Innovative technology shows impact of glycaemic control on peripheral retinal vessels in adolescents with type 1 diabetes

Three-Year Follow-Up Study Investigating Changes in Retinal Vascular Morphology and the Relationship with Diabetic Retinopathy in Children with Type 1 Diabetes Mellitus

INTRODUCTION

This study aimed to investigate changes in retinal microvascular morphology and associated factors, and their relationship with diabetic retinopathy (DR) in children with type 1 diabetes mellitus (T1DM).

METHODS

Thirty-eight children enrolled in this 3-year follow-up study underwent complete ophthalmic examinations including fundus photography. Retinal vascular parameters were measured automatically and compared between baseline and follow-up. Multiple linear regression was used to investigate factors affecting changes in vascular parameters. Binary logistic regression was used to analyze the relationship between retinal microvascular morphology and DR.

RESULTS

The caliber of all retinal vessels (within 1-1.5 papillary diameter [PD] from the center of the optic disc, p = 0.030; 1.5-2 PD, p = 0.003), arterioles, and venules (1.5-2 PD, p = 0.001) was narrower in nearly all regions in the follow-up group compared with the baseline group. Vascular tortuosity increased in the central part of the retina and decreased in the periphery. The density (1-1.5 PD, p = 0.030) and fractal dimension (p = 0.037) of retinal vessels were increased at the end of the follow-up compared with baseline. Retinal vascular caliber was independently correlated with DR (odds ratio 0.793 [95% confidence interval 0.633-0.993]; p = 0.044).

CONCLUSION

Retinal microvascular morphology in children with T1DM varied with the disease course. Narrower retinal vessels may be an independent risk factor for DR. Results of this study emphasized the importance of regular follow-up of fundus vascular morphology for the detection of early DR in children with T1DM.

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.

Baseline extended zone retinal vascular calibres associate with sensory nerve abnormalities in adolescents with type 1 diabetes: A prospective longitudinal study

OBJECTIVE

The relationship between retinal vascular calibres (RVCs) and diabetic neuropathy is unclear. We investigated associations between RVCs and sensory nerve abnormality in adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In a prospective longitudinal study of 889 adolescents with type 1 diabetes with baseline mean (±SD) age 14.1 ± 1.5 years and HbA_1c IFCC 69.4 ± 14.1 mmol/mol (8.6 ± 1.3%), RVCs were assessed from baseline retinal photographs: 'central zone' calibres, summarized as central retinal arteriolar (CRAE) and venular equivalents (CRVE) and 'extended zone' calibres: mean width of arterioles (MWa) and venules (MWv). Sensory nerve abnormality was defined as at least one abnormal sensory quantitative testing from two thermal and two vibration threshold tests measured at foot every 1-2 years. Associations between baseline RVC and sensory nerve function were examined using generalized estimating equations and cumulative risk by Cox regression analyses.

RESULTS

During a median study follow-up of 6.2 [IQR 3.7-10.4] years, sensory nerve abnormality was found in 27% of adolescents. Narrower extended zone calibre quartiles but not CRAE or CRVE quartiles were independently associated with sensory nerve abnormality: MWa (Q1 vs. Q2-4: OR 1.35 (95% CI 1.02, 1.61) and MWv (Q1 vs. Q2-4: 1.31 (1.03, 1.7)), after adjusting for HbA_1c , duration and blood pressure. Similarly, in Cox regression, the narrowest quartiles were associated with sensory nerve abnormality: MWa hazard ratio (HR) 1.5 (1.3, 1.8) and MWv 1.6 (1.4, 1.9).

CONCLUSIONS

Narrower extended zone retinal calibres were associated with sensory nerve abnormality in adolescents with type 1 diabetes and may present useful biomarkers to understand the pathophysiology of neuropathy.

Imaging the eye and its relevance to diabetes care

Diabetes is a major cause of vision loss globally, yet this devastating complication is largely preventable. Early detection and treatment of diabetic retinopathy necessitates screening. Ocular imaging is widely used clinically, both for the screening and management of diabetic retinopathy. Common eye conditions, such as glaucoma, cataracts and retinal vessel thrombosis, and signs of systemic conditions, such as hypertension, are frequently revealed. As well as imaging by a skilled clinician during an eye examination, non-ophthalmic clinicians, such as general practitioners, endocrinologists, nurses and trained health workers, can also can carry out diabetic eye screening. This process usually comprises local imaging with remote grading, mostly human grading. However, grading incorporating artificial intelligence is emerging. In a clinical research context, retinal vasculature analyses using semi-automated software in many populations have identified associations between retinal vessel geometry, such as vessel caliber, and the risk of diabetic retinopathy and other chronic complications of type 1 and type 2 diabetes. Similarly, evaluation of corneal nerves by corneal confocal microscopy is revealing diabetes-related abnormalities, and associations with and predictive power for other chronic diabetes complications. As yet, the value of retinal vessel geometry and corneal confocal microscopy measures at an individual level is uncertain. In this article, targeting non-ocular clinicians and researchers, we review existent and emerging ocular imaging and grading tools, including artificial intelligence, and their associations between ocular imaging findings and diabetes and its chronic complications.

Comprehensive retinal vascular measurements: a novel association with renal function in type 2 diabetic patients in China

To examine the association between various retinal vascular measurements and microalbuminuria in patients with type 2 diabetes in a northwestern China study. Data from 911 patients with type 2 diabetes were analyzed. Novel retinal vascular measurements from the whole vascular tree were extracted using a validated fully automatic computer program. Retinal vascular measurements were analyzed continuously and categorically for associations with microalbuminuria using multiple logistic regressions, adjusted for related variables. In logistic regression adjusting for multiple variables, microalbuminuria was associated with smaller peripheral arteriolar caliber, larger peripheral venular caliber, larger arteriolar tortuosity, and smaller arteriolar fractal dimension (p = 0.028, p < 0.001, p = 0.038, p = 0.035, respectively). In further categorical analyses, microalbuminuria was related to smaller peripheral arteriolar caliber [T1 vs. T3: odds ratio (OR) 2.029; 95% confidence interval (CI) 1.186–3.473], larger peripheral venular caliber (T1 vs. T3: OR 0.609; 95% CI 0.362–1.024), and smaller arteriolar fractal dimension (T1 vs. T3: OR 1.659; 95% CI 1.028–2.675). Microalbuminuria in type 2 diabetes is associated with both retinal vascular caliber and geometry. These noninvasive vascular measurements serve as potential preclinical markers to identify populations at high risk of early kidney disease in the course of diabetes.

Hemoglobin A1c and retinal arteriolar narrowing in children with type 1 diabetes: the diagnostics of early atherosclerosis risk in kids study

BACKGROUND/OBJECTIVE

Microvascular alterations play a key role in the development of diabetes complications. Retinal vessel analysis is a unique method to examine microvascular changes in brain-derived vessels.

METHODS

Sixty-seven pediatric and adolescent type 1 diabetes patients and 58 healthy control persons (mean age 12.4 ± 2.9 years) underwent non-mydriatic retinal photography of both eyes. Central retinal arteriolar and central retinal venular (CRVE) diameter equivalents as well as the arteriolar-to-venular ratio were calculated using a semiautomated software. All anthropometric and laboratory parameters were measured according to standardized procedures for children.

RESULTS

Retinal vessel diameter did not differ between type 1 diabetic children and healthy controls. However, there was an independent association of higher hemoglobin A1c (HbA1c) levels with arteriolar narrowing. Arteriolar narrowing of 5.4 μm was observed with each percent increase in HbA1c. Longer duration of diabetes was associated with wider retinal arterioles. CRVE was not associated with diabetes duration or HbA1c.

CONCLUSIONS

Microvascular arteriolar alterations are already present in childhood and may indicate subclinical atherosclerosis and increased risk of diabetes complications later in life. Future research will have to investigate the potential use of retinal vessel diameters for treatment monitoring and guidance of therapy in children.

Quantitative retinal microvasculature in children using swept-source optical coherence tomography: the Hong Kong Children Eye Study

AIMS

To evaluate the distributions of quantitative optical coherence tomography angiography (OCT-A) metrics and its associated factors in children.

METHODS

1059 children aged 6-8 years were recruited from the Hong Kong Children Eye Study. All the participants underwent OCT-A with a swept-source OCT. Retinal microvasculature on superficial capillary plexus was assessed and quantified by a customised automated image analysis programme. Univariable and multiple linear regression analyses were performed to determine systemic (body mass index (BMI), waist circumference, head circumference and blood pressure), demographic and ocular (axial length (AL), macular thickness and volume, retinal nerve fibre layer (RNFL) thickness and visual acuity) variables (independent variables) associated with OCT-A metrics (dependent variables).

RESULTS

In multiple linear regression analyses, enlarged foveal avascular zone area was associated with female gender (β=0.110, p<0.001), decreased AL (β=-0.097, p<0.001) and decreased central macular thickness (β=-0.008, p<0.001). Decreased vessel density was associated with increased BMI (β=-4.12×10-4, p=0.006), decreased AL (β=0.003, p<0.001) and decreased central macular thickness (β=7.87×10-5, p=0.001). Increased vessel diameter index was associated with female gender (β=0.020, p=0.007) and decreased AL (β=-0.020, p<0.001). Decreased fractal dimension was associated with older age (β=-0.001, p=0.008). There were no significant correlations between OCT-A metrics with visual acuity, RNFL thickness, central corneal thickness, waist circumference, head circumference and blood pressure (all p>0.05).

CONCLUSION

Our findings provides new information on baseline morphology of retinal microvasculature and its associated factors in school children, which will be useful for interpreting OCT-A metrics and for identifying and characterising pathological changes in retinal microvasculature.

The Adolescent Cardio-Renal Intervention Trial (AdDIT): retinal vascular geometry and renal function in adolescents with type 1 diabetes

AIMS/HYPOTHESIS

We examined the hypothesis that elevation in urinary albumin creatinine ratio (ACR) in adolescents with type 1 diabetes is associated with abnormal retinal vascular geometry (RVG) phenotypes.

METHODS

A cross-sectional study at baseline of the relationship between ACR within the normoalbuminuric range and RVG in 963 adolescents aged 14.4 ± 1.6 years with type 1 diabetes (median duration 6.5 years) screened for participation in AdDIT. A validated algorithm was used to categorise log₁₀ ACR into tertiles: upper tertile ACR was defined as 'high-risk' for future albuminuria and the lower two tertiles were deemed 'low-risk'. RVG analysis, using a semi-automated computer program, determined retinal vascular calibres (standard and extended zones) and tortuosity. RVG measures were analysed continuously and categorically (in quintiles: Q1-Q5) for associations with log₁₀ ACR and ACR risk groups.

RESULTS

Greater log₁₀ ACR was associated with narrower vessel calibres and greater tortuosity. The high-risk group was more likely to have extended zone vessel calibres in the lowest quintile (arteriolar Q1 vs Q2-Q5: OR 1.67 [95% CI 1.17, 2.38] and venular OR 1.39 [0.98, 1.99]) and tortuosity in the highest quintile (Q5 vs Q1-Q4: arteriolar OR 2.05 [1.44, 2.92] and venular OR 2.38 [1.67, 3.40]). The effects of retinal vascular calibres and tortuosity were additive such that the participants with the narrowest and most tortuous vessels were more likely to be in the high-risk group (OR 3.32 [1.84, 5.96]). These effects were independent of duration, blood pressure, BMI and blood glucose control.

CONCLUSIONS/INTERPRETATION

Higher ACR in adolescents is associated with narrower and more tortuous retinal vessels. Therefore, RVG phenotypes may serve to identify populations at high risk of diabetes complications during adolescence and well before onset of clinical diabetes complications.