Smaller Birth Size is Associated With Narrower Retinal Arterioles in Early Adolescence

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

Purpose

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

Methods

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

Results

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

Conclusions

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

A Comprehensive Review on Social Inequalities and Pregnancy Outcome-Identification of Relevant Pathways and Mechanisms

Scientific literature tends to support the idea that the pregnancy and health status of fetuses and newborns can be affected by maternal, parental, and contextual characteristics. In addition, a growing body of evidence reports that social determinants, measured at individual and/or aggregated level(s), play a crucial role in fetal and newborn health. Numerous studies have found social factors (including maternal age and education, marital status, pregnancy intention, and socioeconomic status) to be linked to poor birth outcomes. Several have also suggested that beyond individual and contextual social characteristics, living environment and conditions (or "neighborhood") emerge as important determinants in health inequalities, particularly for pregnant women. Using a comprehensive review, we present a conceptual framework based on the work of both the Commission on Social Determinants of Health and the World Health Organization (WHO), aimed at describing the various pathways through which social characteristics can affect both pregnancy and fetal health, with a focus on the structural social determinants (such as socioeconomic and political context) that influence social position, as well as on intermediary determinants. We also suggest that social position may influence more specific intermediary health determinants; individuals may, on the basis of their social position, experience differences in environmental exposure and vulnerability to health-compromising living conditions. Our model highlights the fact that adverse birth outcomes, which inevitably lead to health inequity, may, in turn, affect the individual social position. In order to address both the inequalities that begin in utero and the disparities observed at birth, it is important for interventions to target various unhealthy behaviors and psychosocial conditions in early pregnancy. Health policy must, then, support: (i) midwifery availability and accessibility and (ii) enhanced multidisciplinary support for deprived pregnant women.

Retinal vessel diameters and function in cardiovascular risk and disease

In the last two decades evidence has gradually accumulated suggesting that the eye may be a unique window for cardiovascular risk stratification based on the assessment of subclinical damage of retinal microvascular structure and function. This can be facilitated by non-invasive analysis of static retinal vessel diameters and dynamic recording of flicker light-induced and endothelial function-related dilation of both retinal arterioles and venules. Recent new findings have made retinal microvascular biomarkers strong candidates for clinical implementation as reliable risk predictors. Beyond a review of the current evidence and state of research, the article aims to discuss the methodological benefits and pitfalls and to identify research gaps and future directions. Above all, the potential use for screening and treatment monitoring of cardiovascular disease risk are highlighted. The article provides fundamental comprehension of retinal vessel imaging by explaining anatomical and physiological essentials of the retinal microcirculation leading to a detailed description of the methodological approach. This allows for better understanding of the underlying retinal microvascular pathology associated with the prevalence and development of cardiovascular disease. A body of new evidence is presented on the clinical validity and predictive value of retinal vessel diameters and function for incidence cardiovascular disease and outcome. Findings in children indicate the potential for utility in childhood cardiovascular disease prevention, and the efficacy of exercise interventions highlight the treatment sensitivity of retinal microvascular biomarkers. Finally, coming from the availability of normative data, solutions for diagnostic challenges are discussed and conceptual steps towards clinical implementation are put into perspective.

Neuronal Dysfunction Is Linked to the Famine-Associated Risk of Proliferative Retinopathy in Patients With Type 2 Diabetes

Persons with type 2 diabetes born in the regions of famine exposures have disproportionally elevated risk of vision-threatening proliferative diabetic retinopathy (PDR) in adulthood. However, the underlying mechanisms are not known. In the present study, we aimed to investigate the plausible molecular factors underlying progression to PDR. To study the association of genetic variants with PDR under the intrauterine famine exposure, we analyzed single nucleotide polymorphisms (SNPs) that were previously reported to be associated with type 2 diabetes, glucose, and pharmacogenetics. Analyses were performed in the population from northern Ukraine with a history of exposure to the Great Ukrainian Holodomor famine [the Diagnostic Optimization and Treatment of Diabetes and its Complications in the Chernihiv Region (DOLCE study), n = 3,583]. A validation of the top genetic findings was performed in the Hong Kong diabetes registry (HKDR, n = 730) with a history of famine as a consequence of the Japanese invasion during WWII. In DOLCE, the genetic risk for PDR was elevated for the variants in ADRA2A, PCSK9, and CYP2C19*2 loci, but reduced at PROX1 locus. The association of ADRA2A loci with the risk of advanced diabetic retinopathy in famine-exposed group was further replicated in HKDR. The exposure of embryonic retinal cells to starvation for glucose, mimicking the perinatal exposure to famine, resulted in sustained increased expression of Adra2a and Pcsk9, but decreased Prox1. The exposure to starvation exhibited a lasting inhibitory effects on neurite outgrowth, as determined by neurite length. In conclusion, a consistent genetic findings on the famine-linked risk of ADRA2A with PDR indicate that the nerves may likely to be responsible for communicating the effects of perinatal exposure to famine on the elevated risk of advanced stages of diabetic retinopathy in adults. These results suggest the possibility of utilizing neuroprotective drugs for the prevention and treatment of PDR.

Perinatal famine is associated with excess risk of proliferative retinopathy in patients with type 2 diabetes

PURPOSE

Intrauterine undernutrition is associated with increased risk of type 2 diabetes. Children born premature or small for gestational age were reported to have abnormal retinal vascularization. However, whether intrauterine famine act as a trigger for diabetes complications, including retinopathy, is unknown. The aim of the current study was to evaluate long-term effects of perinatal famine on the risk of proliferative diabetic retinopathy (PDR).

METHODS

We studied the risk for PDR among type 2 diabetes patients exposed to perinatal famine in two independent cohorts: the Ukrainian National Diabetes Registry (UNDR) and the Hong Kong Diabetes Registry (HKDR). We analysed individuals born during the Great Famine (the Holodomor, 1932-1933) and the WWII (1941-1945) famine in 101 095 (3601 had PDR) UNDR participants. Among 3021 (251 had PDR) HKDR participants, we studied type 2 diabetes patients exposed to perinatal famine during the WWII Japanese invasion in 1942-1945.

RESULTS

During the Holodomor and WWII, perinatal famine was associated with a 1.76-fold (p = 0.019) and 3.02-fold (p = 0.001) increased risk of severe PDR in the UNDR. The risk for PDR was 1.66-fold elevated among individuals born in 1942 in the HKDR (p < 0.05). The associations between perinatal famine and PDR remained statistically significant after corrections for HbA1c in available 18 507 UNDR (p_{additive interaction}  < 0.001) and in 3021 HKDR type 2 diabetes patients (p < 0.05).

CONCLUSION

In conclusion, type 2 diabetes patients, exposed to perinatal famine, have increased risk of PDR compared to those without perinatal famine exposure. Further studies are needed to understand the underlying mechanisms and to extend this finding to other diabetes complications.

Assessment of inner retinal oxygen metrics and thickness in a mouse model of inherited retinal degeneration

The retinal degeneration 1 (rd1) mouse is a well-established model of inherited retinal degeneration, displaying photoreceptor degeneration and retinal vasculature damage. The purpose of the current study was to determine alterations in the rate of oxygen delivery from retinal circulation (DO₂), the rate of oxygen extraction from the retinal circulation for metabolism (MO₂), and oxygen extraction fraction (OEF) in rd1 mice. The study was performed in a total of 18 wild type (WT) and 10 rd1 mice at both 3-weeks and 12-weeks of age. Retinal arterial and venous oxygen contents (O_2A and O_2V) were measured using phosphorescence lifetime imaging. Total retinal blood flow (TRBF) was determined by fluorescence and red-free imaging. DO₂ and MO₂ were determined as TRBF × O_2A and TRBF × (O_2A-O_2V), respectively. OEF was calculated as MO₂/DO₂. The thickness of individual retinal layers was measured from histology sections and inner retina (IR) and total retina (TR) thickness were calculated. TRBF, DO₂ and MO₂ were lower in rd1 mice compared to WT mice (P ≤ 0.001), whereas OEF was not significantly different between rd1 and WT mice (P = 0.4). TRBF and DO₂ were lower at 3-weeks of age compared to 12-weeks of age (P ≤ 0.01), while MO₂ was not significantly different between age groups (P = 0.4) and OEF was higher at 3-weeks of age compared to 12-weeks of age (P = 0.003). Additionally, the outer and inner retinal cell layer thicknesses were decreased in rd1 mice at 12-weeks of age compared to both age-matched WT mice and rd1 mice at 3-weeks of age (P ≤ 0.02). MO₂ was directly correlated with both IR and TR thickness (R ≥ 0.50; P ≤ 0.03, N = 20). The findings indicate that the rate oxygen is supplied by the retinal circulation is decreased and the reduction in oxygen extracted for metabolism is related to retinal cell layer thinning in rd1 mice.

Adverse Birth Outcomes Related to NO2 and PM Exposure: European Systematic Review and Meta-Analysis

There is a growing number of international studies on the association between ambient air pollution and adverse pregnancy outcomes, and this systematic review and meta-analysis has been conducted focusing on European countries, to assess the crucial public health issue of this suspected association on this geographical area. A systematic literature search (based on Preferred Reporting Items for Systematic reviews and Meta-Analyses, PRISMA, guidelines) has been performed on all European epidemiological studies published up until 1 April 2020, on the association between maternal exposure during pregnancy to nitrogen dioxide (NO₂) or particular matter (PM) and the risk of adverse birth outcomes, including: low birth weight (LBW) and preterm birth (PTB). Fourteen articles were included in the systematic review and nine of them were included in the meta-analysis. Our meta-analysis was conducted for 2 combinations of NO₂ exposure related to birth weight and PTB. Our systematic review revealed that risk of LBW increases with the increase of air pollution exposure (including PM₁₀, PM_2.5 and NO₂) during the whole pregnancy. Our meta-analysis found that birth weight decreases with NO₂ increase (pooled beta = −13.63, 95% confidence interval (CI) (−28.03, 0.77)) and the risk of PTB increase for 10 µg/m3 increase in NO₂ (pooled odds ratio (OR) = 1.07, 95% CI (0.90, 1.28)). However, the results were not statistically significant. Our finding support the main international results, suggesting that increased air pollution exposure during pregnancy might contribute to adverse birth outcomes, especially LBW. This body of evidence has limitations that impede the formulation of firm conclusions. Further studies, well-focused on European countries, are called to resolve the limitations which could affect the strength of association such as: the exposure assessment, the critical windows of exposure during pregnancy, and the definition of adverse birth outcomes. This analysis of limitations of the current body of research could be used as a baseline for further studies and may serve as basis for reflection for research agenda improvements.

Associations of retinal microvascular caliber with large arterial function and structure: A population-based study of 11 to 12 year-olds and midlife adults

OBJECTIVE

We examined associations between retinal microvascular and large arterial phenotypes to explore relationships between the micro- and macro-vasculature in childhood and midlife.

METHODS

Participants were 1288 children (11-12 years, 50.9% female) and 1264 adults (mean age 44 years, 87.6% female) in a cross-sectional population-based study. Exposures were retinal arteriolar and venular caliber quantified from retinal images. Outcomes included arterial function (pulse wave velocity; carotid arterial elasticity) and structure (carotid intima-media thickness). Multivariable regression models were performed adjusting for age, sex, and family socioeconomic position.

RESULTS

In children, one standard deviation wider arteriolar caliber was associated with slower pulse wave velocity (-0.15 SD, 95% CI -0.21, -0.09) and higher elasticity (0.13 SD, 95% CI 0.06, 0.20); per SD wider venular caliber was associated with faster pulse wave velocity (0.09 SD, 95% CI 0.03, 0.15) and lower elasticity (-0.07 SD, 95% CI -0.13, -0.01). The size of adult associations was approximately double. Wider arteriolar caliber was associated with smaller carotid intima-media thickness (-0.09 SD, 95% CI -0.16, -0.03) in adults but not children. Venular caliber and carotid intima-media thickness showed little evidence of association.

CONCLUSIONS

Narrower retinal arterioles and wider venules are associated with large arterial function as early as mid-childhood. Associations strengthen by midlife and also extend to arterial structure, although effect sizes remain small.

Do body mass index and waist-to-height ratio over the preceding decade predict retinal microvasculature in 11-12 year olds and midlife adults?

BACKGROUND/OBJECTIVES

Microvascular changes may contribute to obesity-associated cardiovascular disease. We examined whether body mass index (BMI) and waist-to-height ratio (WHtR) (1) at multiple earlier time points and (2) decade-long trajectories predicted retinal microvascular parameters in mid-childhood/adulthood.

METHODS

Participants/design: 1288 11-12 year olds (51% girls) and 1264 parents (87% mothers) in the population-based Child Health CheckPoint (CheckPoint) module within the Longitudinal Study of Australian Children (LSAC). LSAC exposure measures: biennial BMI z-score and WHtR for children at five time points from age 2-3 to 10-11 years and self-reported parent BMI at six time points from child age 0-1 years to 10-11 years. CheckPoint outcome measures: retinal arteriolar and venular caliber.

ANALYSES

BMI/WHtR trajectories were identified by group-based trajectory modeling; linear regression models estimated associations between BMI/WHtR at each time point/trajectories and later retinal vascular caliber, adjusted for age, sex, and family socioeconomic status.

RESULTS

In time point analyses, higher child BMI/WHtR from age 4 to 5 years was associated with narrower arteriolar caliber at the age of 11-12 years, but not venular caliber. For example, each standard deviation higher in BMI z-score at 4-5 years was associated with narrower arteriolar caliber at 11-12 years (standardized mean difference (SMD): -0.05, 95% confidence interval (CI): -0.10 to 0.01); by 10-11 years, associations had doubled to -0.10 (95% CI: -0.16 to -0.05). In adults, these finding were similar, except the magnitude of BMI and arteriolar associations were similar across all time points (SMD: -0.11 to -0.13). In child and adult BMI trajectory analyses, less favorable trajectories predicted narrower arteriolar (p-trend < 0.05), but not venular (p-trend > 0.1), caliber. Compared with those in the average BMI trajectory, SMDs in arterial caliber for children and adults in the highest trajectory were -0.25 (95% CI: -0.44 to -0.07) and -0.42 (95% CI: -0.73 to -0.10), respectively. Venular caliber showed late associations with child WHtR, but not with BMI in children or adults.

CONCLUSIONS

Associations of decade-long high BMI trajectories with narrowed retinal arteriolar caliber emerge in children, and are clearly evident by midlife. Adiposity appears to exert its early adverse life course impacts on the microcirculation more via arteriolar than venular mechanisms.

Retinal microvascular development in the first two years

The link between in utero and early life insults and the development of chronic illness remains to be fully understood, but there is increasing data to indicate that microvasculature pathology plays an important mechanistic role. Currently available data indicate that retinal microvasculature changes are detectable in children as young as six years of age, however, there are no data for younger children. We present retinal microvasculature measurement from the first two years of life. Retinal images suitable for analysis were available from 18 infants in our proof-of-concept study. The mean and standard deviation (SD) for birth weight and gestation was 3410 (384) g and 39.1(1.4) weeks, respectively. Retinal vessel calibres were summarized as the mean(SD) central retinal arteriolar equivalent (CRAE) at six months of age was 156 (32) μm, increased to 175 (75) μm by 12 months and a slightly declined by 24 months of age to 168 (50) μm. In a similar pattern, mean(SD) central retinal venular equivalent (CRVE) at six months was 211 (19) μm, increased to 238 (25) μm by 12 months of age followed by a slight decline at 24 months of age to 222 (36) μm. The arterio-venous ratio and tortuosity index remained the same at 6, 12 and 24 months. Findings from this study could help future investigators better understand early microvasculature changes and adaptation that occur early in life.

Visual Function and Fundus Morphology in Relation to Growth and Cardiovascular Status in 10-Year-Old Moderate-to-Late Preterm Children

PURPOSE

To study visual function and ocular fundus morphology in relation to growth, metabolic status, and blood pressure in moderate-to-late preterm (MLP) children at 10 years of age.

DESIGN

Prospective cohort study.

METHODS

In this population-based observational study, nonsyndromic MLP children born in Gothenburg, Sweden, were examined neonatally in the years 2002-2003 concerning length, weight, head circumference, and insulin-like growth factor I (IGF-I). At 10 years of age, 33 children (10 girls) were examined regarding previously mentioned variables, and regarding visual acuity, refraction, fundus morphology, IGF binding protein 3, leptin, adiponectin, and blood pressure. An age- and sex-matched control group consisted of 28 children (9 girls).

RESULTS

Myopia was more commonly found in MLP children than in controls (P = .004, 95% CI 1.8 to 49.8). The MLP group had smaller optic disc area (P = .01, 95% CI -0.5 to -0.1), smaller rim area (P = .001, 95% CI -0.5 to -0.2), fewer branching points (P = .0001, 95% CI -5.7 to -2.1), and higher index of tortuosity of arteries (P = .03, 95% CI 0.002 to 0.03) and veins (P = .02, 95% CI 0.003 to 0.02). Refraction correlated with IGF-I (P = .0005, r_s = 0.60 in right eye, and P = .002, r_s = 0.55 in left eye) at 10 years of age. Tortuosity of arteries at assessment correlated with neonatal IGF-I levels (P = .03, r_s = -0.39). Tortuosity of veins correlated with a leptin/adiponectin ratio at assessment (P = .04, r_s = 0.37).

CONCLUSION

The findings suggest that being born MLP is associated with myopia, smaller optic disc and rim areas, and abnormal retinal vascularization. Furthermore, metabolic status and growth factors seem to have an impact on ocular development.

Ambient air pollution and pregnancy outcomes: A comprehensive review and identification of environmental public health challenges

There is a growing number of studies on the association between ambient air pollution and adverse pregnancy outcomes, but their results have been inconsistent. Consequently, a comprehensive review of this research area is needed. There was a wide variability in studied pregnancy outcomes, observed gestational windows of exposure, observed ambient air pollutants, applied exposure assessment methods and statistical analysis methods Gestational duration, preterm birth, (low) birth weight, and small for gestational age/intrauterine growth restriction were most commonly investigated pregnancy outcomes. Gestational windows of exposure typically included were whole pregnancy period, 1st, 2nd, 3rd trimester, first and last gestational months. Preterm birth was the outcome most extensively studied across various gestational windows, especially at the beginning and at the end of pregnancy. Particulate matter, nitrogen dioxide, ozone, and carbon monoxide were the most commonly used markers of ambient air pollution. Continuous monitoring data were frequently combined with spatially more precisely modelled estimates of exposure. Exposure to particulate matter and ozone over the entire pregnancy was significantly associated with higher risk for preterm birth: the pooled effect estimates were 1.09 (1.03-1.16) per 10 μg/m³ increase in particulate matter with an aerodynamic diameter of 10 µm or less (PM₁₀)_,1.24 (1.08-1.41) per 10 μg/m³ increase in particulate matter with an aerodynamic diameter of 2.5 µm or less (PM_2.5), and 1.03 (1.01-1.04) per 10 ppb increase in ozone. For pregnancy outcomes other than PTB, ranges of observed effect estimates were reported due to smaller number of studies included in each gestational window of exposure. Further research is needed to link the routine pregnancy outcome data with spatially and temporally resolved ambient air pollution data, while adjusting for commonly defined confounders. Methods for assessing exposure to mixtures of pollutants, indoor air pollution exposure, and various other environmental exposures, need to be developed.

Insulin Sensitivity and Inflammation Mediate the Impact of Fitness on Cerebrovascular Health in Adolescents

BACKGROUND/OBJECTIVES

To investigate in adolescents the relationships between retinal vessel diameter, physical fitness, insulin sensitivity, and systemic inflammation.

METHODS

We evaluated 157 adolescents, 112 with excessive weight and 45 lean, all without type 2 diabetes mellitus. All received detailed evaluations, including measurements of retinal vessel diameter, insulin sensitivity, levels of inflammation, and physical fitness.

RESULTS

Overweight/obese adolescents had significantly narrower retinal arteriolar and wider venular diameters, significantly lower insulin sensitivity, and physical fitness. They also had decreased levels of anti-inflammatory and increased levels of proinflammatory markers as well as an overall higher inflammation balance score. Fitness was associated with larger retinal arteriolar and narrower venular diameters and these relationships were mediated by insulin sensitivity. We demonstrate that inflammation also mediates the relationship between fitness and retinal venular, but not arterial diameter; insulin sensitivity and inflammation balance score jointly mediate this relationship with little overlap in their effects.

CONCLUSIONS

Increasing fitness and insulin sensitivity and reducing inflammation among adolescents carrying excess weight may improve microvascular integrity. Interventions to improve physical fitness and insulin function and reduce inflammation in adolescents, a group likely to benefit from such interventions, may reduce not only cardiovascular disease in middle age, but also improve cerebrovascular function later in life.

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.

A case-control study of sporadic retinoblastoma in relation to maternal health conditions and reproductive factors: a report from the Children's Oncology group

Background

The early age at retinoblastoma occurrence, the most common eye malignancy in childhood, suggests that perinatal factors may contribute to its etiology.

Methods

In a large multicenter study of non-familial retinoblastoma, we conducted structured interviews with the parents of 280 cases and 146 controls to elicit information on health during the perinatal period. We used unconditional logistic regression to assess associations between retinoblastoma and parental fertility treatment, birth control use in the year prior to pregnancy, maternal health conditions and the use of prescription medications during pregnancy, and whether mothers breastfed the index child.

Results

Bilateral retinoblastoma was related to maternal underweight (body mass index <18.5) prior to pregnancy [Odds Ratio (OR) = 4.5, 95 % confidence interval (CI) 1.0, 20]. With regards to unilateral retinoblastoma, we observed a negative association with the use of condoms in the year prior to pregnancy (OR = 0.4, CI 0.2, 0.9), and a trend towards a positive association with maternal diabetes (OR = 2.2, CI 0.8, 6.6).

Conclusions

Results from our study suggest a role for several maternal health and reproductive factors. Given that there are few epidemiologic studies of retinoblastoma, our results require replication in studies which utilize medical record review.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1773-0) contains supplementary material, which is available to authorized users.

Design and feasibility of "PREMATurity as predictor of children's Cardiovascular-renal Health" (PREMATCH): A pilot study

The microvasculature and macrovasculature undergo extensive, organ-specific perinatal maturation. Multiple studies show associations between low birth weight and subsequent cardiovascular dysfunction in adulthood, suggesting that extreme preterm birth interferes with this maturation process. Therefore, we designed PREMATCH (PREMATurity as predictor of Cardiovascular–renal Health) to phenotype the microcirculation and macrocirculation during childhood in former preterm infants. A well-characterized cohort of former extreme preterm birth survivors and gender- and age-matched controls (aged 8–13 years) will be investigated for microvascular and macrovascular structure and function. In addition to cognitive performance and anthropometrics, we will investigate (i) the microvascular structure and function by endothelial function (photoplethysmography), sublingual capillary glycocalyx function (sidestream dark field imaging) and retinal structure (diameters of arterioles and venules); and (ii) the macrovascular phenotype by cardiac and renal ultrasound, repeated blood pressure measurements and arterial pulse-wave recordings. The PREMATCH study is unique in its design, and ongoing recruitment demonstrates excellent feasibility. The expectation is that the results of this study will identify risk factors during childhood for subsequent cardiovascular–renal disease in the adult life of former preterm infants, while further analysis on mediators in neonatal life of this cardiovascular–renal outcome may provide new information on perinatal risk factors.

Nanocarriers for treatment of ocular neovascularization in the back of the eye: new vehicles for ophthalmic drug delivery

Pathologic neovascularization of the retina is a major cause of substantial and irreversible loss of vision. Drugs are difficult to deliver to the lesions in the back of the eye and this is a major obstacle for the therapeutics. Current pharmacological approach involves an intravitreal injection of anti-VEGF agents to prevent aberrant growth of blood vessels, but it has limitations including therapeutic efficacy and side-effects associated with systemic exposure and invasive surgery. Nanotechnology provides novel opportunities to overcome the limitations of conventional delivery system to reach the back of the eye through fabrication of nanostructures capable of encapsulating and delivering small molecules. This review article introduces various forms of nanocarrier that can be adopted by ocular drug delivery systems to improve current therapy. The application of nanotechnology in medicine brings new hope for ocular drug delivery in the back of the eye to manage the major causes of blindness associated with ocular neovascularization.

Skin capillary density in infants born to normotensive mothers: a comparison between singleton and twin infants

OBJECTIVE

Twin infants tend to have LBW and microvascular alterations but do not appear to have an increase in cardiovascular mortality later in life as singleton infants. We hypothesized that twin infants born to normotensive mothers would not have capillary rarefaction at birth.

METHODS

We studied 26 dizygotic twin infants and compared them with 115 consecutive singleton infants to normotensive mothers. We used orthogonal polarized spectroscopy to measure basal (i.e., functional) and maximal (i.e., structural) skin capillary density according to a well-standardized protocol.

RESULTS

Twin infants have significantly higher BCD (mean difference 4.3 capillaries/mm(2) , 95% CI: 0.4, 8.1, p = 0.03) and have marginally significantly higher MCD (mean difference 3.9 capillaries/mm(2) , 95% CI: -0.6, 8.3, p = 0.086) compared to singleton infants. Birth weight was significantly associated with BCD and MCD (p = 0.003 and 0.006).

CONCLUSIONS

Twin infants with low and NBWs tend to have higher functional and structural capillary densities compared to singleton infants. Further longitudinal studies of skin capillary density and of retinal vascular parameters commencing from birth to various stages in early childhood are essential to identify the dynamics and the exact timing, if any, of the remodeling of microcirculation in these individuals.

Update on retinal vessel structure measurement with spectral-domain optical coherence tomography

This study was conducted to demonstrate a new scan method for retinal vessel structure measurement in a specific region of fundus (zone B) using spectral-domain optical coherence tomography (SD-OCT), and to assess its reliability. One temporal superior retinal vessel pair passing through a concentric ring (zone B), which was defined between half and one disc distance from the optic disc border, was chosen for the measurement using a volume scan in SD-OCT. On the SD-OCT image, retinal arteriolar outer diameter (RAOD), retinal arteriolar lumen diameter (RALD), retinal venular outer diameter (RVOD) and retinal venular lumen diameter (RVLD) were measured. Retinal vessel diameters on color fundus photographs were also analyzed. Fifty-five healthy individuals were recruited to evaluate intraobserver and interobserver reproducibility between the two examiners. The intraobserver intraclass correlation coefficient (ICC) ranged from 0.972 to 0.981, and the interobserver ICC ranged from 0.968 to 0.980. In the Bland-Altman plot, the 95% limits of interobserver agreement for the RAOD, RALD, RVOD and RVLD were -5.60 to 4.84μm, -5.78 to 5.05μm, -7.52 to 5.62μm and -7.10 to 5.63μm, respectively. The retinal arteriolar and venular lumen diameters on the SD-OCT image were close to the mean arteriolar and venular diameters obtained from the color fundus photographs. Volume scan method produced better images of retinal vessels showing the fine structures of the vessel wall, and provided reliable retinal vessel structure measurement in zone B with good repeatability and reproducibility.

Birth weight is the most important predictor of abnormal retinal vascularisation in moderately preterm infants

AIM

To find predictors of abnormal retinal vascularisation in moderately to late preterm newborn infants considered to have no risk of developing retinopathy of prematurity.

METHODS

Seventy-eight infants (34 girls) were recruited from a longitudinal study of otherwise healthy premature children born at a gestational age of 32 + 0-36 + 6 weeks. Retinal vessel morphology was evaluated at mean postnatal age 7 days. Insulin-like growth factor-I (IGF-I) levels were analysed in umbilical cord blood.

RESULTS

Of the 78 infants, 21 (27%) had abnormal retinal vessel morphology; they had significantly lower median (range) birth weight [1850 g, (1190-3260), vs. 2320, (1330-3580), p < 0.0001], shorter birth length [43.0 cm, (38-49), vs. 46.0, (40-50), p < 0.0001] and smaller head circumference [31.0 cm, (27.7-34.0), vs. 32.0, (27.5-36.5), p = 0.003]. They also had significantly lower gestational age [34 + 1 weeks, (32 + 2-35 + 3), vs. 34 + 6, (32 + 2-36 + 6), p = 0.004] and mean ± SD IGF-I levels (24.6 ± 17.0 μg/L vs. 46.7 ± 21.5, p < 0.0001). A higher percentage of these infants were small for gestational age (57.1% vs. 15.8%, p = 0.001), and maternal hypertension/preeclampsia rates were also higher (47.6% vs. 19.3%, p = 0.03). Step-wise logistic regression showed that birth weight was the strongest predictor of abnormal retinal vascularisation (p < 0.0001, odds ratio 0.040, 95% confidence interval 0.007-0.216).

CONCLUSION

In this population of moderately to late preterm newborns, birth weight appeared to affect the retinal vascular system.

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.

Birth weight and time spent in outdoor physical activity during adolescence

PURPOSE

We investigated the association between birth parameters (weight, length, and head circumference) and time spent in physical activity (outdoor and indoor) and screen time (TV viewing, computer, and videogame usage) among adolescents.

METHODS

A longitudinal cohort study surveyed 1794 children in 2004-2005 (median age = 12.7 yr), and 752 were resurveyed 5 yr later in 2009-2010 (age = 17-18 yr). Adolescents completed detailed activity questionnaires. Parents extracted birth parameter data from their child's health record booklet.

RESULTS

After adjusting for age, sex, ethnicity, gestational age, parental education, home ownership, exposure to passive smoking, and body mass index, 12-yr-old children in the highest compared with the lowest quartile of birth weight spent on average approximately 56 and 62 min more in total (Ptrend = 0.02) and outdoor physical activity (Ptrend = 0.02) per week, respectively. Similarly, 12-yr-old children in the high (>4000 g) versus very low (<2000 g) birth weight group spent approximately 1.3 h·wk more in outdoor activity (Ptrend = 0.02). Among those age 17-18 yr, increasing birth weight (lowest to highest quartile) was associated with greater time spent in outdoor physical activity (∼1 h·wk-1, Ptrend = 0.04). Significant associations were not observed between all birth parameters and recreational screen time. Also, no associations were observed between head circumference or birth length with physical activity and screen time.

CONCLUSIONS

Birth weight could be a potential determinant of physical activity, but not of screen time during adolescence. Hence, this could be part of the underlying mechanism between prenatal influences and future disease risk and could have possible clinical implications.

Relationship between birth weight and retinal microvasculature in newborn infants

OBJECTIVE

The purposes of this study were to determine the normal retinal microvasculature measurements in human infants who are born at term and to determine whether birth weight influences measurements of retinal microvasculature.

STUDY DESIGN

Retinal arteriole and venule measurements were obtained in a cohort of 24 infants who were born at term. Digital images of both the retinas were obtained using a digital retinal camera after pupillary dilation.

RESULT

In all, 24 newborn infants born at term (12 females and 12 males) were analyzed in this study. The measured retinal arteriole diameters were from 66.8 to 147.8 μm (mean, 94.2±19.6 μm), and the venule diameters were from 102.0 to 167.8 μm (mean, 135.2±19.1 μm). Seven babies in the sample had low birth weight (LBW), while 17 babies were born with normal weight. Babies with lower birth weights had larger arteriole (113.1±17.9 μm vs 86.4±14.4 μm; P=0.0009) and venule diameters (151.7±14.9 μm vs 128.4±16.9 μm; P=0.0040).

CONCLUSION

Retinal venules and arterioles in LBW babies are larger compared with those of normal-birth-weight babies. We postulate that the difference observed in our study was due to in utero pathophysiological changes that occurred in the cerebral circulation of growth-restricted fetuses.

Differences in association between birth parameters and blood pressure in children from preschool to high school

We aimed to investigate the association between birth parameters with blood pressure (BP) among preschool- and school-aged children. Two separate childhood datasets were used: (1) 1295 children aged 3-6 years were examined during 2007-2009; and (2) 1741 and 2353 children aged 6 and 12 years, respectively, were examined during 2004-2006. Birth parameter data were obtained from parental records. BP was measured using standard protocols. Among 6-year-old children, each 1 kg decrease in birth weight was associated with a 1.33- and 1.20-mm Hg higher systolic and diastolic BP, respectively, after multivariable adjustment. In 6-year-old children, a decrease of 1 week in gestational age was independently associated with a 0.33- and 0.37-mm Hg higher systolic and diastolic BP, respectively. Six-year-old children in the low birth weight category (≤ 2499 g) versus those in the normal/high birth weight category (≥ 2500 g) had significantly higher systolic BP (P<0.0001). Girls in the low birth weight category versus those in the normal/high weight category had higher systolic BP (P=0.02). Significant associations were not observed among preschool-aged children and preadolescents. Birth weight and gestational age were strongly associated with BP among 6-year-old children, particularly girls, but not among preschoolers or preadolescents.