Changes of the retinal and choroidal vasculature in cerebral small vessel disease

Peripapillary vessels density is closely related to cerebral white matter hyperintensities: An OCTA study

BACKGROUND

Chronic cerebral hypoperfusion triggers the development of white matter hyperintensities (WMHs), common in cerebral small vessel disease (CSVD). However, conventional imaging techniques cannot visualize cerebral small vessels. The retina, a direct extension of the central nervous system, has an unclear correlation with WMHs. This study employs Optical coherence tomographic angiography (OCTA) to investigate vascular changes in the retina and explore its correlation with WMHs, aiming to provide a new method for assessing perfusion in early ischemic brain WMHs.

METHODS

Forty-nine patients with WMHs were stratified into mild and moderate/severe WMHs groups based on MRI findings, utilizing the Fazekas and Scheltens scales. OCTA assessed fundus vessel microcirculation. Logistic regression analyzed the correlation between ocular fundus microcirculation and WMH severity and location. Additionally, ROC curves evaluated the diagnostic efficacy of each fundus vascular microcirculation index in determining WMH severity.

RESULTS

After adjusting for multiple confounders, finding consistently indicated that the moderate/ severe WMHs group exhibited lower vessel density (VD) in the superior quadrant of the inner peripapillary region compared to the mild group [OR = 0.487, CI (0.255,0.929), p < 0.05]. ROC curves revealed that when combined with age, diabetes, and superior quadrant VD of the inner peripapillary region, specificity could be increased to 94.1%.

CONCLUSION

Peripapillary vessel density correlates closely with the severity of cerebral WMHs. Early morphological changes due to chronic hypoperfusion may initiate from the inner layer of the optic disc, and OCTA could offer a novel method for evaluating blood perfusion in ischemic WMHs.

In vivo volumetric analysis of retinal vascular hemodynamics in mice with spatio-temporal optical coherence tomography

Significance

Microcirculation and neurovascular coupling are important parameters to study in neurological and neuro-ophthalmic conditions. As the retina shares many similarities with the cerebral cortex and is optically accessible, a special focus is directed to assessing the chorioretinal structure, microvasculature, and hemodynamics of mice, a vital animal model for vision and neuroscience research.

Aim

We aim to introduce an optical imaging tool enabling in vivo volumetric mouse retinal monitoring of vascular hemodynamics with high temporal resolution.

Approach

We translated the spatio-temporal optical coherence tomography (STOC-T) technique into the field of small animal imaging by designing a new optical system that could compensate for the mouse eye refractive error. We also developed post-processing algorithms, notably for the assessment of (i) localized hemodynamics from the analysis of pulse wave-induced Doppler artifact modulation and (ii) retinal tissue displacement from phase-sensitive measurements.

Results

We acquired high-quality, in vivo volumetric mouse retina images at a rate of 113 Hz over a lateral field of view of ∼ 500    μ m . We presented high-resolution en face images of the retinal and choroidal structure and microvasculature from various layers, after digital aberration correction. We were able to measure the pulse wave velocity in capillaries of the outer plexiform layer with a mean speed of 0.35 mm/s and identified venous and arterial pulsation frequency and phase delay. We quantified the modulation amplitudes of tissue displacement near major vessels (with peaks of 150 nm), potentially carrying information about the biomechanical properties of the retinal layers involved. Last, we identified the delays between retinal displacements due to the passing of venous and arterial pulse waves.

Conclusions

The developed STOC-T system provides insights into the hemodynamics of the mouse retina and choroid that could be beneficial in the study of neurovascular coupling and vasculature and flow speed anomalies in neurological and neuro-ophthalmic conditions.

Advances in retinal imaging biomarkers for the diagnosis of cerebrovascular disease

The increasing incidence and mortality rates of cerebrovascular disease impose a heavy burden on both patients and society. Retinal imaging techniques, such as fundus photography, optical coherence tomography, and optical coherence tomography angiography, can be used for rapid, non-invasive evaluation of cerebral microcirculation and brain function since the retina and the central nervous system share similar embryonic origin characteristics and physiological features. This article aimed to review retinal imaging biomarkers related to cerebrovascular diseases and their applications in cerebrovascular diseases (stroke, cerebral small vessel disease [CSVD], and vascular cognitive impairment [VCI]), thus providing reference for early diagnosis and prevention of cerebrovascular diseases.

Cerebral Small Vessel Disease in Population-Based Research: What are We Looking at - and What not?

Cerebral small vessel disease (CSVD) is considered as one of the main causes of cognitive decline and dementia. However, despite extensive research, the pathogenesis of CSVD and the mechanisms through which CSVD leads to its clinical manifestations remain largely unclear. The challenging in vivo quantification of CSVD hampers progress in further unraveling the pathogenesis and pathophysiology of CSVD. Currently, markers of CSVD are mainly brain abnormalities attributed to CSVD, but these are limited in reflecting morphological and functional changes of the microvasculature. We describe aspects of CSVD that are reflected by currently used techniques and those that are still insufficiently captured.

Association of Retinal Neurovascular Impairment with Disease Severity in Patients with Major Depressive Disorder: An Optical Coherence Tomography Angiography Study

Background

Identifying the fundus objective biomarkers for the major depressive disorders (MDD) may help promote mental health. The aim of this study was to evaluate retinal neurovascular changes and further investigate their association with disease severity in MDD.

Methods

This cross-sectional study conducted in the hospital enrolled patients with MDD and healthy controls.The retinal neurovascular parameters for all subjects, including vessel density (VD), thickness of ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL), and optic nerve head (ONH) eg are automatically calculated by the software in optical coherence tomography angiography (OCTA). The severity of MDD including depressive symptoms, anxiety, cognition, and insomnia was assessed by Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Scale (HAMA), Montreal Cognitive Assessment (MoCA), and Insomnia Severity Index (ISI) respectively.

Results

This study included 74 MDD patients (n=74 eyes) and 60 healthy controls (HCs) (n=60 eyes). MDD patients showed significantly decreased VD of superficial and deep capillary plexus, thickness of GCC and RNFL, and volume of ONH (all p<0.05) and increased vertical cup-to-disc ratio and global loss volume (GLV) (all p<0.05) compared to HCs. Positive associations were found between HAMD scores and cup area (r=0.30, p=0.035), cup volume (r=0.31, p=0.029), and disc area (r=0.33, p=0.020) as well as ISI scores and RNFL thickness (r=0.34, p=0.047).

Conclusion

We found the retinal neurovascular impairment and its association with disease severity in MDD patients. OCTA showed promise as a potential complementary assessment tool for MDD.

Quantitative evaluation of choroidal and retinal microvasculature post-alcohol consumption: A pilot study

PURPOSE

The aim of this study was to assess the impact of acute, heavy alcohol consumption on the ocular microvasculature, providing insight into the largely unexplored response of microvascular structures to excessive drinking.

METHODS

Healthy volunteers in this prospective pilot study were tasked with consuming spirits, wine, and water at different times. Alcohol intake was measured according to body weight (g/kg). The ocular microvascular parameters primarily including choroidal volume (CV) and choroidal vessel volume (CVV) reflecting arteriolovenularity, and choroidal capillary density (CCD) reflecting capillary, were evaluated using swept-source optical coherence tomography angiography at baseline and 0.5-, 1-, 2-, and 3-hour post-consumption.

RESULTS

A total of 34 eyes underwent 170 successful examinations in this study. After consuming spirits or wine, we observed significant decreases in CV and CVV values (all P < 0.01 for 0.5-, 1-, 2-, and 3-hour post-consumption), along with significant increase in CCD (P < 0.05 at 0.5-, 1-, 2-hour post-spirits consumption and 1-hour post-wine consumption). The most pronounced changes occurred 1-hour after spirits or wine consumption (all P < 0.001 in both univariate and multivariate model). However, post-consumption changes in the ocular microvasculature showed no significant differences between spirits and wine (P > 0.05). Additionally, no significant differences were observed in any parameters after water intake (all P > 0.05).

CONCLUSIONS

Excessive alcohol consumption leads to ocular arteriolovenular vasoconstriction and capillary vasodilation, most evident 1-hour post-consumption of spirits and wine. Our research provides insight into alcohol's immediate ocular microvascular effects, hinting at systemic microvascular effects.

Macular vessel density in the superficial plexus is not a proxy of cerebrovascular damage in non-demented individuals: data from the NORFACE cohort

INTRODUCTION

Optical coherence tomography angiography (OCT-A) is a novel tool that allows the detection of retinal vascular changes. We investigated the association of macular vessel density (VD) in the superficial plexus assessed by OCT-A with measures of cerebrovascular pathology and atrophy quantified by brain magnetic resonance imaging (MRI) in non-demented individuals.

METHODS

Clinical, demographical, OCT-A, and brain MRI data from non-demented research participants were included. We analyzed the association of regional macular VD with brain vascular burden using the Fazekas scale assessed in a logistic regression analysis, and the volume of white matter hyperintensities (WMH) assessed in a multiple linear regression analysis. We also explored the associations of macular VD with hippocampal volume, ventricle volume and Alzheimer disease cortical signature (ADCS) thickness assessed in multiple linear regression analyses. All analyses were adjusted for age, sex, syndromic diagnosis and cardiovascular variables.

RESULTS

The study cohort comprised 188 participants: 89 with subjective cognitive decline and 99 with mild cognitive impairment. No significant association of regional macular VD with the Fazekas categories (all, p > 0.111) and WMH volume (all, p > 0.051) were detected. VD in the nasal quadrant was associated to hippocampal volume (p = 0.007), but no other associations of macular VD with brain atrophy measures were detected (all, p > 0.05).

DISCUSSION

Retinal vascular measures were not a proxy of cerebrovascular damage in non-demented individuals, while VD in the nasal quadrant was associated with hippocampal atrophy independently of the amyloid status.

[Retinal optical coherence tomography biomarkers in dementia]

BACKGROUND

Due to the general aging of society, the prevalence and incidence of dementia are expected to increase considerably. In order to timely identify patients and assess their need for treatment and/or supportive measures, comprehensive and easy access screening methods are required, which, however, are yet to be developed. To date, several biomarkers for the presence of dementia on high-resolution spectral domain optical coherence tomography (OCT) and OCT angiography (OCT-A) images were identified.

AIM

To summarize previously identified OCT biomarkers in dementia and to assess their suitability for comprehensive screening examinations.

MATERIAL AND METHODS

A literature search was conducted on PubMed until March 2023 for the keywords "dementia", "mild cognitive impairment", "OCT", "OCT angiography" and "retinal biomarkers". Relevant publications were identified and summarized.

RESULTS

Numerous unspecific alterations on OCT imaging and OCT‑A were identified in patients with (predementia) dementia according to many population and clinical studies. These include a reduced thickness of the peripapillary retinal nerve fiber layer, the ganglion cell complex and the central retinal region. Additionally, a reduced vascular density and an enlarged foveal avascular zone (FAZ) were identified on OCT‑A imaging.

CONCLUSION

The currently known OCT biomarkers are too unspecific, and there is to date no OCT or OCT-A-based signature distinguishing between different types of dementia. Further longitudinal studies with larger sample sizes are warranted to develop and evaluate such distinct OCT signatures for different types of dementia and their respective early disease stages and to assess their prognostic value. Only then is the inclusion in comprehensive screening investigations feasible.

Exploring the contribution of ARMS2 and HTRA1 genetic risk factors in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of severe irreversible central vision loss in individuals over 65 years old. Genome-wide association studies (GWASs) have shown that the region at chromosome 10q26, where the age-related maculopathy susceptibility (ARMS2/LOC387715) and HtrA serine peptidase 1 (HTRA1) genes are located, represents one of the strongest associated loci for AMD. However, the underlying biological mechanism of this genetic association has remained elusive. In this article, we extensively review the literature by us and others regarding the ARMS2/HTRA1 risk alleles and their functional significance. We also review the literature regarding the presumed function of the ARMS2 protein and the molecular processes of the HTRA1 protein in AMD pathogenesis in vitro and in vivo, including those of transgenic mice overexpressing HtrA1/HTRA1 which developed Bruch's membrane (BM) damage, choroidal neovascularization (CNV), and polypoidal choroidal vasculopathy (PCV), similar to human AMD patients. The elucidation of the molecular mechanisms of the ARMS2 and HTRA1 susceptibility loci has begun to untangle the complex biological pathways underlying AMD pathophysiology, pointing to new testable paradigms for treatment.

The Correlation between Retinal and Choroidal Thickness with Age-Related White Matter Hyperintensities in Progressive Supranuclear Palsy

Progressive supranuclear palsy (PSP) is a rare neurodegenerative disease. Recently, several retinal layers in PSP compared to healthy controls. were found to be thinner. However, no studies evaluating the correlation between retinal layers and cerebral white matter changes, nor eventual choroidal changes in PSP, have been conducted so far. The goals of the present study were to explore potential differences in choroidal structure between PSP and healthy controls, and to describe the relationship between retinal layers' thickness and volume, using spectral-domain optical coherence tomography (SD-OCT) and age-related white matter change scores (ARWMC) using magnetic resonance imaging (MRI) of the brain. Choroidal structures of 26 PSP patients and 26 healthy controls using standard SD-OCT with an enhanced depth imaging (EDI) approach were analyzed; then, retinal the structures of 16 of these PSP patients using standard SD-OCT were examined; finally, the same patients underwent brain MRI, and their cerebral white matter changes were calculated. Non-statistically significant differences between PSP patients' and healthy controls' choroidal structure were found. On the contrary, PSP patients' inner retinal layers (INR), retinal pigmented epithelium (RPE) and all retinal layers' thicknesses in the macular region were found to be significantly correlated with ARWMC, independently from age and axial length (AL). PSP patients' neurological alterations go hand in hand with retinal ones, independently from age and axial length. Our results suggest a mutual relationship between cerebral and retinal structure pathological alterations. On the other hand, no significant differences in the choroidal evaluation compared to healthy controls have been found.

Modifications in ocular microperfusion after transcatheter aortic valve implantation

Cerebral embolization is a known complication of transcatheter aortic valve implantation (TAVI) but the effect of the procedure on the ocular perfusion is currently unclear. Thus, we investigated post-procedural morphologic and perfusion changes of the retina and choroid, using optical coherence tomography angiography (OCTA) and color fundus photography (CFP) in a prospective cohort study. Ophthalmic examinations were conducted pre- and post-TAVI. OCTA images were analyzed quantitatively based on vessel density and skeleton density of the superficial and deep retinal plexus as well as the signal intensity and flow deficits in the choriocapillaris. CFP images were assessed for presence of acute retinal ischemia, optic nerve swelling, vessel emboli, hemorrhages and cotton wool spots. Data was analyzed using linear mixed models. Twenty patients (9 women; 11 men) at a mean age of 81 ± 6 years were included. Pre- and post-interventional ocular imaging data were available for 32 eyes. The analysis revealed a significant impairment of the choriocapillaris perfusion after TAVI with an increased proportion of flow deficits (p = 0.044). When controlling for blood pressure, the average size of choriocapillaris flow voids was significantly increased (systolic and diastolic, p = 0.039 and 0.029). Qualitatively, focal areas of retinal ischemia were detected on OCTA in 33% of participants. Silent emboli or cotton wool spots were identified on CFP in 21%. Our findings indicate a reduced choroidal perfusion as well as areas of retinal ischemia and embolization in a considerable proportion of patients following TAVI. Pending confirmation in a larger sample, these complications merit monitoring as well as inclusion in consent procedures for TAVI.

Progress on Prevention and Treatment of Cerebral Small Vascular Disease Using Integrative Medicine

Cerebral small vessel disease (CSVD) is a senile brain lesion caused by the abnormal structure and function of arterioles, venules and capillaries in the aging brain. The etiology of CSVD is complex, and disease is often asymptomatic in its early stages. However, as CSVD develops, brain disorders may occur, such as stroke, cognitive dysfunction, dyskinesia and mood disorders, and heart, kidney, eye and systemic disorders. As the population continues to age, the burden of CSVD is increasing. Moreover, there is an urgent need for better screening methods and diagnostic markers for CSVD, in addition to preventive and asymptomatic- and mild-stage treatments. Integrative medicine (IM), which combines the holistic concepts and syndrome differentiations of Chinese medicine with modern medical perspectives, has unique advantages for the prevention and treatment of CSVD. In this review, we summarize the biological markers, ultrasound and imaging features, disease-related genes and risk factors relevant to CSVD diagnosis and screening. Furthermore, we discuss IM-based CSVD prevention and treatment strategies to stimulate further research in this field.

Case report: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) as a risk factor for central serous chorioretinopathy

Purpose

To describe an atypical case of central serous chorioretinopathy (CSC) in a patient with cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL).

Methods

A retrospective case report.

Results

A 43-year-old white man with a genetic diagnosis of CADASIL was referred to our hospital because of reduced visual acuity in his right eye (20/30). In the previous 2 months, he developed CSC with subretinal fluid (SRF) and damage to the retinal pigmented epithelium without pachychoroid and pachyvessels or known risk factors for CSC. The patient was treated with transfoveal subthreshold micropulse yellow laser (577 nm) therapy. One month later, there were no signs of SRF, and visual acuity improved to 20/20.

Conclusions

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a genetic condition that primarily affects vascular smooth cells in small cerebral vessels and retinal arterioles. However, we hypothesize that CADASIL could also be responsible for an alteration of the vascular smooth cells in the choroidal arterioles, leading to choriocapillaris ischemia and CSC, even in the absence of a pachychoroid spectrum.

Structural retinal changes in cerebral small vessel disease

Cerebral small vessel disease (CSVD) is an important contributor to cognitive impairment and stroke. Previous research has suggested associations with alterations in single retinal layers. We have assessed changes of all individual retinal layers in CSVD using high-resolution optical coherence tomography (OCT) for the first time. Subjects with recent magnetic resonance imaging (MRI) underwent macular and peripapillary retinal imaging using OCT for this case-control study. Number and volume ratio index (WMRI) of white matter lesions (WML) were determined on MRI. Data were analyzed using multiple linear regression models. 27 CSVD patients and 9 control participants were included. Ganglion cell layer (GCL) volume was significantly reduced in patients with CSVD compared to age-matched controls (p = 0.008). In patients with CSVD, larger foveal outer plexiform layer (OPL) volume and decreased temporal peripapillary retinal nerve fiber layer (RNFL) thickness were significantly associated with a higher WMRI in linear regression when controlling for age (p ≤ 0.033). Decreased foveal GCL volume and temporal-inferior RNFL thickness at Bruch's membrane opening (MRW), and increased temporal MRW were associated with a higher WML burden (p ≤ 0.037). Thus, we identified alterations in several OCT layers in individuals with CSVD (GCL, OPL, MRW and RNFL). Their potential diagnostic value merits further study.