorithm in the macular region. This technique could reduce the cost and effort incurred when training vessel segmentation algorithms. To incentivize research in this field, we will make the dataset publicly available to the scientific community.

Evaluation of microvascular changes in the retina and choriocapillaris in primary glaucoma and neuromyelitis optica spectrum disorder with optical coherence tomography angiography

BACKGROUND

To assess quantitatively the microvascular changes in the retina and choroid of healthy eyes, eyes of subjects with primary angle-closure glaucoma (PACG), primary open-angle glaucoma (POAG) and neuromyelitis optica spectrum disorder (NMOSD) using optical coherence tomography angiography (OCTA).

METHODS

A series of healthy individuals and subjects with PACG, POAG and NMOSD were recruited in this cross-sectional study. OCTA was performed to capture the optic nerve head and macula images and the vessel density (VD) and retinal nerve fiber layer (RNFL) thickness were quantified. The choriocapillary flow density (CFD) was calculated as the percentage of flow area to the whole selected area.

RESULTS

A total of 68 PACG subjects, 25 POAG subjects, 51 NMOSD subjects and 37 healthy controls were enrolled. Significant decreases in peripapillary VD and RNFL thickness were observed in PACG (p < 0.001) and POAG (p < 0.001) eyes and also in NMOSD subjects with an optic neuritis history (p < 0.001) compared with healthy controls. Unaffected eyes in PACG and POAG subjects had lower baseline peripapillary VD than healthy controls (p = 0.002 and p = 0.011, respectively). PACG eyes showed a lower baseline CFD than POAG (p = 0.0027) and the CFD in early and advanced PACG eyes showed a significantly much more decrease than POAG (p = 0.002 and p < 0.001, respectively).

CONCLUSIONS

The peripapillary vessel density and RNFL thickness was reduced in glaucomatous and NMOSD eyes compared with healthy controls. PACG eyes showed a lower CFD than POAG and the distinct peripapillary and choriocapillaris microvasculature changes may be correlated to different PACG and POAG pathogenesis.

Association of retinal microvascular abnormalities and neuromyelitis optica spectrum disorders with optical coherence tomography angiography

Introduction

Neuromyelitis optica spectrum disorders (NMOSD) are autoimmune central nervous system diseases characterized by the immune system's abnormal attack on glial cells and neurons. Optic neuritis (ON) is one of the indicators of NMOSD, often starting unilaterally and potentially affecting both eyes later in the disease progression, leading to visual impairment. Optical coherence tomography angiography (OCTA) has the potential to aid in the early diagnosis of NMOSD by examining ophthalmic imaging and may offer a window for disease prevention.

Methods

In this study, we collected OCTA images from 22 NMOSD patients (44 images) and 25 healthy individuals (50 images) to investigate retinal microvascular changes in NMOSD. We employed effective retinal microvascular segmentation and foveal avascular zone (FAZ) segmentation techniques to extract key OCTA structures for biomarker analysis. A total of 12 microvascular features were extracted using specifically designed methods based on the segmentation results. The OCTA images of NMOSD patients were classified into two groups: optic neuritis (ON) and non-optic neuritis (non-ON). Each group was compared separately with a healthy control (HC) group.

Results

Statistical analysis revealed that the non-ON group displayed shape changes in the deep layer of the retina, specifically in the FAZ. However, there were no significant microvascular differences between the non-ON group and the HC group. In contrast, the ON group exhibited microvascular degeneration in both superficial and deep retinal layers. Sub-regional analysis revealed that pathological variations predominantly occurred on the side affected by ON, particularly within the internal ring near the FAZ.

Discussion

The findings of this study highlight the potential of OCTA in evaluating retinal microvascular changes associated with NMOSD. The shape alterations observed in the FAZ of the non-ON group suggest localized vascular abnormalities. In the ON group, microvascular degeneration in both superficial and deep retinal layers indicates more extensive vascular damage. Sub-regional analysis further emphasizes the impact of optic neuritis on pathological variations, particularly near the FAZ's internal ring.

Conclusion

This study provides insights into the retinal microvascular changes associated with NMOSD using OCTA imaging. The identified biomarkers and observed alterations may contribute to the early diagnosis and monitoring of NMOSD, potentially offering a time window for intervention and prevention of disease progression.

Utility of the visual system to monitor neurodegeneration in multiple sclerosis

Neurodegeneration occurs early in the multiple sclerosis (MS) disease course and is an important driver of permanent disability. Current immunomodulatory therapies do not directly target neuronal health; thus, there is a critical need to develop neuroprotective strategies in MS. Outcome measures in clinical trials primarily evaluate disease activity and clinical disability scores rather than measures of neurodegeneration. The visual system provides a noninvasive correlate of brain atrophy and neuronal function through structural and functional exams. Furthermore, optic nerve axons and their respective neuronal cell bodies in the retina, in addition to their synaptic input to the thalamus, provide a distinct anatomy to investigate neurodegenerative processes. This review discusses the utility of the visual system as an early output measure of neurodegeneration in MS as well as an important platform to evaluate neuroprotective strategies in preclinical models.

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

BACKGROUND AND OBJECTIVES

Recent literature on multiple sclerosis (MS) demonstrates the growing implementation of optical coherence tomography-angiography (OCT-A) to discover potential qualitative and quantitative changes in the retina and optic nerve. In this review, we analyze OCT-A studies in patients with MS and examine its utility as a surrogate or precursor to changes in central nervous system tissue.

METHODS

PubMed and EMBASE were systematically searched to identify articles that applied OCT-A to evaluate the retinal microvasculature measurements in patients with MS. Quantitative data synthesis was performed on all measurements which were evaluated in at least two unique studies with the same OCT-A devices, software, and study population compared to controls. A fixed-effects or random-effects model was applied for the meta-analysis based on the heterogeneity level.

RESULTS

The study selection process yielded the inclusion of 18 studies with a total of 1552 evaluated eyes in 673 MS-associated optic neuritis (MSON) eyes, 741 MS without optic neuritis (MSNON eyes), and 138 eyes without specification for the presence of optic neuritis (ON) in addition to 1107 healthy control (HC) eyes. Results indicated that MS cases had significantly decreased whole image superficial capillary plexus (SCP) vessel density when compared to healthy control subjects in the analyses conducted on Optovue and Topcon studies (both P < 0.0001). Likewise, the whole image vessel densities of deep capillary plexus (DCP) and radial peripapillary capillary (RPC) were significantly lower in MS cases compared to HC (all P < 0.05). Regarding optic disc area quadrants, MSON eyes had significantly decreased mean RPC vessel density compared to MSNON eyes in all quadrants except for the inferior (all P < 0.05). Results of the analysis of studies that used prototype Axsun machine revealed that MSON and MSNON eyes both had significantly lower ONH flow index compared to HC (both P < 0.0001).

CONCLUSIONS

This systematic review and meta-analysis of the studies reporting OCT-A measurements of people with MS confirmed the tendency of MS eyes to exhibit reduced vessel density in the macular and optic disc areas, mainly in SCP, DCP, and RPC vessel densities.

Evaluation of Retinal Microvascular Features in Patients with Amblyopia Based on Optical Coherence Tomography Angiography: A Systematic Review and Meta-Analysis

BACKGROUND

The performance of optical coherence tomography angiography (OCTA) in macular microvasculature of patients with amblyopia has been widely studied, but these studies have yielded different and controversial results.

OBJECTIVES

The aim of this study is to investigate retinal microvascular features in patients with amblyopia undergoing OCTA.

METHODS

PubMed, Embase, and Web of Science were searched for published articles comparing the retinal microvascular features between individuals with amblyopia and controls until April 2022. The mean difference with a 95% confidence interval was used to assess continuous variables.

RESULTS

The analysis included 17 studies. The whole vessel density of the superficial capillary plexus (SCPVD) was lower in amblyopic eyes (AE) than in normal eyes (NE) in 3 × 3 mm2 scans, while the perifoveal vessel density of superficial and deep capillary plexus was lower in 6 × 6 mm2 scans. The whole, parafoveal vessel density of deep capillary plexus (DCPVD) and parafoveal SCPVD were lower in both scans. The comparison between AE and fellow eyes (FE) revealed no statistical difference in all quadrants except the parafoveal and perifoveal SCPVD and the foveal DCPVD. Additionally, SCPVD in all quadrants except the fovea and DCPVD in all quadrants except the parafoveal were higher in FE compared to NE. No significant difference was found in the foveal avascular area between AE and NE, AE and FE, or NE and FE.

CONCLUSIONS

The retinal vessel density of superficial and deep capillary plexus in AE and FE was lower than in NE, and differences were more likely discovered using 6 × 6 mm2 scans. Consequently, OCTA might be explored as a diagnostic tool to identify and monitor patients with amblyopia.

Microvascular impairments detected by optical coherence tomography angiography in multiple sclerosis patients: A systematic review and meta-analysis

Purpose

A systematic review and meta-analysis was conducted to investigate changes in retinal and choroidal microvasculature in patients with multiple sclerosis (MS) using optical coherence tomography angiography (OCTA).

Methods

PubMed and Google Scholar were searched for studies that compared retinal and choroidal microvasculature between MS and healthy controls (HC) with OCTA. MS patients were divided into 2 groups: MS with (MSON) or without optic neuritis (MSNON).

Results

Totally, 13 studies including 996 MS eyes and 847 HC eyes were included. Compared with the HC, the vessel density of the whole superficial vascular complex (SVC) was reduced by 2.27% and 4.30% in the MSNON and MSON groups, respectively. The peripapillary vessel density was 2.28% lower and 4.96% lower in the MSNON and MSON groups, respectively, than in the HC. Furthermore, the MSON group had significant lower vessel density of the SVC (mean difference [MD] = -2.17%, P < 0.01) and lower peripapillary vessel density (MD = -2.02%, P = 0.02) than the MSNON group. No significant difference was found in the deep vascular complex or choriocapillaris densities among MSNON, MSON or HC groups (P > 0.05). Meta-regression analyses suggested that illness duration and the Expanded Disability Status Scale scores of MS patients were possible sources of heterogeneity (P < 0.05).

Conclusion

The retinal SVC and peripapillary vessel density decreased significantly in MS eyes, especially in eyes with optic neuritis. Retinal microvasculature is a potential biomarker of disease progression in MS.

Comparative study on retinal microvasculature changes between acute and chronic central serous chorioretinopathy

OBJECTIVES

Central serous chorioretinopathy (CSC) is generally a common fundus disease in young and middle-aged Asian men. Acute and chronic CSC can lead to different degrees of injury to the retinal blood flow. This study aims to observe and compare the blood flow density in different retinal capillary layers in patients with acute and chronic CSC using optical coherence tomography angiography (OCTA) technology.

METHODS

Twelve patients with acute CSC and 8 patients with chronic CSC including 12 eyes with acute CSC (acute CSC eye group), 11 eyes with chronic CSC (chronic CSC eye group), and 17 normal eyes (normal eye group) were enrolled in this study. All patients underwent 3 mm×3 mm, 6 mm×6 mm macular OCTA scanning. The retinal microvascu-lature was divided into superficial vascular complexes (SVC), intermediate capillary plexuses (ICP), and deep capillary plexuses (DCP) using the projection resolved-OCTA algorithm. Inner retina includes SVC, ICP, and DCP. The vessel density in each retinal layer and the inner retina were calculated and compared.

RESULTS

Macular OCTA scanning of 3 mm×3 mm showed that there was no significant difference in blood flow density of SVC and ICP among the 3 groups (both P>0.05); blood flow density of DCP and inner retina in the chronic CSC eye group was significantly lower than that in the acute CSC eye group and the normal eye group (all P<0.05); there was no significant difference in retinal blood flow density of different layer between the acute CSC eye group and the normal eye group (all P>0.05). Macular OCTA scanning of 6 mm×6 mm showed that inner retinal blood flow density of the chronic CSC eye group was significantly lower than that of the acute CSC eye group and the normal eye group (both P<0.05); there was no significant difference in blood flow density of SVC among the 3 groups (P>0.05).

CONCLUSIONS

The vessel density of DCP and inner retina in the eyes with chronic CSC are significantly reduced, which may result in impaired visual function. Therefore, we recommend that patients with acute CSC should be properly treated to avoid progressing into chronic CSC.

Peripapillary structural and microvascular alterations in early dysthyroid optic neuropathy

Background

To explore the changes in blood supply and structure around the optic nerve head (ONH) in thyroid-associated ophthalmopathy (TAO) patients with suspected dysthyroid optic neuropathy (DON).

Methods

TAO patients [19 with DON; 24 non-DON (NDON); 20 with equivocal DON (EDON)], and 34 control subjects were examined. Optical coherence tomography angiography (OCTA) was used to obtain peripapillary retinal nerve fiber layer (p-RNFL) and vessel density parameters, including the ONH whole image vessel density (ONH-wiVD) and the radial peripapillary capillary vessel density (RPC-VD) in early DON.

Results

Although there were no differences in p-RNFL thickness among the groups, there were differences in the ONH-wiVD of each grid section and the RPC-VD in all areas (P < 0.01). Compared with healthy controls, the EDON eyes had significantly lower RPC-VDs in all aeras (P < 0.05).The peripapillary region was further divided into eight sectors, and the RPC-VD in the temporal upper, superior temporal, and temporal lower sectors in the EDON group were significantly lower than in the controls. The visual impairment was closely related to the loss of peripapillary capillary vessel density. Univariate correlation analysis showed that the ONH-wiVD and RPC-VD of the TAO groups were negatively correlated with the intraocular pressure (r = − 0.296, P = 0.006; r = − 0.258, P = 0.016 respectively).

Conclusions

EDON patients had significantly lower ONH-wiVD and RPC-VD than control subjects, and the temporal and upper VDs were more likely to be affected in the early stage of TAO. The combined use of spectral domain optical coherence tomography and OCTA technologies offer a new method for early diagnosis of suspected DON patients.

Abnormalities of Retinal Structure and Microvasculature are Associated with Cerebral White Matter Hyperintensities

PURPOSE

While retinal microvasculature represents cerebral small vessels, the retinal nerve fiber layer is the extended white matter of the brain. We aimed to investigate the correlation between changes in retina and white matter hyperintensities (WMH).

METHODS

64 candidates with WMH received the optical coherence tomography angiography (OCTA) examination. WMH were divided into mild or moderate/severe groups according to the Fazekas score. After imaging superficial capillary plexus (SCP) and deep capillary plexus (DCP), we revealed the microvascular density parameters (vascular perfusion density (VPD), vascular length density (VLD), and fovea avascular zone area (FAZ-A)) and morphological parameters (vessel diameter index (VDI), fractal dimension (FD), and vessel tortuosity (VT)). The software algorithm measured the thickness of the peripapillary retina nerve fiber layer (PRNFL).

RESULTS

32 were classified as having mild WMH and 32 were moderate/severe. The Median (interquartile range) ages of the two groups were 58 (54-64) and 61 (57-67) years, respectively. A decrease of FD, VPD and VLD in either SCP or DCP appeared with an increased risk of moderate/severe WMH. Although changes of capillary plexus were not associated with PWMH, decreased FD, VPD, VLD and FAZ-A in either SCP or DCP was associated with an increased risk of moderate/severe DWMH. Participants with moderate/severe WMH demonstrated reduced PRNFL thickness, particularly in the DWMH, compared with mild WMH.

CONCLUSIONS

Abnormalities of retinal microvascular density, morphological parameters, and PRNFL thickness are correlated with the incidence of moderate/severe WMH, particularly the DWMH, suggesting that arteriosclerosis and hypoperfusion are the causes of DWMH.

Optical Coherence Tomography Angiography in Healthy Adult Subjects: Normative Values, Frequency, and Impact of Artifacts

Aim

This cross-sectional study is aimed at identifying normative ocular coherence tomography angiography (OCTA) values in a cohort of healthy adult Jordanian individuals and assessing the prevalence of different image artifacts and their impact on quantitative OCTA measurements.

Materials and Methods

One hundred and eighty-one eyes from 100 healthy participants were included in this study. All participants underwent a comprehensive ophthalmological examination including best corrected visual acuity, slit lamp examination, and dilated fundoscopy. Swept-source OCTA images were obtained and analyzed for all 181 eyes. We recorded vascularity measurements and analyzed the prevalence and effect of ten different artifacts on superficial and deep retinal and choriocapillaris layer images.

Results

Sixty-two percent of the participants were men (n = 62), and 38% (n = 38) were women. The age of participants ranged between 24 and 75 years (mean 50.5 ± 10.92). The mean central macular thickness was 237.71 (±22.905) μm, and the mean choroidal thickness was 257.73 (±77.027) μm. Artifacts were present in 46.4% of the acquired scans. Images with artifacts had higher mean age (p = 0.03), lower image quality (p < 0.001), higher central vascular density (p < 0.001), and lower inferior vascular density (p < 0.001) compared to artifact-free tomographs. Motion artifact was the most common type, which was present in 29 (16%) of images, followed by blink artifact 18 (9.9%), and Z offset 8 (4.4%).

Conclusion

OCTA artifact detection and correction remains a challenging aspect of the diagnostic and follow-up process of patients with retinal pathologies. To our knowledge, this is the first study to examine the association between OCTA outputs and artifacts in healthy eyes. We report that in this cohort of normal individuals, images with artifacts had a significantly higher central vascular density (22.62 vs. 16.60) and a lower inferior vascular density (46.09 vs. 48.81). We also found that a significant increase in central vascular density is only present in images with Z offset artifact type (49.03). Motion artifact was the most common artifact seen in our series. However, we observed no alteration in quantitative parameters in images with motion artifacts.

Retinal imaging biomarkers of neurodegenerative diseases

The timely detection of neurodegenerative diseases is central to improving clinical care as well as enabling the development and deployment of disease-modifying therapies. Retinal imaging is emerging as a method to detect features of a number of neurodegenerative diseases, given the anatomical and functional similarities between the retina and the brain. This review provides an overview of the current status of retinal imaging biomarkers of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Lewy body dementia, frontotemporal dementia, Huntington's disease and multiple sclerosis. Whilst research findings are promising, efforts to harmonise study designs and imaging methods will be important in translating these findings into clinical care. Doing so may mean that eye care providers will play important roles in the detection of a variety of neurodegenerative diseases in future.

Deciphering the Retinal Epigenome during Development, Disease and Reprogramming: Advancements, Challenges and Perspectives

Retinal neurogenesis is driven by concerted actions of transcription factors, some of which are expressed in a continuum and across several cell subtypes throughout development. While seemingly redundant, many factors diversify their regulatory outcome on gene expression, by coordinating variations in chromatin landscapes to drive divergent retinal specification programs. Recent studies have furthered the understanding of the epigenetic contribution to the progression of age-related macular degeneration, a leading cause of blindness in the elderly. The knowledge of the epigenomic mechanisms that control the acquisition and stabilization of retinal cell fates and are evoked upon damage, holds the potential for the treatment of retinal degeneration. Herein, this review presents the state-of-the-art approaches to investigate the retinal epigenome during development, disease, and reprogramming. A pipeline is then reviewed to functionally interrogate the epigenetic and transcriptional networks underlying cell fate specification, relying on a truly unbiased screening of open chromatin states. The related work proposes an inferential model to identify gene regulatory networks, features the first footprinting analysis and the first tentative, systematic query of candidate pioneer factors in the retina ever conducted in any model organism, leading to the identification of previously uncharacterized master regulators of retinal cell identity, such as the nuclear factor I, NFI. This pipeline is virtually applicable to the study of genetic programs and candidate pioneer factors in any developmental context. Finally, challenges and limitations intrinsic to the current next-generation sequencing techniques are discussed, as well as recent advances in super-resolution imaging, enabling spatio-temporal resolution of the genome.

The Value of Optical Coherence Tomography Angiography (OCT-A) in Neurological Diseases

Optical coherence tomography angiography (OCT-A) was commercially introduced in 2014. OCT-A allows a fast, non-invasive, three-dimensional analysis of the retinal vasculature from the vitreoretinal interface to the choriocapillaris. The results can be evaluated separately in automated or custom-defined retinal layers. Since its introduction, OCT-A has also been used in patients with neurological diseases in order to find and characterize retinal biomarkers. Many neurological diseases have retinal manifestations, often preceding the key symptoms of the neurological disease. Anatomically and developmentally, the retina is a part of the brain. In contrast to the brain, the retina is easily accessible for imaging methods; moreover, retinal imaging is more cost-effective than brain imaging. In this review, the current knowledge about OCT-A findings and possible OCT-A biomarkers in neurological diseases is summarized and discussed regarding the value of OCT-A as a diagnostic tool in neurological diseases.

OCT Angiography as an Interdisciplinary Diagnostic Tool for Systemic Diseases

In recent years, OCT angiography (OCT-A) has emerged as a well established imaging modality of the retina. This allows non-invasive visualisation of the retinal circulation at a micrometre scale in eye disorders and systemic diseases with potential ocular involvement. This review summarises the current state of this topic.

Retinal optical coherence tomography and magnetic resonance imaging in neuromyelitis optica spectrum disorders and MOG-antibody associated disorders: an updated review

INTRODUCTION

Neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein IgG antibody-associated disorders (MOGAD) comprise two groups of rare neuroinflammatory diseases that cause attack-related damage to the central nervous system (CNS). Clinical attacks are often characterized by optic neuritis, transverse myelitis, and to a lesser extent, brainstem encephalitis/area postrema syndrome. Retinal optical coherence tomography (OCT) is a non-invasive technique that allows for in vivo thickness quantification of the retinal layers. Apart from OCT, magnetic resonance imaging (MRI) plays an increasingly important role in NMOSD and MOGAD diagnosis based on the current international diagnostic criteria. Retinal OCT and brain/spinal cord/optic nerve MRI can help to distinguish NMOSD and MOGAD from other neuroinflammatory diseases, particularly from multiple sclerosis, and to monitor disease-associated CNS-damage.

AREAS COVERED

This article summarizes the current status of imaging research in NMOSD and MOGAD, and reviews the clinical relevance of OCT, MRI and other relevant imaging techniques for differential diagnosis, screening and monitoring of the disease course.

EXPERT OPINION

Retinal OCT and MRI can visualize and quantify CNS damage in vivo, improving our understanding of NMOSD and MOGAD pathology. Further efforts on the standardization of these imaging techniques are essential for implementation into clinical practice and as outcome parameters in clinical trials.

Artificial intelligence extension of the OSCAR-IB criteria

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

Optical coherence tomography angiography helps distinguish multiple sclerosis from AQP4-IgG-seropositive neuromyelitis optica spectrum disorder

INTRODUCTION

The aim was to characterize the optical coherence tomography (OCT) angiography measures in patients with multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) and to evaluate their disease discrimination capacity.

METHODS

Patients with MS (n = 83) and AQP4-IgG-seropositive NMOSD (n = 91) with or without a history of optic neuritis, together with healthy controls (n = 34), were imaged. The main outcome measures were peripapillary retinal nerve fiber layer (pRNFL) thickness, macular ganglion cell-inner plexiform layer (GC-IPL) thickness, macular vessel density (VD), and perfusion density (PD) in the superficial capillary plexus. Diagnostic accuracy was assessed using the area under the receiver operating characteristics curve.

RESULTS

Compared with patients with MS, those with NMOSD had a significantly smaller average thickness of the pRNFL and GC-IPL (80.0 [59.0; 95.8] μm versus 92.0 [80.2; 101] μm, p < .001; 68.0 [56.0; 81.0] μm, versus 74.5 [64.2; 81.0] μm, p < .001) and significantly smaller whole VD and PD areas (15.6 [12.6; 17.0] mm^-1 versus 16.7 [14.8; 17.7] mm^-1 , p < .001; 0.38 [0.31; 0.42] mm^-1 versus 0.40 [0.37; 0.43] mm^-1 , p < .01). The combination of structural parameters (average thickness of the pRNFL and GC-IPL) with microvascular parameters (temporal-inner quadrant of VD, temporal-inner, nasal-inferior, and nasal-outer quadrant of PD) was revealed to have a good diagnostic capability for discriminating between NMOSD and MS.

CONCLUSIONS

OCT angiography reveals different structural and microvascular retinal changes in MS and AQP4-IgG-seropositive NMOSD. These combined structural and microvascular parameters might be promising biomarkers for disease diagnosis.