Retinal vascular changes in pre-diabetes and prehypertension: new findings and their research and clinical implications

Association of body roundness index with diabetes and prediabetes in US adults from NHANES 2007-2018: a cross-sectional study

OBJECTIVE

The present study examined the ability of the body roundness index (BRI) to predict the incidence of diabetes and prediabetes among adults in the USA.

METHOD

The study enrolled 11,980 adults aged ≥ 20 years from the National Health and Nutrition Examination Survey (NHANES). Logistic regression served as the primary method for analyzing the relevant link between BRI and the incidence of diabetes and prediabetes, including univariate analysis, multivariate regression analysis, smooth curve fitting analysis, and subgroup analysis. What's more, receiver operating characteristic (ROC) analysis was applied to confirm the predictive values of BRI for diabetes and prediabetes.

RESULTS

Each unit higher than BRI was associated with a 17% increased risk of diabetes and prediabetes after covariate adjustments (OR: 1.17, 95% CI: 1.07-1.27). Those with BRI in the high scores (Q4) possessed an increased likelihood of having diabetes and prediabetes than individuals in the reference group (OR: 1.83, 95% CI: 1.29-2.58). A smooth curve fitting analysis revealed a non-linear trend. The results across all population subgroups were uniform to those of the total population. The ROC curve indicated that the BRI was the best predictor of diabetes and prediabetes among other anthropometric indices.

CONCLUSIONS

Diabetes and prediabetes occurrence rates and BRI have a positive and non-linear relationship in American adults. The BRI indices could function as predictive markers for diabetes and prediabetes.

Plasma Metabolomics Identifies Key Metabolites and Improves Prediction of Diabetic Retinopathy: Development and Validation across Multinational Cohorts

PURPOSE

To identify longitudinal metabolomic fingerprints of diabetic retinopathy (DR) and to evaluate their usefulness in predicting DR development and progression.

DESIGN

Multicenter, multiethnic cohort study.

PARTICIPANTS

This study included 17 675 participants from the UK Biobank (UKB) who had baseline prediabetes or diabetes, identified in accordance with the 2021 American Diabetes Association guidelines, and were free of baseline DR and an additional 638 participants with type 2 diabetes mellitus from the Guangzhou Diabetic Eye Study (GDES) for external validation. Diabetic retinopathy was determined by ICD-10 codes in the UKB cohort and revised ETDRS grading criteria in the GDES cohort.

METHODS

Longitudinal DR metabolomic fingerprints were identified through nuclear magnetic resonance (NMR) assay in UKB participants. The predictive value of these fingerprints for predicting DR development were assessed in a fully withheld test set. External validation and extrapolation analyses of DR progression and microvascular damage were conducted in the GDES cohort using NMR technology. Model assessments included the concordance (C) statistic, net classification improvement (NRI), integrated discrimination improvement (IDI), calibration, and clinical usefulness in both cohorts.

MAIN OUTCOME MEASURES

DR development and progression and retinal microvascular damage.

RESULTS

Of 168 metabolites, 118 were identified as candidate metabolomic fingerprints for future DR development. These fingerprints significantly improved the predictability for DR development beyond traditional indicators (C statistic, 0.802 [95% confidence interval (CI), 0.760-0.843] vs. 0.751 [95% CI, 0.706-0.796]; P = 5.56 × 10-4). Glucose, lactate, and citrate were among the fingerprints validated in the GDES cohort. Using these parsimonious and replicable fingerprints yielded similar improvements for predicting DR development (C statistic, 0.807 [95% CI, 0.711-0.903] vs. 0.617 [95% CI, 0.494-0.740]; P = 1.68 × 10-4) and progression (C statistic, 0.797 [95% CI, 0.712-0.882] vs. 0.665 [95% CI, 0.545-0.784]; P = 0.003) in the external GDES cohort. Improvements in NRIs, IDIs, and clinical usefulness also were evident in both cohorts (all P < 0.05). In addition, lactate and citrate were associated with microvascular damage across macular and optic nerve head regions among Chinese GDES (all P < 0.05).

CONCLUSIONS

Metabolomic profiling may be effective in identifying robust fingerprints for predicting future DR development and progression, providing novel insights into the early and advanced stages of DR pathophysiology.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Advances in Structural and Functional Retinal Imaging and Biomarkers for Early Detection of Diabetic Retinopathy

Diabetic retinopathy (DR), a vision-threatening microvascular complication of diabetes mellitus (DM), is a leading cause of blindness worldwide that requires early detection and intervention. However, diagnosing DR early remains challenging due to the subtle nature of initial pathological changes. This review explores developments in multimodal imaging and functional tests for early DR detection. Where conventional color fundus photography is limited in the field of view and resolution, advanced quantitative analysis of retinal vessel traits such as retinal microvascular caliber, tortuosity, and fractal dimension (FD) can provide additional prognostic value. Optical coherence tomography (OCT) has also emerged as a reliable structural imaging tool for assessing retinal and choroidal neurodegenerative changes, which show potential as early DR biomarkers. Optical coherence tomography angiography (OCTA) enables the evaluation of vascular perfusion and the contours of the foveal avascular zone (FAZ), providing valuable insights into early retinal and choroidal vascular changes. Functional tests, including multifocal electroretinography (mfERG), visual evoked potential (VEP), multifocal pupillographic objective perimetry (mfPOP), microperimetry, and contrast sensitivity (CS), offer complementary data on early functional deficits in DR. More importantly, combining structural and functional imaging data may facilitate earlier detection of DR and targeted management strategies based on disease progression. Artificial intelligence (AI) techniques show promise for automated lesion detection, risk stratification, and biomarker discovery from various imaging data. Additionally, hematological parameters, such as neutrophil-lymphocyte ratio (NLR) and neutrophil extracellular traps (NETs), may be useful in predicting DR risk and progression. Although current methods can detect early DR, there is still a need for further research and development of reliable, cost-effective methods for large-scale screening and monitoring of individuals with DM.

Prediabetes: A Benign Intermediate Stage or a Risk Factor in Itself?

Prediabetes is a condition when the blood glucose levels are above the normal range but below the threshold for defining diabetes. Previously considered benign, it is now recognized to be associated with various macrovascular and microvascular complications, with increases in the risk of cardiovascular events, nephropathy neuropathy, and retinopathy. Early identification of prediabetics may help detect the risk for these future complications at an earlier stage. Moreover, therapeutic options for prediabetes are available, which can retard its progression to diabetes and the subsequent development of complications. Hence, we make a case for the early identification of prediabetes through screening methods and appropriate institution of management strategies.

Assessing interstitial fluid dynamics in type 2 diabetes mellitus and prediabetes cases through diffusion tensor imaging analysis along the perivascular space

Background and purpose

Glymphatic system in type 2 diabetes mellitus (T2DM) but not in the prodrome, prediabetes (Pre-DM) was investigated using diffusion tensor image analysis along the perivascular space (DTI-ALPS). Association between glymphatic system and insulin resistance of prominent characteristic in T2DM and Pre-DM between is yet elucidated. Therefore, this study delves into the interstitial fluid dynamics using the DTI-ALPS in both Pre-DM and T2DM and association with insulin resistance.

Materials and methods

In our cross-sectional study, we assessed 70 elderly individuals from the Bunkyo Health Study, which included 22 with Pre-DM, 18 with T2DM, and 33 healthy controls with normal glucose metabolism (NGM). We utilized the general linear model (GLM) to evaluate the ALPS index based on DTI-ALPS across these groups, considering variables like sex, age, intracranial volume, years of education, anamnesis of hypertension and hyperlipidemia, and the total Fazekas scale. Furthermore, we have explored the relationship between the ALPS index and insulin resistance, as measured by the homeostasis model assessment of insulin resistance (HOMA-IR) using GLM and the same set of covariates.

Results

In the T2DM group, the ALPS index demonstrated a reduction compared with the NGM group [family-wise error (FWE)-corrected p < 0.001; Cohen's d = -1.32]. Similarly, the Pre-DM group had a lower ALPS index than the NGM group (FWE-corrected p < 0.001; Cohen's d = -1.04). However, there was no significant disparity between the T2DM and Pre-DM groups (FWE-corrected p = 1.00; Cohen's d = -0.63). A negative correlation was observed between the ALPS index and HOMA-IR in the combined T2DM and Pre-DM groups (partial correlation coefficient r = -0.35, p < 0.005).

Conclusion

The ALPS index significantly decreased in both the pre-DM and T2DM groups and showed a correlated with insulin resistance. This indicated that changes in interstitial fluid dynamics are associated with insulin resistance.

Optical coherence tomography-angiography findings of prediabetic patients

PURPOSE

The purpose of this study was to evaluate prediabetic patients for microvascular changes using optical coherence tomography-angiography (OCT-A) and compare with diabetic patients and healthy controls.

METHODS

OCT-A images of 60 eyes of 30 patients with diabetes mellitus (DM), 72 eyes of 36 prediabetic patients, and 108 eyes of 54 healthy controls were retrospectively evaluated and compared in this study. A swept-source OCTA (Triton, Topcon) instrument was used for collecting OCT-A images. Duration of the diabetic or prediabetic period, glycated hemoglobin, fasting blood glucose level, postprandial glucose (PPG) level, high-density lipoprotein, low-density lipoprotein, triglyceride, and creatinine values of all participants were recorded.

RESULTS

Microaneurysm, nonperfusion areas, perifoveal capillary disruption, and capillary network disorganization were detected in both prediabetics and diabetics but statistically more common in diabetic patients. Neovascularization and intraretinal microvascular anomalies were detected only in diabetic patients.

CONCLUSIONS

OCT-A seemed to be effective in detecting microvascular changes in diabetic patients. More importantly, results showed us that in prediabetic patients, microvascular changes can be seen before the onset of DM and before or concurrently with neurodegenerative changes.

Contrast Agent-Free 3D Renal Ultrafast Doppler Imaging Reveals Vascular Dysfunction in Acute and Diabetic Kidney Diseases

To combat the irreversible decline in renal function associated with kidney disease, it is essential to establish non-invasive biomarkers for assessing renal microcirculation. However, the limited resolution and/or vascular sensitivity of existing diagnostic imaging techniques hinders the visualization of complex cortical vessels. Here, a 3D renal ultrafast Doppler (UFD) imaging system that uses a high ultrasound frequency (18 MHz) and ultrahigh frame rate (1 KHz per slice) to scan the entire volume of a rat's kidney in vivo is demonstrated. The system, which can visualize the full 3D renal vascular branching pyramid at a resolution of 167 µm without any contrast agent, is used to chronically and noninvasively monitor kidneys with acute kidney injury (AKI, 3 days) and diabetic kidney disease (DKD, 8 weeks). Multiparametric UFD analyses (e.g., vessel volume occupancy (VVO), fractional moving blood volume (FMBV), vessel number density (VND), and vessel tortuosity (VT)) describe rapid vascular rarefaction from AKI and long-term vascular degeneration from DKD, while the renal pathogeneses are validated by in vitro blood serum testing and stained histopathology. This work demonstrates the potential of 3D renal UFD to offer valuable insights into assessing kidney perfusion levels for future research in diabetes and kidney transplantation.

Prevalence of Retinopathy in Prediabetic Populations: A Systematic Review and Meta-Analysis

Among the leading causes of vision impairment and blindness globally, diabetic retinopathy (DR) is one of the most important causes. There is increasing evidence of DR prevalence in the prediabetic population. This systematic review presents collective data on retinopathy in the prediabetic population. This review article aimed to estimate the reported prevalence of retinopathy in prediabetes, impaired glucose tolerance test (GTT) without diabetes mellitus, and the risk factors involved and to summarize it. Literature searches were done using the Web of Science, CINAHL, Google Scholar, Cochrane, EMBASE, and PubMed databases from inception to April 2023. Our search included the words prediabetes, DR, and risk factors. All searches were looked at for methodological quality and evidence. Thirty-one studies were included after the screening. Population-based data were used in 23 studies (82.1%). The prediabetic population screened was 10,539. The prevalence of retinopathy ranged between 0.3% and 20.9%, showing a median of 8.1% with an interquartile range (IQR) of 4.2-11%, showing great variance in estimates due to the use of different screening methods, methods used for retinopathy grading, and study populations. Several studies compared the population with normal GTT with impaired glucose tolerance (IGT) and inferred that there was a lower prevalence of retinopathy in the normal GTT population (3.0%, IQR 0.3-7.4%) than prediabetes (6.7%, IQR 1.9-10.1%). According to this data, a greater retinopathy prevalence was found in prediabetic populations.

Foveal avascular zone size and mfERG metrics in diabetes and prediabetes: a pilot study of the relationship between structure and function

PURPOSE

Previous studies have demonstrated functional and structural retinal changes in type 2 diabetes (T2DM). However, less is understood in prediabetes, which is an important precursor to T2DM. Here, we evaluate the microvasculature structure of the foveal avascular zone (FAZ) and how it is correlated with retinal function as measured by the multifocal electroretinogram (mfERG) across levels of glucose dysfunction to uncover how T2DM and prediabetes alter this structure-function relationship.

METHODS

33 subjects were included: 9 controls, 12 prediabetes, 12 T2DM with no retinopathy or edema. Subjects were aged 30-70 years, had BCVA of 20/25 or better, and had no confounding ocular conditions. Blood was collected via fingerstick to determine Hemoglobin A1c (HbA1c), which was used along with previous diagnosis, to determine study grouping. Optical coherence tomography angiography (OCTA) was used to analyze the FAZ area and was corrected for refractive error. FAZ area was measured by hand using the Heidelberg Spectralis software. mfERG (VERIS 6.3) metrics implicit time (IT) and amplitude were evaluated in the foveal region, macular region, and averaged over the posterior pole of the right eye. Regression analysis was performed between each study group parameter to determine relationships, and t tests with corrections were used to compare groups.

RESULTS

FAZ area (superficial plexus) was negatively correlated with mfERG posterior pole amplitude (p < 0.01, R2 = 0.30), foveal amp (p = 0.02 R2 = 0.17) and macular amplitude (p = 0.02 R2 = 0.18) across all 33 study subjects. FAZ and mfERG metrics were not significantly different between study groups in this cohort except for IT, which was more delayed in the diabetes group compared to other groups.

CONCLUSION

FAZ area is correlated with mfERG amplitudes but not IT. This suggests a link between the structural metrics and retinal function. Longitudinal follow-up work would be helpful to determine the timing of these changes in prediabetes.

Comprehensive retinal vascular measurements: time in range is associated with peripheral retinal venular calibers in type 2 diabetes in China

AIM

Retinal vascular parameters are biomarkers of diabetic microangiopathy. We aimed to investigate the relationship between time in range (TIR) assessed by continuous glucose monitoring (CGM) and retinal vascular parameters in patients with type 2 diabetes in China.

METHODS

The TIR assessed by CGM and retinal photographs were obtained at the same time from adults with type 2 diabetes who were recruited. Retinal vascular parameters were extracted from retinal photographs by a validated fully automated computer program, and TIR was defined as between 3.9-7.8 mmol/L over a 24-h period. The association between TIR and caliber of retinal vessels distributed in different zones were analyzed using multivariable linear regression analyses.

RESULTS

For retinal vascular parameters measurements, the peripheral arteriovenous and middle venular calibers widen with decreasing TIR quartiles (P < 0.05). Lower TIR was associated with wider peripheral venule after adjusting for potential confounders. Even after further correction for GV, there was still a significant correlation between TIR and peripheral vascular calibers (CV: β = - 0.015 [- 0.027, - 0.003], P = 0.013; MAGE: β = - 0.013 [- 0.025, - 0.001], P = 0.038) and SD: β = - 0.013 [- 0.026, - 0.001], P = 0.004). Similar findings were not found for the middle and central venular calibers or arterial calibers located in different zones.

CONCLUSIONS

The TIR was associated with adverse changes to peripheral retinal venules but not central and middle vessels in patients with type 2 diabetes, suggesting that peripheral retinal vascular calibers may be affected by glycemic fluctuations earlier.

Assessment of Retinal Vessel Tortuosity Index in Patients with Fabry Disease Using Optical Coherence Tomography Angiography (OCTA)

Vessel tortuosity (VT) is a parameter used to assess retinal involvement in patients affected by systemic diseases such as Fabry disease (FD). In this study, we assessed a retinal VT index (VTI) using optical coherence tomography angiography (OCTA) in a group of patients with FD (FD cohort) compared to a healthy control group (HC cohort). This is a single-center, retrospective study analysis of all consecutive patients with genetically tested and confirmed FD who underwent regular ophthalmological visits from December 2017 to January 2020 at the Department of Ophthalmology at the University Hospital of Zurich, Switzerland. VTI was calculated for each OCTA image and the results were compared between FD and HC cohort. A total of 56 participants, 32 (male:female ratio 12:20) in the FD cohort and 24 (male:female ratio 13:11) in the HC cohort. Classic onset was determined in 18 patients. Overall, mean VTI (±SD) was 0.21 (±0.07). Male patients with classic-onset FD had a significantly higher mean VTI (0.33, SD ± 0.35) compared to all other subgroups (p-value < 0.05). Further investigations of retinal VTI in patients with FD could be helpful to use OCTA as a noninvasive screening and follow-up modality to assess disease progression in affected patients.

The mitochondrial protein TIMM44 is required for angiogenesis in vitro and in vivo

The mitochondrial integrity and function in endothelial cells are essential for angiogenesis. TIMM44 (translocase of inner mitochondrial membrane 44) is essential for integrity and function of mitochondria. Here we explored the potential function and the possible mechanisms of TIMM44 in angiogenesis. In HUVECs, human retinal microvascular endothelial cells and hCMEC/D3 brain endothelial cells, silence of TIMM44 by targeted shRNA largely inhibited cell proliferation, migration and in vitro capillary tube formation. TIMM44 silencing disrupted mitochondrial functions in endothelial cells, causing mitochondrial protein input arrest, ATP reduction, ROS production, and mitochondrial depolarization, and leading to apoptosis activation. TIMM44 knockout, by Cas9-sgRNA strategy, also disrupted mitochondrial functions and inhibited endothelial cell proliferation, migration and in vitro capillary tube formation. Moreover, treatment with MB-10 ("MitoBloCK-10"), a TIMM44 blocker, similarly induced mitochondrial dysfunction and suppressed angiogenic activity in endothelial cells. Contrarily, ectopic overexpression of TIMM44 increased ATP contents and augmented endothelial cell proliferation, migration and in vitro capillary tube formation. In adult mouse retinas, endothelial knockdown of TIMM44, by intravitreous injection of endothelial specific TIMM44 shRNA adenovirus, inhibited retinal angiogenesis, causing vascular leakage, acellular capillary growth, and retinal ganglion cells degeneration. Significant oxidative stress was detected in TIMM44-silenced retinal tissues. Moreover, intravitreous injection of MB-10 similarly induced oxidative injury and inhibited retinal angiogenesis in vivo. Together, the mitochondrial protein TIMM44 is important for angiogenesis in vitro and in vivo, representing as a novel and promising therapeutic target of diseases with abnormal angiogenesis.

The long-term effects of Kerala Diabetes Prevention Program on diabetes incidence and cardiometabolic risk: a study protocol

INTRODUCTION

India currently has more than 74.2 million people with Type 2 Diabetes Mellitus (T2DM). This is predicted to increase to 124.9 million by 2045. In combination with controlling blood glucose levels among those with T2DM, preventing the onset of diabetes among those at high risk of developing it is essential. Although many diabetes prevention interventions have been implemented in resource-limited settings in recent years, there is limited evidence about their long-term effectiveness, cost-effectiveness, and sustainability. Moreover, evidence on the impact of a diabetes prevention program on cardiovascular risk over time is limited.

OBJECTIVES

The overall aim of this study is to evaluate the long-term cardiometabolic effects of the Kerala Diabetes Prevention Program (K-DPP). Specific aims are 1) to measure the long-term effectiveness of K-DPP on diabetes incidence and cardiometabolic risk after nine years from participant recruitment; 2) to assess retinal microvasculature, microalbuminuria, and ECG abnormalities and their association with cardiometabolic risk factors over nine years of the intervention; 3) to evaluate the long-term cost-effectiveness and return on investment of the K-DPP; and 4) to assess the sustainability of community engagement, peer-support, and other related community activities after nine years.

METHODS

The nine-year follow-up study aims to reach all 1007 study participants (500 intervention and 507 control) from 60 randomized polling areas recruited to the original trial. Data are being collected in two phases. In phase 1 (Survey), we are admintsering a structured questionnaire, undertake physical measurements, and collect blood and urine samples for biochemical analysis. In phase II, we are inviting participants to undergo retinal imaging, body composition measurements, and ECG. All data collection is being conducted by trained Nurses. The primary outcome is the incidence of T2DM. Secondary outcomes include behavioral, psychosocial, clinical, biochemical, and retinal vasculature measures. Data analysis strategies include a comparison of outcome indicators with baseline, and follow-up measurements conducted at 12 and 24 months. Analysis of the long-term cost-effectiveness of the intervention is planned.

DISCUSSION

Findings from this follow-up study will contribute to improved policy and practice regarding the long-term effects of lifestyle interventions for diabetes prevention in India and other resource-limited settings.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trials Registry-(updated from the original trial)ACTRN12611000262909; India: CTRI/2021/10/037191.

Optic disc and retinal vascular features in first 6 years of Chinese children

Purpose

Retinal microvasculature plays an important role in children's fundus lesions and even in their later life. However, little was known on the features of normal retina in early life. The purpose of this study was to explore the normal retinal features in the first 6 years of life and provide information for future research.

Methods

Children, aged from birth to 6 years old and diagnosed with various unilateral ocular diseases were included. Venous phase fundus fluorescein angiography images with the optic disc at the center were collected. Based on the ResUNet convolutional neural network, optic disc and retinal vascular features in the posterior retina were computed automatically.

Results

A total of 146 normal eyes of 146 children were included. Among different age groups, no changes were shown in the optic disc diameter (y = -0.00002x + 1.362, R² = 0.025, p = 0.058). Retinal vessel density and fractal dimension are linearly and strongly correlated (r = 0.979, p < 0.001). Older children had smaller value of fractal dimension (y = -0.000026x + 1.549, R²= 0.075, p = 0.001) and narrower vascular caliber if they were less than 3 years old (y = -0.008x + 84.861, R²= 0.205, p < 0.001). No differences were in the density (y = -0.000007x + 0.134, R²= 0.023, p = 0.067) and the curvature of retinal vessels (lnC = -0.00001x - 4.657, R²= 0.001, p = 0.667).

Conclusions

Age and gender did not impact the optic disc diameter, vessel density, and vessel curvature significantly in this group of children. Trends of decreased vessel caliber in the first 3 years of life and decreased vessel complexity with age were observed. The structural characteristics provide information for future research to better understand the developmental origin of the healthy and diseased retina.

Retinal Vascular Caliber in Coronary Heart Disease and Its Risk Factors

BACKGROUND

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

OBJECTIVE

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

METHOD

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

RESULT

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

CONCLUSION

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

Multifilters-Based Unsupervised Method for Retinal Blood Vessel Segmentation

Fundus imaging is one of the crucial methods that help ophthalmologists for diagnosing the various eye diseases in modern medicine. An accurate vessel segmentation method can be a convenient tool to foresee and analyze fatal diseases, including hypertension or diabetes, which damage the retinal vessel’s appearance. This work suggests an unsupervised approach for vessels segmentation out of retinal images. The proposed method includes multiple steps. Firstly, from the colored retinal image, green channel is extracted and preprocessed utilizing Contrast Limited Histogram Equalization as well as Fuzzy Histogram Based Equalization for contrast enhancement. To expel geometrical articles (macula, optic disk) and noise, top-hat morphological operations are used. On the resulted enhanced image, matched filter and Gabor wavelet filter are applied, and the outputs from both is added to extract vessels pixels. The resulting image with the now noticeable blood vessel is binarized using human visual system (HVS). A final image of segmented blood vessel is obtained by applying post-processing. The suggested method is assessed on two public datasets (DRIVE and STARE) and showed comparable results with regard to sensitivity, specificity and accuracy. The results we achieved with respect to sensitivity, specificity together with accuracy on DRIVE database are 0.7271, 0.9798 and 0.9573, and on STARE database these are 0.7164, 0.9760, and 0.9560, respectively, in less than 3.17 s on average per image.

The requirement of phosphoenolpyruvate carboxykinase 1 for angiogenesis in vitro and in vivo

We here examined the potential biological function of phosphoenolpyruvate carboxykinase 1 (PCK1) in angiogenesis. shRNA- or CRISPR-Cas9-induced PCK1 depletion potently inhibited endothelial cell proliferation, migration, sprouting, and tube formation, whereas ectopic PCK1 overexpression exerted opposite activity. In HUVECs, Gα_i3 expression and Akt activation were decreased following PCK1 depletion, but were augmented by ectopic PCK1 overexpression. In vivo, retinal expression of PCK1 gradually increased from postnatal day 1 (P1) to P5. The intravitreous injection of endothelial-specific PCK1 shRNA adenovirus at P1 potently inhibited the radial extension of vascular plexus at P5. Conditional endothelial knockdown of PCK1 in adult mouse retina increased vascular leakage and the number of acellular capillaries while decreasing the number of RGCs in murine retinas. In diabetic retinopathy patients, PCK1 mRNA and protein levels were up-regulated in retinal tissues. Together, PCK1 is essential for angiogenesis possibly by mediating Gα_i3 expression and Akt activation.

A deep learning model for screening type 2 diabetes from retinal photographs

BACKGROUND AND AIMS

We aimed to develop and evaluate a non-invasive deep learning algorithm for screening type 2 diabetes in UK Biobank participants using retinal images.

METHODS AND RESULTS

The deep learning model for prediction of type 2 diabetes was trained on retinal images from 50,077 UK Biobank participants and tested on 12,185 participants. We evaluated its performance in terms of predicting traditional risk factors (TRFs) and genetic risk for diabetes. Next, we compared the performance of three models in predicting type 2 diabetes using 1) an image-only deep learning algorithm, 2) TRFs, 3) the combination of the algorithm and TRFs. Assessing net reclassification improvement (NRI) allowed quantification of the improvement afforded by adding the algorithm to the TRF model. When predicting TRFs with the deep learning algorithm, the areas under the curve (AUCs) obtained with the validation set for age, sex, and HbA1c status were 0.931 (0.928-0.934), 0.933 (0.929-0.936), and 0.734 (0.715-0.752), respectively. When predicting type 2 diabetes, the AUC of the composite logistic model using non-invasive TRFs was 0.810 (0.790-0.830), and that for the deep learning model using only fundus images was 0.731 (0.707-0.756). Upon addition of TRFs to the deep learning algorithm, discriminative performance was improved to 0.844 (0.826-0.861). The addition of the algorithm to the TRFs model improved risk stratification with an overall NRI of 50.8%.

CONCLUSION

Our results demonstrate that this deep learning algorithm can be a useful tool for stratifying individuals at high risk of type 2 diabetes in the general population.

Improving sensitivity and connectivity of retinal vessel segmentation via error discrimination network

PURPOSE

Automated retinal vessel segmentation is crucial to the early diagnosis and treatment of ophthalmological diseases. Many deep learning-based methods have shown exceptional success in this task. However, current approaches are still inadequate in challenging vessels (e.g., thin vessels) and rarely focus on the connectivity of vessel segmentation.

METHODS

We propose using an error discrimination network (D) to distinguish whether the vessel pixel predictions of the segmentation network (S) are correct, and S is trained to obtain fewer error predictions of D. Our method is similar to, but not the same as, the generative adversarial network (GAN). Three types of vessel samples and corresponding error masks are used to train D, as follows: (1) vessel ground truth; (2) vessel segmented by S; (3) artificial thin vessel error samples that further improve the sensitivity of D to wrong small vessels. As an auxiliary loss function of S, D strengthens the supervision of difficult vessels. Optionally, we can use the errors predicted by D to correct the segmentation result of S.

RESULTS

Compared with state-of-the-art methods, our method achieves the highest scores in sensitivity (86.19%, 86.26%, and 86.53%) and G-Mean (91.94%, 91.30%, and 92.76%) on three public datasets, namely, STARE, DRIVE, and HRF. Our method also maintains a competitive level in other metrics. On the STARE dataset, the F1-score and AUC of our method rank second and first, respectively, reaching 84.51% and 98.97%. The top scores of the three topology-relevant metrics (Conn, Inf, and Cor) demonstrate that the vessels extracted by our method have excellent connectivity. We also validate the effectiveness of error discrimination supervision and artificial error sample training through ablation experiments.

CONCLUSIONS

The proposed method provides an accurate and robust solution for difficult vessel segmentation. This article is protected by copyright. All rights reserved.

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.

Prevalence and risk factors for diabetic retinopathy in prediabetes in Asian Indians

AIM

To assess the prevalence of diabetic retinopathy (DR) and associated risk factors in Asian Indians with prediabetes.

METHODS

In a cross-sectional study conducted at two tertiary care diabetes centres in Chennai, India, clinical and biochemical assessment and nonmydriatic ultra-wide field fundus photography was performed in individuals with prediabetes (impaired fasting glucose [IFG] and/or impaired glucose tolerance [IGT]) based on oral glucose tolerance test (OGTT) and/or glycated hemoglobin (HbA1c) between 5.7% and 6.4% in 2019. The retinal photographs were graded by certified ophthalmologists. Systemic risk factors associated with DR in prediabetes were assessed.

RESULTS

The mean age of the 192 individuals with prediabetes was 48 ± 13 years (55.2% were males). DR was present in 12 (6.3%) individuals of which nine (4.7%) had mild non-proliferative DR (NPDR) and three (1.6%) had moderate NPDR. None had severe sight-threatening DR. The Poisson multiple regression analysis showed that after adjusting for other systemic covariates, HbA1c values ≥ 6% (6-6.4%) was associated with 2 times higher relative risk of DR (Risk ratio 1.95 (95% CI 1.07-3.545, p = 0.028) in comparison to HbA1c < 6%).

CONCLUSION

DR was present in about 6% of the Asian Indians with prediabetes. Higher HbA1c values among individuals with prediabetes was associated with twice the relative risk for DR. Robust control of HbA1c should be encouraged even before the diagnosis of diabetes is established.

Incidence and risk factors of severe non-proliferative/proliferative diabetic retinopathy: More than a decade follow up in the Tehran Lipids and Glucose Study

AIMS/INTRODUCTION

To examine the incidence rate of severe non-proliferative and proliferative diabetic retinopathy (severe-NPDR/PDR) and determine its potential risk factors.

MATERIALS AND METHODS

The study consisted of 1,169 participants (675 women) with type 2 diabetes mellitus, aged ≥20 years. A trained interviewer collected information about the history of pan-retinal photocoagulation as a result of diabetic retinopathy. Multivariable Cox proportional hazards regression models were applied.

RESULTS

We found 187 cases (126 women) of severe-NPDR/PDR during a median follow-up period of 12.7 years; the corresponding incidence rate was 13.6 per 1,000 person-years. Being overweight (hazard ratio [HR], 95% confidence interval [CI] 0.60, 0.39-0.92) and obese (HR 0.48, 95% CI 0.27-0.83) were associated with lower risk, whereas being smoker (HR 1.75, 95% CI 1.12-2.74), having fasting plasma glucose levels 7.22-10.0 mmol/L (HR 2.81, 95% CI 1.70-4.62), fasting plasma glucose ≥10 mmol/L (HR 5.87, 95% CI 3.67-9.41), taking glucose-lowering medications (HR 2.58, 95% CI 1.87-3.56), prehypertension status (HR 1.65, 95% CI 1.05-2.58) and newly diagnosed hypertension (HR 1.96, 95% CI 1.06-3.65) increased the risk of severe-NPDR/PDR. Among newly diagnosed diabetes patients, being male was associated with a 59% lower risk of severe-NPDR/PDR (HR 0.41, 95% CI 0.21-0.79). Furthermore, patients who had an intermediate level of education (6-12 years) had a higher risk of developing PDR (HR 1.86, 95% CI 1.05-3.30) compared with those who had <6 years of education.

CONCLUSIONS

Among Iranians with type 2 diabetes mellitus, 1.36% developed severe-NPDR/PDR annually. Normal bodyweight, being a smoker, out of target fasting plasma glucose level, prehypertension and newly diagnosed hypertension status were independent risk factors of severe-NPDR/PDR. Regarding the sight-threatening entity of advanced diabetic retinopathy, the multicomponent strategy to control diabetes, abstinence of smoking and tight control of blood pressure should be considered.

Tortuosity of branch retinal artery is more associated with the genesis and progress of diabetic retinopathy

OBJECTIVE

The purpose of this study is to investigate the potential of using the tortuosity of branch retinal artery as a more promising indicator for early detection and accurate assessment of diabetic retinopathy (DR).

DESIGN AND METHOD

The diagnoses, consisting of whether DR or not as well as DR severity, were given by ophthalmologists upon the assessment of those fundus images from 495 diabetic patients. Meanwhile, benefiting from those good contrast and high optical resolution fundus images taken by confocal scanning laser ophthalmoscope, the branch arteries, branch veins, main arteries and main veins in retina can be segmented independently, and the tortuosity values of them were further extracted to investigate their potential correlations with DR genesis and progress based on one-way ANOVA test.

RESULTS

For both two comparisons, i.e., between non-DR group and DR group as well as among groups with different DR severity levels, larger tortuosity increments were always observed in retinal arteries and the increments in branch retinal vessels were even larger. Furthermore, it was newly found that branch arterial tortuosity was significantly associated with both DR genesis (p=0.030) and DR progress (p<0.001).

CONCLUSION

Based on this cohort study of 495 diabetic patients without DR and with different DR severity, the branch arterial tortuosity has been found to be more closely associated with DR genesis as well as DR progress. Therefore, the branch arterial tortuosity is expected to be a more direct and specific indicator for early detection of DR as well as accurate assessment of DR severity, which can further guide timely and rational management of DR to prevent from visual impairment or even blindness resulting from DR.

Facilitators and Barriers to Uptake of Community-Based Diabetes Prevention Program Among Multi-Ethnic Asian Patients With Prediabetes

OBJECTIVE

This study aimed to identify facilitators and barriers to the uptake of a community-based diabetes prevention program (DPP) from the perspectives of decliners with prediabetes in a multi-ethnic Asian community.

METHODS

Semi-structured interviews were conducted with 29 individuals with prediabetes who declined participation in a large community-based diabetes prevention program in Singapore. Thematic analysis was undertaken to identify themes, which were subsequently mapped onto the Capacity-Opportunity-Motivation and Behavior model (COM-B).

RESULTS

We identified 16 key themes under three COM-B domains. Health status at the time of invitation, perceived ability of self-management, understanding of prediabetes condition and/or the program intention (Capability) were important determinants. Family commitment had the strong potential to enable or hinder physical and social Opportunity related to participation. Many participants desired involvement of physician as part of program invitation and component. Fear of exacerbation coupled with an automatic aversion for suffering influenced Motivation for participation.

CONCLUSION

Identifying facilitators and barriers embedded in the COM-B will assist systematic program modifications to increase participation of individuals with prediabetes. How information about modifiable risk factors is communicated by physicians at the point of diagnosis and program introduction is key to participation. Co-locating programs with family activity, development of mHealth, readiness assessment, and tailored explanation of program purpose may increase participation. These findings will be used to guide future national interventions in the community to ensure successful implementation.

Pericyte Insulin Receptors Modulate Retinal Vascular Remodeling and Endothelial Angiopoietin Signaling

Pericytes regulate vascular development, stability, and quiescence; their dysfunction contributes to diabetic retinopathy. To explore the role of insulin receptors in pericyte biology, we created pericyte insulin receptor knockout mice (PIRKO) by crossing PDGFRβ-Cre mice with insulin receptor (Insr) floxed mice. Their neonatal retinal vasculature exhibited perivenous hypervascularity with venular dilatation, plus increased angiogenic sprouting in superficial and deep layers. Pericyte coverage of capillaries was unaltered in perivenous and periarterial plexi, and no differences in vascular regression or endothelial proliferation were apparent. Isolated brain pericytes from PIRKO had decreased angiopoietin-1 mRNA, whereas retinal and lung angiopoietin-2 mRNA was increased. Endothelial phospho-Tie2 staining was diminished and FoxO1 was more frequently nuclear localized in the perivenous plexus of PIRKO, in keeping with reduced angiopoietin-Tie2 signaling. Silencing of Insr in human brain pericytes led to reduced insulin-stimulated angiopoietin-1 secretion, and conditioned media from these cells was less able to induce Tie2 phosphorylation in human endothelial cells. Hence, insulin signaling in pericytes promotes angiopoietin-1 secretion and endothelial Tie2 signaling and perturbation of this leads to excessive vascular sprouting and venous plexus abnormalities. This phenotype mimics elements of diabetic retinopathy, and future work should evaluate pericyte insulin signaling in this disease.

Prevention of Microvascular Complications of Diabetes

Microvascular complications of diabetes present a significant challenge due to their diverse presentations, significant morbidity, and as strong predictors of cardiovascular disease. Prevention and management strategies should focus on lifestyle modification, education and awareness, systematic screening for early complications, and intensive management of modifiable risk factors. This review discusses the microvascular complications of diabetes, including diabetic retinopathy, diabetic kidney disease, and diabetic neuropathy, and provides best practice clinical care recommendations to guide health care professionals to better manage people with these conditions.

A novel multiple subdivision-based algorithm for quantitative assessment of retinal vascular tortuosity

Vascular tortuosity as an indicator of retinal vascular morphological changes can be quantitatively analyzed and used as a biomarker for the early diagnosis of relevant disease such as diabetes. While various methods have been proposed to evaluate retinal vascular tortuosity, the main obstacle limiting their clinical application is the poor consistency compared with the experts' evaluation. In this research, we proposed to apply a multiple subdivision-based algorithm for the vessel segment vascular tortuosity analysis combining with a learning curve function of vessel curvature inflection point number, emphasizing the human assessment nature focusing not only global but also on local vascular features. Our algorithm achieved high correlation coefficients of 0.931 for arteries and 0.925 for veins compared with clinical grading of extracted retinal vessels. For the prognostic performance against experts' prediction in retinal fundus images from diabetic patients, the area under the receiver operating characteristic curve reached 0.968, indicating a good consistency with experts' predication in full retinal vascular network evaluation.

Validation of Indian Diabetes Risk Score for Screening Prediabetes in West Tripura District of India

Background:

Viswanathan Mohan and his team have developed “Indian Diabetes Risk Score” (IDRS) for identifying the Indians at risk for developing diabetes and prediabetes. Due to heterogeneity of Indian population, this risk score needs further validation in different parts across the country.

Objectives:

The objective is to estimate the sensitivity, specificity, positive, and negative predictive values of IDRS for screening prediabetes in West Tripura District.

Methodology:

It was a community-based cross-sectional study conducted in West Tripura district during January 1, 2018–December 31, 2019 among 325 self-declared nondiabetic individuals, selected by multistage sampling. Fasting blood sugar value was used as the gold standard to validate IDRS. Data were collected using a validated and pretested interview schedule. Data entry and analysis were performed in computer using SPSS-24. Receiver operating characteristic (ROC) curve was constructed to validate IDRS.

Results:

Among the study individuals, 19% and 6.5% were identified as prediabetic and diabetics, respectively. Optimum sensitivity of 83.13% and specificity of 82.64%, with positive and negative predictive values 62.16% and 93.45%, respectively, were observed at an IDRS score of ≥60 for identifying prediabetes and diabetes in this study population. IDRS showed good accuracy with an area under ROC curve of 0.832 (95% confidence interval: 0.77–0.88).

Conclusion:

IDRS is found to be a valid tool for screening prediabetes at community level in West Tripura district of India.

Differential artery-vein analysis in quantitative retinal imaging: a review

Quantitative retinal imaging is essential for eye disease detection, staging classification, and treatment assessment. It is known that different eye diseases or severity stages can affect the artery and vein systems in different ways. Therefore, differential artery-vein (AV) analysis can improve the performance of quantitative retinal imaging. In this article, we provide a brief summary of technical rationales and clinical applications of differential AV analysis in fundus photography, optical coherence tomography (OCT), and OCT angiography (OCTA).

Metabolic and Energy Imbalance in Dysglycemia-Based Chronic Disease

Metabolic flexibility is the ability to efficiently adapt metabolism based on nutrient availability and requirement that is essential to maintain homeostasis in times of either caloric excess or restriction and during the energy-demanding state. This regulation is orchestrated in multiple organ systems by the alliance of numerous metabolic pathways under the master control of the insulin-glucagon-sympathetic neuro-endocrine axis. This, in turn, regulates key metabolic enzymes and transcription factors, many of which interact closely with and culminate in the mitochondrial energy generation machinery. Metabolic flexibility is compromised due to the continuous mismatch between availability and intake of calorie-dense foods and reduced metabolic demand due to sedentary lifestyle and age-related metabolic slowdown. The resultant nutrient overload leads to mitochondrial trafficking of substrates manifesting as mitochondrial dysfunction characterized by ineffective substrate switching and incomplete substrate utilization. At the systemic level, the manifestation of metabolic inflexibility comprises reduced skeletal muscle glucose disposal rate, impaired suppression of hepatic gluconeogenesis and adipose tissue lipolysis manifesting as insulin resistance. This is compounded by impaired β-cell function and progressively reduced β-cell mass. A consequence of insulin resistance is the upregulation of the mitogen-activated protein kinase pathway leading to a pro-hypertensive, atherogenic, and thrombogenic environment. This is further aggravated by oxidative stress, advanced glycation end products, and inflammation, which potentiates the risk of micro- and macro-vascular complications. This review aims to elucidate underlying mechanisms mediating the onset of metabolic inflexibility operating at the main target organs and to understand the progression of metabolic diseases. This could potentially translate into a pharmacological tool that can manage multiple interlinked conditions of dysglycemia, hypertension, and dyslipidemia by restoring metabolic flexibility. We discuss the breadth and depth of metabolic flexibility and its impact on health and disease.

Retinal capillary rarefaction is associated with arterial and kidney damage in hypertension

Microvascular disease and rarefaction are key pathological hallmarks of hypertension. The retina uniquely allows direct, non-invasive investigation of the microvasculature. Recently developed optical coherence tomography angiography now allows investigation of the fine retinal capillaries, which may provide a superior marker of overall vascular damage. This was a prospective cross-sectional study to collect retinal capillary density data on 300 normal eyes from 150 hypertensive adults, and to investigate possible associations with other organ damage markers. The average age of participants was 54 years and there was a greater proportion of males (85; 57%) than females. Multivariate, confounder adjusted linear regression showed that retinal capillary rarefaction in the parafovea was associated with increased pulse wave velocity (β = − 0.4, P = 0.04), log-albumin/creatinine ratio (β = − 0.71, P = 0.003), and with reduced estimated glomerular filtration rate (β = 0.04, P = 0.02). Comparable significant associations were also found for whole-image vascular-density, for foveal vascular-density significant associations were found with pulse wave velocity and estimated glomerular filtration rate only. Our results indicate that retinal capillary rarefaction is associated with arterial stiffness and impaired kidney function. Retinal capillary rarefaction may represent a useful and simple test to assess the integrated burden of hypertension on the microvasculature irrespective of current blood pressure levels.

Prevalence of retinopathy in prediabetes: protocol for a systematic review and meta-analysis

INTRODUCTION

There is growing evidence of a higher than expected prevalence of retinopathy in prediabetes. This paper presents the protocol of a systematic review and meta-analysis of retinopathy in prediabetes. The aim of the review is to estimate the prevalence of retinopathy in prediabetes and to summarise the current data.

METHODS AND ANALYSIS

This protocol is developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) guidelines. A comprehensive electronic bibliographic search will be conducted in MEDLINE, EMBASE, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Google Scholar and the Cochrane Library. Eligible studies will report prevalence data for retinopathy on fundus photography in adults with prediabetes. No time restrictions will be placed on the date of publication. Screening for eligible studies and data extraction will be conducted by two reviewers independently, using predefined inclusion criteria and prepiloted data extraction forms. Disagreements between the reviewers will be resolved by discussion, and if required, a third (senior) reviewer will arbitrate.The primary outcome is the prevalence of any standard features of diabetic retinopathy (DR) on fundus photography, as per International Clinical Diabetic Retinopathy Severity Scale (ICDRSS) classification. Secondary outcomes are the prevalence of (1) any retinal microvascular abnormalities on fundus photography that are not standard features of DR as per ICDRSS classification and (2) any macular microvascular abnormalities on fundus photography, including but not limited to the presence of macular exudates, microaneurysms and haemorrhages. Risk of bias for included studies will be assessed using a validated risk of bias tool for prevalence studies. Pooled estimates for the prespecified outcomes of interest will be calculated using random effects meta-analytic techniques. Heterogeneity will be assessed using the I² statistic.

ETHICS AND DISSEMINATION

Ethical approval is not required as this is a protocol for a systematic review and no primary data are to be collected. Findings will be disseminated through peer-reviewed publications and presentations at national and international meetings including Diabetes UK, European Association for the Study of Diabetes, American Diabetes Association and International Diabetes Federation conferences.

PROSPERO REGISTRATION NUMBER

CRD42020184820.

Vascular morphology and blood flow signatures for differential artery-vein analysis in optical coherence tomography of the retina

Differential artery-vein (AV) analysis is essential for retinal study, disease detection, and treatment assessment. This study is to characterize vascular reflectance profiles and blood flow patterns of retinal artery and vein systems in optical coherence tomography (OCT) and OCT angiography (OCTA), and establish them as robust signatures for objective AV classification. A custom designed OCT was employed for three-dimensional (3D) imaging of mouse retina, and corresponding OCTA was reconstructed. Radially resliced OCT B-scans revealed two, i.e. top and bottom, hyperreflective wall boundaries in retinal arteries, while these wall boundaries were absent in OCT of retinal veins. Additional OCTA analysis consistently displayed a layered speckle distribution in the vein, which may indicate the venous laminar flow. These OCT and OCTA differences offer unique signatures for objective AV classification in OCT and OCTA.

Retinal vascular caliber changes after laser photocoagulation in diabetic retinopathy

BACKGROUND Diabetic retinopathy causes vascular dilatation caused by hypoxia, whereas oxygen tension improvement leads to retinal vessels narrowing. Given that laser photocoagulation aims to increase the oxygen tension in the retina, we hypothesized that the narrowing of vessel caliber after the treatment could be possibly demonstrated. This study aimed to assess the changes in the caliber of retinal vessels before and after laser photocoagulation in diabetic retinopathy. METHODS This research was a prospective cohort study on the treatment of diabetic retinopathy by laser photocoagulation, and it was conducted at Universitas Hasanuddin Hospital, Makassar, Indonesia between November 2017–April 2018. Retinal vascular caliber changes were analyzed before and 6–8 weeks after photocoagulation in 30 diabetic eyes. Central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were measured using the vessel assessment and measurement platform software for images of the retina (VAMPIRE) manual annotation tool. RESULTS A significant decrease of CRVE was observed after laser photocoagulation (p<0.001), but CRAE was not reduced significantly (p = 0.067). No difference was recorded between CRVE and CRAE post-laser photocoagulation (p = 0.14), implying a reduction in vein caliber toward normal in the treated eyes. CONCLUSIONS Laser photocoagulation decreases the CRVE in diabetic retinopathy despite the absence of changes in the grade of diabetic retinopathy.

Chronic Microvascular Complications in Prediabetic States-An Overview

A prediabetic state is a major risk factor for the development of diabetes, and, because of an identical pathophysiological background of both conditions, their prevalence increases parallelly and equally fast. Long-term hyperglycemia is the main cause inducing chronic complications of diabetes, yet the range of glucose levels at which they start has not been yet unequivocally determined. The current data show that chronic microvascular complications of diabetes can be observed in patients with abnormal glucose metabolism in whom glycaemia is higher than optimal but below diagnostic criteria for diabetes. Prediabetes is a heterogenous nosological unit in which particular types are differently characterized and show different correlations with particular kinds of complications. Analysis of the latest research results shows the need to continue studies in a larger population and can imply the need to verify the currently employed criteria of diagnosing diabetes and chronic complications of diabetes in people with prediabetes.

A deep-learning system for the assessment of cardiovascular disease risk via the measurement of retinal-vessel calibre

Retinal blood vessels provide information on the risk of cardiovascular disease (CVD). Here, we report the development and validation of deep-learning models for the automated measurement of retinal-vessel calibre in retinal photographs, using diverse multiethnic multicountry datasets that comprise more than 70,000 images. Retinal-vessel calibre measured by the models and by expert human graders showed high agreement, with overall intraclass correlation coefficients of between 0.82 and 0.95. The models performed comparably to or better than expert graders in associations between measurements of retinal-vessel calibre and CVD risk factors, including blood pressure, body-mass index, total cholesterol and glycated-haemoglobin levels. In retrospectively measured prospective datasets from a population-based study, baseline measurements performed by the deep-learning system were associated with incident CVD. Our findings motivate the development of clinically applicable explainable end-to-end deep-learning systems for the prediction of CVD on the basis of the features of retinal vessels in retinal photographs.

Pancreatic Angiopathy Associated With Islet Amyloid and Type 2 Diabetes Mellitus

OBJECTIVES

Type 2 diabetes (T2D) is histopathologically characterized by islet amyloid and is closely connected with vascular complications. Here, we explore the presence of pancreatic angiopathy (PA) associated with islet amyloid and T2D.

METHODS

From a total of 172 autopsy cases who had a history of T2D diagnosis, we randomly selected 30 T2D autopsy cases with islet amyloid (DA+) in comparison with islet amyloid-free (DA-) 30 T2D cases and 60 nondiabetic (ND) controls. Amyloid deposits and PA including atherosclerosis of pancreatic interlobar arteries, arterial calcification, atheroembolism, hyaline arteriosclerosis of small arterioles, and islet capillary density were detected in all groups.

RESULTS

Pancreatic angiopathy was found in 91.7% of patients with T2D and in 68.3% of ND controls (P < 0.01). Furthermore, 100% of DA+ patients and 83.3% of DA- subjects showed PA. The intraislet capillary density was significantly lower in DA+ subjects than DA- subjects (mean [standard deviation], DA+: 205 [82] count/mm; DA-: 344 [76] count/mm; ND: 291 [94] count/mm; P < 0.01). Finally, interlobar arteriosclerosis (R = 0.603, P < 0.01) was linearly correlated with the severity of islet amyloid deposits.

CONCLUSIONS

Pancreatic angiopathy might be both a cause and a consequence of islet amyloid and T2D.

Fasting plasma glucose level and the risk of open angle glaucoma: Nationwide population-based cohort study in Korea

Background

The level of fasting plasma glucose (FPG) is positively associated with intraocular pressure. Diabetes causes early structural changes of retina, especially on ganglion cell layer. In this regard, the FPG level itself may also show an independent association with open angle glaucoma (OAG) development in general population. Herein, we investigate the association of the FPG level with the incidence of OAG.

Methods

Using nationally representative data from the Korean National Health Insurance System, 374,376 subjects ≥40 years of age without OAG who underwent health examinations from 2009 to 2013 were enrolled and followed to the end of 2014. Incident cases of OAG using the International Classification of Diseases 10 codes and medication information were analyzed based on the levels of FPG.

Results

Subjects with the highest FPG level (≥160 mg/dL), compared with the lowest level (<80 mg/dL), showed a higher hazard ratio (HR) [2.189; 95% confidence interval (CI): 1.779–2.695; P for trend < 0.001] for OAG after adjustments for age and sex. This result persisted after further adjustments for the presence of type 2 diabetes, current smoking, drinking, and exercise habits, diastolic blood pressure, body mass index (BMI), and total cholesterol level (HR: 1.588; 95% CI: 1.268–1.989; P for trend < 0.001). The positive association between the FPG level and the incidence of OAG was distinct in subjects 40–64 years of age, those with a BMI <25 kg/m², and those without hypertension (HR 2.022; 95% CI: 1.494–2.736; P for trend <0.001: HR 1.817; 95% CI: 1.372–2.407; P for trend < 0.001: HR 1.706; 95% CI: 1.180–2.467; P for trend <0.001, respectively).

Conclusions

This nationwide population-based cohort study showed that the fasting glucose was associated with an increased risk of OAG. These findings suggest that subjects with high FPG levels require special attention when screening for glaucoma.

Assessment of retinal vascular oxygenation and morphology at stages of diabetic retinopathy in African Americans

BACKGROUND

Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of blindness in working-age adults. The likelihood of visual impairment associated with DR is two-fold higher in the African-American (AA) compared to non-Hispanic white. Although alterations in retinal vessel oxygenation and morphology have been reported in DR, there is limited knowledge about these vascular changes in AA subjects. The purpose of the current study was to investigate alterations in retinal vascular oxygen saturation (SO2), vessel diameter (D) and tortuosity at severity stages of DR in AA subjects.

METHODS

A nested case-control study of 56 AA subjects was conducted. Right eyes were grouped as non-diabetic (ND) (N = 26), no clinical DR (NDR) (N = 19), or moderate/severe non-proliferative DR (NPDR) (N = 11). Imaging was performed using a commercially available scanning laser ophthalmoscope. Images were analyzed to determine retinal arterial and venous SO2 (SO2A and SO2V), diameter (DA and DV), and vessel tortuosity index (VTI) (VTIA and VTIV).

RESULTS

SO2V and DV were higher in NPDR compared to ND and NDR groups (P < 0.05). There were no significant differences in SO2A and DA among ND, NDR, and NPDR groups (P > 0.8). Maximum VTIA was higher in diabetics (NDR and NPDR) compared to non-diabetics (P < 0.03). There was no significant difference in maximum VTIV among the 3 groups (P = 0.5).

CONCLUSIONS

The findings advance our understanding of DR pathophysiology in the AA population and may propel identification of race-specific retinal vascular biomarkers for improved diagnosis and monitoring of DR.

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

PURPOSE

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

DESIGN

Prospective, longitudinal, multiethnic study.

PARTICIPANTS

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

METHODS

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

MAIN OUTCOME AND MEASURES

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

RESULTS

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

CONCLUSIONS

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

Prediabetes among HIV-infected individuals receiving antiretroviral therapy: prevalence, diagnostic tests, and associated factors

Background

Metabolic complications in human immunodeficiency virus (HIV)-infected individuals are common. Prediabetes represents a high risk for future diabetes development. This study aimed to determine the prevalence, diagnostic methods, and associated factors of prediabetes among HIV-infected individuals receiving antiretroviral therapy (ART).

Methods

A cross-sectional study was conducted among HIV-infected adults without a history of diabetes who were receiving ART. Fasting plasma glucose (FPG), 2-hour plasma glucose (2-h PG) after a 75-g oral glucose tolerance test, and hemoglobin A1c (HbA1c) were assessed.

Results

A total of 397 patients with a mean age of 47.0 ± 9.8 years and 55.7% male, were studied. All received ART with undetectable plasma viral load. The mean duration of ART was 9.6 ± 5.2 years, and the mean CD4 cell count was 554 ± 235 cells/mm³. Among the patients, 28 (7.1%) had first-diagnosed diabetes, and 133 (33.5%) patients had prediabetes. Glycemia estimation by FPG, 2-h PG, and HbA1c showed a prediabetes prevalence of 17.4%, 14.7%, and 12.5%, respectively. The kappa statistics for the agreement of FPG and 2-h PG, HbA1c and 2-h PG, and HbA1c and FPG were 0.317, 0.429, and 0.396, respectively. In multivariate analysis, hypertension [odds ratio (OR) 3.38; 95% confidence interval (CI), 1.16-9.91; p = 0.026), and triglycerides > 150 mg/dL (OR 2.11; 95% CI, 1.01-4.44; p = 0.047) were factors significantly associated with prediabetes.

Conclusions

Prediabetes among HIV-infected individuals receiving ART is common. The agreements of glycemia estimation methods are minimal to weak. HbA1c may underestimate prediabetes prevalence. Using FPG together with HbA1c increases the detection rate to approximately three-quarters of prediabetes patients. HIV-infected individuals who had hypertension and hypertriglyceridemia should be regularly assessed for prediabetes.

Trial registration ClinicalTrial.gov, NCT03545217. Registered 1 June 2018—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03545217

Impact of hypertension on retinal capillary microvasculature using optical coherence tomographic angiography

Objective:

Reduction in capillary density or rarefaction is a hallmark of essential hypertension. We measured the retinal capillary density using noninvasive optical coherence tomographic angiography (OCT-A) in adults with treated systemic hypertension and determined possible correlations with ambulatory blood pressure (BP) and renal parameters.

Methods:

This observational cross-sectional study consisted of 153 normal eyes from 77 nondiabetic hypertensive adults [mean (SD) age, 58 (9) years; 49% women; 23% poorly controlled BP]. Data on 24-h ambulatory BP monitoring, serum creatinine, and urine microalbumin/creatinine ratio (MCR) were collected. Estimated glomerular filtration rate (eGFR) was calculated based on CKD-EPI Creatinine Equation. Retinal capillary density measured with the OCT-A (AngioVue) at superficial (SVP) and deep vascular plexuses (DVP). Linear regression was used to investigate the association of risk factors with capillary density.

Results:

Retinal capillary density (percentage) at DVP was reduced in patients with poorly controlled BP (SBP = 148 ± 8 mmHg; 27.2 ± 13.0) compared with those with well controlled BP (SBP = 125 ± 9 mmHg; 34.7 ± 11.3). In the multivariable analysis, poorly controlled BP [β = −6.49, 95% confidence interval (CI), −12.39 to −0.59], higher SBP (β = −0.23, 95% CI −0.44 to −0.02) and lower eGFR (β = 6.42, 95% CI 1.25–11.60) were associated with sparser retinal capillary density. Systemic factors were not associated with capillary density at SVP (all P > 0.05).

Conclusion:

In adults with treated systemic hypertension, retinal capillary density reduced with higher BP and poorer eGFR. These findings highlight the potential role of OCT-A to study early microvascular changes because of systemic hypertension.

Relation between retinal vascular abnormalities and working memory impairment in patients with schizophrenia and bipolar disorder

Emerging evidence indicates abnormal retinal micro-vasculature in schizophrenia (SCZ) and bipolar disorder (BD) and its relation to cognitive functions. However, the association of these abnormalities with the cognitive deficits in these disorders has not been examined till date. Hence, we explored this aspect in patients with SCZ, BD, and healthy volunteers (HV). We examined 34 with SCZ, 39 with BD, and 45 HV. Retinal images were acquired using nonmydriatic fundus camera. The retinal images were analyzed, and average diameters of retinal arterioles and venules were calculated. Working memory was assessed using computerized one-back test from Cogstate® battery. There was significant difference between groups in retinal venules and arterioles caliber (p < 0.001). Both SCZ and BD patients had wider venules and narrower arterioles. They had significantly lower working memory accuracy (p = 0.008) and higher log mean speed (p < 0.001). There was significant positive correlation between one-back test accuracy and retinal arteriolar caliber (r = 0.22; p = 0.01) and between log mean speed score and retinal venular caliber (r = 0.20; p = 0.02). Findings suggest association between working memory and retinal vascular caliber, a potential pointer towards understanding the vascular pathology in cognitive deficits in SCZ and BD. Future studies need to examine whether retinal vascular could be a biomarker for SCZ and BD.

Structural analysis of retinal blood vessels in patients with COPD during a pulmonary rehabilitation program

Cardiovascular diseases are frequently present in chronic obstructive pulmonary disease (COPD). Population-based studies found associations between retinal vessel diameters and cardiovascular health, but it is unknown whether this also applies to COPD patients. Therefore, we measured retinal vessel diameters in COPD patients and aimed to determine the association with cardiovascular risk factors, lung function, and functional outcomes. In addition, we investigated whether an exercise-based pulmonary rehabilitation (PR) program would change retinal vessel diameters, as a proxy for improved microvascular health. Demographics and clinical characteristics, including pulmonary function, exercise capacity, blood pressure, blood measurements and level of systemic inflammation were obtained from 246 patients during routine assessment before and after PR. Retinal vessel diameters were measured from digital retinal images. Older age and higher systolic blood pressure were associated with narrower retinal arterioles (β: -0.224; p = 0.042 and β: -0.136; p < 0.001, respectively). Older age, higher systolic blood pressure and lower level of systemic inflammation were associated with narrower retinal venules (β: -0.654; -0.229; and -13.767, respectively; p < 0.05). No associations were found between retinal vessel diameters and lung function parameters or functional outcomes. After PR, no significant changes in retinal venular or arteriolar diameter were found. To conclude, retinal vessel diameters of COPD patients were significantly associated with systolic blood pressure and systemic inflammation, whilst there was no evidence for an association with lung function parameters, functional outcomes or other cardiovascular risk factors. Furthermore, an exercise-based PR program did not affect retinal vessel diameter.

Association of the mean platelet volume and red cell distribution width with dipper and non-dipper blood pressure in prehypertensive non-smokers

OBJECTIVE

Absence of nocturnal blood pressure (BP) dipping is associated with poor health outcomes, including increased mortality. Non-dipper BP seems to be a predictor of cardiovascular damage in hypertensive patients. The aim of this study was to investigate the association of the mean platelet volume (MPV) and red cell distribution width (RDW) with nocturnal dipping/non dipping status in newly diagnosed and untreated prehypertensive non-smokers, using ambulatory BP monitoring.

RESULTS

Twenty-eight patients (15 males) in the dipper group and 24 patients (11 males) in the non-dipper group were evaluated in this study. The age of patients was 41.64 ± 15.01 and 37.96 ± 15.08 years in the dipper and non-dipper groups, respectively. The rate of nocturnal systolic BP drop in the dipper and non-dipper groups was 13.79 ± 3.35% (10.20-22.10) and 5.96 ± 2.87% (1.10-9.30) (P < 0.001), respectively. Also, the mean rate of nocturnal diastolic BP drop in the dipper and non-dipper groups was 17.02 ± 5.09% (10.30-26.90) and 6.19 ± 2.75% (1.20-9.70) (P < 0.001), respectively. RDW and MPV were significantly higher in non-dipper patients than dipper patients (P = 0.001 and P = 0.012, respectively). Bivariate analysis revealed that MPV was inversely correlated with the nocturnal systolic BP drop (P = 0.005, r = - 0.385). Furthermore, RDW was inversely correlated with systolic BP drop (P = 0.019, r = - 0.324).

Retinal vascular fractal dimension in bipolar disorder and schizophrenia

BACKGROUND

Bipolar disorder (BD) and schizophrenia (SCZ), are associated with greater vascular co-morbidities and adverse vascular events. Owing to shared developmental origins and morphology, retinal vasculature is a proxy assessment measure of the cerebral vasculature. Although retinal vascular fractal dimension (D_f), a measure of vascular geometry and complexity of branching, has been shown to be directly associated with cerebrovascular pathology, it has not been examined in SCZ and BD.

METHODS

We studied 277 participants (92 healthy volunteers, 98 SCZ, and 87 BD) from 18 to 50 years of age. Images were acquired by trained personnel using a non-mydriatic fundus camera and the retinal vascular D_f was calculated by the box-counting method using an automated algorithm. The average D_f across the left and right eyes were calculated.

RESULTS

Both SCZ and BD had significantly increased D_f compared to HV despite controlling for possible confounding factors. However, there was no significant difference between SCZ and BD. These findings suggest abnormal retinal vascular D_f in psychoses.

LIMITATIONS

The study design was cross-sectional, and patients were on medications. Confound of lifestyle factors such as diet and exercise, if any, was not controlled. Sub-group analysis between BD-I and BD-II was not performed in view of the small sample.

CONCLUSIONS

Considering the easy accessibility, affordability, and non-invasive nature of the examination, retinal vascular D_f could serve as a surrogate marker for cerebral vascular abnormality and could potentially identify BD and SCZ patients at risk of developing adverse vascular events.

The relationship of blood pressure with uric acid and bilirubin in young lean and overweight/obese men and women: the African-PREDICT study

Mounting evidence supports the central role of oxidative stress and inflammation in obesity and the development of hypertension. However, most studies focusing on the non-enzymatic antioxidants, such as uric acid and bilirubin, and their relationship with obesity and hypertension were done in older populations with overt cardiovascular disease. The aim of this study was therefore to compare measures of cardiovascular function (blood pressure and arterial stiffness) and non-enzymatic antioxidants (uric acid and bilirubin) between young healthy lean and overweight/obese men and women and to investigate the link between these variables. We grouped 967 men and women (aged 20-30 years) according to body mass index (BMI) categories (lean BMI < 25 kg/m²; overweight/obese BMI ≥ 25 kg/m²). Cardiovascular measurements included 24 h blood pressure and carotid-femoral pulse wave velocity. Serum samples were used to analyse uric acid and bilirubin. Women and men with a BMI ≥ 25 kg/m² displayed higher 24 h blood pressure (P < 0.001) and uric acid (P ≤ 0.014) than their lean counterparts; lean women showed higher bilirubin (P < 0.001). In multi-variable adjusted regression analyses we found that 24 h systolic blood pressure was independently associated with uric acid (R² = 0.10; β = 0.19; P = 0.017) only in overweight/obese women. In lean women a negative association of 24 h systolic blood pressure with bilirubin (R² = 0.03; β = -0.14; P = 0.018) was found. No associations were found in men. In conclusion, we found adverse associations between blood pressure and uric acid in young healthy women with increased adiposity, but not in lean women or men.

Type 2 diabetes and pre-diabetes mellitus: a systematic review and meta-analysis of prevalence studies in women of childbearing age in the Middle East and North Africa, 2000-2018

BACKGROUND

Investing in women's health is an inevitable investment in our future. We systematically reviewed the available evidence and summarized the weighted prevalence of type 2 diabetes (T2DM) and pre-diabetes mellitus (pre-DM) in women of childbearing age (15-49 years) in the Middle East and North African (MENA) region.

METHODS

We comprehensively searched six electronic databases to retrieve published literature and prevalence studies on T2DM and pre-DM in women of childbearing age in the MENA. Retrieved citations were screened and data were extracted by at least two independent reviewers. Weighted T2DM and pre-DM prevalence was estimated using the random-effects model.

RESULTS

Of the 10,010 screened citations, 48 research reports were eligible. Respectively, 46 and 24 research reports on T2DM and pre-DM prevalence estimates, from 14 and 10 countries, were included. Overall, the weighted T2DM and pre-DM prevalence in 14 and 10 MENA countries, respectively, were 7.5% (95% confidence interval [CI], 6.1-9.0) and 7.6% (95% CI, 5.2-10.4). In women sampled from general populations, T2DM prevalence ranged from 0.0 to 35.2% (pooled, 7.7%; 95% CI, 6.1-9.4%) and pre-DM prevalence ranged from 0.0 to 40.0% (pooled, 7.9%; 95% CI, 5.3-11.0%). T2DM was more common in the Fertile Crescent countries (10.7%, 95% CI, 5.2-17.7%), followed by the Arab Peninsula countries (7.6%, 95% CI, 5.9-9.5%) and North African countries and Iran (6.5%, 95% CI, 4.3-9.1%). Pre-DM prevalence was highest in the Fertile Crescent countries (22.7%, 95% CI, 14.2-32.4%), followed by the Arab Peninsula countries (8.6%, 95% CI, 5.5-12.1%) and North Africa and Iran (3.3%, 95% CI, 1.0-6.7%).

CONCLUSIONS

T2DM and pre-DM are common in women of childbearing age in MENA countries. The high DM burden in this vital population group could lead to adverse pregnancy outcomes and acceleration of the intergenerational risk of DM. Our review presented data and highlighted gaps in the evidence of the DM burden in women of childbearing age, to inform policy-makers and researchers.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017069231.

Retinal vascular abnormalities in schizophrenia and bipolar disorder: A window to the brain

OBJECTIVES

The examination of retinal microvascular abnormalities through fundus photography is currently the best available non-invasive technique for assessment of cerebral vascular status. Several studies in the last decade have reported higher incidences of adverse cerebrovascular events in Schizophrenia (SCZ) and bipolar disorder (BD). However, retinal microvasculature abnormalities in SCZ and BD have remained under-explored, and no study has compared this aspect of SCZ and BD till date.

METHODS

Retinal Images of 100 SCZ patients, BD patients, and healthy volunteers each were acquired by trained individuals using a non-mydriatic camera with a 40-degree field of view. The retinal images were quantified using a valid semi-automated method. The average of left and right eye diameters of the venules and arterioles passing through the extended zone between 0.5 and 2 disc diameters from the optic disc were calculated.

RESULTS

The groups differed significantly with respect to average diameters of both retinal venules (P < 0.001) and retinal arterioles (P < 0.001), after controlling for age and sex. Both SCZ and BD patients had significantly narrower arterioles and wider venules compared to HV. There were also significant differences between SCZ and BD patients; patients with BD had narrower arterioles and wider venules.

CONCLUSION

Considering the affordability and easy accessibility of the investigative procedure, retinal microvascular examination could serve as a potential screening tool to identify individuals at risk for adverse cerebrovascular events. The findings of the current study also provide a strong rationale for further systematic examination of retinal vascular abnormalities in SCZ and BD.