Retinal vascular caliber and brachial flow-mediated dilation: the Multi-Ethnic Study of Atherosclerosis

Atherosclerotic burden and cerebral small vessel disease: exploring the link through microvascular aging and cerebral microhemorrhages

Cerebral microhemorrhages (CMHs, also known as cerebral microbleeds) are a critical but frequently underestimated aspect of cerebral small vessel disease (CSVD), bearing substantial clinical consequences. Detectable through sensitive neuroimaging techniques, CMHs reveal an extensive pathological landscape. They are prevalent in the aging population, with multiple CMHs often being observed in a given individual. CMHs are closely associated with accelerated cognitive decline and are increasingly recognized as key contributors to the pathogenesis of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD). This review paper delves into the hypothesis that atherosclerosis, a prevalent age-related large vessel disease, extends its pathological influence into the cerebral microcirculation, thereby contributing to the development and progression of CSVD, with a specific focus on CMHs. We explore the concept of vascular aging as a continuum, bridging macrovascular pathologies like atherosclerosis with microvascular abnormalities characteristic of CSVD. We posit that the same risk factors precipitating accelerated aging in large vessels (i.e., atherogenesis), primarily through oxidative stress and inflammatory pathways, similarly instigate accelerated microvascular aging. Accelerated microvascular aging leads to increased microvascular fragility, which in turn predisposes to the formation of CMHs. The presence of hypertension and amyloid pathology further intensifies this process. We comprehensively overview the current body of evidence supporting this interconnected vascular hypothesis. Our review includes an examination of epidemiological data, which provides insights into the prevalence and impact of CMHs in the context of atherosclerosis and CSVD. Furthermore, we explore the shared mechanisms between large vessel aging, atherogenesis, microvascular aging, and CSVD, particularly focusing on how these intertwined processes contribute to the genesis of CMHs. By highlighting the role of vascular aging in the pathophysiology of CMHs, this review seeks to enhance the understanding of CSVD and its links to systemic vascular disorders. Our aim is to provide insights that could inform future therapeutic approaches and research directions in the realm of neurovascular health.

The association of microvascular disease and endothelial dysfunction with vertebral trabecular bone mineral density : The MESA study

Retinopathy and albuminuria are associated with hip fracture risk. We investigated whether these disorders and endothelial dysfunction (which underlies microvascular diseases) were associated with low trabecular bone density. No significant associations were found, suggesting that microvascular diseases are not related to fracture risk through low trabecular bone density.

PURPOSE

Microvascular diseases of the eye, kidney, and brain are associated with endothelial dysfunction and increased hip fracture risk. To explore the basis for higher hip fracture risk, we comprehensively examined whether markers of microvascular disease and/or endothelial dysfunction are related to trabecular bone mineral density (BMD), a proximate risk factor for osteoporotic fractures.

METHODS

Among 6814 participants in the Multi-Ethnic Study of Atherosclerosis study (MESA), we derived thoracic vertebral trabecular BMD from computed tomography of the chest and measured urine albumin to creatinine ratios (UACR), retinal arteriolar and venular widths, flow mediated dilation (FMD) of the brachial artery after 5 min of ischemia; and levels of five soluble endothelial adhesion markers (ICAM-1, VCAM-1, L-selectin, P-selectin, and E-selectin). Linear regression models were used to examine the association of trabecular BMD with markers of microvascular disease and with markers of endothelial dysfunction.

RESULTS

We observed no significant associations of UACR, retinal arteriolar or venular widths, or FMD with BMD. We also observed no statistically significant association of spine trabecular BMD with levels of endothelial adhesion markers. Men and women had largely similar results.

CONCLUSION

We conclude that there is little evidence to connect thoracic spine trabecular BMD to microvascular disorders or to endothelial dysfunction among multi-ethnic middle-aged and older adults. Other factors beyond trabecular BMD (e.g., bone quality or predisposition to falling) may be responsible for the associations of microvascular disease with osteoporotic fractures.

ApoB, non-HDL-C, and LDL-C Are More Prominent in Retinal Artery Occlusion Compared to Retinal Vein Occlusion

PURPOSE

To evaluate and compare the blood lipid profile in retinal artery occlusion (RAO) and retinal vein occlusion (RVO).

METHODS

We included 82 RAO patients and 95 RVO patients in this retrospective case-control study. Controls were matched to RAO or RVO patients at a 1:1 ratio, respectively. Associated lipid variates were analyzed in multivariable logistic regression models.

RESULTS

LDL-C (OR = 1.69), non-HDL-C (OR = 1.87), and ApoB (OR = 11.72) individually significantly increased the risk of RAO. ApoA1 was associated with RVO (OR = 0.02), and with 75.8% sensitivity and 67.4% specificity. TG (OR = 1.61), LDL-C (OR = 1.69), non-HDL-C (OR = 1.91), and ApoB (OR = 12.12) each significantly increased the risk of RAO when compared with RVO.

CONCLUSIONS

ApoB, non-HDL-C, and LDL-C may be potential biomarkers in RAO patients. Low ApoA1 is an independent risk factor for the development of RVO.

Retinal vascular structure independently predicts the initial treatment response in neovascular age-related macular degeneration

PURPOSE

Prediction of the early treatment response is important in neovascular age-related macular degeneration (nAMD). Hence, we aimed to test if non-invasive measurements of the retinal vascular structure were able to predict a successful outcome of initial intravitreal treatment.

METHODS

In 58 eyes of 58 patients with treatment-naïve nAMD, advanced markers of retinal vascular structure were measured by Singapore I Vessel Assessment prior to initial intravitreal treatment with three monthly injections of aflibercept with subsequently categorization of patients as full treatment responders (FTR) or non/partial treatment responders (N/PR), with the former defined as loosing fewer than five Early Treatment Diabetic Retinopathy Study letters and having no residual intra- or subretinal fluid or macular haemorrhage.

RESULTS

Of 54 eyes attending follow-up, 44.4% were categorized as FTR. Patients with FTR were older (81.5 vs. 77 years, p = 0.04), and prior to treatment those eyes had a lower retinal arteriolar fractal dimension (Fd) (1.21 vs. 1.24 units, p = 0.02) and venular length-diameter ratio (LDR) (7.3 vs. 15.9 units, p = 0.006), but did not differ with respect to other retinal vascular parameters. In multiple logistic regression models, a lower chance of FTR was independently predicted by a higher retinal venular LDR (odds ratio [OR] 0.91, 95% CI 0.82-0.99, p = 0.03, for each 1 unit increment) and marginally by a higher retinal arteriolar Fd (OR 0.83, 95% CI 0.68-1.00, p = 0.05, for each 0.01 unit increment).

CONCLUSION

Retinal venular LDR independently predicted the initial treatment response in nAMD. If confirmed by long-term, prospective studies, this might help to guide treatment.

Empirical retinal venous pulse wave velocity using modified photoplethysmography

OBJECTIVE

Using the novel imaging method of high-speed modified photoplethysmography we measured the retinal venous pulse wave velocity in a single case.

RESULTS

A healthy 30-year-old subject underwent high-speed modified photoplethysmography (120 frames per second) with simultaneous ophthalmodynamometry at 26 Meditron units. A video of the optic nerve was analyzed using custom software. A harmonic regression model was fitted to each pixel in the time series and used to quantify the retinal vascular pulse wave parameters. Retinal venous pulsation at the optic disc was observed as a complex dynamic wall motion, whereas contraction commenced at a point in the vein at the center of the optic disc, and progressed centrifugally. The empirically estimated retinal venous pulse wave velocity at this segment was approximately 22.24694 mm/s. This measurement provides an estimate for future studies in the field.

Increased retinal venular calibre in acute infections

Population-based studies have demonstrated that increased retinal venular calibre is a risk factor for cardiac disease, cardiac events and stroke. Venular dilatation also occurs with diabetes, obesity, dyslipidemia and autoimmune disease where it is attributed to inflammation. This study examined whether the inflammation associated with infections also affected microvascular calibre. Participants with infections and CRP levels  >  100 mg/L were recruited from the medical wards of a teaching hospital and assisted to complete a demographic and vascular risk factor questionnaire, and to undergo non-mydriatic retinal photography (Canon CR5-45NM, Japan). They were then treated with appropriate antibiotics, and underwent repeat retinal imaging when their CRP levels had fallen to less than 100 mg/L. Retinal images were examined for arteriole and venular calibre using validated semi-automated software based on Knudtson's modification of the Parr-Hubbard formula (IVAN, U Wisconsin). Differences in inflammatory markers and calibre were examined using the paired t-test for continuous variables. Determinants of calibre were calculated from multiple linear regression analysis. Forty-one participants with respiratory (27, 66%), urinary (6, 15%), skin (5, 12%), or miscellaneous (3, 7%) infections were studied. After antibiotic treatment, participants' mean CRP levels fell from 172.9 ± 68.4 mg/L to 42.2 ± 28.2 mg/L (p < 0.0001) and mean neutrophil counts fell from 9 ± 4 × 109/L to 6 ± 3 × 109/L (p < 0.0001). The participants' mean venular calibre (CRVE) decreased from 240.9 ± 26.9 MU to 233.4 ± 23.5 MU (p = 0.0017) but arteriolar calibre (CRAE) was unchanged (156.9 ± 15.2 MU and 156.2 ± 16.0 MU, p = 0.84). Thirteen additional participants with infections had a CRP > 100 mg/L that persisted at review (199.2 ± 59.0 and 159.4 ± 40.7 mg/L, p = 0.055). Their CRAE and CRVE were not different before and after antibiotic treatment (p = 0.96, p = 0.78). Hospital inpatients with severe infections had retinal venular calibre that decreased as their infections resolved and CRP levels fell after antibiotic treatment. The changes in venular calibre with intercurrent infections may confound retinal vascular assessments of, for example, blood pressure control and cardiac risk.

Vascular health assessment with flow-mediated dilatation and retinal image analysis: a pilot study in an adult population from Cape Town

AIM

Flow-mediated dilatation (FMD) and retinal vascular analysis (RVA) may assist in predicting cardiovascular disease (CVD) but are poorly characterised in South Africa. We recorded baseline FMD and retinal vascular widths in healthy participants, and investigated associations with cardiovascular risk factors.

METHODS

Endothelial function (measured with FMD), microvascular structure (evaluated via fundus image analysis) and major CVD risk factors were assessed in 66 participants from Cape Town.

RESULTS

Median FMD% was 9.6%, with higher values in females. Mean retinal arteriolar and venular widths were ˜156 and ˜250 µm, respectively. FMD was not associated with CVD risk factors. Hypertension was associated with narrower retinal arterioles and venules.

CONCLUSIONS

We report novel baseline FMD data in healthy South African adults from the Western Cape, and show that retinal microvascular calibres are associated with blood pressure. Our baseline FMD and RVA data could serve as a reference for future studies in South Africa.

Retinal Vessel Diameter Changes in COVID-19 Infected Patients

Purpose: To evaluate the longitudinal changes in retinal vessel diameters in patients with coronavirus disease 2019 (COVID-19).Methods: This study included 25 patients with COVID-19 (Group 1) and 25 healthy subjects (Group 2). The diameters of peripapillary temporal and nasal retinal arteries and veins were measured at baseline and at 4 months after remission.Results: The baseline diameters of the inferior temporal vein and the artery were increased in group 1 compared to controls (p = .007 and p = .041, respectively). There was also an increase in the diameters of the inferior and superior nasal veins and arteries in group 1 at baseline (p = .001, p = .019, p = .037, and p = .008, respectively). Retinal vessel diameters decreased after remission in all quadrants in comparison to baseline measurements (all p < .05).Conclusion: Increased retinal vessel diameters were measured in COVID-19 patients during the disease. Measurement of retinal vessel diameters may be a noninvasive method of estimating the vascular risk.

Sex steroids and markers of micro- and macrovascular damage among women and men from the general population

AIMS

The contribution of sex hormones to micro- and macrovascular damage might differ among women and men. In particular, little is known about the association between sex hormones and small vessel disease. Therefore, we examined the association of total oestradiol, total testosterone, free-androgen index (FAI), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and androstenedione levels with micro- and macrovascular diseases.

METHODS AND RESULTS

This cross-sectional study included 2950 women and 2495 men from the population-based Rotterdam Study. As proxy of microvascular damage, we measured diameters of retinal arterioles and venules. Markers of macrovascular damage included carotid intima-media thickness and carotid plaque, coronary artery calcification (CAC), and peripheral artery disease. Linear and logistic regression models were used and adjusted for age, cardiovascular risk factors, and years since menopause. Associations with microvasculature: In women, total testosterone [mean difference per 1-unit increase in natural-log transformed total testosterone (95% confidence interval, CI): 2.59 (0.08-5.09)] and androstenedione [4.88 (1.82-7.95)] and in men DHEAS [2.80 (0.23-5.37)] and androstenedione [5.83 (2.19-9.46)] were associated with larger venular caliber. Associations with markers of large vessel disease: In women, higher total testosterone [-0.29 (-0.56 to -0.03)], FAI [-0.33 (-0.56 to -0.10)], and androstenedione levels [-0.33 (-0.64 to -0.02)] were associated with lower CAC burden and FAI [odds ratio (95% CI): 0.82 (0.71-0.94)] was associated with lower prevalence of plaque.

CONCLUSION

A more androgenic profile was associated with more microvascular damage in both women and men. Among women, however, higher androgen levels were also associated with less macrovascular damage. Our findings suggest that androgens might have distinct effects on the vasculature, depending on the vascular bed and stages of the atherosclerosis process.

The eye, the kidney, and cardiovascular disease: old concepts, better tools, and new horizons

Chronic kidney disease (CKD) is common, with hypertension and diabetes mellitus acting as major risk factors for its development. Cardiovascular disease is the leading cause of death worldwide and the most frequent end point of CKD. There is an urgent need for more precise methods to identify patients at risk of CKD and cardiovascular disease. Alterations in microvascular structure and function contribute to the development of hypertension, diabetes, CKD, and their associated cardiovascular disease. Homology between the eye and the kidney suggests that noninvasive imaging of the retinal vessels can detect these microvascular alterations to improve targeting of at-risk patients. Retinal vessel-derived metrics predict incident hypertension, diabetes, CKD, and cardiovascular disease and add to the current renal and cardiovascular risk stratification tools. The advent of optical coherence tomography (OCT) has transformed retinal imaging by capturing the chorioretinal microcirculation and its dependent tissue with near-histological resolution. In hypertension, diabetes, and CKD, OCT has revealed vessel remodeling and chorioretinal thinning. Clinical and preclinical OCT has linked retinal microvascular pathology to circulating and histological markers of injury in the kidney. The advent of OCT angiography allows contrast-free visualization of intraretinal capillary networks to potentially detect early incipient microvascular disease. Combining OCT's deep imaging with the analytical power of deep learning represents the next frontier in defining what the eye can reveal about the kidney and broader cardiovascular health.

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.

Examination of retinal vascular trajectory in schizophrenia and bipolar disorder

AIM

Evidence suggests microvascular dysfunction (wider retinal venules and narrower arterioles) in schizophrenia (SCZ) and bipolar disorder (BD). The vascular development is synchronous with neuronal development in the retina and brain. The retinal vessel trajectory is related to retinal nerve fiber layer thinning and cerebrovascular abnormalities in SCZ and BD and has not yet been examined. Hence, in this study we examined the retinal vascular trajectory in SCZ and BD in comparison with healthy volunteers (HV).

METHODS

Retinal images were acquired from 100 HV, SCZ patients, and BD patients, respectively, with a non-mydriatic fundus camera. Images were quantified to obtain the retinal arterial and venous trajectories using a validated, semiautomated algorithm. Analysis of covariance and regression analyses were conducted to examine group differences. A supervised machine-learning ensemble of bagged-trees method was used for automated classification of trajectory values.

RESULTS

There was a significant difference among groups in both the retinal venous trajectory (HV: 0.17 ± 0.08; SCZ: 0.25 ± 0.17; BD: 0.27 ± 0.20; P < 0.001) and the arterial trajectory (HV: 0.34 ± 0.15; SCZ: 0.29 ± 0.10; BD: 0.29 ± 0.11; P = 0.003) even after adjusting for age and sex (P < 0.001). On post-hoc analysis, the SCZ and BD groups differed from the HV on retinal venous and arterial trajectories, but there was no difference between SCZ and BD patients. The machine learning showed an accuracy of 86% and 73% for classifying HV versus SCZ and BD, respectively.

CONCLUSION

Smaller trajectories of retinal arteries indicate wider and flatter curves in SCZ and BD. Considering the relation between retinal/cerebral vasculatures and retinal nerve fiber layer thinness, the retinal vascular trajectory is a potential marker for SCZ and BD. As a relatively affordable investigation, retinal fundus photography should be further explored in SCZ and BD as a potential screening measure.

Retinal vascular fractal dimension in bipolar disorder and schizophrenia

BACKGROUND

Bipolar disorder (BD) and schizophrenia (SCZ), are associated with greater vascular co-morbidities and adverse vascular events. Owing to shared developmental origins and morphology, retinal vasculature is a proxy assessment measure of the cerebral vasculature. Although retinal vascular fractal dimension (D_f), a measure of vascular geometry and complexity of branching, has been shown to be directly associated with cerebrovascular pathology, it has not been examined in SCZ and BD.

METHODS

We studied 277 participants (92 healthy volunteers, 98 SCZ, and 87 BD) from 18 to 50 years of age. Images were acquired by trained personnel using a non-mydriatic fundus camera and the retinal vascular D_f was calculated by the box-counting method using an automated algorithm. The average D_f across the left and right eyes were calculated.

RESULTS

Both SCZ and BD had significantly increased D_f compared to HV despite controlling for possible confounding factors. However, there was no significant difference between SCZ and BD. These findings suggest abnormal retinal vascular D_f in psychoses.

LIMITATIONS

The study design was cross-sectional, and patients were on medications. Confound of lifestyle factors such as diet and exercise, if any, was not controlled. Sub-group analysis between BD-I and BD-II was not performed in view of the small sample.

CONCLUSIONS

Considering the easy accessibility, affordability, and non-invasive nature of the examination, retinal vascular D_f could serve as a surrogate marker for cerebral vascular abnormality and could potentially identify BD and SCZ patients at risk of developing adverse vascular events.

Retinal vascular abnormalities in schizophrenia and bipolar disorder: A window to the brain

OBJECTIVES

The examination of retinal microvascular abnormalities through fundus photography is currently the best available non-invasive technique for assessment of cerebral vascular status. Several studies in the last decade have reported higher incidences of adverse cerebrovascular events in Schizophrenia (SCZ) and bipolar disorder (BD). However, retinal microvasculature abnormalities in SCZ and BD have remained under-explored, and no study has compared this aspect of SCZ and BD till date.

METHODS

Retinal Images of 100 SCZ patients, BD patients, and healthy volunteers each were acquired by trained individuals using a non-mydriatic camera with a 40-degree field of view. The retinal images were quantified using a valid semi-automated method. The average of left and right eye diameters of the venules and arterioles passing through the extended zone between 0.5 and 2 disc diameters from the optic disc were calculated.

RESULTS

The groups differed significantly with respect to average diameters of both retinal venules (P < 0.001) and retinal arterioles (P < 0.001), after controlling for age and sex. Both SCZ and BD patients had significantly narrower arterioles and wider venules compared to HV. There were also significant differences between SCZ and BD patients; patients with BD had narrower arterioles and wider venules.

CONCLUSION

Considering the affordability and easy accessibility of the investigative procedure, retinal microvascular examination could serve as a potential screening tool to identify individuals at risk for adverse cerebrovascular events. The findings of the current study also provide a strong rationale for further systematic examination of retinal vascular abnormalities in SCZ and BD.

Retinal vascular tortuosity in schizophrenia and bipolar disorder

The micro-vasculature of retina and brain share common morphological, physiological, and pathological properties. Retina being easily accessible, retinal vascular examination provides an indirect assessment of cerebral vasculature. Considering the high prevalence of vascular morbidity in SCZ and BD a few studies have examined retinal vascular caliber and have reported increased retinal venular caliber in schizophrenia (SCZ). Retinal vascular tortuosity could serve as a better structural measure than caliber as it is static and less susceptible to pulse period variations. However, to date, no study has examined retinal vascular tortuosity in SCZ and bipolar disorder (BD). Hence, we examined retinal vascular tortuosity in comparison with healthy volunteers (HV). We included 255 subjects (78 HV, 79 SCZ, and 86 BD) in the age range of 18 to 50 years. Trained personnel acquired images using a non-mydriatic fundus camera. To measure the average retinal arteriolar tortuosity index (RATI) and retinal venular tortuosity index (RVTI), we used a previously validated, semi-automatic algorithm. The results showed significant differences across the three groups in RATI but not in RVTI; both BD and SCZ had significantly increased RATI compared to HV. There was also a significant difference between SCZ and BD, with BD having higher RATI. If shown to be of predictive utility in future longitudinal studies, it has the potential to identify patients at risk of development of adverse vascular events. As retinal vascular imaging is non-invasive and inexpensive, it could serve as a proxy marker and window to cerebral vasculature.

Association of dietary nitrate intake with retinal microvascular structure in older adults

PURPOSE

Existing research suggests that changes to retinal vascular caliber reflect nitric oxide (NO)-dependent endothelial dysfunction. Dietary nitrate is an important source of NO; however, studies on the link between dietary nitrate intake and retinal microvasculature are lacking. We aimed to assess the cross-sectional association between intake of dietary nitrate (from vegetable and non-vegetable sources) and retinal arteriolar and venular caliber among older adults.

METHODS

Participants from the Blue Mountains Eye Study aged 49+ years with complete data at baseline on diet and retinal vessel measures were analyzed (n = 2813). Dietary intake was assessed using a validated semi-quantitative food-frequency questionnaire. Nitrate intake from vegetable and non-vegetable sources was estimated using a validated comprehensive database and other published data where necessary. Fundus photographs were taken and retinal vascular caliber measured using validated computer-assisted techniques and summarized.

RESULTS

Participants in the lowest versus highest tertile of vegetable nitrate intake had significantly narrower retinal arterioles: 186.2 ± 0.48 versus 187.6 ± 0.48 µm (multivariable-adjusted p = 0.04). After multivariable adjustment, each 10-unit higher intake of total nitrate and vegetable nitrate was associated with 0.089 ± 0.004 and 0.090 ± 0.004 µm wider retinal arteriolar caliber, respectively, both p = 0.03. Each 10-unit higher vegetable nitrate intake was associated with 0.092 ± 0.005 µm narrower retinal venules (p = 0.05).

CONCLUSION

Intake of dietary nitrate, particularly from vegetable sources, was associated with beneficial variations in both retinal arteriolar and venular caliber among older adults. Further research into associations between dietary nitrate and the retinal microvasculature could allow for greater understanding and possible prevention of clinical cardiovascular events.

[Diagnostics of early signs of ocular pathology in patients with HIV/tuberculosis co-infection]

The current epidemic situation in Russia is characterized by increasing rate of co-infection (HIV/tuberculosis). Damage to the organ of vision is more common among patients with this pathology, presenting significant difficulties in diagnosis of the ophthalmic manifestations. High-tech imaging method - optical coherence tomography (OCT) allows exploration of the eye tissues with high accuracy and depth, as well as evaluation of the structure of the choroid and microcirculation parameters of the anterior and posterior eye segments.

Retinal vascular changes and right ventricular structure and function: the MESA-Right Ventricle and MESA-Eye studies

Retinal vessel diameters have been associated with left ventricular morphology and function but their relationship with the right ventricle (RV) has not been studied. We hypothesized that wider retinal venules and narrower retinal arterioles are associated with RV morphology and function. RV end-diastolic mass (RVEDM), end-diastolic volume (RVEDV), end-systolic volume (RVESV), stroke volume (RVSV), and ejection fraction (RVEF) were assessed using cardiac magnetic resonance imaging (MRI) scans of 4204 participants without clinical cardiovascular disease at the baseline examination; retinal photography was obtained at the second examination. Mean diameters of retinal arterioles and venules were measured and summarized as central retinal vein and artery equivalents (“veins” and “arteries,” respectively). After adjusting for covariates, wider veins were associated with greater RVEDM and RVEDV in women (P = 0.04 and P = 0.02, respectively), whereas there was an inverse association with RVEDV in men (P = 0.02). In both sexes, narrower arteries were associated with lower RVEDM (P < 0.001 in women and P = 0.002 in men) and smaller RVEDV (P < 0.001 in women and P = 0.04 in men) in adjusted models. Narrower arteries were also associated with lower RVEF in men but this was of borderline significance after adjusting for the LVEF (P = 0.08). Wider retinal venular diameter was associated with sex-specific changes in RVEDM and RVEDV in adults without clinical cardiovascular disease. Narrower retinal arteriolar diameter was associated with significantly lower RVEDM and smaller RVEDV in both sexes.

Shiftwork and the Retinal Vasculature Diameters Among Police Officers

OBJECTIVE

To investigate associations of central retinal arteriolar equivalent (CRAE), a measure of retinal arteriolar width, and central retinal venular equivalents (CRVE), a measure of retinal venular width, with shiftwork in 199 police officers (72.9% men).

METHODS

Shiftwork (day, afternoon, night) was assessed using electronic payroll records. Four digital retinal images per officer were taken. Mean diameters of the retinal vasculature were compared across shifts using analysis of variance (ANOVA)/analysis of covariance (ANCOVA).

RESULTS

Among all officers (mean age = 46.6 ± 6.8 years), shiftwork was not significantly associated with CRAE or CRVE. However, among current and former smokers, night-shift officers had a wider mean (±standard error [SE]) CRVE (230.0 ± 4.5 μm) compared with day shift officers (215.1 ± 3.5 μm); adjusted P = 0.014.

CONCLUSIONS

Night shift schedule in current and former smokers is associated with wider retinal venules. Reasons for this association are not known. Longitudinal studies are warranted.

Retinal photography: A window into the cardiovascular-brain link in adolescent bipolar disorder

OBJECTIVE

The burden of cardiovascular disease in bipolar disorder (BD) exceeds what can be explained by traditional cardiovascular risk factors (CVRFs), lifestyle, and/or medications. Moreover, neurocognitive deficits are a core feature of BD, and are also related to CVRFs. We examined retinal vascular photography, a proxy for cerebral microvasculature, in relation to CVRFs, peripheral microvascular function, and neurocognition among BD adolescents.

METHODS

Subjects were 30 adolescents with BD and 32 healthy controls (HC). Retinal photography was conducted using a Topcon TRC 50 DX, Type IA camera, following pupil dilation. Retinal arteriolar and venular caliber was measured, from which the arterio-venular ratio (AVR) was computed. All measures were conducted masked to participant diagnosis. Peripheral arterial tonometry measured endothelial function. Neurocognition was assessed using the Cambridge Neuropsychological Tests Automated Battery.

RESULTS

AVR was not significantly different between groups (Cohen's d=0.18, p=0.103). Higher diastolic blood pressure (BP) was associated with lower (worse) AVR in BD (r=-0.441, p=0.015) but not HC (r=-0.192, p=0.293). Similarly, in the BD group only, higher (better) endothelial function was associated with higher AVR (r=0.375, p=0.041). Hierarchical regression models confirmed that, independent of covariates, retinal vascular caliber was significantly associated with diastolic BP and endothelial function in BD. Within the BD group, mood scores were significantly negatively correlated with AVR (β=-0.451, p=0.044).

LIMITATIONS

This study's limitations include a small sample size, a cross-sectional study design, and a heterogeneous sample.

CONCLUSION

Retinal photography may offer unique insights regarding the cardiovascular and neurocognitive burden of BD. Larger longitudinal studies are warranted.

Retinal microcirculation in association with caffeinated and alcoholic drinks in subjects at increased cardiovascular risk

OBJECTIVES

The association of caffeinated and alcoholic drinks with microcirculation is poorly investigated. The aim of the study was to investigate the associations of daily consumption of caffeinated and alcoholic drinks with retinal vessel calibers.

METHODS

In consecutive adults at increased risk but free of CVD and diabetes mellitus, (n=181, age: 51.32±12.42 y, 51.4% women), we determined CRAE, CRVE and AVR, respectively. Daily consumption of caffeinated and alcoholic drinks was assessed through 24 h recalls.

RESULTS

After adjustment for potential confounders: (i) caffeine was positively associated with CRVE (b=0.177, P=.006 for left, b=0.208, P=.002 for right eye, respectively) (ii) decaffeinated coffee was positively associated with CRAE (b=0.141, P=.035 for left eye) and negatively associated with CRVE (b=-0.234, P<.001 for left, b=-0.189, P=.006 for right eye, respectively). Regular coffee, tea, alcohol, and any type of alcoholic drink did not associate with retinal vessel calibers.

CONCLUSIONS

Alcohol and alcoholic drinks' consumption were not associated, while decaffeinated coffee and caffeine consumption were associated in an opposing pattern with retinal vessel calibers. The reason of this controversy merits further investigation.

Retinal vessels caliber changes after strabismus surgery: results of 6mo follow-up

AIM

To evaluate the effect of strabismus surgery on retinal vessels calibers with digital color fundus photographs.

METHODS

Two hundred consecutive strabismus patients underwent surgery, and 118 patients (female/male, 55/63) who finished 6-month follow-up were finally included in this study. Optic disc-centered digital color fundus photographs of both eyes of all patients were taken prior to surgery and 6mo post surgery. The retinal vascular caliber of 116 operated eyes were measured using the computer program IVAN. The operated eyes were divided into 3 groups according to the surgical methods, recession of one muscle, one muscle recession and one muscle folding, one muscle resection and one muscle recession. The effect of number of altered muscles on retinal vessels was analyzed using statistic software SPSS 16.0.

RESULTS

The mean age was 12.4±8.6y. Averaged central retinal artery equivalent (CRAE) of all patients was 120.31±23.02 µm preoperatively, and 122.87±15.93 µm six months after surgery. Averaged central retinal vein equivalent (CRVE) was 171.11±31.73 µm preoperatively and 175.02±21.00 µm postoperatively. There was no significant difference of averaged CRAE (P=0.22) or CRVE (P=0.19) before and after operation. Averaged arteriole to venule ratio (AVR) was 0.71±0.07 before surgery and 0.70±0.07 after surgery. Comparison of preoperative and postoperative retinal vessels calibers among different surgical groups did not show significant differences. Also, there was no advantage of rectus muscle folding to muscle resection.

CONCLUSION

Up to 6mo after strabismus surgery, the retinal vascular calibers were not altered. No more than two muscles in one surgery are safe for retinal perfusion.

Associations of work hours, job strain, and occupation with endothelial function: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To investigate associations of work hours, job control, job demands, job strain, and occupational category with brachial artery flow-mediated dilation (FMD) in 1499 Multi-Ethnic Study of Atherosclerosis participants.

METHODS

Flow-mediated dilation was obtained using high-resolution ultrasound. Mean values of FMD were examined across categories of occupation, work hours, and the other exposures using regression analyses.

RESULTS

Occupational category was significantly associated with FMD overall, with blue-collar workers showing the lowest mean values-management/professional = 4.97 ± 0.22%; sales/office = 5.19 ± 0.28%; services = 4.73 ± 0.29%; and blue-collar workers = 4.01 ± 0.26% (adjusted P < 0.001). There was evidence of effect modification by sex (interaction P = 0.031)-significant associations were observed among women (adjusted P = 0.002) and nearly significant results among men (adjusted P = 0.087). Other exposures were not significantly associated with FMD.

CONCLUSIONS

Differences in endothelial function may account for some of the variation in cardiovascular disease across occupational groups.

Retinal microvessels reflect familial vulnerability to psychotic symptoms: A comparison of twins discordant for psychotic symptoms and controls

Mounting evidence suggests that individuals with schizophrenia have an underlying vulnerability to cardiovascular disease, and a recent study suggested that this vulnerability might be reflected in the retinal microvasculature. The purpose of this study was to test the hypothesis that the retinal microvessels reflect familial vulnerability to psychotic symptoms. Participants were 531 adolescent and young adult twins who took part in the Brisbane Longitudinal Twin Study and the Twins Eye Study in Tasmania. The twins had photographs taken of their retina when they were adolescents or young adults (M age=20.6 years), and retinal vessel diameter was assessed using computer software. The twins completed an assessment of psychosis symptoms approximately six years later. We compared retinal venular diameters of individuals with one or more symptoms of psychosis (n=45), their unaffected co-twins (n=24), and controls (n=462). Individuals with one or more symptoms of psychosis had wider venules (standardized mean=0.29) than controls (standardized mean=-0.04; p=.03), and unaffected co-twins had venular diameters that were intermediate (standardized mean=0.13) between the two groups, suggesting that wide venules may represent a proxy marker of familial vulnerability to psychosis symptoms. Consistent with previous work, there were no differences in arteriolar diameter between individuals with and without symptoms of psychosis. Findings suggest that wide retinal venules may serve as a proxy marker of familial liability to psychosis symptoms. The pathophysiological mechanisms linking psychosis and cardiovascular disease may be operative from early in life, possibly at the level of the microvasculature.

C-reactive protein and chitinase 3-like protein 1 as biomarkers of spatial redistribution of retinal blood vessels on digital retinal photography in patients with diabetic retinopathy

The aim of the study was to investigate the correlation between the levels of C-reactive protein (CRP) and chitinase 3-like protein 1 (YKL-40) in blood samples with morpohometric parameters of retinal blood vessels in patients with diabetic retinopathy. Blood laboratory examination of 90 patients included the measurement of glycemia, HbA1C, total cholesterol, LDL-C, HDL-C, triglycerides and CRP. Levels of YKL-40 were detected and measured in serum by ELISA (Micro VueYKL-40 EIA Kit, Quidel Corporation, San Diego, USA). YKL-40 correlated positively with diameter and negatively with number of retinal blood vessels. The average number of the blood vessels per retinal zone was significantly higher in the group of patients with mild non-proliferative diabetic retinopathy than in the group with severe form in the optic disc and all five retinal zones. The average outer diameter of the evaluated retinal zones and optic disc vessels was significantly higher in the group with severe compared to the group with mild diabetic retinopathy. Morphological analysis of the retinal vessels on digital fundus photography and correlation with YKL-40 may be valuable for the follow-up of diabetic retinopathy.

The effects of ranibizumab injections on fluorescein angiographic findings and visual acuity recovery in age-related macular degeneration

Aim

The objective of the study reported here was to evaluate the effect of ranibizumab on retinal circulation times and vessel caliber and to analyze the correlation of these factors with visual acuity (VA) prognosis in patients with age-related macular degeneration (AMD).

Subjects and methods

This prospective cohort study included 52 eyes of 46 patients (mean age 73.5 years [standard deviation 7.7]; 28 males, 18 females). The study parameters were best-corrected visual acuity (BCVA), central macular thickness (CMT) (pre- and posttreatment: for 3 months after the last injection), retinal circulation times, diameter of retinal arteriole (DRA), and diameter of retinal vein (DRV) (pre- and posttreatment: after a loading dose of three consecutive injections of ranibizumab with a 4-week interval in the initial phase). The pretreatment, posttreatment measurements, and their differences were recorded for analyses. The injections were repeated when needed. Eyes were grouped into one of two groups according to VA recovery: Group 1, cases showing significant recovery of VA (n=21, 37%), and Group 2, cases showing preservation of VA (n=22, 42%) and deterioration of VA (n=11, 21%). Differences were compared statistically in and between groups. Logistic regression analysis was undertaken to determine the correlation of these parameters with VA recovery.

Results

There was a significant reduction in DRA (P=0.007) and CMT levels (P<0.001) in both study groups after treatment. When the two groups were compared, the differences in pretreatment values of DRA (P=0.001), DRV (P=0.017), CMT (P=0.039), and mean BCVA (P=0.00) were found to be statistically significant. Posttreatment changes in DRA (P=0.013) and mean CMT (P=0.010) were found to be factors related to VA recovery by logistic regression analysis.

Conclusion

Our findings reveal that ranibizumab treatment is associated with decrease in DRA, CMT, and significant improvement in VA recovery. Further, taking into account the cases in which VA was preserved, when needed, ranibizumab should be re-injected after the loading dose.

Microvascular abnormality in schizophrenia as shown by retinal imaging

OBJECTIVE

Retinal and cerebral microvessels are structurally and functionally homologous, but unlike cerebral microvessels, retinal microvessels can be noninvasively measured in vivo by retinal imaging. The authors tested the hypothesis that individuals with schizophrenia exhibit microvascular abnormality and evaluated the utility of retinal imaging as a tool for schizophrenia research.

METHOD

Participants were members of the Dunedin Study, a population-representative cohort followed from birth with 95% retention. Study members underwent retinal imaging at age 38. The authors assessed retinal arteriolar and venular caliber for all members of the cohort, including individuals who developed schizophrenia.

RESULTS

Study members who developed schizophrenia were distinguished by wider retinal venules, suggesting microvascular abnormality reflective of insufficient brain oxygen supply. Analyses that controlled for confounding health conditions suggested that wider retinal venules are not simply an artifact of co-occurring health problems in schizophrenia patients. Wider venules were also associated with a dimensional measure of adult psychosis symptoms and with psychosis symptoms reported in childhood.

CONCLUSIONS

The findings provide initial support for the hypothesis that individuals with schizophrenia show microvascular abnormality. Moreover, the results suggest that the same vascular mechanisms underlie subthreshold symptoms and clinical disorder and that these associations may begin early in life. These findings highlight the promise of retinal imaging as a tool for understanding the pathogenesis of schizophrenia.

Age- and hypertension-dependent changes in retinal vessel diameter and wall thickness: an optical coherence tomography study

PURPOSE

To validate and evaluate the reliability of retinal vessel diameter measurements by optical coherence tomography (OCT). The effects of age and hypertension on vessel diameter were also examined.

DESIGN

Prospective, cross-sectional study.

METHODS

Two hundred thirty-eight eyes (238 subjects) with no ocular disease were included. Hypertension was present in 106 subjects and absent in 132 subjects. Spectralis HRA+OCT was used to scan a circular region around the optic disc. Outer and inner diameters of the 4 largest retinal arteries and veins were measured using OCT vascular wall reflections, and vessel wall thickness was calculated.

RESULTS

Intervisit, interexaminer, and interevaluator intraclass correlation coefficients of randomly selected vessel measurements were all greater than 0.90. Mean inner arterial and venous diameters were 87.8 ± 9.4 μm and 113.7 ± 12.5 μm, respectively. The OCT-measured mean inner arterial and venous diameters were significantly correlated to fundus photography caliber measurements (P = .005 and P = .001, respectively). Arterial and venous wall thicknesses were 17.4 ± 2.4 μm and 13.7 ± 2.1 μm, respectively, both of which were highly correlated with subject age (arterial: r = 0.612, P < .001, venous: r = 0.455, P < .001). Additionally, both mean arterial and venous wall thicknesses were significantly greater in subjects with hypertension than in age-matched subjects without hypertension (P = .020 and P = .015, respectively).

CONCLUSIONS

Retinal vessel diameter measurements obtained with OCT were highly reproducible and vessel wall thicknesses, calculated using outer and inner diameter measurements, were significantly thickened by both aging and systemic hypertension.

Retinal microvascular responses to short-term changes in particulate air pollution in healthy adults

BACKGROUND

Microcirculation plays an important role in the physiology of cardiovascular health. Air pollution is an independent risk factor for the development and progression of cardiovascular diseases, but the number of studies on the relation between air pollution and the microcirculation is limited.

OBJECTIVES

We examined the relationship between short-term changes in air pollution and microvascular changes.

METHODS

We measured retinal microvasculature using fundus image analysis in a panel of 84 healthy adults (52% female), 22-63 years of age, during January-May 2012. Blood vessels were measured as central retinal arteriolar/venular equivalent (CRAE/CRVE), with a median of 2 measurements (range, 1-3). We used monitoring data on particulate air pollution (PM10) and black carbon (BC). Mixed-effect models were used to estimate associations between CRAE/CRVE and exposure to PM10 and BC using various exposure windows.

RESULTS

CRAE and CRVE were associated with PM10 and BC concentrations, averaged over the 24 hr before the retinal examinations. Each 10-µg/m3 increase in PM10 was associated with a 0.93-µm decrease (95% CI: -1.42, -0.45; p = 0.0003) in CRAE and a 0.86-µm decrease (95% CI: -1.42, -0.30; p = 0.004) in CRVE after adjusting for individual characteristics and time varying conditions such as ambient temperature. Each 1-µg/m3 increase in BC was associated with a 1.84-µm decrease (95% CI: -3.18, -0.51; p < 0.001) in CRAE.

CONCLUSIONS

Our findings suggest that the retinal microvasculature responds to short-term changes in air pollution levels. These results support a mechanistic pathway through which air pollution can act as a trigger of cardiovascular events at least in part through effects on the microvasculature.

Ocular parameters of biological ageing in HIV-infected individuals in South Africa: relationship with chronological age and systemic biomarkers of ageing

HIV-infected individuals have an increased risk of age-related morbidity despite antiretroviral treatment (ART). Several anatomic and functional ophthalmological parameters are associated with increasing chronological age. These may, therefore, potentially serve as biomarkers of ageing. We investigated associations between ocular parameters (lens density, retinal vessel calibre, corneal endothelium and retinal nerve fibre layer thickness) and two 'cellular' biomarkers of ageing (leukocyte telomere length and CDKN2A expression) and with frailty in a cross-sectional study of 216 HIV-infected individuals. All ocular parameters, telomere length and frailty were associated with chronological age, whereas CDKN2A expression was not. Retinal venular calibre and lens density were associated with shorter telomere length (p-trend=0.04, and 0.08, respectively), whereas CDKN2A expression and frailty status were not associated with ocular parameters. Longitudinal studies are warranted to assess the integration of retinal vascular calibre and lens density with systemic markers to develop an overall index of biological ageing in HIV infection.

Impact of arterial hypertension on the eye

Systemic hypertension has been linked to a wide range of major eye diseases. High arterial blood pressure (BP) decreases choroidal circulatory flow, increases intraocular pressure, and is associated with retinal microvascular abnormalities and prevalence of retinal vein occlusion (RVO) and retinopathy. This review offers a comprehensive overview of ocular diseases associated with hypertension and emphasizes their importance as predictors to future cardiovascular events. It also gives evidence-based clinical data for the therapeutic approach of eye disease in hypertensive patients.

Brachial artery diameter and the right ventricle: the Multi-Ethnic Study of Atherosclerosis-right ventricle study

BACKGROUND

Endothelial dysfunction is associated with left ventricular morphology and long-term cardiovascular outcomes. The purpose of this study was to assess the relationship between both baseline brachial artery diameter and peripheral endothelial function (assessed by brachial artery ultrasonography) and right ventricular (RV) mass, RV end-diastolic volume (RVEDV), and RV ejection fraction (RVEF).

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) performed cardiac MRI and brachial artery ultrasonography on participants without clinical cardiovascular disease. Baseline brachial artery diameter and flow-mediated dilation were assessed.

RESULTS

The mean age was 60.9 years, and 49.4% of subjects were men (n = 2,425). In adjusted models, larger brachial artery diameter was strongly associated with greater RV mass (β = 0.55 g, P &lt; .001), larger RVEDV (β = 3.99 mL, P &lt; .001), and decreased RVEF (β = -0.46%, P = .03). These relationships persisted after further adjustment for the respective left ventricular parameters. Flow-mediated dilation was not associated with RV mass or RVEF and was only weakly associated with RVEDV.

CONCLUSIONS

Brachial artery diameter is associated with greater RV mass and RVEDV, as well as lower RVEF. Changes in the systemic arterial circulation may have pathophysiologic links to pulmonary vascular dysfunction or abnormalities in RV perfusion.

The association of systemic microvascular changes with lung function and lung density: a cross-sectional study

Smoking causes endothelial dysfunction and systemic microvascular disease with resultant end-organ damage in the kidneys, eyes and heart. Little is known about microvascular changes in smoking-related lung disease. We tested if microvascular changes in the retina, kidneys and heart were associated with obstructive spirometry and low lung density on computed tomography. The Multi-Ethnic Study of Atherosclerosis recruited participants age 45-84 years without clinical cardiovascular disease. Measures of microvascular function included retinal arteriolar and venular caliber, urine albumin-to-creatinine ratio and, in a subset, myocardial blood flow on magnetic resonance imaging. Spirometry was measured following ATS/ERS guidelines. Low attenuation areas (LAA) were measured on lung fields of cardiac computed tomograms. Regression models adjusted for pulmonary and cardiac risk factors, medications and body size. Among 3,397 participants, retinal venular caliber was inversely associated with forced expiratory volume in one second (FEV(1)) (P<0.001) and FEV(1)/forced vital capacity (FVC) ratio (P = 0.04). Albumin-to-creatinine ratio was inversely associated with FEV(1) (P = 0.002) but not FEV(1)/FVC. Myocardial blood flow (n = 126) was associated with lower FEV(1) (P = 0.02), lower FEV(1)/FVC (P = 0.001) and greater percentage LAA (P = 0.04). Associations were of greater magnitude among smokers. Low lung function was associated with microvascular changes in the retina, kidneys and heart, and low lung density was associated with impaired myocardial microvascular perfusion. These cross-sectional results suggest that microvascular damage with end-organ dysfunction in all circulations may pertain to the lung, that lung dysfunction may contribute to systemic microvascular disease, or that there may be a shared predisposition.

Retinal arterioles narrow with increasing duration of anti-retroviral therapy in HIV infection: a novel estimator of vascular risk in HIV?

OBJECTIVES

HIV infection is associated with an increased risk of age-related morbidity mediated by immune dysfunction, atherosclerosis and inflammation. Changes in retinal vessel calibre may reflect cumulative structural damage arising from these mechanisms. The relationship of retinal vessel calibre with clinical and demographic characteristics was investigated in a population of HIV-infected individuals in South Africa.

METHODS

Case-control study of 491 adults ≥30 years, composed of 242 HIV-infected adults and 249 age- and gender-matched HIV-negative controls. Retinal vessel calibre was measured using computer-assisted techniques to determine mean arteriolar and venular diameters of each eye.

RESULTS

The median age was 40 years (IQR: 35-48 years). Among HIV-infected adults, 87.1% were receiving highly active antiretroviral therapy (HAART) (median duration, 58 months), their median CD4 count was 468 cells/µL, and 84.3% had undetectable plasma viral load. Unadjusted mean retinal arteriolar diameters were 163.67±17.69 µm in cases and 161.34±17.38 µm in controls (p = 0.15). Unadjusted mean venular diameters were 267.77±18.21 µm in cases and 270.81±18.98 µm in controls (p = 0.07). Age modified the effect of retinal arteriolar and venular diameters in relation to HIV status, with a tendency towards narrower retinal diameters in HIV cases but not in controls. Among cases, retinal arteriolar diameters narrowed with increasing duration of HAART, independently of age (167.83 µm <3 years of HAART vs. 158.89 µm >6 years, p-trend = 0.02), and with a HIV viral load >10,000 copies/mL while on HAART (p = 0.05). HIV-related venular changes were not detected.

CONCLUSIONS

Narrowing of retinal arteriolar diameters is associated with HAART duration and viral load, and may reflect heightened inflammatory and pro-atherogenic states of the systemic vasculature. Measurement of retinal vascular calibre could be an innovative non-invasive method of estimating vascular risk in HIV-infected individuals.

Retinal Vessel Analysis as a Tool to Quantify Risk of Diabetic Retinopathy

Diabetic retinopathy remains a leading cause of visual impairment and blindness worldwide. Identifying high-risk asymptomatic individuals who will likely develop the sight-threatening forms of diabetic retinopathy is an important clinical goal as it allows early, targeted implementation of preventive strategies to reduce their risk of vision loss. However, diabetic retinopathy is not a linear disease. Predicting the risk of diabetic retinopathy is challenging, and the current approach simply based on an assessment of traditional risk factors lacks precision. Retinal vessel analysis may offer a novel and noninvasive tool to improve risk prediction for diabetic retinopathy. With the use of this technology, studies have shown that a spectrum of structural alterations in the retinal vasculature can now be reliably quantified. In particular, variations in retinal vessel caliber have been consistently associated with the risks of retinopathy development and progression and shown to have prognostic predictive value above and beyond the conventional risk factors. Despite the promising results, there remain several unresolved issues that need to be addressed before the research findings on retinal vessel analysis are translated into clinical application. Coupling with standard clinical assessment, the additional information obtained from this technology could potentially guide clinical decision making, patient prognostication, and possibly monitor therapeutic response.

Retinal vascular changes following intravitreal ranibizumab injections for neovascular AMD over a 1-year period

PURPOSE

To assess retinal vascular calibre changes in eyes with neovascular age-related macular degeneration (AMD), treated with intravitreal anti-vascular endothelial growth factor agents, over a 1-year period and compare any such changes to untreated fellow eyes.

METHODS

Treatment naïve patients with neovascular AMD received three consecutive intravitreal injections of ranibizumab, followed by a pro re nata dosing regimen up to 1 year, with the aim of maintaining a 'fluid-free' macula. Retinal arteriolar and venular calibre was measured from digital fundus photographs at baseline and at three monthly intervals to 1 year, and summarised as central retinal artery equivalent (CRAE) and central retinal venular equivalent (CRVE), respectively.

RESULTS

A total of 53 injected eyes and 41 fellow, non-injected eyes were analysed. At baseline, there were no differences in retinal vascular calibre between injected and non-injected eyes (mean CRAE (SD) 144.93 (14.07) vs 145.74 (13.10) μm, P=0.80 and mean CRVE (SD) 216.23 (25.93) vs 219.91 (22.82) μm, P=0.53). Over a 12-month period, retinal venular calibre dilatation occurred in injected eyes (mean CRVE change +5.71 (14.71) μm, P=0.007), with no change in retinal arterioles, +0.69 (14.71) μm, P=0.68. In non-injected eyes, arteriolar narrowing occurred as a whole, mean CRAE change -4.20 (7.00) μm, P=0.001, over 12 months, with a trend for narrowing in venules, -2.16 (11.56) μm, P=0.28. In injected eyes, after controlling for covariates, the changes in CRVE over 12 months mirrored improvements in macular thickness, -0.06 (-0.005, -0.11) μm, P=0.04, and visual acuity, +9.66 (-0.30, +19.32) μm, P=0.06.

CONCLUSION

Intravitreal ranibizumab significantly dilated retinal venules after a 1-year period.

Retinal vessel caliber and risk factors for branch retinal vein occlusion

PURPOSE

To describe the association between retinal vessel caliber and risk factors for branch retinal vein occlusion (BRVO).

MATERIALS AND METHODS

We included 10,890 participants who underwent a health checkup at Kangbuk Samsung Hospital between January 2006 and December 2006. BRVO was diagnosed from retinal photographs taken for both eyes. Retinal vascular caliber measurements were performed using a computer-assisted program. Risk factors were assessed based on a patient-answered questionnaire and laboratory investigations. Logistic regression analyses were performed to identify potential risk factors for BRVO.

RESULTS

The overall prevalence of BRVO was 0.8%. Among all BRVO patients, the mean central retinal artery equivalent (CRAE) was 142.59 µm (±14.63 µm), and the mean central retinal vein equivalent (CRVE) was 203.46 µm (±18.84 µm). The mean CRAE and CRVE of the control eyes were 148.15 µm (± 15.89 µm) and 211.12 µm (±18.54 µm), respectively. There were significant differences in mean CRAE and CRVE between the control group and the BRVO group (P < 0.05). Arterial hypertension was an important risk factor for BRVO (OR: 1.02 (1.01-1.03).

CONCLUSIONS

Eyes with BRVO had narrow CRAE and CRVE when compared with age- and gender-matched normal eyes. Generalized attenuation of retinal vessel caliber may be characteristic of eyes with BRVO. Emphasis on blood pressure control is needed for the prevention of BRVO.

Influence of Physical Activity and Screen Time on the Retinal Microvasculature in Young Children

Objective—

It is not clear whether physical activity and sedentary behavior affect retinal microvascular caliber. We investigated associations among physical activity (outdoor and indoor sporting activities), sedentary behaviors (including screen time, television [TV] viewing, and computer and videogame usage), and retinal microvascular caliber in schoolchildren.

Methods and Results—

Six-year-old students (1765/2238) from a random cluster sample of 34 Sydney schools were examined. Parents completed questionnaires about physical and sedentary activities. Retinal images were taken, and retinal vessel caliber was quantified. After adjusting for age, sex, ethnicity, eye color, axial length, body mass index, birth weight, and mean arterial blood pressure, children who spent more time in outdoor sporting activities (in the highest tertile of activity) had 2.2 μm (95% CI 0.65 to 3.71) wider mean retinal arteriolar caliber than those in the lowest tertile ( P trend =0.004). Increasing quartiles of time spent watching TV were associated with narrower mean retinal arteriolar caliber ≈2.3 μm (95% CI 0.73 to 3.92), P trend =0.003.

Conclusion—

These data suggest that physical activity could have a beneficial influence, whereas screen time has a potential adverse influence on retinal microvascular structure. The magnitude of arteriolar narrowing associated with each hour daily of TV viewing is similar to that associated with a 10-mm Hg increase in systolic blood pressure in children.