Retinal Arteriolar Narrowing Predicts 5-Year Risk of Hypertension in Japanese People: The Funagata Study

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.

Retinal venular vessel diameters are smaller during ten days of bed rest

Older individuals experience cardiovascular dysfunction during extended bedridden hospital or care home stays. Bed rest is also used as a model to simulate accelerated vascular deconditioning occurring during spaceflight. This study investigates changes in retinal microcirculation during a ten-day bed rest protocol. Ten healthy young males (22.9 ± 4.7 years; body mass index: 23.6 ± 2.5 kg·m-2) participated in a strictly controlled repeated-measures bed rest study lasting ten days. High-resolution images were obtained using a hand-held fundus camera at baseline, daily during the 10 days of bed rest, and 1 day after re-ambulation. Retinal vessel analysis was performed using a semi-automated software system to obtain metrics for retinal arteriolar and venular diameters, central retinal artery equivalent and central retinal vein equivalent, respectively. Data analysis employed a mixed linear model. At the end of the bed rest period, a significant decrease in retinal venular diameter was observed, indicated by a significantly lower central retinal vein equivalent (from 226.1 µm, CI 8.90, to 211.4 µm, CI 8.28, p = .026), while no significant changes in central retinal artery equivalent were noted. Prolonged bed rest confinement resulted in a significant (up to 6.5%) reduction in retinal venular diameter. These findings suggest that the changes in retinal venular diameter during bedrest may be attributed to plasma volume losses and reflect overall (cardio)-vascular deconditioning.

Clinical Significance of Altered Vascular Morphology and Function in Normotension

PURPOSE OF REVIEW

To review current literature examining the presence of subclinical micro- and macrovascular alterations in normotensive individuals and their clinical significance in terms of hypertension prediction. Emphasis is placed on alterations that can be detected in peripheral vascular beds using non-invasive, easily applicable methodology, as these are in general easier to capture and evaluate in clinical practice compared to more complex invasive or functional tests.

RECENT FINDINGS

Arterial stiffness, increased carotid intima-media thickness, and altered retinal microvascular diameters predict the progression from the normotensive to the hypertensive state. By contrast, there is substantial lack of relevant prospective studies for skin microvascular alterations. Although conclusions regarding causality cannot be safely deduced from available studies, detection of morphological and functional vascular alterations in normotensive individuals emerges as a sensitive indicator of progression to hypertension and hence increased CVD risk. An increasing amount of evidence suggests that early detection of subclinical micro- and macrovascular alterations would be clinically useful for the early identification of individuals at high risk for future hypertension onset. Methodological issues and gaps in knowledge need to be addressed before detection of such changes could guide the development of strategies to prevent new-onset hypertension in normotensive individuals.

Sex Variations in Retinal Microcirculation Response to Lower Body Negative Pressure

INTRODUCTION

Lower body negative pressure (LBNP) is routinely used to induce central hypovolemia. LBNP leads to a shift in blood to the lower extremities. While the effects of LBNP on physiological responses and large arteries have been widely reported, there is almost no literature regarding how these cephalad fluid shifts affect the microvasculature. The present study evaluated the changes in retinal microcirculation parameters induced by LBNP in both males and females.

METHODOLOGY

Forty-four participants were recruited for the present study. The retinal measurements were performed at six time points during the LBNP protocol. To prevent the development of cardiovascular collapse (syncope) in the healthy participants, graded LBNP until a maximum of -40 mmHg was applied. A non-mydriatic, hand-held Optomed Aurora retinal camera was used to capture the retinal images. MONA Reva software (version 2.1.1) was used to analyze the central retinal arterial and venous diameter changes during the LBNP application. Repeated measures ANOVAs, including sex as the between-subjects factor and the grade of the LBNP as the within-subjects factor, were performed.

RESULTS

No significant changes in retinal microcirculation were observed between the evaluated time points or across the sexes.

CONCLUSIONS

Graded LBNP application did not lead to changes in the retinal microvasculature across the sexes. The present study is the first in the given area that attempted to capture the changes in retinal microcirculation caused by central hypovolemia during LBNP. However, further research is needed with higher LBNP levels, including those that can induce pre-fainting (presyncope), to fully understand how retinal microcirculation adapts during complete cardiovascular collapse (e.g., during hypovolemic shock) and/or during severe hemorrhage.

RV-ESA: A novel computer-aided elastic shape analysis system for retinal vessels in diabetic retinopathy

Diabetic retinopathy (DR), one of the most common and serious complications of diabetes, has become one of the main blindness diseases. The retinal vasculature is the only part of the human circulatory system that allows direct noninvasive visualization of the body's microvasculature, which provides the opportunity to detect the structural and functional changes before DR becomes unable to intervene. For decades, as the fundamental step in computer-assisted analysis of retinopathy, retinal vascular extraction methods have been largely developed. However, further research focusing on retinal vascular analysis is still in its infancy. Meanwhile, due to the complexity of retinal vascular structure, the relationship between vascular geometry and DR has never been concluded. This paper aims to provide a novel computer-aided shape analysis system for retinal vessels. To perform retinal vascular shape analysis, a mathematical geometric representation is firstly generated by utilizing the proposed shape modeling method. Then, several useful statistical tools (e.g. Graph Mean, Graph PCA) are adopted to quantitatively analyze the vascular shape. Besides, in order to visualize the changes in vascular shape in the progression of DR, a geodesic tool is used to display the deformation process for ophthalmologists to observe. The efficacy of this analysis system is demonstrated in the EyePACS dataset and the subsequent visit records of 98 patients from the proprietary dataset. The experimental results show that there is a certain correlation between the variation of retinal vascular shape and DR progression, and the Graph PCA scores of retinal vessels are negatively correlated with DR grades. The code of our RV-ESA system can be publicly available at github.com/XiaolingLuo/RV-ESA.

The effect of calcium channel blocker (CCB) treatment on retinal and choroidal vessels in a group of hypertensive patients

PURPOSE

The present study was designed to observe the vasoreactivity in retina and choroid after calcium channel blocker (CCB) treatment in a group of hypertensive patients.

METHOD

The study was based on 56 hypertensive patients (56 eyes) and 56 control subjects (56 eyes). Choroidal scans and the measurement of peripapillary retinal vessel diameters was performed at baseline and optical coherence tomography (OCT) scans were also performed at first month . Subfoveal choroidal thickness (SFCT) and the diameters of superior temporal artery (STA), inferior temporal artery (ITA), superior temporal vein (STV), inferior temporal vein (ITV) were compared between the groups.

RESULTS

The baseline diameters of the STA, ITA were significantly decreased in the patient group compared with the control group (all p < .05). There was a significant increase at first month after the CCB treatment in comparison to baseline measurements (all p < .05). When compared with the controls, the diameter of venules showed a decrease at baseline but was not significant. After the treatment, the diameters of venules were insignificantly increased compared with baseline measurements (p = .178 and p = .275) and there were also no significant differences between the control group and the patient group in first month (all p > .05). The average choroidal thickness measurements of the hypertensive group was lower than the control group (p = .404) and there was a tendency to increase after the treatment (p = .055).

CONCLUSION

This study demonstrates that, treatment with CCB seems to improve retinal arteries and has almost no affect on the choroidal thickness in newly diagnosed hypertensive patients.

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.

The application of arterio-venous ratio (AVR) cut-off values in clinic to stratify cardiovascular risk in patients

INTRODUCTION

Cardiovascular risk calculators are a useful tool for identifying at-risk individuals. There are standardised methods for assessing the retinal microcirculation which alters as a consequence of cardiovascular disease (CVD). This study aimed to explore if a standardised retinal vessel assessment conducted in primary optometric care reflects current cardiovascular risk, as measured using two validated CVD risk calculators (QRISK 2; Mayo Clinic).

METHODS

A total of 120 subjects were included in the analyses. Following a routine eye examination, participants had disc-centred retinal photographs and systemic blood pressure taken. Retinal vessel parameters (central retinal artery and vein equivalent and arterio-venous ratio (AVR)) were calculated using semi-automated software. Participants were then grouped into AVR quintiles as defined by the Atherosclerosis Risk in Communities Study (ARIC). Cardiovascular risk was calculated with the validated QRISK and Mayo Clinic health calculators.

RESULTS

Systolic blood pressure was significantly greater in those with an AVR value falling in the lowest quintile compared to the highest quintile (150.65 mmHg vs. 132.21 mmHg [p = 0.001]). Similarly, CVD risk was significantly higher in those with the lowest AVR compared to the highest (QRISK: 14.28% vs. 9.87% [p = 0.05]; MAYO risk: 36.35% vs. 19.21% [p = 0.01]). Chi squared analyses showed a significant difference in the number of hypertensives in the lowest AVR quintile compared to those in the highest [p = 0.02].

CONCLUSION

Whilst the ARIC population is not directly comparable to the population used to develop the QRISK calculator, it has been shown that its application could help to identify at risk individuals using retinal vessel analyses.

Curv-net: Curvilinear structure segmentation network based on selective kernel and Multi-BI-ConvLSTM

PURPOSE

Accurately segmenting curvilinear structures, e.g., retinal blood vessels or nerve fibers, in the medical image is essential to the clinical diagnosis of many diseases. Recently, deep learning has become a popular technology to deal with the image segmentation task and it has obtained remarkable achievement. However, the existing methods still have many problems when segmenting the curvilinear structures in medical images, such as losing the details of curvilinear structures, producing many false-positive segmentation results. To mitigate these problems, we propose a novel end-to-end curvilinear structure segmentation network called Curv-Net.

METHODS

Curv-Net is an effective encoder-decoder architecture constructed based on selective kernel (SK) and multi-bidirectional convolutional LSTM (Multi-Bi-ConvLSTM). To be specific, we first employ the SK module in the convolutional layer to adaptively extract the multi-scale features of the input image, and then we design a Multi-Bi-ConvLSTM as the skip concatenation to fuse the information learned in the same stage and propagate the feature information from the deep stages to the shallow stages, which can enable the feature captured by Curv-Net to contain more detail information and high-level semantic information simultaneously to improve the segmentation performance.

RESULTS

The effectiveness and reliability of our proposed Curv-Net are verified on three public datasets: two color fundus datasets (DRIVE and CHASE_DB1) and one corneal nerve fiber dataset (CCM-2). We calculate the ACC (accuracy), SE (sensitivity), SP (specificity), Dice (Dice similarity coefficient) and AUC (area under the receiver) for the DRIVE and CHASE_DB1 datasets. The ACC, SE, SP, Dice and AUC of the DRIVE dataset are 0.9629, 0.8175, 0.9858, 0.8352 and 0.9810, respectively. For the CHASE_DB1 dataset, the values are 0.9810, 0.8564, 0.9899, 0.8143 and 0.9832, respectively. To validate the corneal nerve fiber segmentation performance of the proposed Curv-Net, we test it on the CCM-2 dataset and calculate Dice, SE and FDR (false discovery rate) metrics. The Dice, SE and FDR achieved by Curv-Net are 0.8114±0.0062, 0.8903±0.0113 and 0.2547±0.0104, respectively.

CONCLUSIONS

Curv-Net is evaluated on three public datasets. Extensive experimental results demonstrate that Curv-Net outperforms the other superior curvilinear structure segmentation methods. This article is protected by copyright. All rights reserved.

Short-term effect of angiotensin-converting enzyme inhibitor on retinal vessel diameter in patients with systemic hypertension

PURPOSE

To determine the retinal vessel diameter changes after angiotensin-converting enzyme (ACE) inhibitor treatment in a group of hypertensive patients.

METHODS

This study included 60 treatment-naive hypertensive patients who were treated with ACE inhibitor. Sixty healthy volunteers served as control group. An optical coherence tomography scan protocol including the measurement of peripapillary retinal vessel diameters was performed at baseline and at 1st month. The diameters of superior temporal artery (STA), inferior temporal artery (ITA), superior temporal vein (STV), inferior temporal vein (ITV), superior nasal artery (SNA), inferior nasal artery (INA), superior nasal vein (SNV) and inferior nasal vein (INV) were statistically compared.

RESULTS

The baseline diameters of the STA, ITA, SNA, and INA were significantly decreased in the patient group compared with the control group (all p < 0.05). There was a significant increase at 1st month after the treatment in comparison to baseline measurements (all p < 0.05). When compared with the controls, only the diameter of SNV showed a significant decrease at baseline (p = 0.031). After the treatment, the diameters of SNV and INV were significantly increased compared with baseline measurements (p = 0.049 and p = 0.035, respectively). There were no significant differences between the control group and the patient group at 1st month (all p > 0.05).

CONCLUSION

Short-term treatment with ACE inhibitor led to a significant improvement in the retinal vessel diameters of patients with hypertension.

Comparison of Static Retinal Vessel Caliber Measurements by Different Commercially Available Platforms

SIGNIFICANCE

Commercially available platforms show good agreement in clinical outcomes for retinal vessel caliber measurements, despite differing absolute values. Tighter agreement is observed when right and left eye data are averaged, suggesting an approach suitable for clinical practice.

PURPOSE

The purpose of this study was to compare the retinal vessel caliber measurements generated by different commercially available platforms and their associations with systemic blood pressure and age.

METHODS

A total of 209 participants were recruited from a UK optometric practice. After a routine eye examination, participants had disc-centered retinal photographs and systemic blood pressure taken. Retinal vessel calibers (central retinal artery equivalent, central retinal vein equivalent, and arteriovenous ratio) were calculated using both MONA REVA and VesselMap.

RESULTS

An inverse Pearson correlation was observed between central retinal artery equivalent and mean arterial blood pressure on both platforms (r = -0.275 [P ≤ .001] and r = -0.388 [P ≤ .001] for MONA REVA and VesselMap, respectively); this correlation was also observed with arteriovenous ratio and blood pressure. An inverse correlation was observed between central retinal artery equivalent and age (r = -0.362 [P ≤ .001] and r = -0.404 [P ≤ .001] for MONA REVA and VesselMap, respectively); this was also seen between central retinal vein equivalent and age (r = -0.322 [P ≤ .001] and r = -0.369 [P ≤ .001]). Arteriovenous ratio remained independent from age for both platforms. Bland-Altman plots demonstrated good agreement between the platforms for all three variables.

CONCLUSIONS

Although absolute caliber measurements differed between the platforms, the correlations observed were of similar magnitudes, with good agreement between the two platforms. Tighter spaced limits of agreement were observed when right and left eye data were averaged for each subject. In the absence of localized ocular pathology, this approach should be used.

Association of Alk1 and Endoglin Polymorphisms with Cardiovascular Damage

Cardiovascular diseases are associated to risk factors as obesity, hypertension and diabetes. The transforming growth factor-β1 receptors ALK1 and endoglin regulate blood pressure and vascular homeostasis. However, no studies relate the association of ALK1 and endoglin polymorphisms with cardiovascular risk factors. We analysed the predictive value of the ALK1 and endoglin polymorphisms on cardiovascular target organ damage in hypertensive and diabetic patients in 379 subjects with or without hypertension and diabetes in a Primary Care setting. The ALK1 rs2071219 polymorphism (AA genotype) is associated with a lower presence of diabetic retinopathy and with the absence of altered basal glycaemia. Being carrier of the ALK1 rs3847859 polymorphism (G allele) is associated with lower basal heart rate and with higher LDL-cholesterol levels. The endoglin rs3739817 polymorphism (AA genotype) is associated with higher levels of LDL-cholesterol, and being carrier of the endoglin rs10987759 polymorphism (C allele) is associated with higher haemoglobin levels and with an increased heart rate. Summarizing, several ALK1 and endoglin gene polymorphisms increase the risk of cardiovascular events. The analysis of these polymorphisms in populations at risk, in combination with the determination of other parameters and biomarkers, could implement the diagnosis and prognosis of susceptibility to cardiovascular damage.

Radial Pulse Wave Signals Combined with Ba-PWV for the Risk Prediction of Hypertension and the Monitoring of Its Accompanying Metabolic Risk Factors

Our aim was to study whether radial pulse wave signals can improve the risk prediction of incident hypertension and are associated with its concomitant metabolic risk factors beyond the traditional cardiovascular risk factor Ba-PWV. By enrolling 523 Chinese subjects in this study, linear and stepwise regression analysis was performed to assess the association of radial artery pulse wave signals and Ba-PWV with blood pressure and its related metabolic risk factors such as fasting plasma glucose (FPG), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and uric acid (UA). The area under the receiver-operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were calculated by risk assessment plot to compare the discriminative ability among models with and without radial artery pulse wave signals. After adjusting related confounding factors, radial artery pulse wave variable h 3/h 1 was selected as the sensitive influential factor for blood pressure. Moreover, a new model with h 3/h 1 had a higher AUC than the reference model without it (0.86 vs 0.84; P=0.030). And the NRI and IDI for the new model was 50.0% (P=0.017) and 3.16% (P=0.044), respectively. In addition to Ba-PWV, we found that the decrease of t 4, t 5, and h 5 might be associated with higher FPG, TC, LDL-C, and UA and lower HDL-C. This research might provide a valuable additional tool for remote wearable monitoring of radial artery pulse wave signals in hypertension risk evaluation and management.

Exploring the effect of hypertension on retinal microvasculature using deep learning on East Asian population

Hypertension is the leading risk factor of cardiovascular disease and has profound effects on both the structure and function of the microvasculature. Abnormalities of the retinal vasculature may reflect the degree of microvascular damage due to hypertension, and these changes can be detected with fundus photographs. This study aimed to use deep learning technique that can detect subclinical features appearing below the threshold of a human observer to explore the effect of hypertension on morphological features of retinal microvasculature. We collected 2012 retinal photographs which included 1007 from patients with a diagnosis of hypertension and 1005 from normotensive control. By method of vessel segmentation, we removed interference information other than retinal vasculature and contained only morphological information about blood vessels. Using these segmented images, we trained a small convolutional neural networks (CNN) classification model and used a deep learning technique called Gradient-weighted Class Activation Mapping (Grad-CAM) to generate heat maps for the class “hypertension”. Our model achieved an accuracy of 60.94%, a specificity of 51.54%, a precision of 59.27%, and a recall of 70.48%. The AUC was 0.6506. In the heat maps for the class “hypertension”, red patchy areas were mainly distributed on or around arterial/venous bifurcations. This indicated that the model has identified these regions as being the most important for predicting hypertension. Our study suggested that the effect of hypertension on retinal microvascular morphology mainly occurred at branching of vessels. The change of the branching pattern of retinal vessels was probably the most significant in response to elevated blood pressure.

Hypertension Is Predicted by Both Large and Small Artery Disease

Both small and large artery disease might precede the development of hypertension. However, no prospective trial has yet determined the role of small and large artery disease on the rate of new-onset hypertension in a normotensive general population. This study investigated associations between both arterial stiffness and small artery retinopathy and the development of hypertension in adults from Japan. Normotensive individuals who underwent a baseline health checkup from 2005 to 2015 and at least 1 annual follow-up were eligible. The cardio-ankle vascular index (CAVI) was measured, and retinal fundus photography was performed at baseline. Follow-up visits included measurement of clinic blood pressure. The primary end point was new-onset hypertension (blood pressure ≥140/90 mm Hg or initiation of antihypertensive medication with self-reported hypertension). The analysis included 34 649 subjects (mean age, 44.2 years; 46.4% male). Mean follow-up duration was 3.18±2.50 years. The cumulative incidence of new-onset hypertension during the 10-year follow-up period was 40% of patients overall, with rates increasing in parallel with baseline CAVI (quartile [Q]1, 23%; Q2, 33%; Q3, 42%; Q4, 58%; P<0.001), and as the severity of retinopathy increased ( P<0.001). CAVI showed good discriminative ability for detecting new-onset hypertension. In multivariate analysis, both CAVI and small artery retinopathy were independent predictors of hypertension development. There was no interaction between CAVI and small artery retinopathy with respect to incident hypertension. In conclusion, we showed that both large and small artery disease predict future hypertension independently of each other and confounding risk factors in a general normotensive population.

Retinal micro-vascular and aortic macro-vascular changes in postmenopausal women with primary hyperparathyroidism

Aim of the study was to evaluate the micro and macro-vascular changes in patients with primary hyperparathyroidism (PHPT) compared to controls. 30 postmenopausal PHPT women (15 hypertensive and 15 normotensive) and 30 normotensive controls underwent biochemical evaluation of mineral metabolism and measurements of arterial stiffness by 24 hour ambulatory blood pressure monitoring. Retinal microcirculation was imaged by a Retinal Vessel Analyzer. PHPT patients also underwent bone mineral density measurements and kidney ultrasound. PHPT patients had higher mean calcium and parathyroid hormone values compared to controls. Evaluating macro-vascular compartment, we found higher values of 24 hours-systolic, diastolic blood pressure, aortic pulse wave velocity (aPWV) and aortic augmentation index (Aix) in hypertensive PHPT, but not in normotensive PHPT compared to controls. The eye examination showed narrowing arterial and venular diameters of retinal vessels in both hypertensive and normotensive PHPT compared to controls. In hypertensive PHPT, 24 hours systolic blood pressure was associated only with parathyroid hormone (PTH) levels (beta = 0.36, p = 0.04). aPWV was associated with retinal diameter (beta = -0.69, p = 0.003), but not with PTH. Retinal artery diameter was associated with PTH (beta = -0.6, p = 0.008). In the normotensive PHPT, only PTH was associated with retinal artery diameter (beta = -0.60, p = 0.01) and aortic AIx (beta = 0.65, p = 0.02). In conclusion, we found macro-vascular impairment in PHPT and that micro-vascular impairment is negatively associated with PTH, regardless of hypertension in PHPT.

Association between blood pressure and retinal arteriolar and venular diameters in Chinese early adolescent children, and whether the association has gender difference: a cross-sectional study

Background

To establish the independent association between blood pressure (BP) and retinal vascular caliber, especially the retinal venular caliber, in a population of 12-year-old Chinese children.

Methods

We have examined 1501 students in the 7th grade with mean age of 12.7 years. A non-mydriatic fundus camera (Canon CR-2, Tokyo, Japan) was used to capture 45⁰ fundus images of the right eyes. Retinal vascular caliber was measured using a computer-based program (IVAN). BP was measured using an automated sphygmomanometer (HEM-907, Omron, Kyoto, Japan).

Results

The mean retinal arteriolar caliber was 145.3 μm (95% confidence interval [CI], 110.6–189.6 μm) and the mean venular caliber was 212.7 μm (95% CI, 170.6–271.3 μm). After controlling for age, sex, axial length, BMI, waist, spherical equivalent, birth weight, gestational age and fellow retinal vessel caliber, children in the highest quartile of BP had significantly narrower retinal arteriolar caliber than those with lower quartiles (P for trend< 0.05). Each 10-mmHg increase in BP was associated with narrowing of the retinal arterioles by 3.00 μm (multivariable-adjusted P < 0.001), and the results were consist in three BP measurements. The association between BP measures and retinal venular caliber did not persist after adjusting for fellow arteriolar caliber. And there was no significant interaction between BP and sex, age, BMI, and birth status.

Conclusions

In a large population of adolescent Chinese children, higher BP was found to be associated with narrower retinal arterioles, but not with retinal venules. Sex and other confounding factors had no effect on the relationship of BP and retinal vessel diameter.

Comparisons of microvascular and macrovascular changes in aldosteronism-related hypertension and essential hypertension

Case-control observational study to evaluate the microvascular and macrovascular changes in patients with hypertension secondary to primary aldosteronism (PA), essential hypertension (EH) and healthy subjects. Measurements of arterial stiffness including augmentation index (AIx) and pulse wave velocity (PWV) were assessed using a TensioClinic arteriograph system. Retinal microcirculation was imaged by a Retinal Vessel Analyzer (RVA) and a non-midriatic camera (Topcon-TRC-NV2000). IMEDOS software analyzed the retinal artery diameter (RAD), retinal vein diameters (RVD) and arteriole-to-venule ratio (AVR) of the vessels coming off the optic disc. Thirty, 39 and 35 patients were included in the PA, EH and control group, respectively. The PA group showed higher PWV values compared only with the control group. The mean brachial and aortic AIx values did not show significant difference between groups. In the PA group, the mean RVD and AVR values were significantly lower than in the EH and control groups, whereas the parameters did not differ between the EH and control groups. In conclusion, AVR appears significantly modified in the PA group compared with the EH group and could represent an early and more reliable indicator of microvascular remodeling.

Asymptomatic carotid artery stenosis and retinal nerve fiber layer thickness. A community-based, observational study

Purpose

To examine whether an abnormally thin retinal nerve fiber layer (RNFL) is associated with cerebrovascular insufficiency.

Design

Community-based study.

Methods

The Asymptomatic Polyvascular Abnormalities in Community Study included Chinese aged 40+ years and without histories of cerebrovascular incidents or coronary heart disease. Using transcranial Doppler and carotid duplex ultrasound examination, we assessed presence and degree of an intracranial arterial stenosis (ICAS) and extracranial carotid arterial stenosis (ECAS) and we measured the RNFL thickness by spectral-domain optical coherence tomography.

Results

The study included 3,376 participants with a mean age of 54.3±10.3 years. Thinner RNFL was significantly correlated with a higher prevalence of ECAS (P = 0.035; standardized regression coefficient beta:-0.04; non-standardized regression coefficient B:-0.99; 95% confidence intervals(CI):-1.90,-0.07), after adjusting for age (P<0.001;beta:-0.25;B:-0.26;95%CI:-0.30,-0.22), gender (P = 0.001;beta:-0.07;B:-1.36;95%CI:-2.14,-0.58) and blood concentration of low-density lipoproteins (P = 0.03;beta:0.04;B:0.52;95%CI:0.05,0.98). In a reverse manner, prevalence of ECAS was associated with a thinner RNFL thickness (P = 0.007; odds ratio (OR):0.99; 95%CI:0.98,0.99) after adjusting for older age (P<0.001;OR:1.06;95%CI:10.05,10.7), higher prevalence of ICAS (P = 0.01;OR:1.34;95%CI:1.07,1.69) and higher prevalence of carotid artery plaques (P<0.001;OR:9.18;95%CI:6.93,12.2), and higher blood concentration of total cholesterol (P = 0.03;OR:1.12;95%CI:1.01,1.23). In univariate analysis, an increasing degree of ECAS was significantly correlated with a thinner RNFL.

Conclusions

Higher prevalence and degree of ECAS were correlated with thinner RNFL and vice versa. Patients with abnormally thin RNFL without ocular disease may undergo carotid artery examination to detect asymptomatic carotid artery stenosis. Examination of the RNFL is useful for the diagnosis of cerebrovascular disease.

Association of VAV2 and VAV3 polymorphisms with cardiovascular risk factors

Hypertension, diabetes and obesity are cardiovascular risk factors closely associated to the development of renal and cardiovascular target organ damage. VAV2 and VAV3, members of the VAV family proto-oncogenes, are guanosine nucleotide exchange factors for the Rho and Rac GTPase family, which is related with cardiovascular homeostasis. We have analyzed the relationship between the presence of VAV2 rs602990 and VAV3 rs7528153 polymorphisms with cardiovascular risk factors and target organ damage (heart, vessels and kidney) in 411 subjects. Our results show that being carrier of the T allele in VAV2 rs602990 polymorphism is associated with an increased risk of obesity, reduced levels of ankle-brachial index and diastolic blood pressure and reduced retinal artery caliber. In addition, being carrier of T allele is associated with increased risk of target organ damage in males. On the other hand, being carrier of the T allele in VAV3 rs7528153 polymorphism is associated with a decreased susceptibility of developing a pathologic state composed by the presence of hypertension, diabetes, obesity or cardiovascular damage, and with an increased risk of developing altered basal glycaemia. This is the first report showing an association between VAV2 and VAV3 polymorphisms with cardiovascular risk factors and target organ damage.

Conventional and Ambulatory Blood Pressure as Predictors of Retinal Arteriolar Narrowing

Supplemental Digital Content is available in the text.

At variance with the long established paradigm that retinal arteriolar narrowing trails hypertension, several longitudinal studies, all based on conventional blood pressure (CBP) measurement, proposed that retinal arteriolar narrowing indicates heightened microvascular resistance and precedes hypertension. In 783 randomly recruited Flemish (mean age, 38.2 years; 51.3% women), we investigated to what extent CBP and daytime (10 am to 8 pm) ambulatory blood pressure (ABP) measured at baseline (1989–2008) predicted the central retinal arteriolar equivalent (CRAE) in retinal photographs obtained at follow-up (2008–2015). Systolic/diastolic hypertension thresholds were 140/90 mm Hg for CBP and 135/85 mm Hg for ABP. In multivariable-adjusted models including both baseline CBP and ABP, CRAE after 10.3 years (median) of follow-up was unrelated to CBP (P≥0.14), whereas ABP predicted CRAE narrowing (P≤0.011). Per 1-SD increment in systolic/diastolic blood pressure, the association sizes were −0.95 µm (95% confidence interval, −2.20 to 0.30)/−0.75 µm (−1.93 to 0.42) for CBP and −1.76 µm (−2.95 to −0.58)/−1.48 µm (−2.61 to −0.34) for ABP. Patients with ambulatory hypertension at baseline (17.0%) had smaller CRAE (146.5 versus 152.6 µm; P<0.001) at follow-up. CRAE was not different (P≥0.31) between true normotension (normal CBP and ABP; prevalence, 77.6%) and white-coat hypertension (elevated CBP and normal ABP, 5.4%) and between masked hypertension (normal CBP and elevated ABP, 10.2%) and hypertension (elevated CBP and ABP, 6.8%). In conclusion, the paradigm that retinal arteriolar narrowing precedes hypertension can be explained by the limitations of CBP measurement, including nonidentification of masked and white-coat hypertension.

Hypertensive retinopathy in a transgenic angiotensin-based model

Severe hypertension destroys eyesight. The RAS (renin-angiotensin system) may contribute to this. This study relied on an established angiotensin, AngII (angiotensin II)-elevated dTGR (double-transgenic rat) model and same-background SD (Sprague-Dawley) rat controls. In dTGRs, plasma levels of AngII were increased. We determined the general retinal phenotype and observed degeneration of ganglion cells that we defined as vascular degeneration. We also inspected relevant gene expression and lastly observed alterations in the outer blood-retinal barrier. We found that both scotopic a-wave and b-wave as well as oscillatory potential amplitude were significantly decreased in dTGRs, compared with SD rat controls. However, the b/a-wave ratio remained unchanged. Fluorescence angiography of the peripheral retina indicated that exudates, or fluorescein leakage, from peripheral vessels were increased in dTGRs compared with controls. Immunohistological analysis of blood vessels in retina whole-mount preparations showed structural alterations in the retina of dTGRs. We then determined the general retinal phenotype. We observed the degeneration of ganglion cells, defined vascular degenerations and finally found differential expression of RAS-related genes and angiogenic genes. We found the expression of both human angiotensinogen and human renin in the hypertensive retina. Although the renin gene expression was not altered, the AngII levels in the retina were increased 4-fold in the dTGR retina compared with that in SD rats, a finding with mechanistic implications. We suggest that alterations in the outer blood-retinal barrier could foster an area of visual-related research based on our findings. Finally, we introduce the dTGR model of retinal disease.

Are Retinal Vessels Calibers Influenced by Blood Pressure Measured at the Time of Retinography Acquisition?

Background

Retinal arterial narrowing is associated with higher office blood pressure (BP) and ambulatory blood pressure monitoring, and increased incidence of cardiovascular disease, but it is still unknown if the vessel caliber is associated with BP measured at the time of retinography acquisition.

Methods

Retinal arteriolar and venular calibers were measured by the microdensitometric method in 448 patients with hypertension. Participants underwent 24-hours ambulatory blood pressure (24-h ABP) monitoring simultaneously with the retinography acquisition. Association between arteriolar and venular calibers with increase of 10 mmHg in the mean 24-hours, daily, and nightly BP, and with BP measured at the time of retinography, was evaluated by ANOVA and multivariate analyses.

Results

Mean 24-hours, daytime and nighttime systolic and diastolic BP were inversely associated with the arteriolar caliber, but not with the venular caliber. Arteriolar caliber decreased -0.8 (95% CI -1.4 to -0.2) μm per 10-mmHg increase in 24-hours mean systolic BP, adjusted for age, gender, fellow vessel, and duration of hypertension (P = 0.01). The corresponding decreasing in arteriolar caliber by 10 mmHg of increasing in mean diastolic BP was -1.1 μm (-2.0 to -0.2, P = 0.02). The decrease of arteriolar caliber by the same increasing of BP measured at the time of retinography was lower and not statistically significant, particularly for mean diastolic BP and outer arterioles calibers: -1.0 (-1.8 to -0.2) μm in the daytime BP average versus -0.3 (-0.9 to 0.3) at the moment of retinography acquisition.

Conclusions

These findings suggest that the caliber of arteriolar retinal vessels in patients with uncontrolled hypertension are not significantly influenced by blood pressure measured at the time of retinography acquisition.

Evaluation of the Retinal Vasculature in Hypertension and Chronic Kidney Disease in an Elderly Population of Irish Nuns

BACKGROUND

Chronic kidney disease (CKD) and hypertension are global public health problems associated with considerable morbidity, premature mortality and attendant healthcare costs. Previous studies have highlighted that non-invasive examination of the retinal microcirculation can detect microvascular pathology that is associated with systemic disorders of the circulatory system such as hypertension. We examined the associations between retinal vessel caliber (RVC) and fractal dimension (DF), with both hypertension and CKD in elderly Irish nuns.

METHODS

Data from 1233 participants in the cross-sectional observational Irish Nun Eye Study (INES) were assessed from digital photographs with a standardized protocol using computer-assisted software. Multivariate regression analyses were used to assess associations with hypertension and CKD, with adjustment for age, body mass index (BMI), refraction, fellow eye RVC, smoking, alcohol consumption, ischemic heart disease (IHD), cerebrovascular accident (CVA), diabetes and medication use.

RESULTS

In total, 1122 (91%) participants (mean age: 76.3 [range: 56-100] years) had gradable retinal images of sufficient quality for blood vessel assessment. Hypertension was significantly associated with a narrower central retinal arteriolar equivalent (CRAE) in a fully adjusted analysis (P = 0.002; effect size = -2.16 μm; 95% confidence intervals [CI]: -3.51, -0.81 μm). No significant associations between other retinal vascular parameters and hypertension or between any retinal vascular parameters and CKD were found.

CONCLUSIONS

Individuals with hypertension have significantly narrower retinal arterioles which may afford an earlier opportunity for tailored prevention and treatment options to optimize the structure and function of the microvasculature, providing additional clinical utility. No significant associations between retinal vascular parameters and CKD were detected.

Optical coherence tomography-based retinal vessel analysis for the evaluation of hypertensive vasculopathy

PURPOSE

Evaluation of retinal vessels in cardiovascular disease traditionally relies upon funduscopy, but more recently digital photo analysis has expanded the spectrum. As spectral domain optical coherence tomography (OCT) allows an in-vivo assessment of retinal tissue and its vessels on a histological scale, our study aimed at using this tool for the analysis of the retinal vasculature.

METHODS

Circumferential peripapillary OCT scans (3DOCT-2000; Topcon Inc., Tokyo, Japan), with centration on the optic nerve head, were taken from 20 eyes (20 participants) with normal blood pressure and 20 eyes (20 participants) with arterial hypertension above 120 mmHg (mean blood pressure). The diameter of all vessels intersecting the scan line was measured in the OCT and used to calculate central vessel equivalents, and the A/V ratios were calculated. Bland-Altman analysis was performed to evaluate reliability. Correlation coefficients were determined for reliability of the method as well as with the individual mean arterial blood pressures.

RESULTS

Forty eyes (40 participants) were included in the study. Mean arterial blood pressure was 96±4 mmHg in the control group and 132±7 mmHg in the hypertonic group. Mean A/V ratio as determined from OCT scans was 0.82±0.13 (normotonic) versus 0.62±0.11 (hypertonic). A Pearson's correlation coefficient of 0.67 (p<0.001) was determined between A/V ratio and blood pressure.

CONCLUSIONS

Our results highlight the feasibility of retinal vessel measurements in spectral domain OCT. A relation between mean arterial blood pressure and OCT-based A/V ratio was established. Further research will elucidate influencing factors and provide a broader basis for therapeutic approaches.

Validation of the automatic image analyser to assess retinal vessel calibre (ALTAIR): a prospective study protocol

INTRODUCTION

The fundus examination is a non-invasive evaluation of the microcirculation of the retina. The aim of the present study is to develop and validate (reliability and validity) the ALTAIR software platform (Automatic image analyser to assess retinal vessel calibre) in order to analyse its utility in different clinical environments.

METHODS AND ANALYSIS

A cross-sectional study in the first phase and a prospective observational study in the second with 4 years of follow-up. The study will be performed in a primary care centre and will include 386 participants. The main measurements will include carotid intima-media thickness, pulse wave velocity by Sphygmocor, cardio-ankle vascular index through the VASERA VS-1500, cardiac evaluation by a digital ECG and renal injury by microalbuminuria and glomerular filtration. The retinal vascular evaluation will be performed using a TOPCON TRCNW200 non-mydriatic retinal camera to obtain digital images of the retina, and the developed software (ALTAIR) will be used to automatically calculate the calibre of the retinal vessels, the vascularised area and the branching pattern. For software validation, the intraobserver and interobserver reliability, the concurrent validity of the vascular structure and function, as well as the association between the estimated retinal parameters and the evolution or onset of new lesions in the target organs or cardiovascular diseases will be examined.

ETHICS AND DISSEMINATION

The study has been approved by the clinical research ethics committee of the healthcare area of Salamanca. All study participants will sign an informed consent to agree to participate in the study in compliance with the Declaration of Helsinki and the WHO standards for observational studies. Validation of this tool will provide greater reliability to the analysis of retinal vessels by decreasing the intervention of the observer and will result in increased validity through the use of additional information, especially in the areas of vascularisation and vessel branching patterns.

TRIAL REGISTRATION NUMBER

Clinical Trials.gov Identifier: NCT02087605.

Complete blood count and retinal vessel calibers

Objective

The influence of hematological indices such as complete blood count on microcirculation is poorly understood. Retinal microvasculature can be directly visualized and vessel calibers are associated with a range of ocular and systemic diseases. We examined the association of complete blood count with retinal vessel calibers.

Methods

Cross-sectional population-based Blue Mountains Eye Study, n = 3009, aged 49+ years. Complete blood count was measured from fasting blood samples taken at baseline examination, 1992–4. Retinal arteriolar and venular calibers were measured from digitized retinal photographs using a validated semi-automated computer program.

Results

All analyses adjusted for age, sex, systolic blood pressure, diabetes, smoking and fellow vessel caliber. Higher hematocrit, white cell count and platelet count were associated with narrower arteriolar caliber (p = 0.02, 0.03 and 0.001 respectively), while higher hemoglobin, hematocrit, red cell count, white cell count and platelet count were associated with wider venular caliber (p<0.0001 for all). Each quintile increase in hematocrit, white cell count and platelet count was associated with approximately 0.5 µm narrower arteriolar caliber; whereas each quintile increase in all of the complete blood count components was associated with approximately 1–2 µm wider venular caliber.

Conclusions

These associations show that elevated levels of hematological indices can have adverse effects on the microcirculation.

Extension of the mitochondria dysfunction hypothesis of metabolic syndrome to atherosclerosis with emphasis on the endocrine-disrupting chemicals and biophysical laws

Metabolic syndrome and its component phenotypes, hyperglycemia, hypertension, (abdominal) obesity and hypertriglyceridemia, are major risk factors for atherosclerosis. Recently, associations between exposure to endocrine‐disrupting chemicals (EDCs), mitochondrial dysfunction, metabolic syndrome and atherosclerosis have been established, suggesting a possible common mechanism underlying these phenomena. Extending a previously proposed mitochondria dysfunction theory of metabolic syndrome and using biophysical laws, such as metabolic scaling, Murray's law and fractal geometry of the vascular branching system, we propose that atherosclerosis could be explained as an ill‐adaptive change occurring in nutrient‐supplying arteries in response to the decreasing tissue energy demand caused by tissue mitochondrial dysfunction. Various aspects of this new hypothesis are discussed.

Relationship between target organ damage and blood pressure, retinal vessel calibre, oxidative stress and polymorphisms in VAV-2 and VAV-3 genes in patients with hypertension: a case-control study protocol (LOD-Hipertension)

INTRODUCTION

Target organ damage (TOD) is associated with increased cardiovascular risk. The study objectives were to analyse the relationship of TOD to blood pressure, size of retinal arteries and veins, oxidative stress and different polymorphisms in the VAV-2 and VAV-3 genes in participants with hypertension.

METHODS AND ANALYSIS

A case-control study to analyse the relationship between clinical, biochemical and genetic parameters and presence of cardiac, vascular and renal TOD in 486 patients with hypertension. Participants with TOD will be considered as cases, and those without TOD will be enrolled as controls. This will be a collaborative study conducted by the groups of Primary Care, Cardiovascular and Metabolic and Degenerative Diseases of the Instituto de Investigación Biomédica of Salamanca (IBSAL). Assessment of cardiac, renal and vascular TOD. Measurement of peripheral and central blood pressure, size of eye fundus arteries and veins, and oxidative stress, and polymorphisms in the VAV-2 and VAV-3 genes.

ETHICS AND DISSEMINATION

The study will be conducted after approval is obtained from the Ethics Committee of Hospital Clínico Universitario of Salamanca. All study participants will sign an informed consent to agree to participate in the study, and another consent to agree on the genetic study, in compliance with the Declaration of Helsinki and the WHO standards for observational studies. The results of this study will allow for an understanding of the relationship of the different TODs with blood pressure, retinal artery and vein diameters, oxidative stress and polymorphisms in VAV-2 and VAV-3 genes.

TRIAL REGISTRATION NUMBER

Clinical Trials. gov Identifier: NCT02022618.

Semi-automated retinal vessel analysis in nonmydriatic fundus photography

PURPOSE

Funduscopic assessment of the retinal vessels may be used to assess the health status of microcirculation and as a component in the evaluation of cardiovascular risk factors. Typically, the evaluation is restricted to morphological appreciation without strict quantification. Our purpose was to develop and validate a software tool for semi-automated quantitative analysis of retinal vasculature in nonmydriatic fundus photography.

METHODS

matlab software was used to develop a semi-automated image recognition and analysis tool for the determination of the arterial-venous (A/V) ratio in the central vessel equivalent on 45° digital fundus photographs. Validity and reproducibility of the results were ascertained using nonmydriatic photographs of 50 eyes from 25 subjects recorded from a 3DOCT device (Topcon Corp.). Two hundred and thirty-three eyes of 121 healthy subjects were evaluated to define normative values.

RESULTS

A software tool was developed using image thresholds for vessel recognition and vessel width calculation in a semi-automated three-step procedure: vessel recognition on the photograph and artery/vein designation, width measurement and calculation of central retinal vessel equivalents. Mean vessel recognition rate was 78%, vessel class designation rate 75% and reproducibility between 0.78 and 0.91. Mean A/V ratio was 0.84. Application on a healthy norm cohort showed high congruence with prior published manual methods. Processing time per image was one minute.

CONCLUSIONS

Quantitative geometrical assessment of the retinal vasculature may be performed in a semi-automated manner using dedicated software tools. Yielding reproducible numerical data within a short time leap, this may contribute additional value to mere morphological estimates in the clinical evaluation of fundus photographs.

Retinal vascular caliber and the development of hypertension: a meta-analysis of individual participant data

OBJECTIVE

Microvascular dysfunction has been suggested to be a major pathogenic factor for the development of hypertension. We examined the association between retinal vascular caliber, a marker of systemic microvascular dysfunction, and incident hypertension on a meta-analysis of individual participant data.

METHODS

We performed a systematic review with relevant studies identified through a search of electronic databases, a review of reference lists, and correspondence with experts. Studies were included if participants were selected from a general population, retinal vascular caliber was measured from photographs using computer-assisted methods at baseline, and individuals were followed up to ascertain the incidence of hypertension. Prespecified individual recorded data from six population-based prospective cohort studies were included. Discrete time proportional odds models were constructed for each study with adjustment for hypertension risk factors. Log odds ratios (ORs) per 20-μm difference were pooled using random-effects meta-analysis.

RESULTS

Among 10 229 participants without prevalent hypertension, diabetes, or cardiovascular disease, 2599 developed new-onset hypertension during median follow-up periods ranging from 2.9 to 10 years. Both narrower retinal arterioles [pooled multivariate-adjusted OR per 20-μm difference 1.29, 95% confidence interval (CI) 1.20-1.39] and wider venules (OR per 20-μm difference 1.14, 95% CI 1.06-1.23) were associated with an increased risk of hypertension. Each 20 μm narrower arterioles at baseline were associated with a 1.12 mmHg (95% CI 0.25-1.99) greater increase in SBP over 5 years.

CONCLUSIONS

Retinal arteriolar narrowing and venular widening were independently associated with an increased risk of hypertension. These findings underscore the importance of microvascular remodeling in the pathogenesis of hypertension.

[Imaging of retinal arteries with adaptative optics, feasibility and reproducibility]

OBJECTIVE

Adaptative optic is a new non-invasive imaging technique that allows to measure arterioles wall thickness and diameter with a resolution near two microns. Our objectives were to evaluate the feasibility and the reproducibility of this technique in untreated hypertensive patients.

DESIGN AND METHODS

In 23 naive hypertensive patients and in 14 normotensives, the internal diameter (ID) and the wall thickness of the superior temporal artery were automatically measured. Those measurements were made on a temporal artery segment and led to determine a whole vessel cross sectional area (WCSA) and a wall to lumen ratio (WLR). Intra-observer reproducibility was evaluated by realizing three consecutive measurements in 14 subjects. Inter-observer reproducibility was assessed by two independent readers in 17 patients. Variation coefficient was calculated as SD/mean values. A comparison of retinal parameters was made between normal and hypertensive subjects.

RESULTS

Inter-observer reproducibility indicated a variation coefficient of 1.3% for ID, 3.7% for the WCSA and 3.2% for the WLR. Intra-observer reproducibility indicated a variation coefficient of 3.2% for the WLR. Arterial remodeling was present in hypertensive patients at baseline with a significantly increased WLR as compared to normal subjects (0.32 ± 0.04 vs. 0.26 ± 0.04; P<0.05), both population having the same ID.

CONCLUSION

Adaptative optics is feasible and reproducible technique. The possibility of a direct and non-invasive assessment of retinal arterioles must assess the attractions in this technique in hypertensive patients' care.

Impact of arterial hypertension on the eye

Systemic hypertension has been linked to a wide range of major eye diseases. High arterial blood pressure (BP) decreases choroidal circulatory flow, increases intraocular pressure, and is associated with retinal microvascular abnormalities and prevalence of retinal vein occlusion (RVO) and retinopathy. This review offers a comprehensive overview of ocular diseases associated with hypertension and emphasizes their importance as predictors to future cardiovascular events. It also gives evidence-based clinical data for the therapeutic approach of eye disease in hypertensive patients.

Localized retinal nerve fiber layer defects and arterial hypertension

BACKGROUND

We examined the relationship between arterial hypertension, localized retinal nerve fiber layer defects (RNFLDs), and retinal vascular abnormalities.

METHODS

The study included 359 patients with arterial hypertension and 331 individuals without hypertension as control subjects. Localized RNFLDs and retinal vascular abnormalities were assessed on fundus photographs.

RESULTS

After adjusting for blood concentrations of glycosylated hemoglobin (HbA1c), high-density lipoproteins, low-density lipoproteins, and hyperlipidemia in a multivariable analysis, localized RNFLDs were, in addition to arterio-venous nicking and generalized arteriolar narrowing, significantly associated with arterial hypertension. After adjusting for body mass index, waist/hip ratio, blood concentrations of glucose, HbA1c, triglycerides, high-density lipoproteins, low-density lipoproteins, and prevalence of diabetes mellitus and hyperlipidemia, categories of arterial blood pressure (optimal/normal/highly normal; mild, moderate and severe hypertension) were significantly associated with localized RNFLDs, which were present significantly more often in hypertension grades 2 and 3, with odds ratios (ORs) of 10.01 and 6.45, respectively. The corresponding ORs for arterio-venous nicking (hypertension grades 1, 2, and 3: ORs of 2.00, 1.68, and 1.99, respectively) and generalized arteriolar narrowing (hypertension grades 1 and 3; ORs of 4.60 and 4.32, respectively) were lower than those for localized RNFLDs.

CONCLUSIONS

Localized RNFLDs, in addition to retinal microvascular abnormalities such as focal and generalized arteriolar narrowing, were associated with different grades of arterial hypertension. Ophthalmoscopic examination for localized RNFLDs may be useful for the assessment of the retinal abnormalities associated with arterial hypertension and for the grading of arterial hypertension.

Retinal microvasculature as a model to study the manifestations of hypertension

The retinal vasculature allows direct noninvasive visualization of the body's mircrovasculature. Because the retina and other end organs (brain and kidney) share similar anatomical features and physiological properties, the retinal vessels offer a unique and easily accessible window to study the health and disease of the human microcirculation. Advanced retinal vascular imaging technologies have been developed to allow a more objective and precise assessment of retinal vascular changes. The changes in the retinal vasculature associated with hypertension can be broadly divided into 3 groups: (1) classic retinal vascular changes in response to blood pressure (referred to as hypertensive retinopathy signs), (2) changes in retinal vascular caliber, and (3) changes in more global geometrical patterns of the retina. In this review, we summarize the current understanding of the relationship between retinal vascular changes and blood pressure, the evidence for the retinal vasculature as a biological model to study the manifestation and early pathogenic correlates of hypertension, the latest advances in retinal vascular imaging technologies, and the future opportunities and challenges of retinal vascular imaging. We suggest that further development of retinal vascular analyses and standardized measurement protocols, evaluation of the clinical use of retinal vascular imaging in assessing cardiovascular risk prediction, and using retinal vascular imaging to test antihypertensive treatments will allow the translation of retinal vascular imaging as a tool to improve the diagnosis, prognosis, and management of hypertension in clinical practice.

Associations between metabolic syndrome and syndrome components and retinal microvascular signs in a rural Chinese population: the Handan Eye Study

BACKGROUND

Our purpose was to determine the relationship of metabolic syndrome (MetS) and its components with retinal microvascular abnormalities in a rural Chinese population.

METHODS

The Handan Eye Study, a population-based survey, recruited 6,830 (90.4 % of eligible) rural Chinese ≥30 years of age. A diagnosis of metabolic syndrome was based on the International Diabetes Federation definition. Retinal microvascular signs and arteriolar and venular diameters were assessed from fundus photographs by graders who were trained at the Retinal Vascular Imaging Centre, University of Melbourne.

RESULTS

After adjusting for age, gender, and smoking status, 5,519 participants with MetS, or with the specific components of large waist circumference, elevated blood pressure (BP), or elevated fasting blood glucose (FG), were more likely to have retinopathy, arteriovenous nicking, focal arteriolar narrowing, enhanced arteriolar wall reflex, and generalized retinal arteriolar narrowing than those without MetS or the corresponding component. Individuals with elevated triglycerides were significantly more likely to have arteriovenous nicking and retinopathy.

CONCLUSION

These results show that individual components of MetS are associated with different retinal microvascular signs and with changes in retinal arteriolar and venular diameters.

Retinal arteriolar diameter and the prevalence and incidence of hypertension: a systematic review and meta-analysis of their association

Hypertension is a leading risk factor for increased mortality and morbidity. One pathogenesis mechanism, increased peripheral vascular resistance, relates to arteriolar diameter. Retinal arterioles, visualized and measured through retinal images, provide an insight into the microvascular structure and hints of peripheral vascular resistance. Multiple studies have demonstrated an inverse association between increasing blood pressure and narrowing retinal arteriolar diameter. This systematic review summarizes the currently available evidence from cross-sectional and longitudinal population-based studies that have investigated this association. A meta-analysis of five cross-sectional studies (19,633 adults) provided an averaged regression coefficient of -3.07 μm (95% CI, -3.73, -2.40) narrowing in retinal arteriolar diameter for every 10 mm Hg increase in mean arterial blood pressure. Four longitudinal studies (6,247 adults) with follow-up periods ranging from 3 to 7 years consistently showed that generalized retinal arteriolar narrowing (defined as the lowest tertile, quartile, or quintile in the population) was associated with an increased risk of incident hypertension (meta-analysis odds ratio 1.91; 95% CI, 1.56-2.34).

A new tool to assess retinal vessel caliber. Reliability and validity of measures and their relationship with cardiovascular risk

OBJECTIVE

To analyze the reliability and validity of a semiautomated tool for assessing retinal vessel caliber and to describe the relationship of measures taken to cardiovascular risk and target organ damage.

METHODS

A total of 210 patients aged 34-75 years were selected with retinography. Retinal photographs were digitized, and superior and inferior temporal vessels were measured in an area 0.5-1 disk diameter from the optic disc with semiautomated software [arteriole/venule index (AVIx) calculator]. AVIx was also estimated. Vascular damage was assessed using carotid intima-media thickness and pulse wave velocity, cardiac damage using Cornell voltage-duration product, renal damage using the glomerular filtration rate and microalbuminuria, and cardiovascular risk with the Framingham score.

RESULTS

Interobserver intraclass correlation coefficient (ICC) ranged from 0.96 [95% confidence interval (CI) 0.94-0.97] to 0.99 (95% CI 0.98-0.99), and intraobserver ICC ranged from 0.97 (95% CI 0.94-0.98) to 0.99 (95% CI 0.99-0.99). In the Bland-Altman plot, the limit of interobserver agreement was -0.009 (0.066 to -0.086) in right AVIx and -0.001 (0.083 to -0.085) in left AVIx, whereas the limit of intraobserver agreement for overall AVIx was -0.005 (-0.057 to -0.047). Cardiovascular risk and albumin-creatinine ratio were higher in the first tertile of AVIx as compared with the other two (P < 0.05). In multiple regression, AVIx and venule caliber, but not artery caliber, behaved as predictors of cardiovascular risk and microalbuminuria.

CONCLUSION

This tool showed a high intraobserver and interobserver reliability, and results of the validity analysis agree with those from large studies in estimation of cardiovascular risk and evaluation of target organ damage.

How does hypertension affect your eyes?

Hypertension has profound effects on various parts of the eye. Classically, elevated blood pressure results in a series of retinal microvascular changes called hypertensive retinopathy, comprising of generalized and focal retinal arteriolar narrowing, arteriovenous nicking, retinal hemorrhages, microaneurysms and, in severe cases, optic disc and macular edema. Studies have shown that mild hypertensive retinopathy signs are common and seen in nearly 10% of the general adult non-diabetic population. Hypertensive retinopathy signs are associated with other indicators of end-organ damage (for example, left ventricular hypertrophy, renal impairment) and may be a risk marker of future clinical events, such as stroke, congestive heart failure and cardiovascular mortality. Furthermore, hypertension is one of the major risk factors for development and progression of diabetic retinopathy, and control of blood pressure has been shown in large clinical trials to prevent visual loss from diabetic retinopathy. In addition, several retinal diseases such as retinal vascular occlusion (artery and vein occlusion), retinal arteriolar emboli, macroaneurysm, ischemic optic neuropathy and age-related macular degeneration may also be related to hypertension; however, there is as yet no evidence that treatment of hypertension prevents vision loss from these conditions. In management of patients with hypertension, physicians should be aware of the full spectrum of the relationship of blood pressure and the eye.