Retinal Microvascular Signs May Provide Clues to the Underlying Vasculopathy in Patients With Deep Intracerebral Hemorrhage

A Siamese ResNeXt network for predicting carotid intimal thickness of patients with T2DM from fundus images

Objective

To develop and validate an artificial intelligence diagnostic model based on fundus images for predicting Carotid Intima-Media Thickness (CIMT) in individuals with Type 2 Diabetes Mellitus (T2DM).

Methods

In total, 1236 patients with T2DM who had both retinal fundus images and CIMT ultrasound records within a single hospital stay were enrolled. Data were divided into normal and thickened groups and sent to eight deep learning models: convolutional neural networks of the eight models were all based on ResNet or ResNeXt. Their encoder and decoder modes are different, including the standard mode, the Parallel learning mode, and the Siamese mode. Except for the six unimodal networks, two multimodal networks based on ResNeXt under the Parallel learning mode or the Siamese mode were embedded with ages. Performance of eight models were compared via the confusion matrix, precision, recall, specificity, F1 value, and ROC curve, and recall was regarded as the main indicator. Besides, Grad-CAM was used to visualize the decisions made by Siamese ResNeXt network, which is the best performance.

Results

Performance of various models demonstrated the following points: 1) the RexNeXt showed a notable improvement over the ResNet; 2) the structural Siamese networks, which extracted features parallelly and independently, exhibited slight performance enhancements compared to the traditional networks. Notably, the Siamese networks resulted in significant improvements; 3) the performance of classification declined if the age factor was embedded in the network. Taken together, the Siamese ResNeXt unimodal model performed best for its superior efficacy and robustness. This model achieved a recall rate of 88.0% and an AUC value of 90.88% in the validation subset. Additionally, heatmaps calculated by the Grad-CAM algorithm presented concentrated and orderly mappings around the optic disc vascular area in normal CIMT groups and dispersed, irregular patterns in thickened CIMT groups.

Conclusion

We provided a Siamese ResNeXt neural network for predicting the carotid intimal thickness of patients with T2DM from fundus images and confirmed the correlation between fundus microvascular lesions and CIMT.

A narrative review of retinal vascular parameters and the applications (Part II): Diagnosis in stroke

The retina, as an external extension of the diencephalon, can be directly, noninvasively observed by ocular fundus photography. Therefore, it offers a convenient and feasible mode to study nervous system diseases. Caliber, tortuosity, and fractal dimension, as three commonly used retinal vascular parameters, are not only the reflection of structural changes in the retinal microcirculation but also capture the branching pattern or density changes of the retinal microvascular network. Therefore, it contributes to better reflecting the subclinical pathological changes (e.g., lacunar stroke and small cerebral vascular disease) and predicting the risk of incident stroke and recurrent stroke.

Impact of total cerebral small vessel disease score on ophthalmic artery morphologies and hemodynamics

BACKGROUND

Cerebral small vessel disease (CSVD) is a systemic disease, affecting not only the brain, but also eyes and other organs. The total CSVD score is a tool for comprehensive evaluation of brain lesions in patients with CSVD. The ophthalmic artery (OA) is a direct response to ocular blood flow. However, little is known about the correlation between CSVD and characteristics of OA. We investigated the OA morphologies and hemodynamics in patients with CSVD and the correlation between these changes and the total CSVD score.

METHODS

This cross-sectional observational study included 34 eyes from 22 patients with CSVD and 10 eyes from 5 healthy controls. The total CSVD score was rated according to the CSVD signs on magnetic resonance imaging. OA morphological characteristics were measured on the basis of 3D OA model reconstruction. OA hemodynamic information was calculated using computational fluid dynamics simulations.

RESULTS

The total CSVD score negatively correlated with the OA diameter, blood flow velocity, and mass flow ratio (all P < 0.05). After adjusting for potential confounding factors, the total CSVD score was still independently correlated with the OA blood velocity (β = - 0.202, P = 0.005). The total CSVD score was not correlated with OA angle (P > 0.05). The presence of cerebral microbleeds and enlarged perivascular spaces was correlated with the OA diameter (both P < 0.01), while the lacunar infarcts and white matter hyperintensities were correlated with the OA blood velocity (both P < 0.001).

CONCLUSIONS

The decrease of the blood velocity in the OA was associated with the increase in the total CSVD score. The changes of the OA diameter and velocity were associated with the presence of various CSVD signs. The findings suggest that more studies are needed in the future to evaluate CSVD by observing the morphologies and hemodynamics of OA.

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

Background

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

Study design

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

Results

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

Conclusion

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

The spectrum and systemic associations of microvascular dysfunction in the heart and other organs

Microvascular dysfunction (MVD) contributes to several conditions that increase morbidity and mortality, including ischemic heart disease, heart failure, dementia, chronic kidney disease and hypertension. Consequently, MVD imposes a substantial burden on healthcare systems worldwide. In comparison to macrovascular dysfunction, MVD has been incompletely investigated, and it remains uncertain whether MVD in an organ constitutes a distinct pathology or a manifestation of a systemic disorder. Here, we summarize and appraise the techniques that are used to diagnose MVD. We review the disorders of the heart, brain and kidneys in which the role of MVD has been highlighted and summarize evidence hinting at a systemic or multi-organ nature of MVD. Finally, we discuss the benefits and limitations of implementing MVD testing in clinical practice with a focus on new interventions that are beginning to emerge.

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.

Fundus image segmentation via hierarchical feature learning

Fundus Image Segmentation (FIS) is an essential procedure for the automated diagnosis of ophthalmic diseases. Recently, deep fully convolutional networks have been widely used for FIS with state-of-the-art performance. The representative deep model is the U-Net, which follows an encoder-decoder architecture. I believe it is suboptimal for FIS because consecutive pooling operations in the encoder lead to low-resolution representation and loss of detailed spatial information, which is particularly important for the segmentation of tiny vessels and lesions. Motivated by this, a high-resolution hierarchical network (HHNet) is proposed to learn semantic-rich high-resolution representations and preserve spatial details simultaneously. Specifically, a High-resolution Feature Learning (HFL) module with increasing dilation rates was first designed to learn the high-level high-resolution representations. Then, the HHNet was constructed by incorporating three HFL modules and two feature aggregation modules. The HHNet runs in a coarse-to-fine manner, and fine segmentation maps are output at the last level. Extensive experiments were conducted on fundus lesion segmentation, vessel segmentation, and optic cup segmentation. The experimental results reveal that the proposed method shows highly competitive or even superior performance in terms of segmentation performance and computation cost, indicating its potential advantages in clinical application.

Reduced Retinal Microvascular Perfusion in Patients With Stroke Detected by Optical Coherence Tomography Angiography

Currently there is a shortage of biomarkers for stroke, one of the leading causes of death and disability in aging populations. Retinal vessels offer a unique and accessible “window” to study the microvasculature in vivo. However, the relationship between the retinal microvasculature and stroke is not entirely clear. To investigate the retinal microvascular characteristics in stroke, we recruited patients with stroke and age-matched control subjects from a tertiary hospital in China. The macular vessel density (VD) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), foveal avascular zone (FAZ) metrics, and optical coherence tomography angiography (OCTA) measured optic disc VD were recorded for analysis. A total of 189 patients with stroke and 195 control subjects were included. After adjusting for sex, visual acuity, systolic and diastolic blood pressure, a history of smoking, levels of hemoglobulin (HbA1c), cholesterol, and high-density lipoprotein (HDL), the macular VD of SCP and DCP in all sectors was decreased in patients with stroke. In the stroke group, the VD around the FAZ and the VD of the optic disk were lower. Logistic regression found the parafovea-superior-hemi VD of DCP > 54.53% [odds ratio (OR): 0.169] as a protective factor of stroke. Using the integration of all OCTA parameters and traditional risk factors, the area under the receiver operating characteristic (AUC) curve of distinguishing patients with stroke was 0.962, with a sensitivity of 0.944 and a specificity of 0.871. Our study demonstrates that the retinal VD is decreased in patients with stroke independently of the traditional risk factors of stroke, which may shed light on the monitoring of stroke using the retinal microvascular parameters.

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

Background

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

Methods

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

Results

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

Conclusions

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

Retinal microvascular changes in microvascular angina: Findings from the Australian Heart Eye Study

OBJECTIVE

Microvascular changes in microvascular angina are poorly understood due to difficulties in imaging the coronary microcirculation in vivo. The retinal microvasculature may reflect changes in coronary microcirculation. We assessed microvascular changes in the retina in patients with microvascular angina and compared them with patients with angiographically proven coronary artery disease.

METHODS

We performed retinal photography and coronary angiography on 915 patients. Retinal vessel calibers were measured using a validated computer-assisted method; coronary artery disease was graded from coronary angiograms. Microvascular angina was defined as angina with <25% stenosis in all coronary epicardial arteries.

RESULTS

A total of 139 patients (15.2%) had microvascular angina, while 776 (84.8%) had coronary artery disease. Participants with microvascular angina and coronary artery disease had similar retinal arteriolar and venular calibers. After adjustment for age, ethnicity, mean arterial pressure, diabetes, current smoking, body mass index, and fellow vessel caliber, women with smaller venules were threefold more likely to have microvascular angina than women with larger venules (multivariable-adjusted odds ratio 3.54, 95% confidence interval 1.35 to 9.24, P < 0.01). This difference was not observed in men.

CONCLUSIONS

Microvascular angina in women was associated with microvascular changes distinct from those in coronary artery disease.

A Review on the Extraction of Quantitative Retinal Microvascular Image Feature

Digital image processing is one of the most widely used computer vision technologies in biomedical engineering. In the present modern ophthalmological practice, biomarkers analysis through digital fundus image processing analysis greatly contributes to vision science. This further facilitates developments in medical imaging, enabling this robust technology to attain extensive scopes in biomedical engineering platform. Various diagnostic techniques are used to analyze retinal microvasculature image to enable geometric features measurements such as vessel tortuosity, branching angles, branching coefficient, vessel diameter, and fractal dimension. These extracted markers or characterized fundus digital image features provide insights and relates quantitative retinal vascular topography abnormalities to various pathologies such as diabetic retinopathy, macular degeneration, hypertensive retinopathy, transient ischemic attack, neovascular glaucoma, and cardiovascular diseases. Apart from that, this noninvasive research tool is automated, allowing it to be used in large-scale screening programs, and all are described in this present review paper. This paper will also review recent research on the image processing-based extraction techniques of the quantitative retinal microvascular feature. It mainly focuses on features associated with the early symptom of transient ischemic attack or sharp stroke.

Blood-ocular barrier disruption in patients with acute stroke

OBJECTIVE

Prompted by the unexpected finding of gadolinium leakage into ocular structures (GLOS) in acute stroke patients, we studied the frequency and nature of this finding in 167 patients.

METHODS

Patients were selected who had an MRI with gadolinium at baseline and another MRI with fluid-attenuated inversion recovery (FLAIR) imaging at 2 and/or 24 hours later. GLOS was detected as lack of vitreous and/or aqueous fluid suppression on postcontrast FLAIR images.

RESULTS

GLOS, evident on postcontrast FLAIR MRI, occurred in 127/167 (76%) patients: 86/109 (79%) patients treated with tissue plasminogen activator and 41/58 (71%) who were untreated. At 2 hours after administration of the contrast, GLOS was more common in the aqueous chamber alone, occurring in 67% of patients, compared to the vitreous chamber alone, seen in 6% of patients; it occurred in both chambers in 27% of patients. At 24 hours, GLOS was present in 121/162 (75%) patients, always involving the vitreous chamber, but also affecting the aqueous chamber in 6% of cases. Vitreous GLOS at 24 hours was associated with increasing age (p = 0.002) and a higher burden of cerebral white matter hyperintensities (p = 0.017). Patients with rapid diffuse GLOS, defined as GLOS involving both chambers at 2 hours, had larger infarcts (p = 0.022) and a higher degree of blood-brain barrier permeability (p = 0.025).

CONCLUSIONS

We found GLOS to be common in patients with acute stroke; delayed GLOS was a marker for chronic vascular disease. The mechanism for acute GLOS remains uncertain but may be a remote effect of acute cerebral injury on the blood-ocular barrier.

Automated retinal imaging and trend analysis - a tool for health monitoring

Most current diagnostic devices are expensive, require trained specialists to operate and gather static images with sparse data points. This leads to preventable diseases going undetected until late stage, resulting in greatly narrowed treatment options. This is especially true for retinal imaging. Future solutions are low cost, portable, self-administered by the patient, and capable of providing multiple data points, population analysis, and trending. This enables preventative interventions through mass accessibility, constant monitoring, and predictive modeling.

Imaging retina to study dementia and stroke

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

Retinal microvascular network alterations: potential biomarkers of cerebrovascular and neural diseases

Increasing evidence suggests that the conditions of retinal microvessels are indicators to a variety of cerebrovascular, neurodegenerative, psychiatric, and developmental diseases. Thus noninvasive visualization of the human retinal microcirculation offers an exceptional opportunity for the investigation of not only the retinal but also cerebral microvasculature. In this review, we show how the conditions of the retinal microvessels could be used to assess the conditions of brain microvessels because the microvascular network of the retina and brain share, in many aspects, standard features in development, morphology, function, and pathophysiology. Recent techniques and imaging modalities, such as optical coherence tomography (OCT), allow more precise visualization of various layers of the retina and its microcirculation, providing a "microscope" to brain microvessels. We also review the potential role of retinal microvessels in the risk identification of cerebrovascular and neurodegenerative diseases. The association between vision problems and cerebrovascular and neurodegenerative diseases, as well as the possible role of retinal microvascular imaging biomarkers in cerebrovascular and neurodegenerative screening, their potentials, and limitations, are also discussed.

Differential Effect of White-Matter Lesions and Covert Brain Infarcts on the Risk of Ischemic Stroke and Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

We examined the association of white-matter hyperintensity (WMH) volume and covert brain infarcts, which are the 2 major magnetic resonance imaging markers of covert cerebrovascular disease in older adults, with long-term risk of ischemic stroke and intracerebral hemorrhage (ICH) in the general population.

METHODS

Participants were 1731 individuals aged ≥65 years from the Three-City Dijon study. We studied the association of WMH volume and brain infarct, with incident ischemic stroke overall, and by subtype, and with incident ICH.

RESULTS

High total, periventricular, and deep WMHs were associated with incident ICH. Extensive periventricular WMH volume was associated with increased risk of ischemic stroke (hazard ratio, 1.94; 95% confidence interval, 1.12-3.35), particularly cardioembolic stroke. Covert brain infarcts were associated with incident ICH but not with incident ischemic stroke or its subtypes.

CONCLUSIONS

Although of ischemic nature, both WMH volume and covert brain infarcts portend a major risk of ICH. If confirmed in independent studies, these findings could have important implications for the clinical management of covert vascular brain lesions.

Retinal Vascular Changes are a Marker for Cerebral Vascular Diseases

The retinal circulation is a potential marker of cerebral vascular disease because it shares origin and drainage with the intracranial circulation and because it can be directly visualized using ophthalmoscopy. Cross-sectional and cohort studies have demonstrated associations between chronic retinal and cerebral vascular disease, acute retinal and cerebral vascular disease, and chronic retinal vascular disease and acute cerebral vascular disease. In particular, certain qualitative features of retinopathy, retinal artery occlusion, and increased retinal vein caliber are associated with concurrent and future cerebrovascular events. These associations persist after accounting for confounding variables known to be disease-causing in both circulations, which supports the potential use of retinal vasculature findings to stratify individuals with regards to cerebral vascular disease risk.

Morphometric analysis of small arteries in the human retina using adaptive optics imaging: relationship with blood pressure and focal vascular changes

Objectives:

The wall-to-lumen ratio (WLR) of retinal arteries is a recognized surrogate of end-organ damage due to aging and/or arterial hypertension. However, parietal morphometry remains difficult to assess in vivo. Recently, it was shown that adaptive optics retinal imaging can resolve parietal structures of retinal arterioles in humans in vivo. Here, using adaptive optics retinal imaging, we investigated the variations of parietal thickness of small retinal arteries with blood pressure and focal vascular damage.

Methods:

Adaptive optics imaging of the superotemporal retinal artery was done in 49 treatment-naive individuals [mean age (±SD) 44.9 years (±14); mean systolic pressure 132 mmHg (±22)]. Semi-automated segmentation allowed extracting parietal thickness and lumen diameter. In a distinct cohort, adaptive optics images of arteriovenous nicking (AVN; n = 12) and focal arteriolar narrowing (FAN; n = 10) were also analyzed qualitatively and quantitatively.

Results:

In the cohort of treatment-naive individuals, by multiple regression taking into account age, body mass index, mean, systolic, diastolic and pulse blood pressure, the WLR was found positively correlated to mean blood pressure and age which in combination accounted for 43% of the variability of WLR. In the cohort of patients with focal vascular damage, neither FANs or AVNs showed evidence of parietal growth; instead, at sites of FANs, decreased outer diameter suggestive of vasoconstriction was consistently found, while at sites of AVNs venous narrowing could be seen in the absence of arteriovenous contact.

Conclusion:

High resolution imaging of retinal vessels by adaptive optics allows quantitative microvascular phenotyping, which may contribute to a better understanding and management of hypertensive retinopathy.

Multimodal functional and anatomic imaging identifies preclinical microvascular abnormalities in type 1 diabetes mellitus

Structural and functional changes in the microcirculation in type 1 diabetes mellitus predict future end-organ damage and macrovascular events. We explored the utility of novel signal processing techniques to detect and track changes in ocular hemodynamics in patients with this disease. Twenty-four patients with uncomplicated type 1 diabetes mellitus and eighteen age- and sex-matched control subjects were studied. Doppler ultrasound was used to interrogate the carotid and ophthalmic arteries, and digital photography was used to image the retinal vasculature. Frequency analysis algorithms were applied to quantify velocity waveform structure and retinal photographic data at baseline and after inhalation of 100% O2. Frequency data were compared between groups. No significant differences were found in the resistive index between groups at baseline or after inhaled O2. Frequency analysis of Doppler flow velocity waveforms identified significant differences in bands 3-7 between patients and control subjects in data captured from the ophthalmic artery (P < 0.01 for each band). In response to inhaled O2, changes in frequency band amplitudes were significantly greater in control subjects compared with patients (P < 0.05). Only control subjects demonstrated a positive correlation (R = 0.61) between changes in retinal vessel diameter and frequency band amplitudes derived from ophthalmic artery waveform data. The use of multimodal signal processing techniques applied to Doppler flow velocity waveforms and retinal photographic data identified preclinical changes in the ocular microcirculation in patients with uncomplicated diabetes mellitus. An impaired autoregulatory response of the retinal microvasculature may contribute to the future development of retinopathy in such patients.

Microvascular retinal abnormalities in acute intracerebral haemorrhage and lacunar infarction

BACKGROUND

Retinal microvascular changes have been previously associated with cerebral MRI markers of small vessel disease (SVD). Whether retinal changes differ between patient with intracerebral haemorrhage (ICH) and patients with lacunar infarction (LI) caused by small vessel disease has been poorly investigated.

OBJECTIVE

The study aims to compare the frequency of retinal changes between patients with LI and patients with ICH at the acute stage of stroke-related SVD.

METHODS

Microvascular wall signs (arteriolar occlusion, arteriovenous nicking, focal arterial narrowing) and retinopathy lesions (microanevrysms, cotton wool spots, retinal haemorrhages, hard exudates) were assessed by retinography up to three months after stroke onset.

RESULTS

Forty-eight non-diabetic patients with acute stroke-related to SVD (26 LI, 22 ICH) were recruited prospectively in the study. Retinal wall signs (arteriovenous nicking, and focal arterial narrowing) were found in more than three quarters of subjects and most often bilaterally in both groups. Retinopathy lesions (cotton wool spots, retinal haemorrhages) were found more frequently in ICH patients than in LI patients (22.2% vs. 15.4%, 50% vs. 34% respectively, P>0.005). The frequency of bilateral cotton wool spots and of bilateral retinal haemorrhages was significantly higher in ICH patients than in LI patients (12.5% vs. 0%, P=0.012, 41.2% vs. 7.7%, P=0.029 respectively).

CONCLUSION

These results confirm the high frequency of microvascular alterations in patients with hypertension-related SVD leading to LI or ICH and suggest that retinal tissue alterations are more frequent in ICH than in LI. Further investigations are needed to investigate the mechanisms underlying this difference.

A 3-year follow-up study on the risk of stroke among patients with conjunctival haemorrhage

PURPOSE

To the best of our knowledge, no large population-based studies on the relationship between conjunctival haemorrhage and stroke have been conducted to date. Using a nationwide population-based data set, this study investigated the relationship between conjunctival haemorrhage and the subsequent risk of stroke within a 3-year period following diagnosis.

METHODS

We analysed data sourced from the Taiwan Longitudinal Health Insurance Database 2000. The study cohort consisted of 17 349 patients with conjunctival haemorrhage and 86 745 comparison subjects. Each patient was individually tracked for a 3-year period from their index date to identify all those who had subsequently received a diagnosis of stroke.

RESULTS

  The incidence rate of stroke was 2.44 (95% CI = 2.31-2.55) per 100 person-years in patients with conjunctival haemorrhage and 1.63 (95% CI = 1.59-1.68) per 100 person-years in comparison patients. After adjusting for patients' monthly income and geographic location, as well as for hypertension, atrial fibrillation, diabetes, hyperlipidaemia and coronary heart disease, stratified Cox proportional hazards regressions revealed a statistically significant hazard ratio for stroke in patients with conjunctival haemorrhage (HR = 1.33; 95% CI = 1.24-1.42, p < 0.001).

CONCLUSIONS

In this study, patients with conjunctival haemorrhage were found to be at a significant risk of stroke during a 3-year follow-up period after diagnosis.

International epidemiology of intracerebral hemorrhage

Intracerebral hemorrhage is the second most common subtype of stroke. In recent decades our understanding of intracerebral hemorrhage has improved. New risk factors have been identified; more knowledge has been obtained on previously known risk factors; and new imaging techniques allow for in vivo assessment of preclinical markers of intracerebral hemorrhage. In this review the latest developments in research on intracerebral hemorrhage are highlighted from an epidemiologic point of view. Special focus is on frequency, etiologic factors and pre-clinical markers of intracerebral hemorrhage.

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.

Differing Associations of White Matter Lesions and Lacunar Infarction with Retinal Microvascular Signs

Background

White matter lesions (WML) and lacunar infarcts (LI) are believed to have microvascular etiologies but the exact microvascular changes occurring in each is unclear. Aim Using the retina as a proxy, we assessed retinal microvascular changes in WML and LI.

Methods

We prospectively recruited 1211 acute stroke patients. Four subgroups were identified from neuroimaging: WML alone, LI alone, both WML and LI, neither WML nor LI. Masked retinal photographs identified retinopathy and retinal arteriolar wall signs and measured retinal vascular caliber.

Results

Compared with 448 controls with neither WML nor LI, 384 patients with only WML were more likely to have retinopathy [odds ratio (OR) 1·5, 95% confidence interval (CI) 1·1 to 2·1] and enhanced arteriolar light reflex (OR 1·6, 95% CI 1·1 to 2·3); 200 patients with only LI were more likely to have arteriolar narrowing (OR 1·6, 95% CI 1·1 to 2·3) and enhanced arteriolar light reflex (OR 1·6, 95% CI 1·0 to 2·4); and 179 patients with both WML and LI were more likely to have arteriovenous nicking (OR 1·7, 95% CI 1·1 to 2·6), enhanced arteriolar light reflex (OR 2·0, 95% CI 1·3 to 3·2) and wider venules (OR 2·3, 95% CI 1·4 to 3·6). All analyses were adjusted for age, gender, study site and cardiovascular risk factors.

Conclusion

Both WML and LI were associated with retinal microvascular signs, supporting a microvascular etiology. Differing patterns of association suggest different mechanisms may predominate, e.g. greater endothelial permeability in WML, and ischemia associated with arteriolar wall disease in LI.

Retinal vascular calibers and the risk of intracerebral hemorrhage and cerebral infarction: the Rotterdam Study

BACKGROUND AND PURPOSE

Narrower retinal arteriolar calibers and wider venular calibers are associated with cardiovascular disease, including cerebral infarction. We investigated the association between retinal vascular calibers and the long-term risk for stroke and its subtypes with particular focus on intracerebral hemorrhage.

METHODS

We included 5518 participants (aged ≥ 55 years) from the prospective population-based Rotterdam Study who were stroke-free at baseline (1990-1993) and of whom digital retinal images were available. Follow-up for incident stroke was complete up to January 1, 2007. Data were analyzed with Cox proportional hazards models adjusted for age and sex and additionally for potential confounders. Arteriolar and venular calibers were entered both separately and simultaneously in the models.

RESULTS

During an average follow-up of 11.5 years, 623 participants developed a first-ever stroke (50 hemorrhagic, 361 ischemic, 212 unspecified). Larger venular caliber was independently associated with an increased risk for stroke (hazard ratio [HR] per SD increase: 1.20; 95% confidence interval [CI]: 1.09 to 1.33), cerebral infarction (HR: 1.28; 95% CI: 1.13 to 1.46), and intracerebral hemorrhage (HR: 1.53; 95% CI: 1.09 to 2.15). Much weaker, only borderline significant associations were found between arteriolar caliber and risk for stroke (HR per SD decrease: 1.12; 95% CI: 0.99 to 1.23), cerebral infarction (HR: 1.12; 95% CI, 0.98 to 1.27), and intracerebral hemorrhage (HR: 1.25; 95% CI: 0.87 to 1.79). Retinal vascular calibers were strongly associated with lobar hemorrhages and oral anticoagulant-related hemorrhages.

CONCLUSIONS

Larger retinal venular caliber is associated with an increased risk for stroke in the general population and, in particular, with an increased risk for intracerebral hemorrhage.