Associations between retinal arteriolar and venular calibre with the prevalence of impaired fasting glucose and diabetes mellitus: A cross-sectional study

A deep learning system for retinal vessel calibre improves cardiovascular risk prediction in Asians with chronic kidney disease

Backgraund

Cardiovascular disease (CVD) and mortality is elevated in chronic kidney disease (CKD). Retinal vessel calibre in retinal photographs is associated with cardiovascular risk and automated measurements may aid CVD risk prediction.

Methods

Retrospective cohort study of 860 Chinese, Malay and Indian participants aged 40-80 years with CKD [estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2] who attended the baseline visit (2004-2011) of the Singapore Epidemiology of Eye Diseases Study. Retinal vessel calibre measurements were obtained by a deep learning system (DLS). Incident CVD [non-fatal acute myocardial infarction (MI) and stroke, and death due to MI, stroke and other CVD] in those who were free of CVD at baseline was ascertained until 31 December 2019. Risk factors (established, kidney, and retinal features) were examined using Cox proportional hazards regression models. Model performance was assessed for discrimination, fit, and net reclassification improvement (NRI).

Results

Incident CVD occurred in 289 (33.6%) over mean follow-up of 9.3 (4.3) years. After adjusting for established cardiovascular risk factors, eGFR [adjusted HR 0.98 (95% CI: 0.97-0.99)] and retinal arteriolar narrowing [adjusted HR 1.40 (95% CI: 1.17-1.68)], but not venular dilation, were independent predictors for CVD in CKD. The addition of eGFR and retinal features to established cardiovascular risk factors improved model discrimination with significantly better fit and better risk prediction according to the low (<15%), intermediate (15-29.9%), and high (30% or more) risk categories (NRI 5.8%), and with higher risk thresholds (NRI 12.7%).

Conclusions

Retinal vessel calibre measurements by DLS were significantly associated with incident CVD independent of established CVD risk factors. Addition of kidney function and retinal vessel calibre parameters may improve CVD risk prediction among Asians with CKD.

Peripheral retinal vessel whitening in patients with diabetes mellitus

This study aimed to identify retinal vessel whitening outside the standard Early Treatment Diabetic Retinopathy Study (ETDRS) fields and to correlate the findings with vision and severity of diabetic retinopathy. Patients with diabetes mellitus who were seen in the retinal clinic to assess diabetic retinopathy status were included. Retinal vessel whitening was identified using ultra-widefield imaging. Four hundred and forty-five eyes of 260 patients were included. Thirty-five eyes in 24 patients (7.9%) were noted to have peripheral retinal vessel whitening. Thirty-one eyes with peripheral retinal vessel whitening did not have vessel whitening within the standard 7 ETDRS fields (p < 0.001). The proportion of whitening increased as DR severity increased, from 4.0% for patients with no DR (OR 0.249) to 33.3% for those with severe NPDR and PDR (OR 6.430 and 7.232, respectively). In addition, patients with peripheral retinal vessel whitening had worse visual acuity (logMAR = 0.34) compared to those without (logMAR = 0.15) (p < 0.001). In conclusion, we found an association between peripheral retinal vessel whitening in diabetic patients which correlated with diabetic retinopathy severity. Additionally, we found an association between vessel whitening and reduced vision, suggesting that vessel whitening identified using ultra-widefield imaging may be a prognostic indicator of vision in diabetic retinopathy.

Association Between the Metabolic Syndrome and Retinal Microvascular Diameters Among Police Officers

OBJECTIVES

We examined the associations of the metabolic syndrome severity score (MSSS) and the metabolic syndrome (MetSyn) components with central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE).

METHODS

Participants in this cross-sectional study were 253 officers from the Buffalo Cardio-Metabolic Occupational Police Stress study (2011-2014). The MSSS is a z -score that represents the severity of MetSyn and was estimated using a sex/race-specific equation and the five MetSyn components. Associations of MSSS and the MetSyn with CRAE/CRVE were obtained using linear regression models or analysis of covariance.

RESULTS

For every 1-standard deviation of MSSS, CRAE decreased by 2.3 μm (SE = 1.2, P = 0.0262) and CRVE increased by 3.4 μm (SE = 1.6, P = 0.0308) after adjusting for confounders.

CONCLUSIONS

Officers with higher MSSS had narrower (ie, worse) arteriolar diameters and wider (ie, worse) venular diameters.

Higher prevalence of diabetic retinopathy among female Chinese diabetic patients with metabolic syndrome

PURPOSE

To investigate the association between metabolic syndrome (MetS) and diabetic retinopathy (DR), as well as the association between MetS and retinal vessel caliber, among Chinese patients with type 2 diabetes mellitus in north-eastern China.

STUDY DESIGN

Cross-sectional study.

PATIENTS AND METHODS

The patients were recruited from a community-based study, the Fushun Diabetic Retinopathy Cohort Study (FS-DIRECT). The presence of DR was determined using a modified version of the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. The central retinal arteriolar equivalent (CRAE) and the central retinal venular equivalent (CRVE) were identified by use of Integrative Vessel Analysis software. The presence of MetS was defined according to the Joint Interim Statement proposed in 2009.

RESULTS

The prevalence of DR was significantly higher among female patients with MetS than among those without it (47.2% vs 30.9%, P = 0.002), and it increased as the number of MetS components increased (P = 0.003). Furthermore, the presence of MetS (odds ratio 2.43, 95% CI 1.39-4.26) as well as higher numbers of MetS components were significantly associated with DR in female patients, after adjustment for potential risk factors. Patients with MetS (multivariate β coefficient, 95% CI - 6.9, - 10.0, to - 3.8) or a higher number of Mets components tended to have significantly smaller CRAE.

CONCLUSION

In this study cohort, female patients with MetS had a higher prevalence of DR. Patients tended to have thinner central retinal arterioles as the number of MetS components increased.

Retinal microvascular parameters are not associated with diabetes in the Northern Ireland Cohort for the Longitudinal Study of Ageing

BACKGROUND

The retinal microvasculature offers unique non-invasive evaluation of systemic microvascular abnormalities. Previous studies reported associations between retinal microvascular parameters (RMPs) and diabetes. The aim of this study was to assess associations between RMPs and diabetes in a cross-sectional analysis of older persons from the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA).

METHODS

RMPs (central retinal arteriolar/venular equivalents, arteriolar to venular ratio, fractal dimension, and tortuosity) were measured from optic disc-centred fundus images using semi-automated software. Associations were assessed between RMPs and diabetes status with adjustment for potential confounders.

RESULTS

Data were included for 1762 participants with 209 classified as having diabetes. Participants had a mean age of 62.1 ± 8.5 years, and 54% were female. As expected, participants with diabetes had significantly higher mean glycated haemoglobin A1c compared to participants without diabetes (57.4 ± 17.6 mmol/mol versus 37.0 ± 4.2 mmol/mol, respectively). In unadjusted and minimally adjusted regression, arteriolar to venular ratio, arteriolar tortuosity and venular tortuosity were significantly associated with diabetes (minimally adjusted odds ratio [OR] = 0.85; 95% confidence intervals [CIs] 0.73, 0.99; P = 0.04, OR = 1.18; 95% CI 1.02, 1.37; P = 0.03 and OR = 1.20; 95% CI 1.04, 1.38; P = 0.01, respectively), although all failed to remain significant following adjustment for potential confounders. No additional associations between other RMPs and diabetes were detected.

CONCLUSION

Despite previously reported associations between diabetes and RMPs, our study failed to corroborate these associations in an older community-based cohort.

Effect of ECG-gating Retinal Photographs on Retinal Vessel Caliber Measurements in Subjects with and without Type 2 Diabetes

Purpose/Aim of this study: Retinal vessel caliber is an independent risk marker of cardiovascular disease risk. However, variable mechanical delays in capturing retinal photographs and cardiac cycle-induced retinal vascular changes have been shown to reduce the accuracy of retinal vessel caliber measurements, but this has only ever been investigated in healthy subjects. This cross-sectional study is the first study to investigate this issue in type 2 diabetes. The aim of this study was to determine whether ECG-gating retinal photographs reduce the variability in retinal arteriolar and venular caliber measurements in controls and type 2 diabetes.Materials and Methods: Fifteen controls and 15 patients with type 2 diabetes were arbitrarily recruited from Westmead Hospital, Sydney, Australia. A mydriatic fundoscope connected to our novel ECG synchronization unit captured 10 ECG-gated (at the QRS) and 10 ungated digital retinal photographs of the left eye in a randomized fashion, blinded to study participants. Two independent reviewers used an in-house semi-automated software to grade single cross-sectional vessel diameters across photographs, between 900 and 1800 microns from the optic disc edge. The coefficient of variation compared caliber variability between retinal arterioles and venules.Results: Our ECG synchronization unit reported the smallest time delay (33.1 ± 48.4 ms) in image capture known in the literature. All 30 participants demonstrated a higher reduction in retinal arteriolar (ungated: 1.02, 95%CI 0.88-1.17% vs ECG-gated: 0.39, 95%CI 0.29-0.49%, p < .0001) than venular (ungated 0.62, 95%CI 0.53-0.73% vs ECG-gated: 0.26, 95%CI 0.19-0.35%, p < .0001) coefficient of variation by ECG-gating photographs. Intra-observer repeatability and inter-observer reproducibility analysis reported high interclass correlation coefficients ranging from 0.80 to 0.86 and 0.80 to 0.93 respectively.Conclusion: ECG-gating photographs at the QRS are recommended for retinal vessel caliber analysis in controls and patients with type 2 diabetes as they refine measurements.

Retinal Neurovascular Coupling in Diabetes

Neurovascular coupling, also termed functional hyperemia, is one of the physiological key mechanisms to adjust blood flow in a neural tissue in response to functional activity. In the retina, increased neural activity, such as that induced by visual stimulation, leads to the dilatation of retinal arterioles, which is accompanied by an immediate increase in retinal and optic nerve head blood flow. According to the current scientific view, functional hyperemia ensures the adequate supply of nutrients and metabolites in response to the increased metabolic demand of the neural tissue. Although the molecular mechanisms behind neurovascular coupling are not yet fully elucidated, there is compelling evidence that this regulation is impaired in a wide variety of neurodegenerative and vascular diseases. In particular, it has been shown that the breakdown of the functional hyperemic response is an early event in patients with diabetes. There is compelling evidence that alterations in neurovascular coupling precede visible signs of diabetic retinopathy. Based on these observations, it has been hypothesized that a breakdown of functional hyperemia may contribute to the retinal complications of diabetes such as diabetic retinopathy or macular edema. The present review summarizes the current evidence of impaired neurovascular coupling in patients with diabetes. In this context, the molecular mechanisms of functional hyperemia in health and disease will be covered. Finally, we will also discuss how neurovascular coupling may in future be used to monitor disease progression or risk stratification.

Association between retinal arterial narrowing and left ventricular diastolic dysfunction in masked hypertensives

Morphological change in retinal vessel diameters has been reported to be associated with negative cardiovascular outcomes, but its association with left ventricular diastolic dysfunction (LVDD) is not clear. This study aimed to examine the association between echocardiographic markers of LVDD and retinal vascular diameters, in untreated masked hypertension (MH). In this observational study, 105 MH patients without other cardiovascular risks were included (mean age 48.4 ± 5.7, female 72.4%). All individuals underwent extensive clinical and laboratory investigations, including echocardiography, ambulatory blood pressure monitoring, and retinal vascular diameters measured by optical coherence tomography. In the group, LVDD was diagnosed in 36 participants evaluated by left ventricular volume index, E/A and E/e' ratio. Compared to non-LVDD, LVDD subjects displayed narrower retinal arteriolar diameter (139.1 ± 33.8 vs 165.1 ± 29.1; adjusted P = .007) and wider retinal venular diameter (237.9 ± 42.2 vs 214.9 ± 44.8; adjusted P = .045). Significant and independent associations were demonstrated for retinal arteriolar narrowing and E/A ratio (adjusted β = 0.744, P = .031) and for retinal arteriolar diameter and E/e' ratio (adjusted β = -0.158, P = .001) after controlling for age, gender, body mass index, ambulatory systolic blood pressure, low-density lipoprotein cholesterol, and retinal venular diameter. In untreated MH subjects, retinal arteriolar diameter, a marker of microvascular damage, was independently associated with echocardiographic markers of diastolic dysfunction. These findings might underscore the hypothesis that microvascular disease could contribute to cardiac remodeling.