Early retinal microvascular abnormalities in patients with chronic kidney disease

Blue Wavelength of Scanning Laser Ophthalmoscope Potentially Detects Arteriosclerotic Lesions in Diabetic Retinopathy

(1) Background: The fundus examination is one of the best and popular methods in the assessment of vascular status in the human body. Direct viewing of retinal vessels by ophthalmoscopy has been utilized in judging hypertensive change or arteriosclerosis. Recently, fundus imaging with the non-mydriatic scanning laser ophthalmoscope (SLO) has been widely used in ophthalmological clinics since it has multimodal functions for optical coherence tomography or angiography with contrast agent dye. The purpose of this study was to examine the utility in detecting arteriosclerosis of retinal vessels in SLO images; (2) Methods: Both color and blue standard field SLO images of eyes with diabetic retinopathy (DR) were examined retrospectively. Retinal arteriosclerosis in color SLO images was graded according to the Scheie classification. Additionally, characteristics of retinal arterioles in blue SLO images were identified and examined for their relevance to arteriosclerosis grades, stages of DR or general complications; (3) Results: Relative to color fundus images, blue SLO images showed distinct hyper-reflective retinal arterioles against a monotone background. Irregularities of retinal arterioles identified in blue SLO images were frequently observed in the eyes of patients with severe arteriosclerosis (Grade 3: 79.0% and Grade 4: 81.8%). Furthermore, the findings on arterioles were more frequently associated with the eyes of DR patients with renal dysfunction (p < 0.05); (4) Conclusions: While color SLO images are equally as useful in assessing retinal arteriosclerosis as photography or ophthalmoscopy, the corresponding blue SLO images show arteriosclerotic lesions with high contrast in a monotone background. Retinal arteriosclerosis in eyes of advanced grades or advanced DR frequently show irregularities of retinal arterioles in the blue images. The findings of low, uneven, or discontinuous attenuation were easier to find in blue than in color SLO images. Consequently, blue SLO images can show pathological micro-sclerosis in retinal arterioles and are potentially one of the safe and practical methods for the vascular assessment of diabetic patients.

Cross-modality Labeling Enables Noninvasive Capillary Quantification as a Sensitive Biomarker for Assessing Cardiovascular Risk

Purpose

We aim to use fundus fluorescein angiography (FFA) to label the capillaries on color fundus (CF) photographs and train a deep learning model to quantify retinal capillaries noninvasively from CF and apply it to cardiovascular disease (CVD) risk assessment.

Design

Cross-sectional and longitudinal study.

Participants

A total of 90732 pairs of CF-FFA images from 3893 participants for segmentation model development, and 49229 participants in the UK Biobank for association analysis.

Methods

We matched the vessels extracted from FFA and CF, and used vessels from FFA as labels to train a deep learning model (RMHAS-FA) to segment retinal capillaries using CF. We tested the model's accuracy on a manually labeled internal test set (FundusCapi). For external validation, we tested the segmentation model on 7 vessel segmentation datasets, and investigated the clinical value of the segmented vessels in predicting CVD events in the UK Biobank.

Main Outcome Measures

Area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity for segmentation. Hazard ratio (HR; 95% confidence interval [CI]) for Cox regression analysis.

Results

On the FundusCapi dataset, the segmentation performance was AUC = 0.95, accuracy = 0.94, sensitivity = 0.90, and specificity = 0.93. Smaller vessel skeleton density had a stronger correlation with CVD risk factors and incidence (P < 0.01). Reduced density of small vessel skeletons was strongly associated with an increased risk of CVD incidence and mortality for women (HR [95% CI] = 0.91 [0.84-0.98] and 0.68 [0.54-0.86], respectively).

Conclusions

Using paired CF-FFA images, we automated the laborious manual labeling process and enabled noninvasive capillary quantification from CF, supporting its potential as a sensitive screening method for identifying individuals at high risk of future CVD events.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Optical coherence tomography angiography for the differentiation of diabetic nephropathy from non-diabetic renal disease

BACKGROUND

To provide a new non-invasive method for the differentiation of diabetic nephropathy (DN) from non-diabetic renal disease (NDRD) by assessing retinal microstructure using optical coherence tomography angiography (OCTA).

METHODS

OCTA parameters were recorded and their relationship with DN was analysed. A differential diagnosis regression model for DN was established, and the diagnostic efficiency was evaluated.

RESULTS

Based on the pathological results of renal biopsy, 31 DN patients and 35 NDRD patients were included. Multivariate logistic regression analysis showed that DN was independently associated with the following parameters: 15.3 mm-1 ≤ vessel density (VD) full < 17.369 mm-1 (odds ratio [OR]=8.523; 95% confidence interval [CI]=1.387-52.352; P = 0.021), VD full < 15.3 mm-1 (OR=8.202; 95% CI=1.110-60.623; P = 0.039), DM duration > 60 months (OR=7.588; 95% CI=1.569-36.692; P = 0.012), and estimated glomerular filtration rate < 60 mL/min/1.73 m2 (OR=24.484; 95% CI=4.308-139.142; P < 0.001). The area under the receiver operating characteristic curve was 0.911, indicating a high diagnostic efficiency.

CONCLUSIONS

VD full < 17.369 mm-1, DM duration > 60 months, and eGFR < 60 mL/min/1.73 m2 may indicate the presence of DN. OCTA may be an effective non-invasive method for identifying DN and NDRD.

Detection of systemic cardiovascular illnesses and cardiometabolic risk factors with machine learning and optical coherence tomography angiography: a pilot study

BACKGROUND/OBJECTIVES

Optical coherence tomography angiography (OCTA) has been found to identify changes in the retinal microvasculature of people with various cardiometabolic factors. Machine learning has previously been applied within ophthalmic imaging but has not yet been applied to these risk factors. The study aims to assess the feasibility of predicting the presence or absence of cardiovascular conditions and their associated risk factors using machine learning and OCTA.

METHODS

Cross-sectional study. Demographic and co-morbidity data was collected for each participant undergoing 3 × 3 mm, 6 × 6 mm and 8 × 8 mm OCTA scanning using the Carl Zeiss CIRRUS HD-OCT model 5000. The data was then pre-processed and randomly split into training and testing datasets (75%/25% split) before being applied to two models (Convolutional Neural Network and MoblieNetV2). Once developed on the training dataset, their performance was assessed on the unseen test dataset.

RESULTS

Two hundred forty-seven participants were included. Both models performed best in predicting the presence of hyperlipidaemia in 3 × 3 mm scans with an AUC of 0.74 and 0.81, and accuracy of 0.79 for CNN and MobileNetV2 respectively. Modest performance was achieved in the identification of diabetes mellitus, hypertension and congestive heart failure in 3 × 3 mm scans (all with AUC and accuracy >0.5). There was no significant recognition for 6 × 6 and 8 × 8 mm for any cardiometabolic risk factor.

CONCLUSION

This study demonstrates the strength of ML to identify the presence cardiometabolic factors, in particular hyperlipidaemia, in high-resolution 3 × 3 mm OCTA scans. Early detection of risk factors prior to a clinically significant event, will assist in preventing adverse outcomes for people.

Optic Nerve Head Capillary Network Quantified by Optical Coherence Tomography Angiography and Decline of Renal Function in Type 2 Diabetes: A Three-Year Prospective Study

PURPOSE

To assess the association of optic capillary perfusion with decline in the estimated glomerular filtration rate (eGFR) and to clarify its added value.

DESIGN

Prospective, observational cohort study.

METHODS

Patients with type 2 diabetes mellitus without diabetic retinopathy (non-DR) underwent standardized examinations annually during a 3-year follow-up period. The superficial capillary plexus (SCP), deep capillary plexus (DCP), and radial peripapillary plexus (RPC) of optic nerve head (ONH) were visualized using optical coherence tomography angiography (OCTA), and the perfusion density (PD) and vascular density were quantified for the whole image and circumpapillary regions of the ONH.  The lowest tercile of annual eGFR slope was defined as the rapidly progressive group, and the highest tercile was considered the stable group.

RESULTS

A total of 906 patients were included for 3-mm × 3-mm OCTA analysis. After adjusting for other confounders, each 1% decrease in baseline whole en face PD in SCP and RPC was associated with accelerated rates of decline in eGFR by -0.53 mL/min/1.73/m2 per year (95% confidence interval [CI] -0.17 to -0.90; P = .004) and -0.60 mL/min/1.73/m2 per year (95% CI 0.28-0.91), respectively. Adding both whole-image PD in SCP and whole-image PD in RPC to the conventional model increased the area under the curve from 0.696 (95% CI 0.654-0.737) to 0.725 (95% CI 0.685-0.765; P = .031). Another cohort of 400 eligible patients with 6-mm × 6 mm OCTA imaging validated the significant associations between ONH perfusion and rate of eGFR decline (P < .05).

CONCLUSIONS

Reduced capillary perfusion of ONH in patients with type 2 diabetes mellitus is associated with a greater eGFR decline, and it has additional predictive value for detecting an early stage and progression.

Diminished vasculogenesis under inflammatory conditions is mediated by Activin A

Severe inflammatory stress often leads to vessel rarefaction and fibrosis, resulting in limited tissue recovery. However, signaling pathways mediating these processes are not completely understood. Patients with ischemic and inflammatory conditions have increased systemic Activin A level, which frequently correlates with the severity of pathology. Yet, Activin A's contribution to disease progression, specifically to vascular homeostasis and remodeling, is not well defined. This study investigated vasculogenesis in an inflammatory environment with an emphasis on Activin A's role. Exposure of endothelial cells (EC) and perivascular cells (adipose stromal cells, ASC) to inflammatory stimuli (represented by blood mononuclear cells from healthy donors activated with lipopolysaccharide, aPBMC) dramatically decreased EC tubulogenesis or caused vessel rarefaction compared to control co-cultures, concurrent with increased Activin A secretion. Both EC and ASC upregulated Inhibin Ba mRNA and Activin A secretion in response to aPBMC or their secretome. We identified TNFα (in EC) and IL-1β (in EC and ASC) as the exclusive inflammatory factors, present in aPBMC secretome, responsible for induction of Activin A. Similar to ASC, brain and placental pericytes upregulated Activin A in response to aPBMC and IL-1β, but not TNFα. Both these cytokines individually diminished EC tubulogenesis. Blocking Activin A with neutralizing IgG mitigated detrimental effects of aPBMC or TNFα/IL-1β on tubulogenesis in vitro and vessel formation in vivo. This study delineates the signaling pathway through which inflammatory cells have a detrimental effect on vessel formation and homeostasis, and highlights the central role of Activin A in this process. Transitory interference with Activin A during early phases of inflammatory or ischemic insult, with neutralizing antibodies or scavengers, may benefit vasculature preservation and overall tissue recovery.

Correlation of ACR and TcPO2 in diabetic kidney disease patients: A pilot study

OBJECTIVE

Transcutaneous oxygen pressure (TcPO2) is used to assess microcirculation clinically; however, it is not widely available especially in rural hospital. The study was designed to explore potential alternatively biomarkers to assess microcirculation in diabetic kidney disease (DKD).

METHODS

A total of 404 patients from Xuzhou first hospital were recruited according to the case records system. Patients were grouped via the ratio of albuminuria and creatinine (ACR; <30 mg/g, 30-300 mg/g, >300 mg/g). Biomarkers in different ACR groups were compared by analysis of variance. Correlation analysis was determined by Pearson or Spearman analysis and binary logistic regression. The receiver operating characteristics (ROC) curve was performed to elucidate the prediction effect of ACR on TcPO2.

RESULTS

A total of 404 diabetic patients were recruited with 248 patients diagnosed as DKD and 156 non-DKDs. Age and cystatin C were significantly higher in the ACR3 group compared with those in the ACR1 group, whereas glomerular filtration rate, low-density lipoprotein cholesterol, and TcPO2 were markedly decreased in the ACR3 group (p < .05). Frequency of low TcPO2 (<40 mm Hg) was markedly increased as increment of ACR stages with 30.2% in the ACR3 group (p < .01). There was a negative correlation between TcPO2 and age, ACR, chronic kidney disease (CKD), fast blood glucose, diabetes mellitus (DM) duration, and diabetic neuropathy. Further, binary logistic regression showed ACR was an independent influence factor for low TcPO2. After adjusting for age, gender, hypertension, DM duration, body mass index, glycated hemoglobin, diabetic neuropathy, and CKD, ACR was still an independent influence factor for TcPO2 (odds ratio = 2.464, p < .01). The area under the ROC curve was 0.768 (95% confidence interval: 0.700-0.836, p < .001) for ACR. The analysis of ROC curves revealed a best cutoff for ACR was 75.25 mg/g and yielded a sensitivity of 71.7% and a specificity of 71.7%.

CONCLUSIONS

ACR could be used as an alternative biomarker for assessing microcirculation in DKD patients.

Retinal Neurodegeneration and Visual Acuity Decline in Patients with Chronic Kidney Disease

INTRODUCTION

Chronic kidney disease (CKD) has been associated with accelerated retinal neurodegeneration. The purpose of this study is to evaluate the association between retinal neurodegeneration and the best-corrected visual acuity (BCVA) decline in patients with CKD.

METHODS

Post hoc analysis of two prospective studies. Patients with CKD stage ≥ 3 were enrolled. Macular thickness, peripapillary retinal nerve fiber layer (pRNFL) thickness, and macular ganglion cell complex (GCC) thickness were measured by optical coherence tomography. Eyes were classified into three groups: Group 1, no GCC defect; Group 2, GCC defect confined to parafoveal area; and Group 3, GCC defects extending beyond the parafoveal area. Each group was matched for age, sex, axial length, lens status, and cataract grading.

RESULTS

A total of 120 eyes (40 eyes in each group) from 120 patients (age 63.0 ± 10.3 years) were included. The logMAR BCVA was 0.076 ± 0.101, 0.100 ± 0.127, and 0.196 ± 0.191 in Group 1, 2, and 3, respectively. Group 3, but not Group 2, had a significantly worse BCVA than Group 1. In simple linear regression, parafoveal inner retinal thickness, pRNFL thickness, presence of pRNFL defect, GCC thickness, GCC global loss volume, GCC focal loss volume, and GCC defect extending beyond parafoveal area were associated with BCVA. Central subfield retinal thickness (CRT), parafoveal full retinal thickness, and parafoveal outer retinal thickness were not associated with BCVA. In backward stepwise linear regression, age and GCC defects extending beyond the parafoveal area were factors associated with BCVA. Moreover, GCC defect extending beyond parafoveal area was connected with worse BCVA in both phakic and pseudophakic subgroups.

CONCLUSIONS

GCC defect extending beyond parafoveal area could be an independent biomarker associated with decreased BCVA in patients with CKD. However, macular thinning measured by CRT or parafoveal full retinal thickness might have low discriminative power in determining BCVA.

The association between retinal microvasculature derived from optical coherence tomography angiography and systemic factors in type 2 diabetics

Aims

To investigate the correlation between the retinal microvasculature using optical coherence tomography angiography (OCTA) and systemic factors in type 2 diabetes mellitus (T2DM) patients.

Methods

This cross-sectional study obtained OCTA data from patients with T2DM administered at hospital and referred to ophthalmic services. Patient data about demographics, comorbid conditions, and blood biomarkers were extracted from electronic medical records. Data from OCTA scans obtained by CIRRUS HD-OCT Model 5,000 were obtained. Vessel density (VD) and perfusion density (PD) within the superficial capillary plexus, and foveal avascular zone (FAZ) area were automatically segmented. These parameters were tested for their correlations with systemic factors by univariate and multivariable linear regression analyses.

Results

A total of 144 T2DM patients (236 eyes) were available for analysis, with mean age of 53.6 (SD = 10.34) and 56.9% were male. Chronic kidney disease, cardiovascular disease, increased serum creatinine (Scr), red blood cell count (RBC), platelets (PLT), apolipoprotein B (APOB), and decreased urine albumin to creatinine ratio (UACR) were significantly associated with lower VD and PD (all p &lt; 0.013). UACR and triglyceride (TRIG) were significantly correlated with FAZ area (all p &lt; 0.017). In multivariate analyses, PLT, eGFR, and APOB were independent risk factors for retinal rarefaction, and UACR was a significant predictor of FAZ area.

Conclusion

We found several systemic risk factors, such as PLT, renal function and lipid profiles were associated with PD, VD, and FAZ area among Chinese T2DM patients.

Association of chorioretinal thickness with chronic kidney disease

OBJECTIVE

To assess retinal and choroidal thickness changes in chronic kidney disease (CKD) patients using spectral domain optical coherence tomography (SD-OCT).

BACKGROUND

CKD is a devastating health trouble. The eye and the kidney share similar structural and genetic pathways, so that kidney disease and ocular disease may be closely linked. OCT is a precise, fast method for high-definition scanning of the retina and choroid.

PATIENTS AND METHODS

A cross sectional study was conducted at Menoufia University Hospital ophthalmology department on 144 eyes of 72 CKD patients divided into 3 groups according to the stage of CKD as follows: group 1: CKD stage 1-2, with Glomerular Filtration Rate (GFR) > 60 ml/min/1.73m² group 2: CKD stage 3, GFR 30-59 ml/min/1.73m² and group 3: CKD stage 4-5, eGFR < 29 ml/min/1.73m². All patients underwent full ophthalmologic examination followed by OCT assessment of retinal, retinal nerve fiber layer (RNFL) and choroidal thickness.

RESULTS

Retinal and choroidal thickness were reduced in group 2 (CKD stage 3) and group 3 (CKD stage 4-5) compared with group 1 (CKD stage 1-2). The reduction was more severe in group 3 than group 2. RNFL thickness did not differ between groups. A thinner retina and choroid were associated with an elevated serum C-reactive protein (CRP) concentration, and greater degrees of proteinuria.

CONCLUSION

Chorioretinal thinning in CKD is associated with a lower eGFR, a higher CRP, and greater proteinuria. Further studies, in a large scale of patients, are needed to detect whether these eye changes reflect the natural history of CKD.

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

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

Macular Vessel Density Measurement in Pediatric Renal and Liver Transplant

OBJECTIVES

Microcirculatory dysfunction is known to be associated with organ failure and increased mortality in transplant patients. Noninvasive monitorization of retinal structures of the eye could be a predictor for systemic microvasculature in these patients. Therefore, in this study we aimed to evaluate the retinal microvascular changes in pediatric patients who had undergone liver or renal transplant surgery, using optical coherence tomography angiography.

MATERIALS AND METHODS

The medical records of pediatric patients who had liver or renal transplant in the past 10 years were reviewed. The macular vessel density parameters were obtained by optical coherence tomography angiography (Avanti RTVue XR). The results were compared with the age-matched, sex-matched, and spherical equivalent-matched healthy participants (control group). The IBM SPSS (version 25.0) statistics program was used for data analysis.

RESULTS

We included 32 eyes of 16 liver transplant patients, 20 eyes of 10 renal transplant patients, and 64 eyes of 32 healthy participants (control group). Superficial macular whole image, superficial perifoveal, and deep foveal vessel densities were found to be lower in the liver transplant group compared with the healthy control group (P = .02, P = .01, and P = .01, respectively). Superficial foveal, deep macular whole image, deep foveal, and deep perifoveal vessel densities were found to be lower in the renal transplant group compared with the healthy control group (P = .03, P = .04, P = .01, and P = .02, respectively).

CONCLUSIONS

Macular vessel density measurements are affected in pediatric renal and liver transplant patients. In those patients, retinal optical coherence tomography and optical coherence tomography angiography measurements may provide a noninvasive window to the microcirculation.

Abnormalities of Retinal Structure and Microvasculature are Associated with Cerebral White Matter Hyperintensities

PURPOSE

While retinal microvasculature represents cerebral small vessels, the retinal nerve fiber layer is the extended white matter of the brain. We aimed to investigate the correlation between changes in retina and white matter hyperintensities (WMH).

METHODS

64 candidates with WMH received the optical coherence tomography angiography (OCTA) examination. WMH were divided into mild or moderate/severe groups according to the Fazekas score. After imaging superficial capillary plexus (SCP) and deep capillary plexus (DCP), we revealed the microvascular density parameters (vascular perfusion density (VPD), vascular length density (VLD), and fovea avascular zone area (FAZ-A)) and morphological parameters (vessel diameter index (VDI), fractal dimension (FD), and vessel tortuosity (VT)). The software algorithm measured the thickness of the peripapillary retina nerve fiber layer (PRNFL).

RESULTS

32 were classified as having mild WMH and 32 were moderate/severe. The Median (interquartile range) ages of the two groups were 58 (54-64) and 61 (57-67) years, respectively. A decrease of FD, VPD and VLD in either SCP or DCP appeared with an increased risk of moderate/severe WMH. Although changes of capillary plexus were not associated with PWMH, decreased FD, VPD, VLD and FAZ-A in either SCP or DCP was associated with an increased risk of moderate/severe DWMH. Participants with moderate/severe WMH demonstrated reduced PRNFL thickness, particularly in the DWMH, compared with mild WMH.

CONCLUSIONS

Abnormalities of retinal microvascular density, morphological parameters, and PRNFL thickness are correlated with the incidence of moderate/severe WMH, particularly the DWMH, suggesting that arteriosclerosis and hypoperfusion are the causes of DWMH.

Retinal Optical Coherence Tomography Angiography Parameters Between Patients With Different Causes of Chronic Kidney Disease

Background

Chronic kidney disease (CKD) is a major public health issue because of the rising number of patients with the risk of progression to end-stage renal disease. The retinal micro-vasculatures provide a unique window to assess systemic microcirculation. Optical Coherence Tomography Angiography (OCTA) parameters may provide a non-invasive method for systemic correlation. This research aims to compare the association of OCTA parameters in different causes of CKD.

Methods

This is a single-center cross-sectional study on patients with CKD at the Universiti Kebangsaan Malaysia Medical Centre over 2 years. Patients with CKD were divided into three groups: DM group (diabetic CKD), HPT group (hypertensive CKD), and AG group (autoimmune-related glomerulonephritis CKD). The OCTA parameters, namely, the foveal avascular zone (FAZ), vascular density (VD), perfusion density (PD), and macular volume (MV), were measured and recorded using OCTA. Blood and urine analyses were taken as the patient's CKD profile. The demographic data, the OCTA parameters and the CKD profiles, were analyzed using SPSS version 23.

Results

The right eyes of 232 patients were included. The median age of the control and CKD subjects were 36 and 61 years old respectively. The proportion of the subjects under the control, diabetes mellitus (DM), HPT, and AG group were 30.6, 53.4, 5.6, and 10.4% respectively. There was no significant difference in FAZ, but there is a significant difference in the VD, PD, and MV between the control and CKD groups. There was a statistically significant difference between the three different causes of CKD in VD and PD (p < 0.001, p = 0.001, respectively). When compared with the control group for VD and PD, there were significant differences between the DM-control group (p < 0.001, p < 0.001) even when the age variable was considered, but no significant difference when comparing the HPT-control and the AG-control. There was a significant correlation between age, FBS, and HbA1c with VD and PD. There was no significant association between CKD profile and FAZ.

Conclusion

Our study showed the meaningful reduction of VD and PD in patients with diabetes and CKD. However, the use of OCTA to screen or predict CKD in patients living with diabetes mellitus, hypertension, or autoimmune nephritis was not shown to be useful.

Relationship of Quantitative Retinal Capillary Network and Myocardial Remodeling in Systemic Hypertension

Background

This study examined the associations between quantitative optical coherence tomography angiography (OCTA) parameters and myocardial abnormalities as documented on cardiovascular magnetic resonance imaging in patients with systemic hypertension.

Methods and Results

We conducted a cross‐sectional study of 118 adults with hypertension (197 eyes). Patients underwent cardiovascular magnetic resonance imaging and OCTA (PLEX Elite 9000, Carl Zeiss Meditec). Associations between OCTA parameters (superficial and deep retinal capillary density) and adverse cardiac remodeling (left ventricular mass, remodeling index, interstitial fibrosis, global longitudinal strain, and presence of left ventricular hypertrophy) were studied using multivariable linear regression analysis with generalized estimating equations. Of the 118 patients with hypertension enrolled (65% men; median [interquartile range] age, 59 [13] years), 29% had left ventricular hypertrophy. After adjusting for age, sex, systolic blood pressure, diabetes, and signal strength of OCTA scans, patients with lower superficial capillary density had significantly higher left ventricular mass (β=−0.150; 95% CI, −0.290 to −0.010), higher interstitial volume (β=−0.270; 95% CI, −0.535 to −0.0015), and worse global longitudinal strain (β=−0.109; 95% CI, −0.187 to −0.032). Lower superficial capillary density was found in patients with hypertension with replacement fibrosis versus no replacement fibrosis (16.53±0.64 mm ‐1 versus 16.96±0.64 mm ‐1 ; P =0.003).

Conclusions

We showed significant correlations between retinal capillary density and adverse cardiac remodeling markers in patients with hypertension, supporting the notion that the OCTA could provide a non‐invasive index of microcirculation alteration for vascular risk stratification in people with hypertension.

Optical coherence tomography angiography changes in cardiovascular systemic diseases and risk factors: A Review

Cardiovascular (CV) disease (CVD) is the main cause of death around the world, and assessing a patient's CV risk factors (CVRF) can play a major role in its prevention. Since it has been shown that retinal vascular alterations may reflect several systemic processes such as CVRF, we conducted a systematic review in order to summarize which ocular microvasculature changes can be found using Optical Coherence Tomography Angiography (OCTA) in patients without ocular diseases and with systemic pathologies/conditions that affect the CV system when compared to healthy subjects. We searched on online databases, namely PubMed, Scopus, Cochrane and Web of Science, and obtained additional studies through citation tracking. Case reports and review articles were excluded. A total of 47 articles were included in our review. We describe that patients with hypertension, diabetes mellitus, kidney disease, preeclampsia, coronary artery disease, carotid artery stenosis and obstructive sleep apnoea syndrome have, in general, lower retinal and choroidal Vessel Density (VD) and Length (VL), as well as an increased foveal avascular zone area and perimeter. Additionally, several characteristics and/or conditions in healthy subjects, such as smoking status, hyper or hypoxia conditions, race, among others, are also related to ocular vascular changes and should be accounted for. We concluded that OCTA could be a useful tool to assess a patient's CV risk profile in a non-invasive way, possibly integrating the diagnostic and prognostic algorithms of the most prevalent CV diseases in the future.

Proinflammatory mediators, TNFα, IFNγ, and thrombin, directly induce lymphatic capillary tube regression

In this work, we sought to investigate the direct effects of proinflammatory mediators on lymphatic endothelial cell (LEC) capillaries and whether they might induce regression. Our laboratory has developed novel in-vitro, serum-free, lymphatic tubulogenesis assay models whereby human LEC tube networks readily form in either three-dimensional collagen or fibrin matrices. These systems were initially conceptualized in the hopes of better understanding the influence of proinflammatory mediators on LEC capillaries. In this work, we have screened and identified proinflammatory mediators that cause regression of LEC tube networks, the most potent of which is TNFα (tumor necrosis factor alpha), followed by IFNγ (interferon gamma) and thrombin. When these mediators were combined, even greater and more rapid lymphatic capillary regression occurred. Surprisingly, IL-1β (interleukin-1 beta), one of the most potent and pathologic cytokines known, had no regressive effect on these tube networks. Finally, we identified new pharmacological drug combinations capable of rescuing LEC capillaries from regression in response to the potent combination of TNFα, IFNγ, and thrombin. We speculate that protecting lymphatic capillaries from regression may be an important step toward mitigating a wide variety of acute and chronic disease states, as lymphatics are believed to clear both proinflammatory cells and mediators from inflamed and damaged tissue beds. Overall, these studies identify key proinflammatory mediators, including TNFα, IFNγ, and thrombin, that induce regression of LEC tube networks, as well as identify potential therapeutic agents to diminish LEC capillary regression responses.

[Structural and microvascular changes in the retina and choroid in patients with chronic kidney disease]

PURPOSE

To study the main structural and microvascular changes in the retina and choroid in patients with diabetic retinopathy (DR) and chronic kidney disease (CKD), and their relationship with impaired renal function.

MATERIAL AND METHODS

The study included 158 patients (304 eyes). The 1^st group consisted of 50 patients with CKD (97 eyes); group 2 - 65 patients with DR (119 eyes), group 3 - 43 patients with CKD and DR (86 eyes). All study patients underwent complete ophthalmological examination, including optical coherence tomography (OCT) and OCT angiography (OCTA) of the macular region.

RESULTS

The analysis of structural parameters in groups of patients showed a decrease in the thickness of the ganglion cell layer and the inner plexiform layer of the retina in patients with DR (70.85±14.49 μm), with the lowest value in the CKD+DR group (65.84±15.34 μm) in comparison with the CKD group (75.64±10.32 μm). In the groups of patients with CKD, the thickness of the choroid (207.3±40.36 μm) was significantly reduced in comparison with the group of patients with DR (258.8±26.63 μm) and correlated with the stage of the disease. Patients in the CKD+DR group had the lowest perfusion and vascular density in the macular region (31.23±10.91% and 13.15±2.73 mm), an increase in the area and perimeter of the foveal avascular zone (0.55±0.26 mm², 3.30±0.84 mm). Pronounced correlations of decrease in choroidal thickness, vascular density, and perfusion volume with low glomerular filtration rate and CKD stage, as well as urea and creatinine levels were determined. An increase in the area of the foveal avascular zone correlated with lower retinal capillary density, decreased perfusion volume, and the stage of both DR and CKD.

CONCLUSION

Structural and hemodynamic disorders of the retina and choroid can be recognized as significant biomarkers for non-invasive diagnosis of microvascular complications of diabetes mellitus and impaired renal function.

Optical Coherence Tomography Angiography in Type 1 Diabetes Mellitus-Report 2: Diabetic Kidney Disease

The purpose of this study is to investigate potential associations between optical coherence tomography angiography (OCTA) parameters and diabetic kidney disease (DKD) categories in type 1 diabetes mellitus (T1DM) patients and controls. A complete ocular and systemic examination, including OCTA imaging tests and bloods, was performed. OCTA parameters included vessel density (VD), perfusion density (PD), foveal avascular zone area (FAZa), perimeter (FAZp) and circularity (FAZc) in the superficial vascular plexus, and DKD categories were defined according to glomerular filtration rate (GFR), albumin-creatinine ratio (ACR) and KDIGO prognosis risk classifications. A total of 425 individuals (1 eye/1 patient) were included. Reduced VD and FAZc were associated with greater categories of GFR (p = 0.002, p = 0.04), ACR (p = 0.003, p = 0.005) and KDIGO risk prognosis classifications (p = 0.002, p = 0.005). FAZc was significantly reduced in greater KDIGO prognosis risk categories (low risk vs. moderate risk, 0.65 ± 0.09 vs. 0.60 ± 0.07, p < 0.05). VD and FAZc presented the best diagnostic performance in ROCs. In conclusion, OCTA parameters, such as VD and FAZc, are able to detect different GFR, ACR, and KDIGO categories in T1DM patients and controls in a non-invasive, objective quantitative way. FAZc is able to discriminate within T1DM patients those with greater DKD categories and greater risk of DKD progression.

OCT Angiography as an Interdisciplinary Diagnostic Tool for Systemic Diseases

In recent years, OCT angiography (OCT-A) has emerged as a well established imaging modality of the retina. This allows non-invasive visualisation of the retinal circulation at a micrometre scale in eye disorders and systemic diseases with potential ocular involvement. This review summarises the current state of this topic.

[Optical coherence tomography angiography in the diagnosis of retinal microvascular changes in chronic kidney disease (clinical observations)]

One distinctive pathological sign of chronic kidney disease (CKD) is microcirculatory disorders, which mark it as a microvascular disease. Similarity in the blood supply of the retina and kidneys, in the anatomy of their vascularization lead to identical complications in these organs. The retinal-choroidal microvascular system is easily accessible for clinical and morphological assessment and can be examined by the reproducible and non-invasive method - optical coherence tomography (OCT) and OCT angiography (OCTA). The study of significant diagnostic tomographic retinal biomarkers in CKD and monitoring of their changes are of great clinical importance. The article presents clinical cases of changes in the retina and choroid depending of the stage of CKD. Retinal microvascular changes precede functional impairment. A significant decrease in retinal and choroidal thickness correlates with a decrease in the glomerular filtration rate (GFR) and the degree of albumin excretion in the urine. All clinical cases were observed to exhibit retinal microcirculation disorders, capillary rarefaction in both capillary plexuses accompanied by a decrease in vessel density and a decrease in the circularity index of the foveal avascular zone as a result of regression of the parafoveal capillary networks. OCTA allowed visualization of morphological changes at the microcirculatory level in the form of blunt ends of capillaries, their increased tortuosity and the presence of local areas of decreased perfusion. The severity of retinal microvascular changes varied depending on the stage of CKD and was not associated with either age or the presence of diabetes mellitus. Assessment of the retinal microvasculature can help with monitoring of microvascular lesions, early prediction of the risk of development and progression of decreased renal function, as well as allow avoiding aggressive diagnostic biopsy.

Radiographic Imaging in Autosomal Dominant Polycystic Kidney Disease: A Claims Analysis

Background

Progression of autosomal dominant polycystic kidney disease (ADPKD) is highly variable, with some patients progressing rapidly to end-stage renal disease (ESRD). Abdominal imaging is an important modality for verifying diagnosis in patients at risk for rapidly progressing ADPKD, targeting them for early treatment that could slow onset of ESRD. Published literature is limited on the real-world abdominal imaging utilization patterns in ADPKD.

Methods

A retrospective healthcare administrative claims analysis examining abdominal imaging scans occurring from January 1, 2014, through June 30, 2017, was conducted using the IBM MarketScan^® commercial and Medicare supplemental databases. Patients in the United States who were at least 18 years old and had at least 1 inpatient claim or 2 outpatient claims (with different dates of service) with an ADPKD diagnosis code, as defined by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM codes 753.12 [polycystic kidney, unspecified type] and 753.13 [polycystic kidney, autosomal dominant] and/or Tenth Revision (ICD-10-CM codes Q61.2 [polycystic kidney, adult type] and Q61.3 [polycystic kidney, unspecified]) were included.

Results

Of the 4637 patients with ADPKD (mean age, 51.2 years [SD = 15.52]), 59% had ≥1 abdominal imaging scan. Of these patients, 46% had ≥1 computed tomography (CT) scan, 25% had ≥1 ultrasound, 10% had ≥1 magnetic resonance imaging scan. Among the 1754 patients (38%) with chronic kidney disease (CKD) stage information, CT imaging was more frequent in later stages (31% stage 1 versus 68% stage 5). The proportion of patients undergoing at least 1 CT or MRI scan increased with disease severity (37% in stage 1, 42% in stage 2, 48% in stage 3, 56% in stage 4, and 71% in stage 5).

Conclusion

Results of this analysis support the need for further investigation into abdominal imaging utilization in managing patients with ADPKD. Future research could clarify barriers and increase access to imaging, which has the potential to inform risk stratification, help patients delay dialysis or transplantation associated with ESRD, and help health systems avoid the costs associated with ESRD.

Chronic kidney disease as a potential risk factor for retinal vascular disease: A 13-year nationwide population-based cohort study in Taiwan

We investigate whether patients with chronic kidney disease (CKD) are at increased risk of retinal vascular disease (RVD). Data was collected from the Taiwan National Health Insurance system and included patients newly diagnosed with CKD between 2000 and 2012. The endpoint of interest was a diagnosis of RVD. Follow-up data of 85,596 patients with CKD and 85,596 matched comparisons (non-CKD) from 2000 to 2012 were analyzed. Patients with CKD were found to have a significantly higher cumulative incidence of RVD (Kaplan-Meier analysis, log-rank test P < .0001). Through multivariate Cox regression analysis, the CKD group was found to have higher risk of developing RVD (adjusted hazard ratio (HR) [95% confidence interval (CI)]: 2.30 [2.16-2.44]) when compared to the control cohort. When comparison of CKD group and non-CKD group was stratified by gender, age and comorbidities (hypertension, diabetes, and hyperlipidemia), the higher risk of RVD in patients with CKD remained significant in all subgroups. Patients with CKD were found to have higher risk of developing RVD in this cohort study. In addition, CKD imposed the same risk for RVD development in all age groups and in patients with or without hypertension or diabetes. Thus, patients with CKD should be vigilant for symptoms of RVD. Understanding the link between CKD and RVD could lead to the development of new treatment and screening strategies for both diseases.

Optical Coherence Tomography Angiography for the Evaluation of Retinal Vasculature in Fabry Disease: Our Experience and Review of Current Knowledge

Purpose: Optical coherence tomography angiography (OCTA) is a non-invasive and objective tool for the evaluation of the retinal microvascular changes in Fabry disease (FD). We investigated changes in retinal vasculature in FD patients, and the possible correlation with systemic parameters, by using OCTA, and reviewed the current status of literature.

Methods: Thirteen FD patients (eight females, five males, mean age 49.85 ± 14.7 years) were compared with 13 age- and sex-matched healthy controls. OCTA 3 × 3 mm macular scans were performed in all subjects. We evaluated the vessel density and vessel perfusion in distinct macular areas (whole, inner, and outer) of both the superficial capillary plexus (SCP VD and SCP VP) and of the deep capillary plexus (DCP VD and DCP VP). We also evaluated the foveal avascular zone (FAZ) metrics (area, perimeter, and circularity), and correlation between systemic and OCTA parameters. A literature review on the current understanding of OCTA in FD is then presented.

Results: FD patients showed significantly lower SCP VD values in the whole area (17.37 ± 2.08 mm⁻¹ vs. 18.54 ± 1.21 mm⁻¹; p-value 0.022), as well as in the outer area (17.46 ± 2.10 mm⁻¹ vs. 19.08 ± 1.14 mm⁻¹; p-value 0.002), but not in the inner. Even the DCP VD was significantly lower in all the imaged areas: whole (17.75 ± 3.93 mm⁻¹ vs. 19.71 ± 1.20 mm⁻¹; p-value 0.024), outer (18.25 ± 4.17 mm⁻¹ vs. 20.33 ± 1.20 mm⁻¹; p-value 0.023), and inner (19.54 ± 4.17 mm⁻¹ vs. 21.96 ± 1.55 mm⁻¹; p-value 0.011). There were no significant differences in vessel perfusion parameters (both SCP VP and DCP VP ones) and FAZ. No significant correlations were found between the OCTA parameters and systemic parameters (maximal left ventricular wall thickness and glomerular filtration rate) in FD patients.

Conclusions: OCTA can be considered as a promising non-invasive tool, which enables a quantitative evaluation of retinal vascular involvement in FD, despite the varying data reported in literature. Our results support the use of OCTA as an objective tool to evaluate retinal vascular abnormalities in FD. The utility of OCTA in FD needs to be validated by longitudinal studies taking into account the overall progression of the disease.

Impact of cardiometabolic factors on retinal vasculature: A 3 × 3, 6 × 6 and 8 × 8-mm ocular coherence tomography angiography study

BACKGROUND

Ocular coherence tomography angiography (OCTA) is available in varying size and resolution. We sought to characterise associations of cardiometabolic factors with retinal microvascular changes using 3 × 3, 6 × 6 and 8 × 8-mm OCTA scans to determine differences in detection with varying scan size.

METHODS

Cross-sectional study of 247 cardiovascular patients from a single-centre tertiary-care hospital. Demographic, comorbidity and medication data were obtained. Patients underwent 3 × 3, 6 × 6 and 8 × 8-mm macula OCTA scanning using Carl Zeiss CIRRUS HD-OCT Model 5000. Angioplex and AngioTool software was used to quantify vascular parameters in the superficial capillary plexus.

RESULTS

Increasing age, hypertension, dyslipidaemia, diabetes, chronic kidney disease, coronary artery disease and peripheral vascular disease were associated with reductions in vessel density, vessel perfusion, average vessel length and/or junction density in 3 × 3-mm OCTA (P < .05 for all). Conversely, smoking was associated with increased vessel density, vessel length and junction density in 3 × 3-mm OCTA (P < .05 for all). Associations of vessel abnormalities with cardiometabolic factors were progressively weakened and statistically attenuated in 6 × 6 and 8 × 8-mm OCTA scans. In multivariate analyses, dyslipidaemia remained an independent predictor of reduced vessel density, average vessel length and junction density (P < .05).

CONCLUSIONS

Cardiometabolic factors are associated with multiple retinal microvascular changes in 3 × 3-mm OCTA scans. These associations were weakened and progressively attenuated in OCTA scans of larger 6 × 6 and 8 × 8-mm size. These findings advance our understanding of microcirculatory dysfunction and may have future implications for the screening and management of patients with cardiometabolic risk factors. Additional studies are required to further investigate these important associations.

[Development, clinical manifestations and diagnosis of retinal changes in chronic kidney disease]

Chronic kidney disease (CKD) is a significant public health problem with a high risk of developing age-dependent eye diseases. Renal glomeruli and the choroid have similar structures and vascular networks; the internal hematoretinal barrier and the glomerular filtration barrier have similar developmental path; the renin-angiotensin-aldosterone hormonal system is found in both the eye and the kidneys. All this determines the similarity of physiological and pathogenetic features of the development of diseases associated with these organs. The article discusses general risk factors and pathophysiological mechanisms of development of retinal and renal lesions in CKD, the influence of various factors of pathogenesis on their development and progression. The anatomical similarity of vascularization, accompanied by microvascular changes in the retina and kidneys, leads to similar complications in both organs. Optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A) are accurate, well reproducible and non-invasive methods for diagnosing and assessing changes in the retinal microvascular bed, which make it possible to assess microvasculature changes in the kidneys. In CKD, the retina shows signs of impaired capillary perfusion, a decrease in their density, expansion of intercapillary spaces, a rarefaction of the density of the parafoveolar capillary network, which may indicate a decrease in peritubular capillary blood flow, blood circulation of the kidneys in general and their ischemia. Significant thinning of the retina and choroid, along with a decrease in macular volume, even in the initial stages of CKD, is accompanied by impaired renal function (changes in the estimated glomerular filtration rate and urinary albumin excretion), which is a sign of systemic microvascular lesion and pathological process in the kidneys. Therefore, monitoring of retinal vessels using OCT and OCT-A can become a reliable indicator of the progression of renal microvascular changes at any stage of the disease.

Retinal Neurovascular Impairment in Non-diabetic and Non-dialytic Chronic Kidney Disease Patients

Background: Widespread neural and microvascular injuries are common in chronic kidney disease (CKD), increasing risks of neurovascular complications and mortality. Early detection of such changes helps assess the risks of neurovascular complications for CKD patients. As an extension of central nervous system, the retina provides a characteristic window to observe neurovascular alterations in CKD. This study aimed to determine the presence of retinal neurovascular impairment in different stages of CKD. Methods: One hundred fifteen non-diabetic and non-dialytic CKD patients of all stages and a control group of 35 healthy subjects were included. Retinal neural and microvascular parameters were obtained by optical coherence tomography angiography (OCTA) examination. Results: CKD 1-2 group (versus control group) had greater odds of having decreased retinal ganglion cell-inner plexiform layer thickness (GC-IPLt) (odds ratio [OR]: 0.92; 95% confidence interval [CI]: 0.86-0.98), increased ganglion cell complex-focal loss volume (GCC-FLV) (OR: 3.51; 95% CI: 1.27-9.67), and GCC-global loss volume (GCC-GLV) (OR: 2.48; 95% CI: 1.27-4.82). The presence of advanced stages of CKD (CKD 3-5 group versus CKD 1-2 group) had greater odds of having decreased retinal vessel density in superficial vascular plexus (SVP)-WholeImage (OR: 0.77, 95% CI: 0.63-0.92), SVP-ParaFovea (OR: 0.83, 95% CI: 0.71-0.97), SVP-ParaFovea (OR: 0.76, 95% CI: 0.63-0.91), deep vascular plexus (DVP)-WholeImage (OR: 0.89, 95% CI: 0.81-0.98), DVP-ParaFovea (OR: 0.88, 95% CI: 0.78-0.99), and DVP-PeriFovea (OR: 0.90, 95% CI: 0.83-0.98). Besides, stepwise multivariate linear regression among CKD patients showed that β2-microglobulin was negatively associated with GC-IPLt (β: -0.294; 95% CI: -0.469 ∼ -0.118), and parathyroid hormone was positively associated with increased GCC-FLV (β: 0.004; 95% CI: 0.002∼0.006) and GCC-GLV (β: 0.007; 95% CI: 0.004∼0.01). Urine protein to creatinine ratio was positively associated with increased GCC-FLV (β: 0.003; 95% CI: 0.001∼0.004) and GCC-GLV (β: 0.003; 95% CI: 0.001∼0.006). Conclusion: Retinal neuronal impairment is present in early stages of CKD (stages 1-2), and it is associated with accumulation of uremic toxins and higher UACR, while retinal microvascular hypoperfusion, which is associated with worse eGFR, was only observed in relatively advanced stages of CKD (stages 3-5). The results highlight the importance of monitoring retinal neurovascular impairment in different stages of CKD.

Evaluation of the reasons for the microvascular changes in patients with Fabry disease using optic coherence tomography angiography

PURPOSE

To investigate the blood flow changes in the choriocapillaris and the superficial and deep capillary plexus of the retina using optic coherence tomography angiography (OCTA) in patients with Fabry disease (FD) and reveal any possible association of these changes with the systemic findings.

METHODS

This cross-sectional study included 38 patients with FD and age- and gender-matched 40 healthy controls. OCTA images were obtained from all patients. Superficial (sCVD) and deep capillary vascular density (dCVD) in the foveal, parafoveal, and perifoveal zones and the whole image were recorded for each patient. Flow area in the choriocapillaris and central macular thickness (CMT) were also recorded.

RESULTS

Patients with FD showed a lower whole image (54.45 ± 5.99% vs 57.32 ± 6.71%, p = 0.004), foveal (34.94 ± 7.60% vs 39.65 ± 7.03%, p = 0.003), parafoveal (57.41 ± 4.85% vs 59.19 ± 4.67%, p = 0.043), and perifoveal (55.87 ± 6.43% vs 58.87 ± 7.02%, p = 0.003) dCVD compared to the healthy controls without a significant difference in the sCVD and choriocapillaris blood flow (p > 0.05). A significantly lower whole image and foveal dCVD in the FD patients with renal involvement was observed compared to the healthy controls (p = 0.027 and p = 0.024, respectively) without any significant difference between the FD patients without renal involvement and healthy controls (p = 0.17 and p = 0.13, respectively). CMT was significantly higher in FD patients with renal involvement compared to the ones without renal involvement (252.1 ± 18.5 µm vs 235.5 ± 17.6 µm, p = 0.016).

CONCLUSION

Patients with FD showed a lower dCVD without any change in sCVD and choriocapillaris compared to the healthy controls. This decrease was associated mostly with the renal involvement and duration of treatment.

Microvascular disease in chronic kidney disease: the base of the iceberg in cardiovascular comorbidity

Chronic kidney disease (CKD) is a relentlessly progressive disease with a very high mortality mainly due to cardiovascular complications. Endothelial dysfunction is well documented in CKD and permanent loss of endothelial homeostasis leads to progressive organ damage. Most of the vast endothelial surface area is part of the microcirculation, but most research in CKD-related cardiovascular disease (CVD) has been devoted to macrovascular complications. We have reviewed all publications evaluating structure and function of the microcirculation in humans with CKD and animals with experimental CKD. Microvascular rarefaction, defined as a loss of perfused microvessels resulting in a significant decrease in microvascular density, is a quintessential finding in these studies. The median microvascular density was reduced by 29% in skeletal muscle and 24% in the heart in animal models of CKD and by 32% in human biopsy, autopsy and imaging studies. CKD induces rarefaction due to the loss of coherent vessel systems distal to the level of smaller arterioles, generating a typical heterogeneous pattern with avascular patches, resulting in a dysfunctional endothelium with diminished perfusion, shunting and tissue hypoxia. Endothelial cell apoptosis, hypertension, multiple metabolic, endocrine and immune disturbances of the uremic milieu and specifically, a dysregulated angiogenesis, all contribute to the multifactorial pathogenesis. By setting the stage for the development of tissue fibrosis and end organ failure, microvascular rarefaction is a principal pathogenic factor in the development of severe organ dysfunction in CKD patients, especially CVD, cerebrovascular dysfunction, muscular atrophy, cachexia, and progression of kidney disease. Treatment strategies for microvascular disease are urgently needed.

Impact of blood pressure control on retinal microvasculature in patients with chronic kidney disease

Chronic kidney disease (CKD) is an emerging disease worldwide. We investigated the relationship between blood pressure (BP) control and parafoveal retinal microvascular changes in patients with CKD. This case–control study enrolled 256 patients with CKD (stage 3–5) and 70 age‐matched healthy controls. Optical coherence tomography angiography showed lower superficial vascular plexus (SVP) vessel density, lower deep vascular plexus (DVP) vessel density, and larger SVP flow void area in the CKD group. The BP parameters at enrollment and during the year before enrollment were collected in patients with CKD. Partial correlation was used to determine the relationship between BP parameters and microvascular parameters after controlling for age, sex, diabetes mellitus, axial length, and intraocular pressure. The maximum systolic blood pressure (SBP) (p = 0.003) and within-patient standard deviation (SD) of SBP (p = 0.006) in 1 year were negatively correlated with SVP vessel density. The average SBP (p = 0.040), maximum SBP (p = 0.001), within-patient SD of SBP (p < 0.001) and proportion of high BP measurement (p = 0.011) in 1 year were positively correlated with the SVP flow void area. We concluded that long-term SBP was correlated with SVP microvascular injury in patients with CKD. Superficial retinal microvascular changes may be a potential biomarker for prior long-term BP control in these patients.

Assessment of Retinal Microangiopathy in Chronic Kidney Disease Patients

INTRODUCTION

Optical coherence tomography angiography (OCT-A) is a useful diagnostic tool for assessing eyes' health in patients with chronic diseases, such as diabetes, hypertension, Parkinson's disease and chronic kidney disease (CKD).

AIM

To detect changes in macular structure and retinal vascular meshwork in the macular area and peripapillary in patients with chronic kidney disease (CKD).

METHODS

This cross-sectional study included 80 eyes of patients with CKD in stages 2, 3 or 4, who were followed-up in the Nephrology Clinic of University Clinical Center Sarajevo. All patients were categorized according to the stage of CKD. All patients were scanned by a high-speed 840-nm-wavelength spectral-domain optical coherence tomography instrument (RTVue XR Avanti; Optovue, Inc, Fremont, California, USA). Blood flow was detected using a split-spectrum amplitude-decorrelation angiography algorithm. A fully automated microstructural analysis of the foveal avascular zone (FAZ), FAZ perimeter, foveal vessel density in a 300-μm area around the FAZ (FD), nonflow area, flow index in superficial and deep vascular plexus, choriocapillary flow, vascular density, radial peripapillary capillary density was performed.

RESULTS

When comparing patients with CKD stage 2 and stage 3 there were no statistically significant changes in microvascular parameters on OCT angiography, as well as when comparing patients with CKD stage 3 and stage 4. But in the comparison between patients with less developed CKD (stage 2) and terminal CKD (stage 4) there was a significant difference between some microvascular parameters such as FAZ area, FAZ perimeter, choriocapillary flow.

CONCLUSION

Many studies demonstrated that evaluation of the microvascular changes in different retinal layers using SS-OCTA may be considered as a key to assessing the systemic perfusion status. Evaluation of retinal microvasculature may ease the management and approach of patients with CKD, having in mind that the retinal and the kidney vascular network are, concerning structure, development and the function, very similar.

Quantitative optical coherence tomography angiography: A review

As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed.

Proinflammatory Mediators, IL (Interleukin)-1β, TNF (Tumor Necrosis Factor) α, and Thrombin Directly Induce Capillary Tube Regression

OBJECTIVE

In this work, we examine the molecular basis for capillary tube regression and identify key proregressive factors, signaling pathways, and pharmacological antagonists of this process. Approach and Results: We demonstrate that the proinflammatory mediators, IL (interleukin)-1β, TNF (tumor necrosis factor) α, and thrombin, singly and in combination, are potent regulators of capillary tube regression in vitro. These proregressive factors, when added to endothelial cell-pericyte cocultures, led to selective loss of endothelial cell-lined tube networks, with retention and proliferation of pericytes despite the marked destruction of adjacent capillary tubes. Moreover, treatment of macrophages with the TLR (toll-like receptor) agonists Pam3CSK4 and lipopolysaccharide generates conditioned media with marked proregressive activity, that is completely blocked by a combination of neutralizing antibodies directed to IL-1β and TNFα but not to other factors. The same combination of blocking antibodies, as well as the anti-inflammatory cytokine IL-10, interfere with macrophage-dependent hyaloid vasculature regression in mice suggesting that proinflammatory cytokine signaling regulates capillary regression in vivo. In addition, we identified a capillary regression signaling signature in endothelial cells downstream of these proregressive agents that is characterized by increased levels of ICAM-1 (intercellular adhesion molecule-1), phospho-p38, and phospho-MLC2 (myosin light chain-2) and decreased levels of phospho-Pak2, acetylated tubulin, phospho-cofilin, and pro-caspase3. Finally, we identified combinations of pharmacological agents (ie, FIST and FISTSB) that markedly rescue the proregressive activities of IL-1β, TNFα, and thrombin, individually and in combination.

CONCLUSIONS

Overall, these new studies demonstrate that the major proinflammatory mediators, IL-1β, TNFα, and thrombin, are key regulators of capillary tube regression-a critical pathological process regulating human disease.

Early retinal microvascular abnormalities in patients with chronic kidney disease

Objective

To evaluate early retinal microvascular abnormalities in patients with chronic kidney disease (CKD) via optical coherence tomography angiography.

Methods

A cross‐sectional study. Two hundred patients with CKD stage ≧3 were enrolled in the CKD group, and 50 age‐matched healthy subjects were enrolled in the control group. Main outcome measures were the differences in parafoveal vessel densities in the superficial vascular plexus (SVP) and deep vascular plexus (DVP) between the CKD and control groups.

Results

The mean ages were 62.7 ± 10.1 in the CKD group and 61.9 ± 9.7 (P = 0.622) in the control group. The CKD group had reduced parafoveal vessel densities in SVP (46.7 ± 4.3 vs 49.7 ± 2.9, P < 0.001) and DVP (50.1 ± 4.1 vs 52. 6 ± 2.9, P < 0.001) when compared to those of the control group. In multiple linear regression models, age, diabetes, estimated glomerular filtration rate, and use of anti‐hypertensive drugs were factors associated with vessel density in SVP, whereas age, diabetes, and smoking were factors associated with vessel density in DVP.

Conclusion

Patients with CKD had reduced vessel densities in parafoveal SVP and DVP, as compared to that of control subjects. Microvasculature in the different retinal layers may be affected by different systemic factors.