Associations of retinal microvascular signs and intracranial large artery disease

Adversarial learning-based domain adaptation algorithm for intracranial artery stenosis detection on multi-source datasets

Intracranial arterial stenosis (ICAS) is characterized by the pathological narrowing or occlusion of the inner lumen of intracranial blood vessels. However, the retina can indirectly react to cerebrovascular disease. Therefore, retinal fundus images (RFI) serve as valuable noninvasive and easily accessible screening tools for early detection and diagnosis of ICAS. This paper introduces an adversarial learning-based domain adaptation algorithm (ALDA) specifically designed for ICAS detection in multi-source datasets. The primary objective is to achieve accurate detection and enhanced generalization of ICAS based on RFI. Given the limitations of traditional algorithms in meeting the accuracy and generalization requirements, ALDA overcomes these challenges by leveraging RFI datasets from multiple sources and employing the concept of adversarial learning to facilitate feature representation sharing and distinguishability learning. In order to evaluate the performance of the ALDA algorithm, we conducted experimental validation on multi-source datasets. We compared its results with those obtained from other deep learning algorithms in the ICAS detection task. Furthermore, we validated the potential of ALDA for detecting diabetic retinopathy. The experimental results clearly demonstrate the significant improvements achieved by the ALDA algorithm. By leveraging information from diverse datasets, ALDA learns feature representations that exhibit enhanced generalizability and robustness. This makes it a reliable auxiliary diagnostic tool for clinicians, thereby facilitating the prevention and treatment of cerebrovascular diseases.

Evaluation of peripapillary retinal nerve fiber layer thickness in intracranial atherosclerotic stenosis

PURPOSE

To evaluate the peripapillary retinal nerve fiber layer thickness (pRNFL) in patients with intracranial atherosclerotic stenosis (ICAS).

METHODS

A cross-sectional study was performed in a general hospital. The intracranial atherosclerotic stenosis was evaluated by digital subtraction angiography (DSA), computed tomography angiography (CTA) or magnetic resonance angiography (MRA). High-definition optical coherence tomography (HD-OCT) was used to evaluate the peripapillary retinal nerve fiber layer thickness.

RESULTS

A total of 102 patients, including 59(57.8%) patients with ICAS and 43(42.2%) patients without ICAS, were finally analysed in the study. The peripapillary retinal nerve fiber layer thickness (pRNFL) was reduced significantly in the average, the superior and the inferior quadrants of the ipsilateral eyes and in the superior quadrant of the contralateral eyes in patients with ICAS compared with patients without ICAS. After multivariate analysis, only the superior pRNFL thickness in the ipsilateral eyes was significantly associated with ICAS (OR,0.968; 95% CI,0.946-0.991; p = 0.006). The area under receiver operator curve was 0.679 (95% CI,0.576-0.782) for it to identify the presence of ICAS. The cut-off value of the superior pRNFL was 109.5 μm, and the sensitivity and specificity were 50.8% and 83.7%, respectively.

CONCLUSION

The superior pRNFL in the ipsilateral eye was significantly associated with ICAS in this study. Larger studies are needed to explore the relation between pRNFL and ICAS further.

Changes of retinal structure and function in patients with internal carotid artery stenosis

BACKGROUND

To investigate the structural and functional changes of the retina in patients with different degrees of internal carotid artery (ICA) stenosis.

METHODS

This cross-sectional study included patients with varying degrees ICA stenosis. Clinical characteristics of 41 patients were collected after being divided into four groups according to the ICA stenosis indicated by computed tomographic angiography (Group 0: without ICA stenosis, Group 1: ipsilateral slight ICA stenosis, Group 2: ipsilateral moderate ICA stenosis, Group 3: ipsilateral severe ICA stenosis). Retinal vessel caliber (RVC) was measured quantitatively with the Integrative Vessel Analysis software. The retinal sensitivity was examined with the MP-3 microperimeter. The relationships among central retinal artery equivalent (CRAE), central retinal vein equivalent, arteriole to venule ratio (AVR), mean retinal sensitivity (MS) and ICA stenosis degree were analysed.

RESULTS

The CRAE in Group 3 were significantly smaller compared with Group 0, Group 1 and Group 2 (P < 0.001, P < 0.001, P = 0.002). Significant decrease was found between Group 3 with other groups in MS at fovea (P < 0.001, P < 0.001, P = 0.002). Moreover, there was a positive correlation found between MS and CRAE (Beta = 0.60, P < 0.001 at fovea; Beta = 0.64, P < 0.001 at 2 degree; Beta = 0.60, P < 0.001 at 4 degree; Beta = 0.55, P < 0.001 at 8 degree; Beta = 0.53, P < 0.001 at 12 degree).

CONCLUSIONS

The present study revealed smaller CRAE and AVR in ipsilateral severe ICA stenosis patients. And the MS decreased in patients with severe ICA stenosis. In addition, MS had a positive correlation with CRAE.

Systemic Stressors and Retinal Microvascular Alterations in People Without Diabetes: The Kailuan Eye Study

Purpose

The purpose of this study was to determine systemic stressors, including fasting plasma glucose (FPG), and other major atherosclerotic cardiovascular disease (ASCVD) risk factors of the retinal microvasculature in people without diabetes.

Methods

The Kailuan Eye Study enrolled applicants from the community-based longitudinal Kailuan Study. Applicants underwent optical coherence tomographic angiography (OCTA) and systemic examinations. Both the macula and optic disc were screened, whereas superficial capillary plexus (SCP), deep capillary plexus (DCP), foveal vessel density in the 300 µm ring (FD-300), and radial peripapillary capillaries (RPCs) density were measured in the study.

Results

This study included 353 eligible applicants (mean age = 49.86 ± 11.41 years; 47% men; FPG =5.32 ± 1.19 mmol/L). Lower DCP density was associated with elder age (P = 0.001), male gender (P < 0.001), and higher FPG (P = 0.008). Male gender (P < 0.001), axial length (P < 0.001), and FPG (P = 0.029) were inversely associated with RPC density. Meanwhile, a higher FPG concentration was significantly correlated with lower DCP density (P = 0.006) and higher intraocular pressure (P = 0.006), after adjusting mean arterial blood pressure (P = 0.001) and sex (P = 0.042).

Conclusions

DCP density showed a significantly negative correlation with FPG concentration in people without diabetes. These data suggest hyperglycemia could cause early retinal capillary alterations in patients without clinical signs of retinopathy and indicate the potential clinical applications of routine OCTA may be beneficial to screen for subclinical microvasculature and monitor patients with high risks of ASCVD.

Retinal vessel changes in cerebrovascular disease

PURPOSE OF REVIEW

The retina is growingly recognized as a window into cerebrovascular and systemic vascular conditions. The utility of noninvasive retinal vessel biomarkers in cerebrovascular risk assessment has expanded due to advances in retinal imaging techniques and machine learning-based digital analysis. The purpose of this review is to underscore the latest evidence linking retinal vascular abnormalities with stroke and vascular-related cognitive disorders; to highlight modern developments in retinal vascular imaging modalities and software-based vasculopathy quantification.

RECENT FINDINGS

Longitudinal studies undertaken for extended periods indicate that retinal vascular changes can predict cerebrovascular disorders (CVD). Cerebrovascular ties to dementia provoked recent explorations of retinal vessel imaging tools for conceivable early cognitive decline detection. Innovative biomedical engineering technologies and advanced dynamic and functional retinal vascular imaging methods have recently been added to the armamentarium, allowing an unbiased and comprehensive analysis of the retinal vasculature. Improved artificial intelligence-based deep learning algorithms have boosted the application of retinal imaging as a clinical and research tool to screen, risk stratify, and monitor with precision CVD and vascular cognitive impairment.

SUMMARY

Mounting evidence supports the use of quantitative retinal vessel analysis in predicting CVD, from clinical stroke to neuroimaging markers of stroke and neurodegeneration.

Cerebral magnetic resonance imaging of coincidental infarction and small vessel disease in retinal artery occlusion

There are several reports in the literature on the association between non-arteritic retinal artery occlusion (NA-RAO) and acute ischemic stroke. We investigated the burden of small vessel disease (SVD) and cerebral coincident infarction observed on cerebral magnetic resonance imaging (MRI) in patients with newly diagnosed NA-RAO. In this retrospective, observational, case-series study, consecutive patients with NA-RAO who underwent cerebral MRI within one month of diagnosis between September 2003 and October 2018 were included. The classification of NA-RAO was based on ophthalmologic and systemic examinations. We also investigated the co-incident infarction and burden of underlying SVD, which were categorized as white matter hyperintensity lesion (WMH), cerebral microbleeds (CMB), and silent lacunar infarction (SLI). Among the 272 patients enrolled in the study, 18% presented co-incident infarction and 73% had SVD, which included WMH (70%), CMB (14%), and SLI (30%). Co-incident infarction, WMH, and SLI significantly increased with age: co-incident infarction was observed in 8% of young (< 50 years) patients and 30% of old (≥ 70 years) patients. The embolic etiology of RAO (large artery atherosclerosis, cardioembolism, and undetermined etiology) was significantly associated with the prevalence of SVD (82%: 70%: 64%, P = 0.002) and co-incident infarction (30%: 19%: 8%; P = 0.009). Therefore, high co-incidence of acute cerebral infarction and underlying SVD burden warrant careful neurologic examination and appropriate brain imaging, followed by management of NA-RAO. Urgent brain imaging is particularly pertinent in elderly patients with NA-RAO.

Hypertension and the eye

PURPOSE OF REVIEW

Hypertension is the primary risk factor for cardiovascular disease and mortality that consists a major public health issue worldwide. Hypertension triggers a series of pathophysiological ocular modifications affecting significantly the retinal, choroidal, and optic nerve circulations that result in a range of ocular effects.The retina is the only place in the body where microvasculature can be directly inspected, providing valuable information on hypertension related systemic risks.The aim of this review is to provide an update on latest advances regarding the detection and significance of hypertension related eye signs.

RECENT FINDINGS

It's been shown that measurable retinal microvascular changes may precede progression of systemic microvascular disease.Last years, there are emerging advances in the field retinal imaging and computer software analysis that have enabled the objective and accurate assessment of retinal vascular caliber, while in association with latest epidemiological studies several other retinal vascular features have been recognized, such as vascular length-to-diameter ratio, and wall-to-lumen ratio that may also be associated to hypertension.Additionally, recent genetic studies have provided some insight to vascular pathophysiological processes having correlated new chromosome's loci to hypertensive retinopathy signs.

SUMMARY

Assessment of hypertensive retinopathy signs may convey additional prognostic information on the risk of end-organ damage and may alert for urgent systemic management or even preventive systemic therapies. Further development of retinal vascular imaging and computerized system may provide a significant tool to improve the diagnosis, prognosis, and management of hypertension in clinical practice.

Relationship of retinal vascular caliber variation with intracranial arterial stenosis

BACKGROUND & PURPOSE

To investigate the associations of retinal vessel parameters with intracranial arterial stenosis (ICAS) assessed by Transcranial Doppler ultrasonography.

METHOD

Data on transcranial Doppler ultrasonography and quantitative retinal vessel parameters from 627 participants in a health screening program were included in this study. ICAS was defined as >50% intracranial arterial stenosis (ICAS) based on criteria modified from the stroke outcomes and neuroimaging of intracranial atherosclerosis (SONIA) trial assessed by transcranial Doppler (TCD) ultrasonography. A semi-automated computer-assisted program (Singapore I Vessel Assessment) was used to measure the retinal vascular parameters from the photographs. Multivariate analysis was performed to identify which retinal vessel parameters were associated with increased risk of ICAS.

RESULTS

Among 627 participants, 24 (3.8%) had ICAS diagnosed by TCD. Subjects with ICAS had eyes with wider mean central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) in comparison to subjects without ICAS. Men (odds ratio [OR]:13.1, 95% confidence interval: 3.13-33.33) and a large standard deviation of mean arterial width (STDWa) were associated with ICAS (first vs. third tertile: OR ratio: 14.04, 95% confidence interval: 1.71-115.32; first vs. third tertile: OR ratio: 22.1, 95% confidence interval: 2.56-190.97) after adjusting for possible confounders.

CONCLUSION

A large variation in retinal arteriolar diameter is associated with ICAS. This study suggests the possible relationship between retina vessel and early changes within the cerebrovascular network.

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.

Severe diabetic retinal disease and dementia risk in type 2 diabetes

BACKGROUND

Persons with type 2 diabetes are at an increased risk of dementia compared to those without, but the etiology of this increased risk is unclear.

OBJECTIVE

Cerebral microvascular disease may mediate the link between diabetes and dementia. Given the anatomical and physiological similarities between cerebral and retinal microvessels, we examined the longitudinal association between diabetic retinal disease and dementia in patients with type 2 diabetes.

METHODS

Longitudinal cohort study of 29,961 patients with type 2 diabetes aged ≥60 years. Electronic medical records were used to collect diagnoses and treatment of severe diabetic retinal disease (i.e., diabetic proliferative retinopathy and macular edema) between 1996-1998 and dementia diagnoses for the next ten years (1998-2008). The association between diabetic retinal disease and dementia was evaluated by Cox proportional hazard models adjusted for sociodemographics, as well as diabetes-specific (e.g., diabetes duration, pharmacotherapy, HbA1c, hypoglycemia, hyperglycemia) and vascular (e.g., vascular disease, smoking, body mass index) factors.

RESULTS

2,008 (6.8%) patients had severe diabetic retinal disease at baseline and 5,173 (17.3%) participants were diagnosed with dementia during follow-up. Those with diabetic retinal disease had a 42% increased risk of incident dementia (demographics adjusted Hazards Ratio (HR) = 1.42, 95% Confidence Interval (CI) 1.27, 1.58); further adjustment for diabetes-specific (HR 1.29; 95% CI 1.14, 1.45) and vascular-related disease conditions (HR 1.35; 95% CI 1.21, 1.52) attenuated the relation slightly.

CONCLUSION

Diabetic patients with severe diabetic retinal disease have an increased risk of dementia. This may reflect a causal link between microvascular disease and dementia.

Novel Method for Automated Analysis of Retinal Images: Results in Subjects with Hypertensive Retinopathy and CADASIL

Morphological analysis of the retinal vessels by fundoscopy provides noninvasive means for detecting and staging systemic microvascular damage. However, full exploitation of fundoscopy in clinical settings is limited by paucity of quantitative, objective information obtainable through the observer-driven evaluations currently employed in routine practice. Here, we report on the development of a semiautomated, computer-based method to assess retinal vessel morphology. The method allows simultaneous and operator-independent quantitative assessment of arteriole-to-venule ratio, tortuosity index, and mean fractal dimension. The method was implemented in two conditions known for being associated with retinal vessel changes: hypertensive retinopathy and Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL). The results showed that our approach is effective in detecting and quantifying the retinal vessel abnormalities. Arteriole-to-venule ratio, tortuosity index, and mean fractal dimension were altered in the subjects with hypertensive retinopathy or CADASIL with respect to age- and gender-matched controls. The interrater reliability was excellent for all the three indices (intraclass correlation coefficient ≥ 85%). The method represents simple and highly reproducible means for discriminating pathological conditions characterized by morphological changes of retinal vessels. The advantages of our method include simultaneous and operator-independent assessment of different parameters and improved reliability of the measurements.

Fundus photography as a convenient tool to study microvascular responses to cardiovascular disease risk factors in epidemiological studies

The microcirculation consists of blood vessels with diameters less than 150 µm. It makes up a large part of the circulatory system and plays an important role in maintaining cardiovascular health. The retina is a tissue that lines the interior of the eye and it is the only tissue that allows for a non-invasive analysis of the microvasculature. Nowadays, high-quality fundus images can be acquired using digital cameras. Retinal images can be collected in 5 min or less, even without dilatation of the pupils. This unobtrusive and fast procedure for visualizing the microcirculation is attractive to apply in epidemiological studies and to monitor cardiovascular health from early age up to old age. Systemic diseases that affect the circulation can result in progressive morphological changes in the retinal vasculature. For example, changes in the vessel calibers of retinal arteries and veins have been associated with hypertension, atherosclerosis, and increased risk of stroke and myocardial infarction. The vessel widths are derived using image analysis software and the width of the six largest arteries and veins are summarized in the Central Retinal Arteriolar Equivalent (CRAE) and the Central Retinal Venular Equivalent (CRVE). The latter features have been shown useful to study the impact of modifiable lifestyle and environmental cardiovascular disease risk factors. The procedures to acquire fundus images and the analysis steps to obtain CRAE and CRVE are described. Coefficients of variation of repeated measures of CRAE and CRVE are less than 2% and within-rater reliability is very high. Using a panel study, the rapid response of the retinal vessel calibers to short-term changes in particulate air pollution, a known risk factor for cardiovascular mortality and morbidity, is reported. In conclusion, retinal imaging is proposed as a convenient and instrumental tool for epidemiological studies to study microvascular responses to cardiovascular disease risk factors.

Retinal microvascular changes in low-birth-weight babies have a link to future health

BACKGROUND

In utero insults that result in low-birth-weight (LBW) infants are now recognized risk factors for the development of vascular-related diseases in adulthood. Microcirculatory pathologies are believed to form a mechanistic link between fetal insult and the manifestation of illness in adulthood.

OBJECTIVES

The challenge has been to investigate microcirculatory changes in vivo. The objective of this review is to determine whether LBW infants and individuals undergo abnormal microvascular changes and, if so, whether these changes can be objectively identified and measured by investigating retinal vessels.

METHODS

An online publication search was carried out using the following keywords to identify and review relevant articles: retinal microvasculature, retinal vessels, small for gestation age, growth restriction, and intrauterine growth restriction. Articles published from 1980 to 2011 were considered.

CONCLUSIONS

The ability of retinal imaging technology to assess and measure retinal microvasculature makes it a valuable assessment tool. The current tool is, however, unsuitable for non-invasive assessment in infants and young children. Once this hurdle has been overcome, a longitudinal study of LBW individuals from infancy to adulthood, with regular retinal microvascular assessments, would help prove the mechanistic link between LBW and cardiovascular disease in adulthood.