Retinal microvascular signs and risk of stroke and stroke mortality

Mean Arteriolar Diameter Measured from Wide-Field Swept-Source OCT Angiography: A Highly Sensitive Indicator for Mean Arterial Pressure

Purpose

To investigate the metrics of retinal arterioles and venules based on the en face images of the superficial retina using wide-field swept-source OCT angiography (SSOCTA) and assess their relationships with specific systemic parameters in a normal sample.

Design

Cross-sectional study.

Participants

Normal volunteers with no history of hypertension, diabetes, or significant eye diseases were recruited at the outpatient clinic of the First Affiliated Hospital of Xi'an Jiaotong University. Eligible eyes had a corrected visual acuity of 20/25 or better and an intraocular pressure (IOP) not exceeding 21 mmHg.

Methods

The SSOCTA scans of 24 × 20 mm in size were acquired from both eyes of each participant, along with measurements of axial length (AL), IOP, real-time mean arterial pressure (MAP), and body mass index (BMI). Retinal arterioles and venules were manually segmented and distinguished from the disc margin to their capillary junctions in the superficial retinal layer. Image processing and calculations were performed using ImageJ.

Main Outcome Measurements

The averaged caliber and fractal dimension of arteries and veins, as well as the arteriovenous ratio, were calculated from binarized vascular images. Generalized linear mixed models were used to test correlations between systemic parameters and these metrics.

Results

A total of 54 eyes from 44 participants were included after screening. Univariate analysis revealed a significant negative impact of MAP on averaged caliber of retinal artery (B = -0.003, P = 0.004) and averaged caliber of retinal vein (ACvein) (B = -0.002, P = 0.045), whereas age, sex, BMI, AL, and IOP showed no significant impact on these metrics. Variations among graders significantly influenced most metrics; however, real-time MAP continued to predict retinal arteriolar caliber after adjusting for graders (B = -0.002, P = 0.03).

Conclusions

The mean arteriolar diameter measured using wide-field SSOCTA could serve as a highly sensitive indicator of systemic vascular changes.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Exploring Endothelial Cell Dysfunction's Impact on the Brain-Retina Microenvironment Connection: Molecular Mechanisms and Implications

The intricate linking between the health of blood vessels and the functioning of neurons has attracted growing attention in the context of disorders that affect the neurological environment. Endothelial cells, forming the blood-brain barrier and blood-retinal barrier, play a fundamental role in maintaining the integrity of the brain-retina microenvironment connection. This review explores the molecular foundations of endothelial cell dysfunction and its implications for the brain-retina interaction. A comprehensive analysis of the complex factors contributing to endothelial dysfunction is presented, including oxidative stress, inflammation, reduced nitric oxide signaling, and disrupted vascular autoregulation. The significance of endothelial dysfunction extends to neurovascular coupling, synaptic plasticity, and trophic support. To our knowledge, there is currently no existing literature review addressing endothelial microvascular dysfunction and its interplay with the brain-retina microenvironment. The review also explains bidirectional communication between the brain and retina, highlighting how compromised endothelial function can disrupt this vital crosstalk and inhibit normal physiological processes. As neurodegenerative diseases frequently exhibit vascular involvement, a deeper comprehension of the interaction between endothelial cells and neural tissue holds promise for innovative therapeutic strategies. By targeting endothelial dysfunction, we may enhance our ability to preserve the intricate dynamics of the brain-retina microenvironment connection and ameliorate the progression of neurological disorders.

Retinal Microvasculature Changes Linked to Executive Function Impairment after COVID-19

Background/Objectives: Studies using optical coherence tomography angiography (OCTA) have revealed that individuals recovering from COVID-19 have a reduced retinal vascular density (VD) and larger foveal avascular zones (FAZs) than healthy individuals, with more severe cases showing greater reductions. We aimed to examine aspects of the retinal microvascularization in patients with post-COVID-19 condition (PCC) classified by COVID-19 severity and how these aspects relate to cognitive performance. Methods: This observational cross-sectional study included 104 PCC participants from the NAUTILUS Project, divided into severe (n = 59) and mild (n = 45) COVID-19 groups. Participants underwent cognitive assessments and OCTA to measure VD and perfusion density (PD) in the superficial capillary plexus (SVP) and FAZ. Analysis of covariance and partial Pearson and Spearman correlations were used to study intergroup differences and the relationships between cognitive and OCTA variables. Results: Severe PCC participants had significantly lower central (p = 0.03) and total (p = 0.03) VD, lower central (p = 0.02) PD measurements, and larger FAZ areas (p = 0.02) and perimeters (p = 0.02) than mild cases. Severe cases showed more cognitive impairment, particularly in speed processing (p = 0.003) and executive functions (p = 0.03). Lower central VD, lower central PD, and larger FAZ areas and perimeters were associated with worse executive function performance in the entire PCC sample and in the mild COVID-19 group. Conclusions: Retinal microvascular alterations, characterized by reduced VD and PD in the SVP and larger FAZ areas, were associated with cognitive impairments in PCC individuals. These findings suggest that severe COVID-19 leads to long-lasting microvascular damage, impacting retinal and cognitive health.

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.

Prediction model for asymptomatic carotid atherosclerosis using retinal microvascular intelligent analysis: A retrospective study

IMPORTANCE

Early detection and timely diagnosis of asymptomatic carotid atherosclerosis significantly assist in the prevention of ischemic stroke for them.

OBJECTIVE

This observational study aimed to develop and validate a novel prediction model to assist in the early diagnosis of carotid atherosclerosis based on new characteristic variables screened by retinal microvascular intelligence analysis.

MAIN OUTCOME(S) AND METHOD (S)

The least absolute shrinkage and selection operator (LASSO) combined with 10-fold cross-validation were screened for characteristic variables, and nomograms were plotted to demonstrate the prediction model. Receiver operating characteristic (ROC) curves and area under the curve (AUC), calibration plots and brier score (BS), and decision curve analysis (DCA) were used to evaluate the risk model's discrimination, calibration, and clinical applicability.

RESULTS

Age, gender, diabetes mellitus (DM), drinking history, vascular branching angle, mean vascular diameter within 0.5-1.0 papillary diameter (PD), curvature tortuosity arteriole in the inferior region of the optic disc, and vascular density in the nasal region of the optic disc were identified as characteristic variables for carotid atherosclerosis with retinal microvascular intelligence analysis. The predictive nomogram model presented good discrimination with AUCs of 0.790 (0.774-0.806), and the calibration curve displayed high consistency between predicted and actual probability. The DCA demonstrated that this nomogram model led to net benefits in a threshold probability range of 20 %-94 % and could be adapted for clinical decision-making. The results of the 100-bootstrap resampling strategy for internal validation also show that the risk model is well discriminated with an AUC of 0.789 and excellent calibration. External validation showed good discrimination with AUCs of 0.703 (0.627 - 0.779) and good calibration, the risk threshold is 10 %-92 % in terms of DCA.

CONCLUSIONS AND RELEVANCE

The novel prediction model based on retinal microvascular intelligence analysis constructed in this study could be effective prognoses for predicting the risk of asymptomatic carotid atherosclerosis in a Chinese screening population.

Eph-ephrin signaling couples endothelial cell sorting and arterial specification

Cell segregation allows the compartmentalization of cells with similar fates during morphogenesis, which can be enhanced by cell fate plasticity in response to local molecular and biomechanical cues. Endothelial tip cells in the growing retina, which lead vessel sprouts, give rise to arterial endothelial cells and thereby mediate arterial growth. Here, we have combined cell type-specific and inducible mouse genetics, flow experiments in vitro, single-cell RNA sequencing and biochemistry to show that the balance between ephrin-B2 and its receptor EphB4 is critical for arterial specification, cell sorting and arteriovenous patterning. At the molecular level, elevated ephrin-B2 function after loss of EphB4 enhances signaling responses by the Notch pathway, VEGF and the transcription factor Dach1, which is influenced by endothelial shear stress. Our findings reveal how Eph-ephrin interactions integrate cell segregation and arteriovenous specification in the vasculature, which has potential relevance for human vascular malformations caused by EPHB4 mutations.

The Eye as the Window to the Heart: Optical Coherence Tomography Angiography Biomarkers as Indicators of Cardiovascular Disease

Alterations in microvasculature represent some of the earliest pathological processes across a wide variety of human diseases. In many organs, however, inaccessibility and difficulty in directly imaging tissues prevent the assessment of microvascular changes, thereby significantly limiting their translation into improved patient care. The eye provides a unique solution by allowing for the non-invasive and direct visualization and quantification of many aspects of the human microvasculature, including biomarkers for structure, function, hemodynamics, and metabolism. Optical coherence tomography angiography (OCTA) studies have specifically identified reduced capillary densities at the level of the retina in several eye diseases including glaucoma. This narrative review examines the published data related to OCTA-assessed microvasculature biomarkers and major systemic cardiovascular disease. While loss of capillaries is being established in various ocular disease, pilot data suggest that changes in the retinal microvasculature, especially within the macula, may also reflect small vessel damage occurring in other organs resulting from cardiovascular disease. Current evidence suggests retinal microvascular biomarkers as potential indicators of major systemic cardiovascular diseases, including systemic arterial hypertension, atherosclerotic disease, and congestive heart failure.

Differences in retinal microvasculature between large artery atherosclerosis and small artery disease: an optical coherence tomography angiography study

Purpose: Recent reports suggest retinal microvasculature mirror cerebral microcirculation. Using optical coherence tomography angiography (OCTA), we investigated the retinal microvasculature differences between ischemic stroke patients with large artery atherosclerosis (LAA) and small artery disease (SAD). Methods: All patients underwent MR imaging and were classified as SAD and LAA; LAA was subdivided into anterior LAS and posterior LAS depending on the location. Swept-source OCTA (SS-OCTA) was used to image and segment the retina into the superficial vascular complex (SVC) and deep vascular complex (DVC) in a 6 × 6 mm area around the fovea. A deep learning algorithm was used to assess the vessel area density (VAD, %) in the retinal microvasculature. Results: Fifty-eight (mean age = 60.26 ± 10.88 years; 81.03% males) were LAA while 64 (mean age = 55.58 ± 10.34 years; 85.94% males) were SAD. LAS patients had significantly reduced VAD in the DVC (P = 0.022) compared to SAD patients; the VAD in the SVC did not show any significant difference between the two groups (P = 0.580). Anterior LAA ischemic stroke showed significantly lower VAD (P = 0.002) in the SVC compared with posterior LAS patients. There was no significant difference in the DVC between the two groups (P = 0.376). Conclusions: We found LAA patients had significantly reduced DVC density compared with SAD; we also showed anterior LAA patients had significantly reduced SVC density compared with posterior LAA. These findings suggest retinal imaging has the potential to be used to detect microvasculature changes in subtypes of ischemic stroke.

Detection of Stroke with Retinal Microvascular Density and Self-Supervised Learning Using OCT-A and Fundus Imaging

Acute cerebral stroke is a leading cause of disability and death, which could be reduced with a prompt diagnosis during patient transportation to the hospital. A portable retina imaging system could enable this by measuring vascular information and blood perfusion in the retina and, due to the homology between retinal and cerebral vessels, infer if a cerebral stroke is underway. However, the feasibility of this strategy, the imaging features, and retina imaging modalities to do this are not clear. In this work, we show initial evidence of the feasibility of this approach by training machine learning models using feature engineering and self-supervised learning retina features extracted from OCT-A and fundus images to classify controls and acute stroke patients. Models based on macular microvasculature density features achieved an area under the receiver operating characteristic curve (AUC) of 0.87-0.88. Self-supervised deep learning models were able to generate features resulting in AUCs ranging from 0.66 to 0.81. While further work is needed for the final proof for a diagnostic system, these results indicate that microvasculature density features from OCT-A images have the potential to be used to diagnose acute cerebral stroke from the retina.

Retinal age gap as a predictive biomarker of stroke risk

BACKGROUND

The aim of this study is to investigate the association of retinal age gap with the risk of incident stroke and its predictive value for incident stroke.

METHODS

A total of 80,169 fundus images from 46,969 participants in the UK Biobank cohort met the image quality standard. A deep learning model was constructed based on 19,200 fundus images of 11,052 disease-free participants at baseline for age prediction. Retinal age gap (retinal age predicted based on the fundus image minus chronological age) was generated for the remaining 35,917 participants. Stroke events were determined by data linkage to hospital records on admissions and diagnoses, and national death registers, whichever occurred earliest. Cox proportional hazards regression models were used to estimate the effect of retinal age gap on risk of stroke. Logistic regression models were used to estimate the predictive value of retinal age and well-established risk factors in 10-year stroke risk.

RESULTS

A total of 35,304 participants without history of stroke at baseline were included. During a median follow-up of 5.83 years, 282 (0.80%) participants had stroke events. In the fully adjusted model, each one-year increase in the retinal age gap was associated with a 4% increase in the risk of stroke (hazard ratio [HR] = 1.04, 95% confidence interval [CI]: 1.00-1.08, P = 0.029). Compared to participants with retinal age gap in the first quintile, participants with retinal age gap in the fifth quintile had significantly higher risks of stroke events (HR = 2.37, 95% CI: 1.37-4.10, P = 0.002). The predictive capability of retinal age alone was comparable to the well-established risk factor-based model (AUC=0.676 vs AUC=0.661, p=0.511).

CONCLUSIONS

We found that retinal age gap was significantly associated with incident stroke, implying the potential of retinal age gap as a predictive biomarker of stroke risk.

Correlation between silent lacunar strokes and retinopathies seen on fundus among patients hospitalized for lacunar strokes: An observational study at the neurology department of Befelatanana University Hospital

Retinal and cerebral arterioles have similar characteristics. Silent infarcts are associated with a risk of incident lacunar stroke and dementia. The objective of our study was to determine the correlation between silent lacunar strokes and retinopathy in patients hospitalized in our department for lacunar strokes. This is an observational, retrospective study, from July 2018 to December 2019, of patients diagnosed with lacunar stroke at the neurology department of Befelatanana Hospital, Antananarivo. Stroke was diagnosed with brain CT scan and retinopathy was classified according to fundus examination. The correlation between the presence of silent lacunar stroke and different types and stages of retinopathy was studied. Silent lacunar lesions were discovered on imaging in 70.59% of patients with lacunar strokes. All patients with symptomatic lacunar stroke, with or without associated silent lacunar lesions, were hypertensives. No statistical difference was found between patients with or without associated silent lacunar lesions according to age and gender. Among patients with silent lacunar lesions, dysexecutive syndrome was more prevalent as compared to patients without silent lesions (52.63% vs. 47.36%, P=0.03). Arteriolopathy was more prevalent in patients with silent lacunar lesions (85.71% vs. 14.28%, P=0.047). Silent lacunar lesions were unique in 72% of cases (P=0.022). The presence of stage II hypertensive retinopathy was significantly correlated with the presence of silent lacunar lesions (OR 5.20 [1.02-267] [1.02-26.47], P=0.018). Upon discovery of stage II hypertensive retinopathy on fundus examination, brain imaging should be performed for silent lacunar stroke screening to optimize hypertension management. This management is expected to prevent the incidence of lacunar stroke and vascular dementia.

A Simple Review of Small Vessel Disease Manifestation in the Brain, Retina, and Kidneys

Small blood vessels express specific phenotypical and functional characteristics throughout the body. Alterations in the microcirculation contribute to many correlated physiological and pathological events in related organs. Factors such as comorbidities and genetics contribute to the complexity of this topic. Small vessel disease primarily affects end organs that receive significant cardiac output, such as the brain, kidney, and retina. Despite the differences in location, concurrent changes are seen in the micro-vasculature of the brain, retina, and kidneys under pathological conditions due to their common histological, functional, and embryological characteristics. While the cardiovascular basis of pathology in association with the brain, retina, or kidneys has been well documented, this is a simple review that uniquely considers the relationship between all three organs and highlights the prevalence of coexisting end organ injuries in an attempt to elucidate connections between the brain, retina, and kidneys, which has the potential to transform diagnostic and therapeutic approaches.

Association Between the Metabolic Syndrome and Retinal Microvascular Diameters Among Police Officers

OBJECTIVES

We examined the associations of the metabolic syndrome severity score (MSSS) and the metabolic syndrome (MetSyn) components with central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE).

METHODS

Participants in this cross-sectional study were 253 officers from the Buffalo Cardio-Metabolic Occupational Police Stress study (2011-2014). The MSSS is a z -score that represents the severity of MetSyn and was estimated using a sex/race-specific equation and the five MetSyn components. Associations of MSSS and the MetSyn with CRAE/CRVE were obtained using linear regression models or analysis of covariance.

RESULTS

For every 1-standard deviation of MSSS, CRAE decreased by 2.3 μm (SE = 1.2, P = 0.0262) and CRVE increased by 3.4 μm (SE = 1.6, P = 0.0308) after adjusting for confounders.

CONCLUSIONS

Officers with higher MSSS had narrower (ie, worse) arteriolar diameters and wider (ie, worse) venular diameters.

Ischemic and haemorrhagic stroke risk estimation using a machine-learning-based retinal image analysis

Background

Stroke is the second leading cause of death worldwide, causing a considerable disease burden. Ischemic stroke is more frequent, but haemorrhagic stroke is responsible for more deaths. The clinical management and treatment are different, and it is advantageous to classify their risk as early as possible for disease prevention. Furthermore, retinal characteristics have been associated with stroke and can be used for stroke risk estimation. This study investigated machine learning approaches to retinal images for risk estimation and classification of ischemic and haemorrhagic stroke.

Study design

A case-control study was conducted in the Shenzhen Traditional Chinese Medicine Hospital. According to the computerized tomography scan (CT) or magnetic resonance imaging (MRI) results, stroke patients were classified as either ischemic or hemorrhage stroke. In addition, a control group was formed using non-stroke patients from the hospital and healthy individuals from the community. Baseline demographic and medical information was collected from participants' hospital medical records. Retinal images of both eyes of each participant were taken within 2 weeks of admission. Classification models using a machine-learning approach were developed. A 10-fold cross-validation method was used to validate the results.

Results

711 patients were included, with 145 ischemic stroke patients, 86 haemorrhagic stroke patients, and 480 controls. Based on 10-fold cross-validation, the ischemic stroke risk estimation has a sensitivity and a specificity of 91.0% and 94.8%, respectively. The area under the ROC curve for ischemic stroke is 0.929 (95% CI 0.900 to 0.958). The haemorrhagic stroke risk estimation has a sensitivity and a specificity of 93.0% and 97.1%, respectively. The area under the ROC curve is 0.951 (95% CI 0.918 to 0.983).

Conclusion

A fast and fully automatic method can be used for stroke subtype risk assessment and classification based on fundus photographs alone.

Retinal vessel diameters and function in cardiovascular risk and disease

In the last two decades evidence has gradually accumulated suggesting that the eye may be a unique window for cardiovascular risk stratification based on the assessment of subclinical damage of retinal microvascular structure and function. This can be facilitated by non-invasive analysis of static retinal vessel diameters and dynamic recording of flicker light-induced and endothelial function-related dilation of both retinal arterioles and venules. Recent new findings have made retinal microvascular biomarkers strong candidates for clinical implementation as reliable risk predictors. Beyond a review of the current evidence and state of research, the article aims to discuss the methodological benefits and pitfalls and to identify research gaps and future directions. Above all, the potential use for screening and treatment monitoring of cardiovascular disease risk are highlighted. The article provides fundamental comprehension of retinal vessel imaging by explaining anatomical and physiological essentials of the retinal microcirculation leading to a detailed description of the methodological approach. This allows for better understanding of the underlying retinal microvascular pathology associated with the prevalence and development of cardiovascular disease. A body of new evidence is presented on the clinical validity and predictive value of retinal vessel diameters and function for incidence cardiovascular disease and outcome. Findings in children indicate the potential for utility in childhood cardiovascular disease prevention, and the efficacy of exercise interventions highlight the treatment sensitivity of retinal microvascular biomarkers. Finally, coming from the availability of normative data, solutions for diagnostic challenges are discussed and conceptual steps towards clinical implementation are put into perspective.

Retinal microvascular abnormalities and risks of incident stroke and its subtypes: The Circulatory Risk in Communities Study

BACKGROUND

This study aimed to investigate the association between retinal microvascular abnormalities and the risk of incident stroke and its subtypes in the general Japanese population.

METHODS

A total of 12 965 residents aged 40-74 years without a history of stroke and/or coronary heart disease underwent retinal photography during the annual health checkups of four Japanese communities between 1990 and 1999. Retinal microvascular abnormalities, such as the presence or absence of generalized arteriolar narrowing, focal arteriolar narrowing, arteriovenous nicking, enhanced arteriolar light reflex, and retinal hemorrhages were graded using standard protocols.

RESULTS

During a median follow-up of 20 years, 817 patients were diagnosed with incident stroke. Retinal microvascular abnormalities were positively associated with the risk of total stroke; after adjustment for age, sex, community, SBP, antihypertensive medication use, and other cardiovascular risk factors, the multivariable hazard ratio [95% confidence interval (CI)] was 1.68 (1.42-1.98), 1.67 (1.34-2.07), 1.41 (1.17-1.72), 1.54 (1.26-1.87), and 1.57 (1.19-2.07) for generalized arteriolar narrowing, focal arteriolar narrowing, arteriovenous nicking, enhanced arteriolar light reflex, and retinal hemorrhages, respectively. Similar positive associations were observed for the risk of stroke subtypes, except for subarachnoid hemorrhage, for which no association was observed. Furthermore, the positive associations were similar in participants with and without hypertension.

CONCLUSION

Retinal microvascular abnormalities were positively associated with the risk of incident stroke in the general Japanese population. Routine retinal photography could provide positive clinical insights into stroke risk stratification independent of blood pressure, antihypertensive medication use, and other risk factors.

Hypertensive eye disease

Hypertensive eye disease includes a spectrum of pathological changes, the most well known being hypertensive retinopathy. Other commonly involved parts of the eye in hypertension include the choroid and optic nerve, sometimes referred to as hypertensive choroidopathy and hypertensive optic neuropathy. Together, hypertensive eye disease develops in response to acute and/or chronic elevation of blood pressure. Major advances in research over the past three decades have greatly enhanced our understanding of the epidemiology, systemic associations and clinical implications of hypertensive eye disease, particularly hypertensive retinopathy. Traditionally diagnosed via a clinical funduscopic examination, but increasingly documented on digital retinal fundus photographs, hypertensive retinopathy has long been considered a marker of systemic target organ damage (for example, kidney disease) elsewhere in the body. Epidemiological studies indicate that hypertensive retinopathy signs are commonly seen in the general adult population, are associated with subclinical measures of vascular disease and predict risk of incident clinical cardiovascular events. New technologies, including development of non-invasive optical coherence tomography angiography, artificial intelligence and mobile ocular imaging instruments, have allowed further assessment and understanding of the ocular manifestations of hypertension and increase the potential that ocular imaging could be used for hypertension management and cardiovascular risk stratification.

Deep Learning of the Retina Enables Phenome- and Genome-Wide Analyses of the Microvasculature

BACKGROUND

The microvasculature, the smallest blood vessels in the body, has key roles in maintenance of organ health and tumorigenesis. The retinal fundus is a window for human in vivo noninvasive assessment of the microvasculature. Large-scale complementary machine learning-based assessment of the retinal vasculature with phenome-wide and genome-wide analyses may yield new insights into human health and disease.

METHODS

We used 97 895 retinal fundus images from 54 813 UK Biobank participants. Using convolutional neural networks to segment the retinal microvasculature, we calculated vascular density and fractal dimension as a measure of vascular branching complexity. We associated these indices with 1866 incident International Classification of Diseases-based conditions (median 10-year follow-up) and 88 quantitative traits, adjusting for age, sex, smoking status, and ethnicity.

RESULTS

Low retinal vascular fractal dimension and density were significantly associated with higher risks for incident mortality, hypertension, congestive heart failure, renal failure, type 2 diabetes, sleep apnea, anemia, and multiple ocular conditions, as well as corresponding quantitative traits. Genome-wide association of vascular fractal dimension and density identified 7 and 13 novel loci, respectively, that were enriched for pathways linked to angiogenesis (eg, vascular endothelial growth factor, platelet-derived growth factor receptor, angiopoietin, and WNT signaling pathways) and inflammation (eg, interleukin, cytokine signaling).

CONCLUSIONS

Our results indicate that the retinal vasculature may serve as a biomarker for future cardiometabolic and ocular disease and provide insights into genes and biological pathways influencing microvascular indices. Moreover, such a framework highlights how deep learning of images can quantify an interpretable phenotype for integration with electronic health record, biomarker, and genetic data to inform risk prediction and risk modification.

The vessel density of the superficial retinal capillary plexus as a new biomarker in cerebral small vessel disease: an optical coherence tomography angiography study

BACKGROUND

Optical coherence tomography angiography (OCTA) is a novel and noninvasive technique for the quantitative assessment of retinal microvascular perfusion. Since the retinal and cerebral small vessels share similar embryological origins, anatomical features, and physiological properties, altered retinal microvasculature might provide a new perspective on the mechanisms of cerebral small vessel disease (CSVD).

OBJECTIVE

We aimed to evaluate retinal vessel density (VD) in patients with CSVD using OCTA and identify associations with cerebral magnetic resonance imaging (MRI) markers and cognitive function.

METHODS

We prospectively recruited 47 CSVD patients and 30 healthy controls (HCs) to participate in the study. All participants underwent OCTA to evaluate retinal microvascular perfusion. The VDs of the macular region in the superficial retinal capillary plexus (SRCP), deep retinal capillary plexus (DRCP), and foveal avascular zone (FAZ) were determined, along with the VD of the optic nerve head (ONH) in the radial peripapillary capillary (RPC) network. Additionally, cerebral MRI and cognitive function tests were performed.

RESULTS

In the macula area, the VD of the CSVD patients was significantly lower than HCs in the temporal quadrant of SRCP. In the ONH area, CSVD patients had lower VD than HCs in the peripapillary RPC network. According to multiple linear regression analysis, decreased VD of the macular SRCP was associated with white matter hyperintensity scores after adjustment for age, hypertension, diabetes, and hyperlipidemia. Furthermore, the VD of the macular SRCP was significantly correlated with CSVD patients' cognitive function, especially global cognition, memory function, attention function, information processing, and executive function.

CONCLUSION

OCTA revealed a significant decrease in retinal microvascular perfusion in CSVD patients, and retinal hypoperfusion was related to MRI markers and cognitive function, suggesting that these parameters could have potential utility as early disease biomarkers.

Risk Stratification Tool for Ischemic Stroke: A Risk Assessment Model Based on Traditional Risk Factors Combined With White Matter Lesions and Retinal Vascular Caliber

Objective: This study aims to establish a risk assessment model based on traditional risk factors combined with the Fazekas classification of white matter lesions and retinal vascular caliber for screening the patients at high risk of ischemic stroke. Methods: This study included 296 patients (128 cases of ischemic stroke and 168 cases in the normal control group). The basic data of the patients were collected. Color fundus photography was performed after pupil dilation, and the retinal vascular caliber was measured using semiautomated vascular measurement software (IVAN Software, Sydney, Australia). The severity of white matter lesions (WML) on cranial nuclear magnetic fluid-attenuated inversion recovery images were assessed using the Fazekas scale. Moreover, logistic regression analysis was used to establish different risk assessment models for ischemic stroke. The effects of models were evaluated through the receiver operating characteristic (ROC) curve and the Delong test compared area under the curve. Results: The sensitivity and specificity of models 1 (the traditional risk factor model), 2 (the retinal vascular caliber model), 3 (the WML model), and 4 (the combined the traditional risk factor, WML and central retinal artery equivalent (CRAE) model) were 71 and 55%, 48 and 71%, 49 and 67%, and 68 and 68.5% with areas under the curve of 0.658, 0.586, 0.601, and 0.708, respectively. The area under the receiver operating characteristic curve in models 1, 2, 3, and 4 showed statistically significant differences. Moreover, no statistical significance exists in the pairwise comparison of other models. Conclusion: The risk assessment model of ischemic stroke combined with Fazekas grade of WML and CRAE is superior to the traditional risk factor and the single-index model. This model is helpful for risk stratification of high-risk stroke patients.

Hypertensive Retinopathy and the Risk of Stroke Among Hypertensive Adults in China

Purpose

This study aimed to investigate the association between hypertensive retinopathy and the risk of first stroke, examine possible effect modifiers in hypertensive patients, and test the appropriateness of the Keith-Wagener-Barker (KWB) classification for predicting stroke risk.

Methods

In total, 9793 hypertensive participants (3727 males and 6066 females) without stroke history from the China Stroke Primary Prevention Trial were included in this study. The primary outcome was first stroke.

Results

Over a median follow-up of 4.4 years, 592 participants experienced their first stroke (509 ischemic, 77 hemorrhagic, and six unclassifiable strokes). In total, 5590 participants were diagnosed with grade 1 retinopathy (57.08%), 1466 with grade 2 retinopathy (14.97%), 231 with grade 3 retinopathy (2.36%), and three with grade 4 retinopathy (0.03%). Grades 1 and 2 were merged and classified as mild retinopathy, and grades 3 and 4 were merged and classified as severe retinopathy. There was a significant positive association between hypertensive retinopathy and the risk of first stroke and first ischemic stroke, and no effect modifiers were found. The hazard ratios (HRs) for first stroke were as follows: mild versus no retinopathy, 1.26 (95% confidence interval [CI], 1.01-1.58, P = 0.040), and severe versus no retinopathy, 2.40 (95% CI, 1.49-3.84, P < 0.001). The HRs for ischemic stroke were as follows: severe versus no retinopathy, 2.35 (95% CI, 1.41-3.90, P = 0.001), and nonsignificantly increased HRs for mild versus no retinopathy, 1.26 (95% CI, 0.99-1.60, P = 0.057).

Conclusions

There was a significant positive association between hypertensive retinopathy and the risk of first stroke in patients with hypertension, indicating that hypertensive retinopathy may be a predictor of the risk of stroke. A simplified two-grade classification system based on the KWB classification is recommended for predicting stroke risk.

Retinal Vascular Signs and Cerebrovascular Diseases

BACKGROUND

Cerebrovascular disease (CeVD), including stroke, is a leading cause of death globally. The retina is an extension of the cerebrum, sharing embryological and vascular pathways. The association between different retinal signs and CeVD has been extensively evaluated. In this review, we summarize recent studies which have examined this association.

EVIDENCE ACQUISITION

We searched 6 databases through July 2019 for studies evaluating the link between retinal vascular signs and diseases with CeVD. CeVD was classified into 2 groups: clinical CeVD (including clinical stroke, silent cerebral infarction, cerebral hemorrhage, and stroke mortality), and sub-clinical CeVD (including MRI-defined lacunar infarct and white matter lesions [WMLs]). Retinal vascular signs were classified into 3 groups: classic hypertensive retinopathy (including retinal microaneurysms, retinal microhemorrhage, focal/generalized arteriolar narrowing, cotton-wool spots, and arteriovenous nicking), clinical retinal diseases (including diabetic retinopathy [DR], age-related macular degeneration [AMD], retinal vein occlusion, retinal artery occlusion [RAO], and retinal emboli), and retinal vascular imaging measures (including retinal vessel diameter and geometry). We also examined emerging retinal vascular imaging measures and the use of artificial intelligence (AI) deep learning (DL) techniques.

RESULTS

Hypertensive retinopathy signs were consistently associated with clinical CeVD and subclinical CeVD subtypes including subclinical cerebral large artery infarction, lacunar infarction, and WMLs. Some clinical retinal diseases such as DR, retinal arterial and venous occlusion, and transient monocular vision loss are consistently associated with clinical CeVD. There is an increased risk of recurrent stroke immediately after RAO. Less consistent associations are seen with AMD. Retinal vascular imaging using computer assisted, semi-automated software to measure retinal vascular caliber and other parameters (tortuosity, fractal dimension, and branching angle) has shown strong associations to clinical and subclinical CeVD. Other new retinal vascular imaging techniques (dynamic retinal vessel analysis, adaptive optics, and optical coherence tomography angiography) are emerging technologies in this field. Application of AI-DL is expected to detect subclinical retinal changes and discrete retinal features in predicting systemic conditions including CeVD.

CONCLUSIONS

There is extensive and increasing evidence that a range of retinal vascular signs and disease are closely linked to CeVD, including subclinical and clinical CeVD. New technology including AI-DL will allow further translation to clinical utilization.

Reduced Superficial Capillary Density in Cerebral Infarction Is Inversely Correlated With the NIHSS Score

Purpose: The retina and the brain share similar neuronal and microvascular features, therein we aimed to assess the structural and microvascular changes in the macula and choriocapillaris (CC) in patients with cerebral infarction when compared with healthy controls using optical coherence tomography angiography (OCTA).

Methods: OCTA was used to image and measure the capillary density in the radial peripapillary capillaries (RPC), superficial capillary plexus (SCP), deep capillary plexus (DCP), choriocapillaris (CC), and mean area of the foveal avascular zone (FAZ) in all participants. Twenty-two cerebral infarction patients based on their magnetic resonance imaging (MRI) and 25 healthy controls were included in our study.

Results: Density of the RPC (P < 0.001), SCP (P = 0.001), DCP (P < 0.001) and CC (P < 0.001) were significantly reduced in cerebral infarction patients when compared with healthy controls, respectively. Retinal thickness measurements (P < 0.05) were significantly reduced in cerebral infarction patients when compared with healthy controls. The mean FAZ area was significantly larger (P = 0.012) in cerebral infarction patients when compared with healthy controls. National Institute of HealthStroke Scale (NIHSS) inversely correlated with SCP density in cerebral infarction patients (Rho = −0.409, P = 0.001). Receiver operating characteristics curve analysis showed that the blood flow of the choriocapillaris had the highest index [area under the receiver operatingcharacteristic (AUROC) = 0.964] to discriminate cerebral infarction patients from the healthy controls.

Conclusions: Our study suggests that cerebral microcirculation dysfunction which occurs in cerebral infarction is mirrored in the macula and choroidal microcirculation. OCTA has the potential to non-invasively characterize the macula and choroidal changes in cerebral infarction in vivo.

Retinal Vasculature Fractal and Stroke Mortality

BACKGROUND AND PURPOSE

Fractal analysis is a method of quantifying the branching complexity and density of the retinal vessels. We hypothesized that reduced fractal dimension, signifying a sparser vascular network, is associated with long-term stroke mortality.

METHODS

We examined the relationship of fractal dimension and stroke mortality in a prospective, population-based cohort of 3143 participants aged 49 years or older. Fractal dimension was measured from digitized fundus photographs using a computer-automated method. Stroke mortality was documented from Australian National Death Index records. We defined reduced fractal dimension as values in the lowest quartile.

RESULTS

Over 12 years, there were 132 (4.2%) stroke-related deaths. Stroke-related mortality was higher in participants with reduced fractal dimension (lowest quartile) compared with the highest quartile (7.7% versus 1.3%, P<0.01). After controlling for age, gender, smoking, blood pressure, history of stroke, and other factors, participants with reduced fractal dimension had higher stroke mortality (hazard ratio, 2.42 [95% CI, 1.15-5.07], lowest versus highest quartile). When modeled as a continuous variable, reduced fractal dimension was associated with increased stroke mortality (multivariable-adjusted hazard ratio, 1.26 [95% CI, 1.06-1.51], per SD decrease).

CONCLUSIONS

Reduced retinal vascular fractal dimension is independently associated with 12-year stroke mortality. Reduced fractal dimension may indicate cerebral tissue hypoxia and increased risk of stroke.

Multimodal Retinal Imaging for Detection of Ischemic Stroke

Background: This study aims to evaluate ocular changes in patients with ischemic stroke using multimodal imaging and explore the predictive value of ocular abnormalities for ischemic stroke. Methods: A total of 203 patients (ischemic stroke group, 62; control group, 141) were enrolled in this study. Basic data from patients, including age; gender; height; weight; history of hypertension, hyperlipidemia, diabetes, alcohol use, and coronary heart disease; and smoking status, were collected. Consequently, Doppler color ultrasound, color fundus photography, and optical coherence tomography (OCT) examinations were conducted. Differences in traditional risk factors and ocular parameters between the two groups were compared, and binary logistic regression was used for multivariate analysis. Results: The central retinal artery equivalent (CRAE) in the ischemic stroke group was 150.72 ± 20.15 μm and that in the control group was 159.68 ± 20.05 μm. The difference was statistically significant (P = 0.004). Moreover, the subfoveal choroidal thickness (SFChT) in the ischemic stroke group was 199.90 ± 69.27 μm and that in the control group was 227.40 ± 62.20 μm. The difference was statistically significant (P = 0.006). Logistic regression results showed that smoking [odds ratio (OR) = 2.823; 95% confidence interval (95% CI) = 1.477-5.395], CRAE (OR = 0.980; 95% CI = 0.965-0.996), and SFChT (OR = 0.994; 95% CI = 0.989-0.999) are associated with increased risk of ischemic stroke when ocular parameters were combined with traditional risk factors. The area under the receiver operating characteristic (ROC) curve was 0.726, which shows good diagnostic accuracy. Conclusion: SFChT may be a diagnostic marker for early detection and monitoring of ischemic stroke. Combined with traditional risks, retinal artery diameter, and choroidal thickness, the prediction model can improve ischemic stroke prediction.

Impact of Retinopathy and Systemic Vascular Comorbidities on All-Cause Mortality

PURPOSE

To assess the impact of retinopathy and systemic vascular comorbidities on the all-cause mortality in a representative U.S. sample.

METHODS

A total of 5703 participants (≥40 years old) from the 2005-2008 National Health and Nutrition Examination Survey. The Early Treatment Diabetic Retinopathy Study grading scale was used to evaluate the retinopathy status. Systemic vascular comorbidities included diabetes mellitus (DM), high blood pressure (HBP), chronic kidney disease (CKD) and cardiovascular disease (CVD). Time to death was calculated as the time from baseline to either the date of death or censoring (December 31^st, 2015), whichever came first. Risks of mortality were estimated using Cox proportional hazards models after adjusting for confounders and vascular comorbidities.

RESULTS

After a median follow-up of 8.33 years (IQR: 7.50-9.67 years), there were 949 (11.8%) deaths from all causes. After adjusting for confounders, the presence of retinopathy predicted higher all-cause mortality (hazard ratio (HR), 1.41; 95% confidence interval (CI), 1.08-1.83). The all-cause mortality among participants with both retinopathy and systemic vascular comorbidities including DM (HR, 1.72; 95% CI, 1.21-2.43), HBP (HR, 1.47; 95% CI, 1.03-2.10), CKD (HR, 1.73; 95% CI, 1.26-2.39) and CVD (HR, 1.92; 95% CI, 1.21-3.04) was significantly higher than that among those without either condition. When stratified by diabetic or hypertension status, the co-occurrence of retinopathy and CKD or CVD further increased the all-cause mortality compared to those without either condition.

CONCLUSIONS

The co-occurrence of retinopathy and systemic vascular conditions predicted a further increase in the risk of mortality. More extensive vascular risk factor assessment and management are needed to detect the burden of vascular pathologies and improve long-term survival in individuals with retinopathy.

Association of Retinal Microvascular Signs with Incident Atrial Fibrillation: The Multi-Ethnic Study of Atherosclerosis

PURPOSE

Microvascular diseases may contribute to the occurrence of atrial fibrillation (AF). Retinal microvascular signs that are similar to other microvasculature in the body and can be visualized directly via ophthalmoscopy may provide insights into such a relationship.

DESIGN

Prospective, longitudinal, multiethnic study.

PARTICIPANTS

We examined the association between retinal microvascular signs and incident AF in 4994 participants 47 to 86 years of age and free of prior AF who underwent fundus photography from 2002 through 2004 and were followed up through 2015 in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

Retinal microvascular signs evaluated include central retinal arteriolar equivalent and central retinal venular equivalent (CRVE) and presence of any retinopathy signs (e.g., retinal microaneurysms or hemorrhages). A multivariate Cox regression analysis was used to determine the relationship while adjusting for traditional risk factors, alcohol intake, body mass index, diabetes status, chronic kidney disease status, hemoglobin A1c level, C-reactive protein level, medications, and prevalent cardiovascular diseases or heart failure.

MAIN OUTCOME AND MEASURES

Incident AF events were identified using 12-lead electrocardiographic findings, hospital discharge records, and Medicare claims data.

RESULTS

During a median follow-up of 14.1 years, 643 AF events were identified. No association was found between any retinal microvascular signs and incident AF except for retinal focal arteriolar narrowing (hazard ratio, 1.75; 95% confidence interval, 1.06-2.87) in the overall population. However, in the subgroup analyses by gender, wider CRVE was associated with a higher risk of incident AF in women, but not in men (hazard ratio for every 10-μm increase in CRVE, 1.08 [95% confidence interval, 1.01-1.15] and 0.97 [95% confidence interval, 0.92-1.03], respectively; P = 0.041 for interaction).

CONCLUSIONS

No consistent pattern of association was found between retinal microvascular signs and incident AF. We observed an association in women, but not in men, of wider retinal venular calibers with incidence of AF. The reasons for a possible interaction are incompletely understood.

The Retinal Vessel Density as a New Vascular Biomarker in Multisystem Involvement in Fabry Disease: An Optical Coherence Tomography Angiography Study

In this study, we evaluated the possible relationship between the changes in retinal vessel density (VD) by optical coherence tomography angiography (OCTA) and the vascular alterations involving renal, cardiovascular and central nervous systems in patients affected by Fabry disease (FD). In 50 FD patients, the retinal superficial capillary plexus (SCP) and deep capillary plexus (DCP) in macular region were evaluated by OCTA examination. The patients also underwent a brain magnetic resonance imaging scan, renal and echocardiographic examinations with quantification of systolic pulmonary arterial pressure (PAPs) and left atrial volume index (LAVi). The VD of SCP and DCP was inversely related with E/e’ ratio, LAVi, interventricular septal thickness, global longitudinal strain (GLS) and PAPs (p < 0.05). No relationship was found, with a multivariate analysis, between OCTA parameters and kidney function and neuroradiological signs of central nervous system involvement. OCTA could be a new vascular biomarker in FD, revealing a strong correlation between retinal capillary damage and myocardial impairment, possibly preceding both renal dysfunction and cerebrovascular involvement.

Characterization of the retinal vasculature in fundus photos using the PanOptic iExaminer system

BACKGROUND

The goal was to characterize retinal vasculature by quantitative analysis of arteriole-to-venule (A/V) ratio and vessel density in fundus photos taken with the PanOptic iExaminer System.

METHODS

The PanOptic ophthalmoscope equipped with a smartphone was used to acquire fundus photos centered on the optic nerve head. Two fundus photos of a total of 19 eyes from 10 subjects were imaged. Retinal vessels were analyzed to obtain the A/V ratio. In addition, the vessel tree was extracted using deep learning U-NET, and vessel density was processed by the percentage of pixels within vessels over the entire image.

RESULTS

All images were successfully processed for the A/V ratio and vessel density. There was no significant difference of averaged A/V ratio between the first (0.77 ± 0.09) and second (0.77 ± 0.10) measurements (P = 0.53). There was no significant difference of averaged vessel density (%) between the first (6.11 ± 1.39) and second (6.12 ± 1.40) measurements (P = 0.85).

CONCLUSIONS

Quantitative analysis of the retinal vasculature was feasible in fundus photos taken using the PanOptic ophthalmoscope. The device appears to provide sufficient image quality for analyzing A/V ratio and vessel density with the benefit of portability, easy data transferring, and low cost of the device, which could be used for pre-clinical screening of systemic, cerebral and ocular diseases.

Retinal Microvascular Changes in Hypertensive Patients with Different Levels of Blood Pressure Control and without Hypertensive Retinopathy

PURPOSE

To determine possible correlations between different levels of blood pressure (BP) control and retinal microvascular changes in the macula and optic nerve head, using coherence tomography angiography (OCTA) in hypertensive patients without hypertensive retinopathy.

METHODS

This was an observational, cross-sectional study. Seventy-three patients and 40 healthy volunteers were included in this study. The patients and volunteers were divided into four groups and from each participant one eye was selected randomly: Group A comprised 32 hypertensive patients with intensive BP control; Group B comprised 26 hypertensive patients with standard BP control; Group C comprised 15 hypertensive patients with poor BP control; Group D comprised 40 control subjects. 6 × 6 mm macula scan and 4.5 × 4.5 mm optic nerve head scan were obtained using OCTA.

RESULTS

In macula scans, most measured regions of retinal VD showed significant reduction in group C, compared to groups A, B, and D (all P < .05). Partial measured regions of retinal VD were significantly lower in group B than groups A and D (all P < .05). In ONH scans, RNFL thickness and inside disc capillary density were significantly thinner and lower in groups B and C than in group D (all P < .05). SBP was significantly correlated with RNFL thickness (R = 0.430, 95% CI -0.583 to -0.201, P ≤ 0.001).

CONCLUSIONS

We demonstrated that the frequency of OCTA follow-up may improve detection of reduced retinal VD, thus avoiding further retinal damage in hypertensive patients; however, the clinical implications of this finding deserve further study. Moreover, further exploration is needed regarding the implication that reduced SBP may be beneficial for lowering the risk of glaucoma.

Retinal vascular abnormalities and their associations with cardiovascular and cerebrovascular diseases: a Study in rural southwestern Harbin, China

Background

Limited data is available on retinal vessel morphology in the north China. The study aimed to evaluate the prevalence of retinal vascular abnormalities (RVAs) and investigate their associations with the self-reported diagnosis of cardiovascular and cerebrovascsular diseases (CCVds) in a rural adult population of northeast China.

Methods

A population-based, cross-sectional study was conducted, using the cluster random sampling method. One eye of each participant was photographed with a non-mydriatic fundus camera. RVAs including focal and general arteriolar narrowing (FAN and GAN), arteriovenous nicking (AVN), arteriolar sheathing (AS), and retinopathy were evaluated. Data on self-reported diagnosis of cardiovascular and cerebrovascular diseases and status of smoking and alcohol drinking were obtained from questionnaires.

Results

Among the 6267 participants with an age ≥ 50 years, photographs were obtained of 99.2%, with quality sufficient to perform retinal evaluations in 82.5%. The prevalence of FAN, AVN, AS, retinopathy and GAN were 9.1, 8.9, 5.0, 6.6 and 6.2%, respectively. All the retinal lesions were associated with hypertension (all P < 0.01). After adjusting for age, gender, and left/right eyes, hypertension, hyperlipidaemia, diabetes mellitus, habits of past or current smoking and alcohol consumption, AVN was strongly associated with the self-reported diagnosis histories of coronary heart diseases(CHD) (OR, 1.44; 95% CI, 1.09, 1.89) and retinopathy was significantly associated with a self-reported diagnosis of stroke (OR, 2.05; 95% CI, 1.18, 3.57).

Conclusions

The overall prevalence of retinal microvascular abnormalities in this population was relatively higher than that reported in other regions of the world. Retinopathy is associated with the self-reported diagnosis of stroke while AVN was associated with the self-reported diagnosis of CHD, but the remaining retinal lesions were not consistently associated with CCVds. Thus, an examination of retinal microvascular characteristics may offer clues to CCVds and could be a potentially novel biomarkers for CCVds risk.

Optical Coherence Tomography Angiography Reveals Distinct Retinal Structural and Microvascular Abnormalities in Cerebrovascular Disease

Cerebrovascular disease (CeVD) is one of the leading global causes of death and severe disability. To date, retinal microangiopathy has become a reflection of cerebral microangiopathy, mirroring the vascular pathological modifications in vivo. To evaluate the retinal structure and microvasculature in patients with CeVD, we conducted a cross-sectional study in Zhongshan Ophthalmic Center and Department of Neurology of Third Affiliated Hospital, Sun Yat-sen University using optical coherence tomography angiography (OCTA). CeVD patients (n = 121; 238 eyes) and healthy controls (n = 44; 57 eyes) were included in the analysis. The CeVD group showed significant thinning of the peripapillary retinal nerve fiber layer (pRNFL) thickness in the temporal and nasal quadrants, and thinning of the macular ganglion cell-inner plexiform layer (GC-IPL) in the inferior quadrant, while macular microvasculature reduction was prominent in all nine quadrants. There were significant correlations between OCTA parameters, visual acuity, and transcranial doppler parameters in the CeVD group. The specific structural parameters combining microvasculature indices showed the best diagnostic accuracies (AUC = 0.918) to discriminate CeVD group from healthy controls. To conclude, we proved that OCTA reveals specific patterns of retinal structural changes and extensive macular microvascular changes in CeVD. Additionally, these retinal abnormalities could prove useful disease biomarkers in the management of individuals at high risk of debilitating complications from a cerebrovascular event.

Prevalence of Retinal Signs and Association With Cognitive Status: The ARIC Neurocognitive Study

OBJECTIVE

To determine the prevalence of retinal microvascular signs and associations between retinal signs and cognitive status.

DESIGN

Cross-sectional analysis of visit 5 (2011-2013) of the Atherosclerosis Risk in Communities (ARIC) cohort. Data analysis took place November 30, 2017, to May 1, 2018.

SETTING

Biracial population-based cohort from four US communities.

PARTICIPANTS

A total of 2624 participants with a mean age of 76 years (SD = 5 years) (19% African American) with data on cognitive status and complete retinal examination.

MEASUREMENTS

Retinal signs measured with fundus photography. Cognitive status: normal cognition, mild cognitive impairment (MCI)/dementia with a primary diagnosis of Alzheimer disease (AD) without cerebrovascular disease (CVD), and MCI/dementia with a primary or secondary diagnosis of CVD (irrespective of AD).

RESULTS

Overall, 6% of the cohort had mild retinopathy and 2% had moderate/severe retinopathy. Of the cohort, 7% had microaneurysms, 6% had retinal hemorrhages, and 8% had arteriovenous (AV) nicking. There was a low prevalence of soft exudates (1%) and focal narrowing (1%). In weighted fully adjusted models, individuals with retinal hemorrhages had a two-fold higher odds of all-cause MCI/dementia (95% confidence interval [CI] = 1.3-3.0; P = .001) and a 2.5-fold higher odds (95% CI = 1.6-3.9; P < .001) of MCI/dementia with CVD compared to individuals with no retinal hemorrhages. Individuals with AV nicking had a 1.6-fold higher odds of MCI/dementia with CVD (95% CI = 1.0-2.4) compared to individuals with no AV nicking (P < .05). There were no associations between retinal signs and MCI/dementia without CVD.

CONCLUSION

Our findings are confirmatory of recent research, and suggest that retinal microvascular signs may reflect microvascular pathology in the brain, potentially contributing to dementia and earlier MCI. The low prevalence of retinal signs and modest associations with cognitive status, however, limit the current clinical utility of these findings. Further work is needed to determine whether more sophisticated imaging may detect more subtle retinal signs with higher sensitivity to identify individuals at risk of dementia.

Retinal vascular flow and choroidal thickness in eyes with early age-related macular degeneration with reticular pseudodrusen

Background

To investigate the characteristics of retinal vessels and retinal thickness in eyes with early age-related macular degeneration (AMD) with or without reticular pseudodrusen.

Methods

We retrospectively evaluated the clinical history and optical coherence tomography (OCT) and OCT angiography images of consecutive patients with early AMD. We calculated the retinal vessel densities of the superficial and deep capillary plexus with the ImageJ software (National Institutes of Health, Bethesda, MD, USA) and investigated the relationship with mean retinal thickness and subfoveal choroidal thickness.

Results

We included 135 early AMD eyes and classified 60 of them into a reticular pseudodrusen group and 75 into a non-reticular pseudodrusen group. The vascular densities of the superficial and deep capillary plexus in the reticular pseudodrusen group (32.35% ± 3.67 and 26.71% ± 2.88%) were not different from those of the non-reticular pseudodrusen group (33.18% ± 2.2% and % 27.43 ± 1.79%; P = 0.546 and P = 0.318, respectively). The retinal thickness of the reticular pseudodrusen group (287.31 μm ± 24.36 μm) did not differ from that of the non-reticular pseudodrusen group (294.27 μm ± 20.71 μm; P = 0.493), while subfoveal choroidal thickness in the reticular pseudodrusen group (158.13 μm ± 42.53 μm) was lower than that in the non-reticular pseudodrusen group (237.89 μm ± 60.94 μm; P <  0.001). Multivariate analysis revealed that lower vascular density of the superficial capillary plexus and subfoveal choroidal thickness were associated with retinal thinning in reticular pseudodrusen group (P = 0.003 and P = 0.036) and older age was associated with retinal thickness in the non-reticular pseudodrusen group (P = 0.005).

Conclusions

Retinal thinning in early AMD patients with reticular pseudodrusen was accompanied by choroidal and retinal vascular loss, which suggests a possible linkage of retinal thinning with vascular alterations.

Electronic supplementary material

The online version of this article (10.1186/s12886-018-0866-3) contains supplementary material, which is available to authorized users.

Associations between retinal arteriolar and venular calibre with the prevalence of impaired fasting glucose and diabetes mellitus: A cross-sectional study

Background

This study aims to explore retinal vessel calibre in individuals at risk of coronary artery disease (CAD), diagnosed with impaired fasting glucose (IFG) or diabetes mellitus (DM), and whether indices of CAD extent and severity modifies these associations with DM.

Methods

A cross-sectional study was undertaken of 1680 patients presenting to Westmead Hospital (Sydney, Australia) for evaluation of potential CAD. Baseline digital retinal photographs, cardiovascular risk factor measurements, fasting blood tests and self-reported diabetes by patient questionnaire was recorded. Extent and severity of CAD was assessed using Extent and Gensini scores from angiography findings, respectively. Multivariate analysis including age and hypertension was undertaken to assess the association between retinal vessel calibre and IFG or DM.

Results

A total of 748 patients were included; 96 (12.8%) and 189 (25.3%), respectively, had IFG or DM (together termed ‘hyperglycaemia’). No consistent association between hyperglycaemia and retinal arteriolar calibre was apparent. Wider retinal venular calibre (second and third tertile) carried a significantly higher odds of DM in men only (multivariable-adjusted OR 2.447, p = 0.005; and OR 2.76, p = 0.002; respectively). No equivalent association was apparent in women. This association was marginally significant (p = 0.08) in patients with CAD Extent scores below the median (i.e. less diffuse CAD). Retinal vessel calibre was not associated with impaired fasting glucose.

Conclusions

This study reports a significant association between retinal venular widening and diabetes mellitus in men. This association was marginally stronger among participants with less diffuse CAD.

Inter-method agreement in retinal blood vessels diameter analysis between Dynamic Vessel Analyzer and optical coherence tomography

PURPOSE

To analyze the inter-methods agreement in arteriovenous ratio (AVR) evaluation between spectral-domain optical coherence tomography (SD-OCT) and Dynamic Vessel Analyzer (DVA).

METHODS

Healthy volunteers underwent DVA and SD-OCT examination. AVR was measured by SD-OCT using the four external lines of the optic nerve head-centered 7-line cube and by DVA using an automated AVR estimation. The mean AVR was calculated, twice, separately by two independent readers for each tool.

RESULTS

Twenty-two eyes of 11 healthy subjects (five women and six men, mean age 35) were included. AVR analysis by DVA showed high inter-observer agreement between reader 1 and 2, and high intra-observer agreement for both reader 1 and reader 2. With regard to AVR analysis on SD-OCT, we found high inter-observer agreement between reader 1 and 2, and low intra-observer agreement for reader 2 but high intra-observer agreement for reader 1. Overall, the mean AVR measured on SD-OCT turned out to be significantly higher than mean AVR measured through DVA (reader 1, 0.9023 ± 0.06 vs 0.8036 ± 0.08; p < 0.001, and reader 2, 0.9067 ± 0.06 vs 0.8083 ± 0.05; p= 0.003).

CONCLUSIONS

No inter-method agreement in AVR could be detected in the present study due to bias in measurements (shift between DVA and SD-OCT). We found significant difference in the two noninvasive methods for AVR measurement, with a tendency for SD-OCT to overestimate retinal vascular caliber in comparison to DVA. This may be useful for achieving greater accuracy in the evaluation of retinal vessel in ocular as well as systemic diseases.

Retinal biomarkers provide "insight" into cortical pharmacology and disease

The retina is an easily accessible out-pouching of the central nervous system (CNS) and thus lends itself to being a biomarker of the brain. More specifically, the presence of neuronal, vascular and blood-neural barrier parallels in the eye and brain coupled with fast and inexpensive methods to quantify retinal changes make ocular biomarkers an attractive option. This includes its utility as a biomarker for a number of cerebrovascular diseases as well as a drug pharmacology and safety biomarker for the CNS. It is a rapidly emerging field, with some areas well established, such as stroke risk and multiple sclerosis, whereas others are still in development (Alzheimer's, Parkinson's, psychological disease and cortical diabetic dysfunction). The current applications and future potential of retinal biomarkers, including potential ways to improve their sensitivity and specificity are discussed. This review summarises the existing literature and provides a perspective on the strength of current retinal biomarkers and their future potential.

Imaging retina to study dementia and stroke

With increase in life expectancy, the number of persons suffering from common age-related brain diseases, including neurodegenerative (e.g., dementia) and cerebrovascular (e.g., stroke) disease is expected to rise substantially. As current neuro-imaging modalities such as magnetic resonance imaging may not be able to detect subtle subclinical changes (resolution <100-500 μm) in dementia and stroke, there is an urgent need for other complementary techniques to probe the pathophysiology of these diseases. The retina - due to its anatomical, embryological and physiological similarities with the brain - offers a unique and accessible "window" to study correlates and consequences of subclinical pathology in the brain. Retinal components such as the microvasculature and retinal ganglion cell axons can now be visualized non-invasively using different retinal imaging techniques e.g., ocular fundus photography and optical coherence tomography. Advances in retinal imaging may provide new and potentially important insights into cerebrovascular neurodegenerative processes in addition to what is currently possible with neuro-imaging. In this review, we present an overview of the current literature on the application of retinal imaging in the study of dementia and stroke. We discuss clinical implications of these studies, novel state-of-the-art retinal imaging techniques and future directions aimed at evaluating whether retinal imaging can be an additional investigation tool in the study of dementia and stroke.

Retinal Vessel Diameters and Their Relationship with Cardiovascular Risk and All-Cause Mortality in the Inter99 Eye Study: A 15-Year Follow-Up

Purpose. To describe associations between retinal vessel diameters and cardiovascular risk markers and mortality. Methods. The present study included 908 persons aged 30 to 60 years. Vessel diameters were expressed as central retinal venular equivalent (CRVE) and central retinal arteriolar equivalent (CRAE). Multiple linear regression analyses and Cox regression models were used. Results. Multiple linear regression analyses showed that narrower CRAE was associated with higher systolic blood pressure, age, and higher HDL cholesterol, whereas wider CRAE and CRVE were associated with smoking. Narrower CRVE was associated with higher HDL cholesterol. In an age-adjusted model, associations between wider CRVE and risk of ischemic heart disease were found (P < 0.001). Wider CRVE was associated with all-cause mortality (HR = 2.02, P = 0.033) in a model adjusted for age, gender, and blood pressure. However, the association was not statistically significant after additional adjustment for smoking. Conclusions. The associations between retinal vessel diameters and known cardiovascular risk factors were confirmed. All-cause mortality was not associated with retinal vessel diameters when adjusting for relevant confounders.

Impact of combined hormonal contraceptives on vessels functionality

PURPOSE

To evaluate the dynamic and static retinal vascular functionality in young females using combined hormonal contraceptive (CHC).

METHODS

Thirty-eight consecutive young female subjects were enrolled in this study between January 2015 and December 2015. Subjects were divided in two groups: CHC group, defined as CHC use for ≥6 months, and control group, defined as no current and prior CHC use. Participants underwent a dynamic and static retinal vessel analysis using the Dynamic Vessel Analyzer (DVA, Imedos, Jena, Germany).

RESULTS

Seventeen subjects continuously took CHC for 54.6 ± 29.3 months, while 21 subjects belonged to control group. No difference was found between the CHC and control groups for age (p = 0.1), smoking status (p = 0.6), and systolic (p = 0.3) and diastolic (p = 0.1) blood pressure. With regard to dynamic analysis, women taking CHC exhibited a marked significant vasoconstriction following flicker stimulation in comparison with control group (-2.43 ± 2.5 vs 0.63 ± 2.1, respectively; p = 0.0002). No significant difference was observed between groups for mean arterial (p = 0.2) and venous dilatations (p = 0.3), arteriovenous ratio (p = 0.09), central retinal artery equivalent (p = 0.4), and central retinal venous equivalent (p = 0.5).

CONCLUSIONS

CHC may affect vessel reactivity to flicker light by increasing arteries constriction. This may reflect systemic changes in vascular functionality in subjects using CHC. Moreover, CHC should be considered as a confounding bias in studies involving DVA.

Dietary glycemic index and retinal microvasculature in adults: a cross-sectional study

Objective

To analyze the relationship between dietary glycemic index (GI) and retinal microvasculature in adults.

Methods

This was a cross-sectional study of 300 subjects from the EVIDENT II study. Dietary GI was calculated using a validated, semi-quantitative food frequency questionnaire. Retinal photographs were digitized, temporal vessels were measured in an area 0.5–1 disc diameter from the optic disc and arteriolar-venular index (AVI) was estimated with semi-automated software.

Results

AVI showed a significant difference between the tertiles of GI, after adjusting for potential confounders. The lowest AVI values were observed among subjects in the highest tertile of GI, whereas the greatest were found among those in the lowest tertile (estimated marginal mean of 0.738 vs. 0.768, p = 0.014).

Conclusions

In adults, high dietary GI implies lowering AVI values regardless of age, gender and other confounding variables.

Trial registration

Clinical Trials.gov Identifier: NCT02016014. Registered 9 December 2013.

Retinal Vessel Calibers in Predicting Long-Term Cardiovascular Outcomes: The Atherosclerosis Risk in Communities Study

BACKGROUND

Narrower retinal arterioles and wider retinal venules have been associated with negative cardiovascular outcomes. We investigated whether retinal vessel calibers are associated with cardiovascular outcomes in long-term follow-up and provide incremental value over the 2013 American College of Cardiology/American Heart Association Pooled Cohort Equations in predicting atherosclerotic cardiovascular disease events.

METHODS

A total of 10 470 men and women without prior atherosclerotic cardiovascular disease events or heart failure in the ARIC Study (Atherosclerosis Risk in Communities) underwent retinal photography at visit 3 (1993-1995).

RESULTS

During a mean follow-up of 16 years, there were 1779 incident coronary heart disease events, 548 ischemic strokes, 1395 heart failure events, and 2793 deaths. Rates of all outcomes were higher in those with wider retinal venules and narrower retinal arterioles. Subjects with wider retinal venules (hazard ratio [HR], 1.13; 95% confidence interval [CI], 1.08-1.18; HR, 1.18; 95% CI, 1.07-1.31; and HR, 1.10; 95% CI, 1.00-1.20 per 1-SD increase) and narrower retinal arterioles (HR, 1.06; 95% CI, 1.01-1.11; HR, 1.14; 95% CI, 1.03-1.26; and HR, 1.13; 95% CI, 1.03-1.24 per 1-SD decrease) had a higher risk of death and stroke in both sexes and incident coronary heart disease in women but not men (interaction P=0.02) after adjustment for the Pooled Cohort Equations risk score variables. The association between retinal vessel caliber and heart failure was nonsignificant after adjustment for systolic blood pressure. Among women with Pooled Cohort Equations-predicted 10-year atherosclerotic cardiovascular disease event risk <5% (overall risk, 3.9%), women in the narrowest arteriolar quartile had a 10-year event rate of 5.6% compared with 2.8% for women in the widest quartile (5.0% versus 3.4% for wider versus narrower venules). Retinal vessel caliber reclassified 21% of low-risk women (11% of all women) as intermediate risk (>5%).

CONCLUSIONS

Narrower retinal arterioles and wider retinal venules conferred long-term risk of mortality and ischemic stroke in both sexes and coronary heart disease in women. These measures serve as an inexpensive, reproducible biomarker that added incremental value to current practice guidelines in atherosclerotic cardiovascular disease event risk prediction in low-risk women.

The Paradoxical Significance of Headache in Hypertension

BACKGROUND

The cardiovascular prognostic value of various types of headache, particularly migraine, in the general population remains controversial. The aim of the present study was to assess their prognostic value for all-cause, cardiovascular and stroke mortalities in hypertensive patients.

METHODS

A total of 1,914 hypertensive individuals were first categorized according to the absence or presence of headache and thereafter according to the 3 subtypes of headache: migraine, daily headache, and other headache.

RESULTS

Multiple regression analysis demonstrated that all headache types were predicted by gender (women), diastolic blood pressure, absence of diabetes, secondary hypertension, and a trend for severe retinopathy. After 30 years of follow-up, 1,076 deaths were observed, 580 of whom were from cardiovascular cause and 97 from acute stroke. In a multivariable Cox model adjusted for major confounders, patients having headache had a decreased risk for all-cause mortality (hazard ratio (HR) 0.82; 95% confidence interval (CI) 0.73-0.93) and cardiovascular mortality (HR 0.80; 95% CI 0.68-0.95), but not for stroke mortality (HR 1.00; 95% CI 0.70-1.43). When considering only patients with headache, "daily headache" had a nonsignificant better prognostic value for all-cause and cardiovascular mortality than "other headache" (HR 0.83; 95% CI 0.68-1.01; HR 0.89; 95% CI 0.69-1.16, respectively) and "migraine" (HR 0.85; 95% CI 0.65-1.11; HR 0.78; 95% CI 0.55-1.10, respectively).

CONCLUSION

Presence of nonspecific headache in hypertensive patients has a paradoxical significance in that it is associated with a high-risk profile but does not result in a worse prognosis over the long term.

Microvasular and macrovascular complications in diabetes mellitus: Distinct or continuum?

Diabetes and related complications are associated with long-term damage and failure of various organ systems. The line of demarcation between the pathogenic mechanisms of microvascular and macrovascular complications of diabetes and differing responses to therapeutic interventions is blurred. Diabetes induces changes in the microvasculature, causing extracellular matrix protein synthesis, and capillary basement membrane thickening which are the pathognomic features of diabetic microangiopathy. These changes in conjunction with advanced glycation end products, oxidative stress, low grade inflammation, and neovascularization of vasa vasorum can lead to macrovascular complications. Hyperglycemia is the principal cause of microvasculopathy but also appears to play an important role in causation of macrovasculopathy. There is thought to be an intersection between micro and macro vascular complications, but the two disorders seem to be strongly interconnected, with micro vascular diseases promoting atherosclerosis through processes such as hypoxia and changes in vasa vasorum. It is thus imperative to understand whether microvascular complications distinctly precede macrovascular complications or do both of them progress simultaneously as a continuum. This will allow re-focusing on the clinical issues with a unifying perspective which can improve type 2 diabetes mellitus outcomes.

Renin-angiotensin system as a potential therapeutic target in stroke and retinopathy: experimental and clinical evidence

As our knowledge expands, it is now clear that the renin-angiotensin (Ang) system (RAS) mediates functions other than regulating blood pressure (BP). The RAS plays a central role in the pathophysiology of different neurovascular unit disorders including stroke and retinopathy. Moreover, the beneficial actions of RAS modulation in brain and retina have been documented in experimental research, but not yet exploited clinically. The RAS is a complex system with distinct yet interconnected components. Understanding the different RAS components and their functions under brain and retinal pathological conditions is crucial to reap their benefits. The aim of the present review is to provide an experimental and clinical update on the role of RAS in the pathophysiology and treatment of stroke and retinopathy. Combining the evidence from both these disorders allows a unique opportunity to move both fields forward.

Hypertensive retinopathy and cerebral small vessel disease in Amerindians living in rural Ecuador: The Atahualpa Project

BACKGROUND

Diagnosis of cerebral small vessel disease (SVD) is a challenge in remote areas where MRI is not available. Hypertensive retinopathy (HTRP) has shown to correlate with SVD in different ethnic groups, but there is no information from indigenous Latin American people. We assessed the usefulness of retinal photographs to detect cases with SVD among Amerindians living in rural Ecuador.

METHODS

Atahualpa residents aged ≥60years with arterial hypertension or prehypertension were identified during a door-to-door survey. A confocal line scanning laser ophthalmoscope was used to identify and grade HTRP (according to the Keith-Wagener-Barker classification). MRIs were read with attention to the presence of white matter hyperintensities (WMH) of presumed vascular origin and lacunar infarcts. Using logistic regression models, we evaluated whether HTRP was independently associated with neuroimaging signatures of SVD.

RESULTS

Of 323 eligible candidates, 241 (75%) were enrolled. MRI readings revealed moderate-to-severe WMH in 49 (20%) cases and lacunar infarcts in 29 (12%). HTRP Grade 1 was noticed in 90 (37%) individuals and Grade 2-3 in 42 (17%). After adjusting for demographics and cardiovascular risk factors, multivariate analyses showed a significant association between Grades 2-3 HTRP and moderate-to-severe WMH (OR: 3.87, 95% C.I.: 1.64-9.13) but not with lacunar infarcts (OR: 2.22, 95% C.I.: 0.83-5.92).

CONCLUSION

Amerindians with HTRP Grades 2-3 are almost four times more likely to have SVD-related subcortical damage than those with no- or only Grade 1-HTRP. Retinal photographs might allow recognition of people who need further investigation and therapy.