Retinal vascular calibre and the risk of coronary heart disease-related death

Standardization and clinical applications of retinal imaging biomarkers for cardiovascular disease: a Roadmap from an NHLBI workshop

The accessibility of the retina with the use of non-invasive and relatively low-cost ophthalmic imaging techniques and analytics provides a unique opportunity to improve the detection, diagnosis and monitoring of systemic diseases. The National Heart, Lung, and Blood Institute conducted a workshop in October 2022 to examine this concept. On the basis of the discussions at that workshop, this Roadmap describes current knowledge gaps and new research opportunities to evaluate the relationships between the eye (in particular, retinal biomarkers) and the risk of cardiovascular diseases, including coronary artery disease, heart failure, stroke, hypertension and vascular dementia. Identified gaps include the need to simplify and standardize the capture of high-quality images of the eye by non-ophthalmic health workers and to conduct longitudinal studies using multidisciplinary networks of diverse at-risk populations with improved implementation and methods to protect participant and dataset privacy. Other gaps include improving the measurement of structural and functional retinal biomarkers, determining the relationship between microvascular and macrovascular risk factors, improving multimodal imaging 'pipelines', and integrating advanced imaging with 'omics', lifestyle factors, primary care data and radiological reports, by using artificial intelligence technology to improve the identification of individual-level risk. Future research on retinal microvascular disease and retinal biomarkers might additionally provide insights into the temporal development of microvascular disease across other systemic vascular beds.

The impact of serum BNP on retinal perfusion assessed by an AI-based denoising optical coherence tomography angiography in CHD patients

Background

To investigate the correlation between retinal vessel density (VD) parameters with serum B-type natriuretic peptide (BNP) in patients with coronary heart disease (CHD) using novel optical coherence tomography angiography (OCTA) denoising images based on artificial intelligence (AI).

Methods

OCTA images of the optic nerve and macular area were obtained using a Canon-HS100 OCT device in 176 patients with CHD. Baseline information and blood test results were recorded.

Results

Retinal VD parameters of the macular and optic nerves on OCTA were significantly decreased in patients with CHD after denoising. Retinal VD of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and radial peripapillary capillary (RPC) was strongly correlated with serum BNP levels in patients with CHD. Significant differences were noted in retinal thickness and retinal VD (SCP, DCP and RPC) between the increased BNP and normal BNP groups in patients with CHD.

Conclusion

Deep learning denoising can remove background noise and smooth rough vessel surfaces. SCP,DCP and RPC may be potential clinical markers of cardiac function in patients with CHD. Denoising shows great potential for improving the sensitivity of OCTA images as a biomarker for CHD progression.

RETINAL MICROVASCULAR CHANGES AND RISK OF CORONARY HEART DISEASE: A Systematic Review and Meta-Analysis

PURPOSE

To quantify associations between various retinal microvascular changes and the risk of the development of coronary heart disease (CHD).

METHODS

PubMed, Embase, Web of Science, and Cochrane Library databases were searched for cohort studies on the association between retinal microvascular changes and incident CHD up to July 31, 2023. The summary risk estimates were estimated using the random-effects model. Subgroup and sensitivity analyses were performed to investigate the potential source of heterogeneity.

RESULTS

The authors identified 21 studies that met the inclusion criteria of this meta-analysis through database searching. This study yielded significant associations between retinal microvascular changes, including arteriolar narrowing, venular widening, vessel occlusion, and other retinal vascular signs, and the risk of CHD, with pooled adjusted hazard ratios of 1.20 (95% confidence interval: 1.13-1.27). In sex- and age-stratified analyses, retinal microvascular changes were associated with a greater risk of developing CHD in female patients and younger adults.

CONCLUSION

A range of retinal microvascular changes was associated with the risk of CHD, particularly in female patients and younger ages. The results of this study support the concept that retinal microvascular abnormalities may be markers for future CHD. Noninvasive retinal microvascular assessments may be helpful in screening patients with increased CHD risk.

Sex-specific association between carotid atherosclerosis and fundus arteriosclerosis in a Chinese population: a retrospective cross-sectional study

OBJECTIVES

Vascular stiffening is highly predictive of major adverse cardiovascular events. It is not clear whether microangiopathy, such as fundus arteriosclerosis, is related to carotid atherosclerosis. Hence, this study was designed to investigate the relationship between carotid atherosclerosis and fundus arteriosclerosis among individuals of different sexes in the Chinese health-examination population.

METHODS

This retrospective cross-sectional study involved 20,836 participants, including 13050 males and 7786 females. All participants underwent a detailed health examination, including medical history assessment, physical examination, assessment of lifestyle factors, fundus photography, Doppler ultrasound examination of the neck, and laboratory examinations. Two trained ophthalmologists analysed fundus arteriosclerosis based on fundus photographs, while carotid atherosclerosis was diagnosed using colour Doppler sonography of the neck. Binary logistic regression was used to analyse the relationship between carotid atherosclerosis and fundus arteriosclerosis.

RESULTS

In participants with fundus arteriosclerosis, the incidence of carotid atherosclerosis was higher than that of participants without fundus arteriosclerosis (52.94% vs. 47.06%). After adjustments for potential confounding factors, fundus arteriosclerosis was significantly associated with the risk of carotid atherosclerosis. The OR with 95% CI for fundus arteriosclerosis was 1.17 (1.02, 1.34) with p = 0.0262, and individuals who did not have fundus arteriosclerosis were used as a reference in the total population. Fundus arteriosclerosis was associated with the incidence of carotid atherosclerosis in males (p = 0.0005) but not in females (p = 0.0746).

CONCLUSIONS

Fundus arteriosclerosis was closely associated with carotid atherosclerosis in the Chinese population. This association was found in males but not in females.

Correlation of RETINAL Artery Diameter with Coronary Artery Disease: The RETINA CAD Pilot Study-Are the Eyes the Windows to the Heart?

INTRODUCTION

This study aimed to determine whether there was any correlation between coronary artery disease (CAD) and retinal artery diameter at an academic tertiary medical center in Trinidad and Tobago.

METHODS

This prospective study evaluated patients (n = 77) with recent invasive coronary angiography (CAG) and the Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score who subsequently underwent optical coherence tomography-angiography (OCT-A) at the Eric Williams Medical Sciences Complex (EWMSC) from January 2021 to March 2021. Routine medical history and cardiovascular medications were also recorded. Spearman's rank correlation coefficient and Mann-Whitney U-tests were used to compare correlations and medians between groups.

RESULTS

The average patient age was 57.8 years old, with the majority being male [n = 55 (71.4%)] and of South Asian ethnicity [n = 53 (68.8%)]. Retinal artery diameter was negatively correlated with the SYNTAX score (-0.332 for the right eye, p = 0.003 and -0.237 for the left eye, p = 0.038). A statistically significant relationship was also demonstrated in females and diabetic patients. There were no serious adverse events (SAEs).

CONCLUSION

A significantly negative correlation was observed between retinal artery diameter and SYNTAX score. This study alludes to the practical use of optical coherence tomography-angiography (OCT-A) as a noninvasive diagnostic modality for patients with cardiovascular disease (CVD). Further large-scale, multicentric studies are required to confirm these exploratory findings.

TRIAL REGISTRATION NUMBER

NCT04233619.

Comparing Common Retinal Vessel Caliber Measurement Software with an Automatic Deep Learning System

PURPOSE

To compare the Retina-based Microvascular Health Assessment System (RMHAS) with Integrative Vessel Analysis (IVAN) for retinal vessel caliber measurement.

METHODS

Eligible fundus photographs from the Lingtou Eye Cohort Study were obtained alongside their corresponding participant data. Vascular diameter was automatically measured using IVAN and RMHAS software, and intersoftware variations were assessed by intra-class correlation coefficients (ICC), and 95% confidence intervals (CIs). Scatterplots and Bland-Altman plots assessed the agreement between programs, and a Pearson's correlation test assessed the strength of associations between systemic variables and retinal calibers. An algorithm was proposed to convert measurements between software for interchangeability.

RESULTS

ICCs between IVAN and RMHAS were moderate for CRAE and AVR (ICC; 95%CI)(0.62; 0.60 to 0.63 and 0.42; 0.40 to 0.44 respectively) and excellent for CRVE (0.76; 0.75 to 0.77). When comparing retinal vascular calibre measurements between tools, mean differences (MD, 95% confidence intervals) in CRAE, CRVE, and AVR were 22.34 (-7.29 to 51.97 µm),-7.01 (-37.68 to 23.67 µm), and 0.12 (-0.02 to 0.26 µm), respectively. The correlation of systemic parameters with CRAE/CRVE was poor and the correlation of CRAE with age, sex, systolic blood pressure, and CRVE with age, sex, and serum glucose were significantly different between IVAN and RMHAS (p < 0.05).

CONCLUSIONS

CRAE and AVR correlated moderately between retinal measurement software systems while CRVE correlated well. Further studies confirming this agreeability and interchangeability in large-scale datasets are needed before softwares are deemed comparable in clinical practice.

Diagnosing Systemic Disorders with AI Algorithms Based on Ocular Images

The advent of artificial intelligence (AI), especially the state-of-the-art deep learning frameworks, has begun a silent revolution in all medical subfields, including ophthalmology. Due to their specific microvascular and neural structures, the eyes are anatomically associated with the rest of the body. Hence, ocular image-based AI technology may be a useful alternative or additional screening strategy for systemic diseases, especially where resources are scarce. This review summarizes the current applications of AI related to the prediction of systemic diseases from multimodal ocular images, including cardiovascular diseases, dementia, chronic kidney diseases, and anemia. Finally, we also discuss the current predicaments and future directions of these applications.

Chronic ocular small vessel disease: An overview of diabetic retinopathy and its relationship with cardiovascular health

Diabetic retinopathy (DR) is a potentially blinding disease originating from small vessel damage in the retina in chronic hyperglycemic states. DR has a complex multi-pathway driven pathogenesis resulting in diabetic macular edema and retinal ischemia, the former being the most common cause of vision impairment in DR. Hypoxia induced cytokines stimulate vascular endothelial growth factor (VEGF) production and subsequent angiogenesis with resultant mechanical retinal damage over time. Anti-VEGF therapy is effective for the treatment of center-involving diabetic macular edema. There is evolving evidence showing the effectiveness of anti-VEGF as both adjuvant and monotherapy in the treatment of proliferative DR, however laser photocoagulation continues to remain the standard of care. DR in large cohort studies has been shown to be an independent risk factor for the development of cardiovascular disease and mortality. In addition, changes in retinal vascular caliber ratios may have implications for risk of macrovascular events with a gender discrepancy towards women.

Evaluation of Retinal Vascularity Index in Patients with COVID-19: A Case-Control Study

INTRODUCTION

The purpose of this study was to evaluate the impact of COVID-19 infection on retinal microvasculature by topographically mapping the retinal arteriole-to-venule ratio (AVR).

METHODS

In a comparative cross-sectional case-control study, fundus photos were obtained in COVID-19-infected patients and healthy controls. AVT was measured over 16 points across the retina using retinal vascularity index (RVI)-a novel semi-automated computerized parameter based on retinal vasculature.

RESULTS

A total of 51 COVID-19-positive patients and 65 healthy controls were enrolled in the study. Overall, the mean RVI of all 16 points across the retina was 0.34 ± 0.02 in patients with COVID-19 and 0.33 ± 0.02 in control subjects (p = 0.64). Out of the 16 points being measured, three points had a statistically significant greater value in patients with COVID compared to normal controls.

CONCLUSION

Localised greater RVI values were found in some of the points in COVID-19-positive patients, which likely indicates a more focal change of the vasculature.

Validation of a deep-learning-based retinal biomarker (Reti-CVD) in the prediction of cardiovascular disease: data from UK Biobank

BACKGROUND

Currently in the United Kingdom, cardiovascular disease (CVD) risk assessment is based on the QRISK3 score, in which 10% 10-year CVD risk indicates clinical intervention. However, this benchmark has limited efficacy in clinical practice and the need for a more simple, non-invasive risk stratification tool is necessary. Retinal photography is becoming increasingly acceptable as a non-invasive imaging tool for CVD. Previously, we developed a novel CVD risk stratification system based on retinal photographs predicting future CVD risk. This study aims to further validate our biomarker, Reti-CVD, (1) to detect risk group of ≥ 10% in 10-year CVD risk and (2) enhance risk assessment in individuals with QRISK3 of 7.5-10% (termed as borderline-QRISK3 group) using the UK Biobank.

METHODS

Reti-CVD scores were calculated and stratified into three risk groups based on optimized cut-off values from the UK Biobank. We used Cox proportional-hazards models to evaluate the ability of Reti-CVD to predict CVD events in the general population. C-statistics was used to assess the prognostic value of adding Reti-CVD to QRISK3 in borderline-QRISK3 group and three vulnerable subgroups.

RESULTS

Among 48,260 participants with no history of CVD, 6.3% had CVD events during the 11-year follow-up. Reti-CVD was associated with an increased risk of CVD (adjusted hazard ratio [HR] 1.41; 95% confidence interval [CI], 1.30-1.52) with a 13.1% (95% CI, 11.7-14.6%) 10-year CVD risk in Reti-CVD-high-risk group. The 10-year CVD risk of the borderline-QRISK3 group was greater than 10% in Reti-CVD-high-risk group (11.5% in non-statin cohort [n = 45,473], 11.5% in stage 1 hypertension cohort [n = 11,966], and 14.2% in middle-aged cohort [n = 38,941]). C statistics increased by 0.014 (0.010-0.017) in non-statin cohort, 0.013 (0.007-0.019) in stage 1 hypertension cohort, and 0.023 (0.018-0.029) in middle-aged cohort for CVD event prediction after adding Reti-CVD to QRISK3.

CONCLUSIONS

Reti-CVD has the potential to identify individuals with ≥ 10% 10-year CVD risk who are likely to benefit from earlier preventative CVD interventions. For borderline-QRISK3 individuals with 10-year CVD risk between 7.5 and 10%, Reti-CVD could be used as a risk enhancer tool to help improve discernment accuracy, especially in adult groups that may be pre-disposed to CVD.

Development and validation of a model to categorize cardiovascular cause of death using health administrative data

Study objective

Develop and evaluate a model that uses health administrative data to categorize cardiovascular (CV) cause of death (COD).

Design

Population-based cohort.

Setting

Ontario, Canada.

Participants

Decedents ≥ 40 years with known COD between 2008 and 2015 in the CANHEART cohort, split into derivation (2008 to 2012; n = 363,778) and validation (2013 to 2015; n = 239,672) cohorts.

Main outcome measures

Model performance. COD was categorized as CV or non-CV with ICD-10 codes as the gold standard. We developed a logistic regression model that uses routinely collected healthcare administrative to categorize CV versus non-CV COD. We assessed model discrimination and calibration in the validation cohort.

Results

The strongest predictors for CV COD were history of stroke, history of myocardial infarction, history of heart failure, and CV hospitalization one month before death. In the validation cohort, the c-statistic was 0.80, the sensitivity 0.75 (95 % CI 0.74 to 0.75) and the specificity 0.71 (95 % CI 0.70 to 0.71). In the primary prevention validation sub-cohort, the c-statistic was 0.81, the sensitivity 0.71 (95 % CI 0.70 to 0.71) and the specificity 0.75 (95 % CI 0.75 to 0.75) while in the secondary prevention sub-cohort the c-statistic was 0.74, the sensitivity 0.81 (95 % CI 0.81 to 0.82) and the specificity 0.54 (95 % CI 0.53 to 0.54).

Conclusion

Modelling approaches using health administrative data show potential in categorizing CV COD, though further work is necessary before this approach is employed in clinical studies.

Retinal Vascular Caliber in Coronary Heart Disease and Its Risk Factors

BACKGROUND

Many clinical and experimental articles have suggested that the retinal vascular diameter can be used as a predictor of coronary heart disease (CHD). However, the results and reliability of the prediction are still controversial.

OBJECTIVE

A meta-analysis of observational study was conducted to clarify the relationships of retinal vessel caliber with CHD and CHD risk factors.

METHOD

PubMed and Embase were searched for all observational studies on the relationship of retinal vessel caliber with CHD and CHD risk factors from 2001 to 2021. The meta-analysis has been registered in PROSPERO (registration number is CRD42021267154).

RESULT

A total of 14 articles were selected for the inclusion in this meta-analysis. In the primary outcome, smaller retinal arteriolar caliber was related to CHD, and the results achieved statistical significance (MD: -5.55, 95% CI: -8.07 to -3.02, p < 0.0001), while there was no significant difference in vein caliber between CHD and healthy people (MD: 1.10, 95% CI: -3.55 to 5.76, p = 0.64 > 0.05). Smaller retinal arteriolar caliber was related to increasing age, male sex, bigger BMI, and hypertension. Bigger retinal arteriolar caliber was related to current smoking. Smaller retinal venule caliber was related to increasing age and hypertension. Bigger retinal venule caliber was related to current smoking, bigger BMI, and diabetes.

CONCLUSION

Smaller retinal arteriolar caliber was related to CHD, while there was no significant difference in venule caliber between CHD and healthy people. Retinal vascular caliber also independently related to CHD risk factors (e.g., age, gender, smoke, BMI, hypertension, and diabetes).

Analysis of Retinal Blood Vessel Diameters in Pregnant Women Practicing Yoga: A Feasibility Study

Studies have shown that practicing yoga during pregnancy beneficially affects maternal and neonatal outcomes. The objective of this study was to determine the effect of prenatal yoga on the microvascular circulatory system via non-invasive measurements of retinal blood vessels. We included 29 women who practiced prenatal yoga in the study. There were no statistically significant differences in arteriolar and venular diameters pre- vs. post-90 min yoga practice (150.5 ± 11.4 μm pre- vs. 151.2 ± 10.2 μm post-yoga; p = 0.53 for arteriolar and 221.8 ± 16.1 μm pre- vs. 223.2 ± 15.7 μm post-yoga; p = 0.51 for venular diameters). The current study demonstrated the feasibility of the setup. More extensive studies are needed to determine the potential microvascular effects of practicing yoga throughout pregnancy.

Retinal Microvascular Changes in Familial Hypercholesterolemia: Analysis with Swept-Source Optical Coherence Tomography Angiography

Familial hypercholesterolemia (FH) is a common but underdiagnosed genetic disorder affecting cholesterol metabolism, leading to atherosclerotic disease. The relationship between retinal microvascular changes and the presence of atheroma in patients with FH (FH group), and in comparison to volunteers without FH (CT group), needs further investigation. This cross-sectional study was conducted in a university hospital between October 1, 2020 and May 31, 2021. Cardiovascular data, including the Coronary Artery Calcium (CAC) score, were recorded for FH patients. Macula angiograms were acquired using swept-source optical coherence tomography angiography (SS OCT-A) to analyze both the superficial capillary plexus (SCP) and deep capillary plexus (DCP). A total of 162 eyes of 83 patients were enrolled in the FH group and 121 eyes of 78 volunteers in the CT group. A statistically significant association was found between the CAC score and both vessel density (β = −0.002 [95% CI, −0.004; −0.0005], p = 0.010) and vessel length (β = −0.00005 [95% CI, −0.00008; −0.00001], p = 0.010) in the DCP. The FH group had a significantly lower foveal avascular zone circularity index than the CT group in multivariate analysis (0.67 ± 0.16 in the FH group vs. 0.72 ± 0.10 in the CT group, β = 0.04 [95% CI, 0.002; 0.07], p = 0.037). Retinal microvascularization is altered in FH and retinal vascular densities are modified according to the CAC score.

Risk Assessment of CHD Using Retinal Images with Machine Learning Approaches for People with Cardiometabolic Disorders

BACKGROUND

Coronary heart disease (CHD) is the leading cause of death worldwide, constituting a growing health and social burden. People with cardiometabolic disorders are more likely to develop CHD. Retinal image analysis is a novel and noninvasive method to assess microvascular function. We aim to investigate whether retinal images can be used for CHD risk estimation for people with cardiometabolic disorders.

METHODS

We have conducted a case-control study at Shenzhen Traditional Chinese Medicine Hospital, where 188 CHD patients and 128 controls with cardiometabolic disorders were recruited. Retinal images were captured within two weeks of admission. The retinal characteristics were estimated by the automatic retinal imaging analysis (ARIA) algorithm. Risk estimation models were established for CHD patients using machine learning approaches. We divided CHD patients into a diabetes group and a non-diabetes group for sensitivity analysis. A ten-fold cross-validation method was used to validate the results.

RESULTS

The sensitivity and specificity were 81.3% and 88.3%, respectively, with an accuracy of 85.4% for CHD risk estimation. The risk estimation model for CHD with diabetes performed better than the model for CHD without diabetes.

CONCLUSIONS

The ARIA algorithm can be used as a risk assessment tool for CHD for people with cardiometabolic disorders.

Association of microvascular biomarkers in fluorescein angiography with macrovascular-related mortality in clinical routine data

Purpose

Early detection of microvascular changes in the retina may be important for the risk assessment of cardiovascular health. Therefore, the purpose of this study was to investigate imaging biomarkers in fluorescein angiography (FA) as potential predictors for cardiovascular mortality.

Methods

In this retrospective, matched case-control study, we included FA images from clinical routine data between 2007 and 2018 of 100 patients who died of macrovascular events (Group 1) and 100 age- and sex-matched controls (Group 2). All patients were under treatment for different, mostly retinal, ocular diseases. FA images were used for the measurement of the foveal avascular zone (FAZ) and the arteriolar and venular caliber.

Results

Patients mean age on examination day was 69.5 ± 8.3 years with a 1:1 female:male subject ratio. Mean FAZ area of our sample was 0.340 ± 0.135 mm² for Group 1 and 0.264 ± 0.137 mm² for Group 2 (P < 0.001), showing a larger FAZ area in patients who subsequently died of macrovascular-related systemic diseases.

Conclusions

Individuals effected by a macrovascular-related disease show a larger FAZ on FA examinations before the event compared to patients which are unaffected. Our results highlight a possible role of the FAZ as additional biomarker for the cardiovascular condition.

Relation between Retinopathy and Progression of Coronary Artery Calcium in Individuals with Versus Without Diabetes Mellitus (From the Multi-Ethnic Study of Atherosclerosis)

Retinopathy is a microvascular complication of diabetes mellitus (DM); however, it is also increasingly recognized in persons without DM. The microvascular diseases may play a prominent role in coronary heart disease (CHD) development in individuals with DM. We performed the study to evaluate the relation between non-DM retinopathy and CHD and also the association between baseline retinopathy and incidence and progression of CHD in individuals with and without DM. We included 5709 subjects with and without DM from the Multi-Ethnic Study of Atherosclerosis, who had retinal photos and coronary artery calcium score (CACS) available. We studied the association between baseline retinopathy and incidence and progression of coronary artery calcification (CAC) in subjects with and without DM. In DM group, the presence of retinopathy was significantly associated with an increased rate of CAC (RR 1.3 (95% CI [1.02, 1.66]) after adjusting for age, sex, race, follow-up time, and CHD risk factors. In non-DM group, the presence of retinopathy was not significantly associated with increased risk of CAC, however, the interaction between presence of retinopathy and DM status was not statistically significant. Within the DM group with CAC present at baseline, the presence of retinopathy was significantly associated with greater CAC progression (113 Agatson units (AU) greater, (95% CI [51-174]). In the non-DM group with present CAC at baseline; the presence of retinopathy was associated with 24 (95% CI [-0.69, 48.76]) AU higher CAC progression. All findings were adjusted for CHD risk factors. In conclusion, after adjustment for major CHD risk factors, retinopathy was associated with progression of CAC in both DM and non-DM individuals. However, the association was stronger in those with DM.

Quantitative Optical Coherence Tomography Angiography (OCTA) Parameters in a Black Diabetic Population and Correlations with Systemic Diseases

This is a cross-sectional, prospective study of a population of black diabetic participants without diabetic retinopathy aimed to investigate optical coherence tomography angiography (OCTA) characteristics and correlations with systemic diseases in this population. These parameters could serve as novel biomarkers for microvascular complications; especially in black populations which are more vulnerable to diabetic microvascular complications. Linear mixed models were used to obtain OCTA mean values ± standard deviation and analyze statistical correlations to systemic diseases. Variables showing significance on univariate mixed model analysis were further analyzed with multivariate mixed models. 92 eyes of 52 black adult subjects were included. After multivariate analysis; signal strength intensity (SSI) and heart disease had statistical correlations to superficial capillary plexus vessel density in our population. SSI and smoking status had statistical correlations to deep capillary plexus vessel density in a univariate analysis that persisted in part of the imaging subset in a multivariate analysis. Hyperlipidemia; hypertension; smoking status and pack-years; diabetes duration; creatinine; glomerular filtration rate; total cholesterol; hemoglobin A1C; and albumin-to-creatinine ratio were not significantly associated with any OCTA measurement in multivariate analysis. Our findings suggest that OCTA measures may serve as valuable biomarkers to track systemic vascular functioning in diabetes mellitus in black patients.

A Deep Learning Architecture for Vascular Area Measurement in Fundus Images

Purpose

To develop a novel evaluation system for retinal vessel alterations caused by hypertension using a deep learning algorithm.

Design

Retrospective study.

Participants

Fundus photographs (n = 10 571) of health-check participants (n = 5598).

Methods

The participants were analyzed using a fully automatic architecture assisted by a deep learning system, and the total area of retinal arterioles and venules was assessed separately. The retinal vessels were extracted automatically from each photograph and categorized as arterioles or venules. Subsequently, the total arteriolar area (AA) and total venular area (VA) were measured. The correlations among AA, VA, age, systolic blood pressure (SBP), and diastolic blood pressure were analyzed. Six ophthalmologists manually evaluated the arteriovenous ratio (AVR) in fundus images (n = 102), and the correlation between the SBP and AVR was evaluated manually.

Main Outcome Measures

Total arteriolar area and VA.

Results

The deep learning algorithm demonstrated favorable properties of vessel segmentation and arteriovenous classification, comparable with pre-existing techniques. Using the algorithm, a significant positive correlation was found between AA and VA. Both AA and VA demonstrated negative correlations with age and blood pressure. Furthermore, the SBP showed a higher negative correlation with AA measured by the algorithm than with AVR.

Conclusions

The current data demonstrated that the retinal vascular area measured with the deep learning system could be a novel index of hypertension-related vascular changes.

Retinal Vascular Fractal Dimensions and Their Association with Macrovascular Cardiac Disease

INTRODUCTION

As the only part of the human vasculature, the retina is available for direct, noninvasive inspection. Retinal vascular fractal dimension (DF) is a method to measure the structure of the retinal vascular tree, with higher noninteger values between 1 and 2 representing a more complex and dense retinal vasculature. Retinal vascular structure has been associated with a variety of systemic diseases, and this study examined the association of DF and macrovascular cardiac disease in a case-control design.

METHODS

Retinal fundus photos were captured with Topcon TRC-50X in 38 persons that had coronary artery bypass grafting (CABG, cases) and 37 cardiovascular healthy controls. The semiautomatic software VAMPIRE was used to measure retinal DF.

RESULTS

Patients with CABG had lower DF of the retinal main venular vessels compared to the control group (1.15 vs. 1.18, p = 0.01). In a multivariable regression model adjusted for gender and age, eyes in the fourth quartile with higher DF were less likely to have CABG compared to patients in the first (OR, 7.20; 95% confidence interval: 1.63-31.86; p = 0.009) and second (OR, 8.25; 95% confidence interval: 1.70-40.01; p = 0.009) quartiles.

CONCLUSIONS

This study demonstrates that lower complexity of main venular vessels associates with higher risk of having CABG. The research supports the hypothesis that the retinal vascular structure can be used to assess nonocular macrovascular disease.

Digital Technology for AMD Management in the Post-COVID-19 New Normal

PURPOSE

The COVID-19 pandemic has put strain on healthcare systems and the availability and allocation of healthcare manpower, resources and infrastructure. With immediate priorities to protect the health and safety of both patients and healthcare service providers, ophthalmologists globally were advised to defer nonurgent cases, while at the same time managing sight-threatening conditions such as neovascular Age-related Macular Degeneration (AMD). The management of AMD patients both from a monitoring and treatment perspective presents a particular challenge for ophthalmologists. This review looks at how these pressures have encouraged the acceptance and speed of adoption of digitalization.

DESIGN AND METHODS

A literature review was conducted on the use of digital technology during COVID-19 pandemic, and on the transformation of medicine, ophthalmology and AMD screening through digitalization.

RESULTS

In the management of AMD, the implementation of artificial intelligence and "virtual clinics" have provided assistance in screening, diagnosis, monitoring of the progression and the treatment of AMD. In addition, hardware and software developments in home monitoring devices has assisted in self-monitoring approaches.

CONCLUSIONS

Digitalization strategies and developments are currently ongoing and underway to ensure early detection, stability and visual improvement in patients suffering from AMD in this COVID-19 era. This may set a precedence for the post COVID-19 new normal where digital platforms may be routine, standard and expected in healthcare delivery.

Retinal Microvascular Signs as Screening and Prognostic Factors for Cardiac Disease: A Systematic Review of Current Evidence

The substantial burden of heart disease promotes an interest in new ways of screening for early disease diagnosis, especially by means of noninvasive imaging. Increasing evidence for association between retinal microvascular signs and heart disease prompted us to systematically investigate the relevant current literature on the subject. We scrutinized the current literature by searching PubMed and Embase databases from 2000 to 2020 for clinical studies of the association between retinal microvascular signs and prevalent or incident heart disease in humans. Following exclusions, we extracted the relevant data from 42 publications (comprising 14 prospective, 26 cross-sectional, and 2 retrospective studies). Our search yielded significant associations between retinal vascular changes, including diameter, tortuosity, and branching, and various cardiac diseases, including acute coronary syndrome, coronary artery disease, heart failure, and conduction abnormalities. The findings of our research suggest that the retinal microvasculature can provide essential data about concurrent cardiac disease status and predict future risk of cardiac-related events.

Retinal Vessel Analysis as a Novel Screening Tool to Identify Childhood Acute Lymphoblastic Leukemia Survivors at Risk of Cardiovascular Disease

BACKGROUND

Microvascular endothelial dysfunction is central to the pathogenesis of cardiovascular disease (CVD). The eye offers direct access for endothelial health assessment via the retinal microvasculature. The aim of the study was to investigate whether image-based retinal vessel analysis is a feasible method of assessing endothelial health in survivors of childhood acute lymphoblastic leukemia (cALL).

MATERIALS AND METHODS

Cardiovascular risk factors (CRFs) were estimated using the 30-year Framingham Risk Score in 73 childhood leukemia survivors (median age: 25; median years from diagnosis: 19) and 78 healthy controls (median age: 23). Radial arterial stiffness was measured using pulse wave analyzer, while endothelial activation markers were measured by soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule 1 (sVCAM-1). Retinal fundus images were analyzed for central retinal artery/vein equivalents (CRAE/CRVE) and arteriolar-venular ratio (AVR).

RESULTS

cALL survivors had higher CRF (P<0.0001), arterial stiffness (P=0.001), and sVCAM-1 (P=0.007) compared with controls. Survivors also had significantly higher CRVE (P=0.021) while AVR was significantly lower (P=0.026) in survivors compared with controls, compatible with endothelial dysfunction. In cALL survivors with intermediate risk for CVD, CRAE, and AVR are significantly lower, while sVCAM-1 and sICAM-1 are significantly higher when compared with survivors with low CVD risk after adjusting with covariates (age, sex, and smoking status).

CONCLUSIONS

cALL survivors have an increased risk of CVD compared with age-matched peers. The survivors demonstrated microvasculopathy, as measured by retinal vascular analysis, in addition to physical and biochemical evidence of endothelial dysfunction. These changes predate other measures of CVD. Retinal vessel analysis may be utilized as a robust screening tool for identifying survivors at increased risk for developing CVD.

Vascular effects of physical activity are not modified by short-term inhaled diesel exhaust: Results of a controlled human exposure study

BACKGROUND

The combined effects of physical activity and air pollution exposure on vascular function are insufficiently understood, particularly after the inhalation of a β₂-agonist, a vasodilating agent.

OBJECTIVE

To assess the micro- and macrovascular response to physical activity after β₂-agonist use while breathing diesel exhaust (DE) in individuals with exercise-induced bronchoconstriction.

METHODS

On four exposure visits, eighteen adults inhaled either 400 μg of the β₂-agonist salbutamol or placebo before resting for 60 min, followed by a 30-min cycling bout. During rest and cycling, participants inhaled filtered air (FA) or DE (300 μg/m³ of PM_2.5). Microvascular (central retinal arteriolar and venular equivalents, CRAE and CRVE, respectively) and macrovascular parameters (blood pressure (BP)) and heart rate (HR)) were assessed at baseline (T₁), 10 min (T₂) and 70 min (T₃) after cycling.

RESULTS

The cycling bout increased CRAE (T₂-T₁ difference (95th % confidence interval): 4.88 μm (4.73, 5.00 μm), p < 0.001; T₃-T₁ difference: 2.10 μm (1.62, 2.58 μm), p = 0.031) and CRVE (T₂-T₁ difference: 3.78 μm (3.63, 3.92 μm), p < 0.001; T₃-T₁ difference: 3.73 μm (3.63, 3.92 μm), p < 0.001). The exposure to DE had no effect on CRAE (FA-DE difference at T₂: 0.46 μm (-0.02, 0.92 μm); p = 0.790; FA-DE difference at T₃: 1.76 μm (1.36, 2.16 μm), p = 0.213) and CRVE (FA-DE difference at T₂: 0.26 μm (-0.35, 0.88 μm), p = 0.906; FA-DE difference at T₃: 0.55 μm (0.05, 1.06 μm), p = 0.750). Compared to T₁, systolic BP was decreased at T₂ by 2.5 mmHg (2.8, 2.3 mmHg, p = 0.047), independent of inhaled exposure. Heart rate at T₂ was significantly increased by 3 bpm (2, 3 bpm, p = 0.025) after the DE-exposure when compared to FA.

DISCUSSION

Acute physical activity induces a vasodilatory response in the micro- and macrovasculature in healthy adults by increasing CRAE and CRVE, and by reducing systolic BP post exercise, despite breathing DE. The DE-associated increase in HR might be indicative of an increased sympathetic response to physical activity while breathing DE.

Analysis of central macular thickness and choroidal thickness changes in patients with cardiovascular risk factors

OBJECTIVES

The aim of this study was to evaluate central macular thickness (CMT) and choroidal thickness (CT) in the eyes of patients with cardiovascular risk factors (CVRF).

METHODS

A cross-sectional, prospective observational study of 92 patients with CVRF and 21 healthy individuals was conducted. Patients were divided into four groups according to the SCORE system. CMT was evaluated via spectral-domain-optical coherence tomography (SD-OCT). CT at five defined points (subfoveal) [SF] and nasal 500 μm [N0.5] and 1500 μm [N1.5] and 500 μm [T0.5] and temporal 1500 μm [T1.5] from the center of the fovea were measured via enhanced depth imaging (EDI)-OCT.

RESULTS

Mean SFCT at right eyes (RE) and left eyes (LE) were 311.21 ± 77.7 μm and 303.5 ± 49.6 μm, respectively, in patients with mild CVRF (Group 1); 266.5 ± 63.2 μm and 267.0 ± 62.6 μm, respectively, in patients with moderate CVRF (Group 2); 264.7 ± 57.5 μm and 272.3 ± 64.6 μm, respectively, in patients with high CVRF (Group 3); 272.3 ± 64.6 μm and 271.2 ± 63.4 μm, respectively, in patients with very high-risk CVRF (with coronary arterial disease (CAD) (Group 4); and 352.0 ± 74.4 μm and 363.1 ± 89.0 μm, respectively, in the control group. CT (at both eyes) was significantly lower at the subfoveal location in all study groups (P < 0.05), but at nasal and at temporal quadrants of group 3 and group 4 (P < 0.05). No significant difference in CMT was detected between the study and control groups.

CONCLUSIONS

This study demonstrated that CVRF might result in a remarkably thinner CT. Furthermore, subretinal drusenoid deposits were detected at a higher rate in the patients with CVRF than controls, and that rate increased in accordance with the severity of CAD. In the future, changes in CT may be used as a promising novel biomarker as part of the SCORE system prior to the development of CAD.

Relation between retinal vessel diameter and posterior segment optical coherence tomography variables in middle-aged Caucasians: the Northern Finland Birth Cohort Eye Study

AIMS

Studying the relationship between retinal vessel diameter (RVD) with (1) macular thickness and volume, (2) retinal nerve fibre layer (RNFL), (3) ganglion cell-inner plexiform layer (GC-IPL) and (4) optic nerve head (ONH) in a population cohort of middle-aged Caucasians.

METHODS

We collected data from 3070 individuals. We used a semiautomated computer-assisted programme to measure central retinal arteriolar equivalent and central retinal venular equivalent. Macular and ONH parameters were assessed by optical coherence tomography.

RESULTS

Data from 2155 persons were analysed. A larger RVD was associated with a thicker macula and increased macular volume; each SD increase in average macular thickness and volume was associated with a 3.28 µm and a 3.19 µm increase in arteriolar diameter and a 5.10 µm and a 5.08 µm increase in venular diameter, respectively (p<0.001 for all). A larger rim area, greater GC-IPL and RNFL thicknesses were associated with larger RVD; each SD increase in rim area, GC-IPL thickness and RNFL thickness was associated with a 1.21 µm, 2.68 µm and a 3.29 µm increase in arteriolar diameter and a 2.13 µm, 4.02 µm and 5.04 µm increase in venular diameter, respectively (p<0.001 for all).

CONCLUSIONS

Increased macular thickness, macular volume, GC-IPL thickness, RNFL thickness and optic nerve rim area were associated with larger RVDs in all subjects. This study clarified the anatomical correlations between both macular and ONH parameters with RVD for middle-aged Caucasians; these can represent a basis for further studies investigating the vascular aetiology of eye diseases.

Physical activity may drive healthy microvascular ageing via downregulation of p66Shc

Background

Narrower retinal arterioles and wider venules are linked to adverse cardiovascular outcomes. The mitochondrial adaptor p66Shc is a major source of ageing-induced generation of reactive oxygen species. Promoter DNA methylation inhibits p66Shc gene transcription. This cross-sectional study was designed to investigate the link between physical activity, retinal vessel diameters and p66Shc expression in active and sedentary ageing subjects.

Design/methods

Altogether 158 subjects were included in the study (mean age 59.4 ± 7.0 years). Thirty-eight subjects were healthy active, 36 were healthy sedentary and 84 were sedentary with ≥2 cardiovascular risk factors. Retinal arteriolar and venular diameters were measured by means of a retinal vessel analyser. As a marker of oxidative stress, plasma 3-nitrotyrosine was determined by enzyme-linked immunosorbent assay. Gene expression of p66Shc and DNA methylation were assessed in mononuclear cells by real-time quantitative polymerase chain reaction and methylated-DNA capture (MethylMiner Enrichment kit) coupled with quantitative polymerase chain reaction, respectively.

Results

Wider retinal arterioles (179 ± 14 vs 172 ± 11 and 171 ± 14 µm; p < 0.05 and narrower venules (204 ± 17 vs 209 ± 11 and 218 ± 16 µm; p < 0.001) were observed in healthy active subjects compared with healthy sedentary subjects and sedentary subjects with ≥2 cardiovascular risk factors, respectively. Furthermore, healthy active subjects had blunted p66Shc expression and lower 3-nitrotyrosine plasma levels compared with healthy sedentary and sedentary subjects with ≥2 cardiovascular risk factors. Accordingly, hypomethylation of p66Shc promoter observed in healthy sedentary and sedentary subjects with ≥2 cardiovascular risk factors was not found in healthy active subjects.

Conclusion

Long-term physical activity-induced DNA methylation of p66Shc may represent a putative mechanistic link whereby active lifestyle promotes healthy microvascular ageing.

Serum Phosphate and Microvascular Function in a Population-Based Cohort

BACKGROUND AND OBJECTIVES

Higher serum phosphate is associated with cardiovascular events and all-cause mortality. Explanations of this association have focused on large vessel calcification and stiffness. Studies suggest that a higher serum phosphate induces microvascular dysfunction, but relationships in humans with direct measures of microvascular function are lacking.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a cross-sectional analysis of 3189 community-living participants that underwent skin capillaroscopy, laser-Doppler flowmetry, and flicker light-induced retinal vessel responses. We used linear regression to assess the association between serum phosphate and each microvascular outcome. The primary outcome was skin capillary recruitment during postocclusive peak reactive hyperemia by capillaroscopy. Secondary outcomes included capillary recruitment during venous congestion, heat-induced skin hyperemic response, flicker light-induced retinal arteriolar, and venular dilation.

RESULTS

The mean age of the cohort was 59±8 years, 48% were women, 7% had an eGFR <60 ml/min per 1.73 m², and the mean serum phosphate concentration was 3.2±0.5 mg/dl. A 1 mg/dl higher serum phosphate was independently associated with a 5.0% lower postocclusive capillary recruitment (95% CI, -10.0% to -0.1%). Results were similar for capillary recruitment with venous congestion (-4.5%; 95% CI, -9.8% to 0.7%). A 1 mg/dl higher serum phosphate was also independently associated with a 0.23% lower retinal venular dilation in response to flicker light (95% CI, -0.44% to -0.02%). A higher serum phosphate was not associated with change in flicker light-induced retinal arteriolar dilation or heat-induced skin hyperemic response, however a higher serum phosphate was associated with a lower heat-induced skin hyperemic response among men (-149% [95% CI, -260 to -38] per 1 mg/dl higher serum phosphate) but not women (P interaction, 0.01).

CONCLUSIONS

Higher serum phosphate concentrations, even within the normal range, are associated with microvascular dysfunction in community-living individuals.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_09_20_CJN02610319.mp3.

Relationship between retinal vessel diameter with both retinal nerve fibre layer thickness and optic nerve head parameters in middle-aged Caucasians: the Northern Finland Birth Cohort Eye study

Purpose

To study the normal relationship between retinal vessel diameter (RVD) with retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) parameters in a cohort of middle‐aged Caucasians.

Methods

We investigated 3070 individuals (6140 eyes). Central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were measured in the right eye using a semi‐automated computer‐assisted program. Retinal nerve fibre layer (RNFL) thickness and ONH parameters were assessed with Heidelberg retinal tomography (HRT).

Results

Data from 2217 persons were analysed including RNFL, CRAE, CRVE, sex, body mass index, mean arterial pressure, diabetes status, smoking status, optic disc area, rim area, spherical refraction and intraocular pressure. A larger RVD was associated with a thicker mean global RNFL thickness especially in global and inferior segments of the retina and with larger optic discs. Each 10 μm increase in the retinal arteriolar calibre was associated with a 5.58 μm increase in mean global RNFL thickness; the corresponding value for a 10 μm increase in venular calibre was 3.79 μm (p < 0.001 for both). Retinal venular calibre displayed consistent associations with RNFL thickness in both genders (p < 0.001 for all), whereas the association of arteriolar calibre and RNFL was more prominent in men (p < 0.001).

Conclusion

We found strong associations between larger RVD and thicker RNFL in all subjects. This study helps to clarify the association between RVD, RNFL thickness and ONH parameters and provides normal values for middle‐aged Caucasians that will help in future studies investigating the role of vascular aetiology in systemic and eye diseases.

A novel method for retinal vessel segmentation and diameter measurement using high speed video

Studying dynamic characteristics of retinal vessels, as opposed to static measures, may provide additional insight into pathophysiological changes associated with local and systemic abnormalities such as glaucoma and hypertension. Various approaches have been developed to derive static biomarkers from retinal still images, but not many for dynamic analysis of video sequences. This study presents a novel method for the assessment of time-dependent diameter changes in high-speed videos (125 fps) from the rat retina. The proposed method is composed of a vessel segmentation and a diameter measurement module. The specificity and sensitivity of the segmentation method over 25 images were 95.1% and 97.3% respectively. The mean and standard deviation of the diameter measurement errors were -0.147±0.41 pixels over 100 measurements.

Detection of smoking status from retinal images; a Convolutional Neural Network study

Cardiovascular diseases are directly linked to smoking habits, which has both physiological and anatomical effects on the systemic and retinal circulations, and these changes can be detected with fundus photographs. Here, we aimed to 1- design a Convolutional Neural Network (CNN), using retinal photographs, to differentiate between smokers and non-smokers; and 2- use the attention maps to better understand the physiological changes that occur in the retina in smokers. 165,104 retinal images were obtained from a diabetes screening programme, labelled with self-reported "smoking" or "non-smoking" status. The images were pre-processed in one of two ways, either "contrast-enhanced" or "skeletonized". Experiments were run on an Intel Xeon Gold 6128 CPU @ 3.40 GHz with 16 GB of RAM memory and a NVIDIA GeForce TiTan V VOLTA 12 GB, for 20 epochs. The dataset was split 80/20 for training and testing sets, respectively. The overall validation outcomes for the contrast-enhanced model were accuracy 88.88%, specificity 93.87%. In contrast, the outcomes of the skeletonized model were accuracy 63.63%, specificity 65.60%. The "attention maps" that were generated of the contrast-enhanced model highlighted the retinal vasculature, perivascular region and the fovea most prominently. We trained a customized CNN to accurately determine smoking status. The retinal vasculature, the perivascular region and the fovea appear to be important predictive features in the determination of smoking status. Despite a high degree of accuracy, the sensitivity of our CNN was low. Further research is required to establish whether the frequency, duration, and dosage (quantity) of smoking would improve the sensitivity of the CNN.

Retinal and choroidal vascular changes in coronary heart disease: an optical coherence tomography angiography study

To reveal the association between retinal microvasculature changes and coronary heart disease (CHD), we assessed the full retinal thicknesses of eight areas, the vessel density of four layers (consisting of nine areas) and the flow area in two layers with optical coherence tomography angiography (OCTA) in CHD patients and healthy controls. The mean vessel density of several layers was significantly lower in patients. The difference in choroid capillary flow (negative correlation) between the two groups was significant. Decreased vessel density and blood flow were associated with coronary artery and branch stenosis. The decreases in retinal vessel density, choroidal vessel density, and blood flow area are closely related to coronary artery and branch stenosis.

Retinal vascular changes and right ventricular structure and function: the MESA-Right Ventricle and MESA-Eye studies

Retinal vessel diameters have been associated with left ventricular morphology and function but their relationship with the right ventricle (RV) has not been studied. We hypothesized that wider retinal venules and narrower retinal arterioles are associated with RV morphology and function. RV end-diastolic mass (RVEDM), end-diastolic volume (RVEDV), end-systolic volume (RVESV), stroke volume (RVSV), and ejection fraction (RVEF) were assessed using cardiac magnetic resonance imaging (MRI) scans of 4204 participants without clinical cardiovascular disease at the baseline examination; retinal photography was obtained at the second examination. Mean diameters of retinal arterioles and venules were measured and summarized as central retinal vein and artery equivalents (“veins” and “arteries,” respectively). After adjusting for covariates, wider veins were associated with greater RVEDM and RVEDV in women (P = 0.04 and P = 0.02, respectively), whereas there was an inverse association with RVEDV in men (P = 0.02). In both sexes, narrower arteries were associated with lower RVEDM (P < 0.001 in women and P = 0.002 in men) and smaller RVEDV (P < 0.001 in women and P = 0.04 in men) in adjusted models. Narrower arteries were also associated with lower RVEF in men but this was of borderline significance after adjusting for the LVEF (P = 0.08). Wider retinal venular diameter was associated with sex-specific changes in RVEDM and RVEDV in adults without clinical cardiovascular disease. Narrower retinal arteriolar diameter was associated with significantly lower RVEDM and smaller RVEDV in both sexes.

Looking into the eye of patients with chronic obstructive pulmonary disease: an opportunity for better microvascular profiling of these complex patients

Chronic obstructive pulmonary disease (COPD) is a complex disease with many patients suffering from cardiovascular comorbidity. However, cardiovascular diseases remain often undiagnosed in COPD. Assessment of the retinal microvasculature can provide value in cardiovascular profiling of these patients. Retinal microvascular assessment carried out via a noninvasive eye exam represents an easy to use tool when examining patients with COPD. The purpose of this review was to provide an overview of studies assessing structural and functional changes in the retinal microvasculature of patients with COPD. Findings demonstrated that structural and functional microvascular changes were more common and severe in COPD patients as compared to non-COPD controls, although few retinal investigations have been performed in patients with COPD. As cardiovascular comorbidities are highly prevalent in COPD, we advocate more research to investigate the value of an eye exam for microvascular phenotyping of COPD patients.

Periodontitis and multiple markers of cardiometabolic risk in the fourth decade: A cohort study

OBJECTIVES

To examine associations between periodontitis at ages 32 and 38 and a range of early cardiometabolic risk biomarkers at age 38.

METHODS

Periodontal probing depth and bleeding on probing data collected during the age-32 and age-38 assessments in the Dunedin Multidisciplinary Health and Development Study were used to quantify periodontal inflammatory load. Retinal microvascular abnormalities, endothelial dysfunction, and metabolic syndrome data were collected during the age-38 assessment. Regression models were used to examine associations between these cardiometabolic risk markers and (1) the inflammatory load at age 38 and (2) the change in inflammatory load between ages 32 and 38.

RESULTS

Periodontal inflammatory load was recorded for 890 Study members at age 32, 891 at age 38, and 856 at both ages. Retinal vessel data were available for 922, endothelial dysfunction data for 909 and metabolic syndrome data for 905 at age 38. Neither the inflammatory load of periodontitis at 38 nor the changes in inflammatory load 32-38 were found to be associated with any of the three cardiometabolic risk markers.

CONCLUSIONS

Periodontitis was not associated with markers of cardiometabolic risk at this relatively early stage in the life course. It is possible that any influence of periodontitis on cardiometabolic health develops later in life, or periodontitis is not involved in the putative causal chain comprising systemic inflammation, cardiometabolic risk markers, and subsequent cardiovascular risk.

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.

Update on retinal vascular caliber

Retinal vessels are the only blood vessels that can be viewed directly, in vivo, repetitively and non-invasively. Retinal vessel caliber is influenced by physiological (age, sex, race, blood pressure, blood glucose, body mass index) and pathological (atherosclerosis, dyslipidemia, smoking) determinants. There are studies on large population groups that demonstrate the associations between retinal vasculature and subclinical or clinical changes in systemic diseases (hypertension, diabetes, stroke, renal or cardiac diseases). The assessment of retinal vessels can provide information about the pathophysiology of many diseases, but it also has a direct applicability in clinic, being used as a screening method that predicts the risk of their occurrence.

Physical Activity as a Determinant of Successful Aging over Ten Years

We aimed to examine the temporal association between physical activity and successful aging. The analyses involved 1,584 adults aged 49 + years living west of Sydney (Australia), who did not have cancer, coronary artery disease and stroke at baseline and who were followed over 10 years. Participants provided information on the performance of moderate or vigorous activities and walking exercise and this was used to determine total metabolic equivalents (METs) minutes of activity per week. Successful aging status was determined through interviewer-administered questionnaire and was classified as the absence of: depressive symptoms, disability, cognitive impairment, respiratory symptoms and systemic conditions (e.g. cancer, coronary artery disease). 249 (15.7%) participants (mean age 59.9 ± 6.1) had aged successfully 10 years later. After multivariable adjustment; older adults in the highest level of total physical activity (≥5000 MET minutes/week; n = 71) compared to those in the lowest level of total physical activity (<1000 MET minutes/week; n = 934) had 2-fold greater odds of aging successfully than normal aging, odds ratio, OR, 2.08 (95% confidence intervals, CI, 1.12–3.88). Older adults who engaged in high levels of total physical activity, well above the current recommended minimum level had a greater likelihood of aging successfully 10 years later.

Retinal vessel morphology in rheumatoid arthritis: Association with systemic inflammation, subclinical atherosclerosis, and cardiovascular risk

OBJECTIVE

Quantification of retinal vessel morphology has emerged as a marker of cardiovascular health. We examined retinal microvascular diameters in RA, particularly in regard to systemic inflammation, subclinical atherosclerosis, and cardiovascular risk.

METHODS

Retinal images from RA patients and controls were processed using computerized software, to obtain CRAE and CRVE and AVR. Subclinical atherosclerosis was assessed with cIMT, and 10-year risk of general cardiovascular disease was calculated.

RESULTS

Both CRAE (78.8 ± 8.9 vs 90.2 ± 9.9 μm, P < .001) and AVR (0.69 ± 0.09 vs 0.81 ± 0.09, P < .001) were decreased in RA patients (n = 87) compared to controls (n = 46), whereas CRVE did not differ. Among RA patients, CRAE and AVR were inversely associated with both cIMT and CRP, whereas CRVE positively correlated with CRP (P < .05 for all). CRAE additionally correlated with cardiovascular risk score (r = -.396, P = .001). In the multivariate analysis, cardiovascular risk was associated with CRAE; age with CRVE, while CRP independently predicted AVR.

CONCLUSIONS

Our study shows altered retinal microvascular morphology in RA patients. Inflammation appears as the biological link for the observed association between retinal microvascular abnormalities and subclinical atherosclerosis. Retinal arteriolar narrowing might play its own role in cardiovascular risk prediction in RA.

Automated classification and quantitative analysis of arterial and venous vessels in fundus images

It is known that retinopathies may affect arteries and veins differently. Therefore, reliable differentiation of arteries and veins is essential for computer-aided analysis of fundus images. The purpose of this study is to validate one automated method for robust classification of arteries and veins (A-V) in digital fundus images. We combine optical density ratio (ODR) analysis and blood vessel tracking algorithm to classify arteries and veins. A matched filtering method is used to enhance retinal blood vessels. Bottom hat filtering and global thresholding are used to segment the vessel and skeleton individual blood vessels. The vessel tracking algorithm is used to locate the optic disk and to identify source nodes of blood vessels in optic disk area. Each node can be identified as vein or artery using ODR information. Using the source nodes as starting point, the whole vessel trace is then tracked and classified as vein or artery using vessel curvature and angle information. 50 color fundus images from diabetic retinopathy patients were used to test the algorithm. Sensitivity, specificity, and accuracy metrics were measured to assess the validity of the proposed classification method compared to ground truths created by two independent observers. The algorithm demonstrated 97.52% accuracy in identifying blood vessels as vein or artery. A quantitative analysis upon A-V classification showed that average A-V ratio of width for NPDR subjects with hypertension decreased significantly (43.13%).

Association of cardiorespiratory fitness with retinal vessel diameters as a biomarker of cardiovascular risk

OBJECTIVE

We aimed to investigate the association of retinal microvascular health with cardiorespiratory fitness (VO₂peak) and cardiovascular risk factors.

METHODS

In a population of 260 obesity-enriched participants we investigated the association of retinal vessel diameters with cardiorespiratory fitness (CRF), body mass index (BMI) and blood pressure (BP). Retinal vessel imaging was performed by use of a fundus camera and a semi-automated processing software, calculating the central retinal arteriolar (CRAE) and venular equivalent (CRVE) as well as the arteriolar-to-venular diameter ratio (AVR).

RESULTS

Participants had a mean age of 45.8 ± 12.5 years and a BMI of 35.8 ± 6.8 kg/m². 45% of patients were diagnosed with hypertension, 26% with diabetes and 30% with dyslipidemia. Increasing VO₂peak was independently associated with lower CRVE (β = -0.600; CI -1.141, -0.060; p = 0.030). Higher BMI and mean arterial pressure were independently associated with narrower CRAE (β = -0.492; CI -0.909, -0.076; p = 0.021 and β = -0.268; CI -0.471, -0.066; p = 0.009, respectively) and lower AVR (β = -0.002; CI -0.003, -0.000; p = 0.026 and β = -0.001; CI -0.002, -0.000; p = 0.001, respectively).

CONCLUSIONS

Higher cardiorespiratory fitness is associated with beneficial retinal microvascular health. Higher BMI and BP were associated with an impairment of retinal microvascular health. Exercise is known for its potential to improve body composition and reduce BP but may also prove to be an efficient therapy to counteract small vessel disease in cardiometabolic disease.

Retinal vascular diameters in relation to physical activity in Danish children - The CHAMPS Eye Study

Our objective was to determine associations between retinal vascular caliber and physical activity (PA) in a school-based child cohort. In a prospective study, we created a childhood cumulative average PA-index using objectively measured PA (accelerometry) assessed at four periods between 2009 and 2015. Cumulative exposure to PA intensities was estimated. Cross-sectional examinations on biomarkers, anthropometry, and ophthalmological data including retinal fundus photographs were performed in 2015. Semi-automated measurements of retinal vascular diameters were performed and summarized into central retinal arteriolar and venular equivalents (CRAE, CRVE). We included 307 participants. Mean age in 2015 was 15.4 years (0.7). The mean CRAE and CRVE were 156.5 μm (2.8) and 217.6 μm (7.7), respectively. After adjusting for age, gender, and axial length, more time in PA was independently related to thinner retinal venules (β-coefficient = -1.25 μm/%, 95% confidence interval = -2.20, -0.30, P < .01). Sedentary time was associated with wider venules (P < .01). Furthermore, birthweight (β-coefficient = 0.56 μm/%, 95% confidence interval = 0.18, 0.95, P < .01) was associated with CRVE. Blood pressure was associated with thinner retinal arterioles (β-coefficient = -0.19 μm/mmHg, 95% confidence interval = -0.36, -0.01, P = .04). We concluded that children with higher PA in childhood had thinner retinal venular caliber. Our results suggest that PA during childhood positively impacts the retinal microcirculation and that retinal vascular analysis may be a possible assessment to detect microvascular impairments in children with an increased risk of future cardiovascular disease.

Combining ODR and Blood Vessel Tracking for Artery-Vein Classification and Analysis in Color Fundus Images

Purpose

This study aims to develop a fully automated algorithm for artery–vein (A-V) and arteriole-venule classification and to quantify the effect of hypertension on A-V caliber and tortuosity ratios of nonproliferative diabetic retinopathy (NPDR) patients.

Methods

We combine an optical density ratio (ODR) analysis and blood vessel tracking (BVT) algorithm to classify arteries and veins and arterioles and venules. An enhanced blood vessel map and ODR analysis are used to determine the blood vessel source nodes. The whole vessel map is then tracked beginning from the source nodes and classified as vein (venule) or artery (arteriole) using vessel curvature and angle information. Fifty color fundus images from NPDR patients are used to test the algorithm. Sensitivity, specificity, and accuracy metrics are measured to validate the classification method compared to ground truths.

Results

The combined ODR-BVT method demonstrates 97.06% accuracy in identifying blood vessels as vein or artery. Sensitivity and specificity of A-V identification are 97.58%, 97.81%, and 95.89%, 96.68%, respectively. Comparative analysis revealed that the average A-V caliber and tortuosity ratios of NPDR patients with hypertension have 48% and 15.5% decreases, respectively, compared to that of NPDR patients without hypertension.

Conclusions

Automated A-V classification has been achieved by combined ODR-BVT analysis. Quantitative analysis of color fundus images verified robust performance of the A-V classification. Comparative quantification of A-V caliber and tortuosity ratios provided objective biomarkers to differentiate NPDR groups with and without hypertension.

Translational Relevance

Automated A-V classification can facilitate quantitative analysis of retinal vascular distortions due to diabetic retinopathy and other eye conditions and provide increased sensitivity for early detection of eye diseases.

Association between optical coherence tomography based retinal microvasculature characteristics and myocardial infarction in young men

Incident myocardial infarction (MI) is a leading cause of adult mortality in the United States. However, because MI has a relatively low incidence in the young population, little information exists on the disease in younger adults. Because the retina has the unique quality that its vasculature is readily and noninvasively visible, the retina is frequently studied to evaluate correlations between vessels and cardiovascular diseases. In the current study, we evaluated the retinal microvasculature of patients who had experienced an MI before 50 years of age (n = 53 subjects) and age- and sex-matched patients who had not experienced an MI (n = 53 patients). We used circular optical coherence tomography (OCT) scans to image peripapillary venules and arterioles. The diameter of each vessel was measured and the respective arterial-venous ratio (AVR) was calculated. We did not detect any significant differences between MI and control subjects in retinal vessel calibre or AVR.

Retinal Vessel Diameters and Physical Activity in Patients With Mild to Moderate Rheumatic Disease Without Cardiovascular Comorbidities

Objectives: Low-grade systemic inflammation is responsible for atherosclerotic lesions in patients with rheumatic diseases. Vascular dysfunction is a precursor of atherosclerosis and can be improved by physical activity (PA). Our aim was to asses micro- and macrovascular function as well as PA and cardiorespiratory fitness (CRF) in patients with rheumatic diseases in the absence of cardiovascular (CV) comorbidities compared to controls. Methods: Fifty-one patients without CV comorbidities were compared to 35 controls. Retinal microvascular diameters were assessed using a Retinal Vessel Analyzer. Arterial stiffness (AST) was measured by applanation tonometry. CRF was assessed as peak oxygen consumption and PA was assessed with a questionnaire. Results: Retinal venular diameters were significantly wider in patients [median 221 μm (interquartile range (IQR) 211, 231)] compared to controls [median 215 μm (IQR 196, 223); p = 0.01]. One hour increase of PA per week led to a venular constriction of -0.56 μm (95%CI -1.09, -0.03; p = 0.04). In our patients with low disease activity (median DAS28 1.9; median BASDAI 2.8), no differences in AST were evident compared to controls. The association of PA and CRF with AST was not independent of blood pressure. Conclusions: Patients with rheumatic disease and mild-to-moderate disease activity show an impairment of the retinal microvasculature but not of large artery stiffness. Retinal vessel analysis seems to be a sensitive biomarker to unmask vascular impairments even in the absence of classic CV risk factors. PA may have the potential to counteract the development of small artery disease at early stages of rheumatic disease.

The relationship of systemic markers of haemostasis with retinal blood vessel responses in cardiovascular disease and/or diabetes

Background Hypercoagulability is a leading factor in diabetes and cardiovascular disease. Retinal vessel responses to flickering light are an important tool for assessing ocular function. We hypothesised a significant relationship between systemic markers of haemostasis and retinal vessel function. Methods Intra-ocular pressure and retinal microcirculation function were measured in 116 patients with diabetes and/or cardiovascular disease using unstimulated and stimulated arterial and venous retinal vessel responses to flickering light. Haemostasis was evaluated by platelet microparticles, soluble P selectin, and five functional markers of fibrin clot formation and lysis, hyperglycaemia by HbA1c. Results Intra-ocular pressure was linked to the rates of clot formation (p = 0.006) and clot dissolution (p = 0.013) whilst central retinal vein equivalent was linked to HbA1c (p = 0.017). In the first of three flickering light cycles only, arterial baseline diameter fluctuation was linked to the lag time to clot formation (p = 0.017), whilst maximum venous dilatation was linked to HbA1c (p = 0.001) and clot density (p = 0.011). HbA1c was linked to venous dilatation amplitude (p = 0.003). There were no significant links between any ocular index and any platelet index. Conclusions In addition to glycaemia, several haemostasis measures, but no measures of platelet activity, are linked to ocular and retinal blood vessel indices in patients with diabetes and/or cardiovascular disease. These associations may have pathophysiological significance.

Prediction of cardiovascular risk factors from retinal fundus photographs via deep learning

Traditionally, medical discoveries are made by observing associations, making hypotheses from them and then designing and running experiments to test the hypotheses. However, with medical images, observing and quantifying associations can often be difficult because of the wide variety of features, patterns, colours, values and shapes that are present in real data. Here, we show that deep learning can extract new knowledge from retinal fundus images. Using deep-learning models trained on data from 284,335 patients and validated on two independent datasets of 12,026 and 999 patients, we predicted cardiovascular risk factors not previously thought to be present or quantifiable in retinal images, such as age (mean absolute error within 3.26 years), gender (area under the receiver operating characteristic curve (AUC) = 0.97), smoking status (AUC = 0.71), systolic blood pressure (mean absolute error within 11.23 mmHg) and major adverse cardiac events (AUC = 0.70). We also show that the trained deep-learning models used anatomical features, such as the optic disc or blood vessels, to generate each prediction.