LPS-induced microvascular leukocytosis can be assessed by blue-field entoptic phenomenon

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

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

Retinal vasculature and 5-year metabolic syndrome among women with gestational diabetes mellitus

BACKGROUND

Women with gestational diabetes mellitus (GDM) are at greater risk of metabolic syndrome (MetS). We studied the association between second-trimester retinal microvasculature and 5-year MetS incidence in women with GDM.

METHODS

A total of 142 mothers with GDM were recruited and followed up 5years after delivery. Retinal photography was performed at 26-28weeks gestation and metabolic outcomes were assessed at the 5-year postpartum follow-up visit. GDM and MetS were defined based on World Health Organization (WHO) guidelines and Adults Treatment Panel (ATP) III guidelines, respectively. Modified-Poisson regression was applied to study the association between second-trimester retinal microvasculature and incident 5-year maternal MetS, after adjusting for major confounders. Area under the curve (AUC) was calculated based on the final model.

RESULTS

Our prospective cohort reported a 9.2% incidence rate of 5-year MetS among women with GDM. After adjusting for maternal age, ethnicity, college degree, pre-pregnancy BMI and fasting glucose at 26-28week gestation, each 10μm widening in retinal venular caliber was associated with an increased relative risk of 1.6 (95% confidence interval [CI]: 1.0, 2.8) in incident MetS. In addition to traditional risks of pre-pregnancy BMI and fasting glucose level at 26-28week gestation, retinal venular caliber mildly increased the prediction of 5-year maternal MetS by 1.8%.

CONCLUSIONS

Second-trimester retinal venular widening was associated with incident 5-year maternal MetS in women with GDM. Our study suggests that mother with GDM at risk of future MetS development may have already presented retinal microvascular abnormalities during pregnancy.

Review of the association between retinal microvascular characteristics and eye disease

Computerized retinal imaging technologies enable the static and dynamic measurement of a range of retinal microvascular parameters. Large population-based studies have reported associations between these microvascular indices and various ophthalmic diseases including diabetes, age-related macular degeneration, retinal artery embolism, retinal vein occlusion, glaucoma and non-glaucomatous optic neuropathies. Increasingly, sophisticated imaging and analysis techniques have the potential to provide relevant clinical information regarding disease risk and progression; however, further studies are required to verify associations and strengthen the predictive power of these techniques. We summarize the current state of knowledge regarding retinal microvascular characteristics and eye disease.

Traffic-related air pollution and spectacles use in schoolchildren

Purpose

To investigate the association between exposure to traffic-related air pollution and use of spectacles (as a surrogate measure for myopia) in schoolchildren.

Methods

We analyzed the impact of exposure to NO₂ and PM_2.5 light absorbance at home (predicted by land-use regression models) and exposure to NO₂ and black carbon (BC) at school (measured by monitoring campaigns) on the use of spectacles in a cohort of 2727 schoolchildren (7–10 years old) in Barcelona (2012–2015). We conducted cross-sectional analyses based on lifelong exposure to air pollution and prevalent cases of spectacles at baseline data collection campaign as well as longitudinal analyses based on incident cases of spectacles use and exposure to air pollution during the three-year period between the baseline and last data collection campaigns. Logistic regression models were developed to quantify the association between spectacles use and each of air pollutants adjusted for relevant covariates.

Results

An interquartile range increase in exposure to NO₂ and PM_2.5 absorbance at home was respectively associated with odds ratios (95% confidence intervals (CIs)) for spectacles use of 1.16 (1.03, 1.29) and 1.13 (0.99, 1.28) in cross-sectional analyses and 1.15 (1.00, 1.33) and 1.23 (1.03, 1.46) in longitudinal analyses. Similarly, odds ratio (95% CIs) of spectacles use associated with an interquartile range increase in exposures to NO₂ and black carbon at school was respectively 1.32 (1.09, 1.59) and 1.13 (0.97, 1.32) in cross-sectional analyses and 1.12 (0.84, 1.50) and 1.27 (1.03, 1.56) in longitudinal analyses. These findings were robust to a range of sensitivity analyses that we conducted.

Conclusion

We observed increased risk of spectacles use associated with exposure to traffic-related air pollution. These findings require further confirmation by future studies applying more refined outcome measures such as quantified visual acuity and separating different types of refractive errors.

Relationship of retinal vascular calibre and diabetic retinopathy in Chinese patients with type 2 diabetes mellitus: the Desheng Diabetic Eye Study

AIMS

To describe the relationship of retinal arteriolar and venular calibre with diabetic retinopathy (DR) and related risk factors, including glucose levels and other biomarkers in a Chinese population with type 2 diabetes mellitus (T2DM).

METHODS

A cross-sectional study. Patients with T2DM were recruited from a local community in urban Beijing. Seven fields 30° colour fundus photographs were taken and examined for the presence and severity of DR using a standardised grading system. Retinal vascular calibres were measured and expressed as average central retinal arteriolar and venular equivalent using a computer-based program.

RESULTS

A total of 1340 patients with T2DM were included for analysis. Of these, 472 (35.22%) had DR. Wider retinal venular calibre, but not arteriolar calibre, was associated with increasing glucose and glycosylated haemoglobin A1c levels (p<0.006) and dyslipidaemia (p for trend <0.05). After adjusting for possible covariates, the higher quartile of retinal venular calibre was associated with higher prevalence of any DR (OR 2, 95% CI 1.36 to 2.95). Venular calibre increased from 224.33 μm in those without retinopathy to 231.21 μm in those with mild, 241.01 μm in those with moderate and 235.65 μm in those with severe retinopathy (p for trend <0.001). Arteriolar calibre was not associated with DR.

CONCLUSIONS

In the current study, wider venular calibre, but not arteriolar calibre, was shown to be associated with development and increased severity of DR independently from other risk factors in a Chinese diabetic population.

Retinal vascular imaging in early life: insights into processes and risk of cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality globally. In recent years, studies have shown that the origins of CVD may be traced to vascular and metabolic processes in early life. Retinal vascular imaging is a new technology that allows detailed non-invasive in vivo assessment and monitoring of the microvasculature. In this systematic review, we described the application of retinal vascular imaging in children and adolescents, and we examined the use of retinal vascular imaging in understanding CVD risk in early life. We reviewed all publications with quantitative retinal vascular assessment in two databases: PubMed and Scopus. Early life CVD risk factors were classified into four groups: birth risk factors, environmental risk factors, systemic risk factors and conditions linked to future CVD development. Retinal vascular changes were associated with lower birth weight, shorter gestational age, low-fibre and high-sugar diet, lesser physical activity, parental hypertension history, childhood hypertension, childhood overweight/obesity, childhood depression/anxiety and childhood type 1 diabetes mellitus. In summary, there is increasing evidence supporting the view that structural changes in the retinal microvasculature are associated with CVD risk factors in early life. Thus, the retina is a useful site for pre-clinical assessment of microvascular processes that may underlie the future development of CVD in adulthood.

Can the retinal microvasculature offer clues to cardiovascular risk factors in early life?

Adulthood cardiovascular diseases (CVD) burdening in adulthood have been suggested to have possible predisposition early in life. We aimed to systematically review the literatures on retinal microvasculature among paediatric population in relation to a range of environmental and systemic changes. Papers with quantitative retinal vascular assessment and epidemiological design were reviewed.

CONCLUSION

This review supports the theory that major vascular diseases have pathological predisposition early in life by providing morphological evidence on retinal microcirculation in vivo.

Retinal vascular changes and diabetic retinopathy

Recent studies support the concept that the retinal vasculature may provide a summary measure of lifetime exposure to the effects of hyperglycemia. Advances in retinal photographic techniques and in image analysis have allowed objective and precise in vivo measurement of retinal vascular changes. In particular, quantitative assessment of retinopathy signs and measurement of retinal vascular caliber have greatly increased our knowledge of early microcirculatory alterations in prediabetes, diabetes, and diabetic micro- and macrovascular complications. Data from recent population-based studies suggest that retinal arteriolar and venular caliber changes reflect different pathophysiologic processes. Retinal arteriolar narrowing, for example, is associated with risk of diabetes and coronary artery disease, whereas retinal venular widening is associated with development and progression of diabetic retinopathy and risk of stroke. Studying these changes offers the potential to improve our understanding of the early pathophysiologic pathways of diabetes development and its complications. Future research will assess the ability of retinal vascular imaging to provide clinically useful prognostic information for patients with diabetes.

Relationship of retinal vascular caliber with diabetes and retinopathy: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To examine the relationship of retinal vascular caliber with diabetes, glycemia, and diabetic retinopathy.

RESEARCH DESIGN AND METHODS

Population-based study using data from the Multi-Ethnic Study of Atherosclerosis (MESA), comprising 5,976 individuals (whites, blacks, Hispanics, and Chinese) residing in six U.S. communities who were free of clinical cardiovascular disease at baseline. Retinal vascular caliber was measured from digital retinal photographs.

RESULTS

There were 4,585 individuals with normal fasting glucose (NFG), 499 with impaired fasting glucose (IFG), 165 with diabetes with retinopathy signs, and 727 with diabetes without retinopathy signs. After multivariate analysis, retinal arteriolar caliber increased from 143.8 microm in subjects with NFG to 144.5 microm in IFG and 146.1 microm in diabetes (P < 0.001 for trend). Retinal venular caliber increased from 214.4 microm in NFG to 216.7 microm in IFG and 218.0 microm in diabetes (P < 0.001 for trend). Retinal venular caliber was significantly larger with increasing levels of fasting glucose and A1C. In a subgroup analysis by ethnicity, the association between wider arteriolar caliber and diabetes was evident in whites only, whereas wider venular caliber and diabetes was evident in Hispanics and Chinese only. In people with diabetes, eyes with retinopathy had larger retinal venular but not arteriolar caliber.

CONCLUSIONS

Retinal arteriolar and venular calibers are larger in individuals with diabetes, but the pattern of associations appears to vary by ethnicity. Retinal venular caliber is additionally associated with retinopathy signs. These findings add further to the concept that variations in retinal vascular caliber may reflect early diabetic microvascular damage.

Retinal vascular manifestations of metabolic disorders

Metabolic diseases have profound effects on the structure and function of the retinal circulation. The recent development of retinal photography and digital imaging has enabled more precise documentation of diabetic retinopathy, as well as other retinal microvascular changes, such as retinal arteriolar narrowing, venular dilation and isolated retinopathy signs in nondiabetic individuals. These retinal microvascular signs have been shown to be associated with long-term risks of type 2 diabetes and hypertension, components of the metabolic syndrome (e.g. obesity, dyslipidemia), and a range of macro- and micro-vascular conditions (e.g. stroke, cardiovascular mortality). There is evidence that endothelial dysfunction and inflammation might be possible mechanisms involved in the development of various retinal microvascular changes in patients with diabetes, hypertension and other metabolic disorders. Further understanding of how these processes influence the retinal vasculature might help to elucidate the diverse vascular manifestations of metabolic diseases.