Is quality of diet associated with the microvasculature? An analysis of diet quality and retinal vascular calibre in older adults

Prevention and Treatment of Retinal Vein Occlusion: The Role of Diet-A Review

Retinal vein occlusion (RVO) is the second most common retinal disorder. In comparison to diabetic retinopathy or age-related macular degeneration, RVO is usually an unexpected event that carries a greater psychological impact. There is strong evidence to suggest that cardiovascular diseases are the most common risk factors in this pathology and it has long been known that a higher consumption of fish, nuts, fruits, and vegetables has a protective effect against these types of conditions. In the last several years, interest in plant-based diets has grown in both the general population and in the scientific community, to the point to which it has become one of the main dietary patterns adopted in Western countries. The aim of this review is to investigate the potential impact of macro- and micronutrients on retinal vein occlusion.

Arterial Hypertension and the Hidden Disease of the Eye: Diagnostic Tools and Therapeutic Strategies

Hypertension is a major cardiovascular risk factor that is responsible for a heavy burden of morbidity and mortality worldwide. A critical aspect of cardiovascular risk estimation in hypertensive patients depends on the assessment of hypertension-mediated organ damage (HMOD), namely the generalized structural and functional changes in major organs induced by persistently elevated blood pressure values. The vasculature of the eye shares several common structural, functional, and embryological features with that of the heart, brain, and kidney. Since retinal microcirculation offers the unique advantage of being directly accessible to non-invasive and relatively simple investigation tools, there has been considerable interest in the development and modernization of techniques that allow the assessment of the retinal vessels’ structural and functional features in health and disease. With the advent of artificial intelligence and the application of sophisticated physics technologies to human sciences, consistent steps forward have been made in the study of the ocular fundus as a privileged site for diagnostic and prognostic assessment of diverse disease conditions. In this narrative review, we will recapitulate the main ocular imaging techniques that are currently relevant from a clinical and/or research standpoint, with reference to their pathophysiological basis and their possible diagnostic and prognostic relevance. A possible non pharmacological approach to prevent the onset and progression of retinopathy in the presence of hypertension and related cardiovascular risk factors and diseases will also be discussed.

Dietary Vitamins A, C, and Potassium Intake Is Associated With Narrower Retinal Venular Caliber

Introduction

The retinal vasculature, a surrogate for the systemic microvasculature, can be observed non-invasively, providing an opportunity to examine the effects of modifiable factors, such as nutrient intake, on microcirculation. We aimed to investigate the possible associations of dietary nutrient intake with the retinal vessel caliber.

Methods

In this cross-sectional study, a total of 584 participants in a medical survey of Japanese descendants living in Los Angeles in 2015 underwent a dietary assessment, fundus photographic examination, and comprehensive physical and blood examinations. Retinal vessel caliber was measured using fundus photographs with a semi-automated computer system and summarized as central retinal artery and vein equivalents (CRAE and CRVE). The association between dietary nutrient intake and retinal vessel caliber was analyzed using a multivariate linear regression model adjusted for two models including potential confounders. The first model was adjusted for age and sex. The second model was adjusted for age, sex, smoking status, body mass index, hypertension, diabetes, dyslipidemia, history of coronary heart disease, and history of stroke.

Results

After adjustment of potential confounders, compared to the quartile with the lowest intake, the difference in CRVE for the highest quartile was −5.33 μm [95% confidence interval (CI): −9.91 to −0.76, P for trend = 0.02] for vitamin A, −4.93 μm (95% CI: −9.54 to −0.32, P for trend = 0.02) for vitamin C and −3.90 μm (95% CI: −8.48 to 0.69, P for trend = 0.04) for potassium.

Conclusions

A significant association was observed between higher vitamins A, C and potassium intakes and narrower retinal venular caliber.

Socioeconomic inequalities, modifiable lifestyle risk factors, and retinal vessel calibers: The African-PREDICT Study

OBJECTIVE

Lifestyle risk factors vary between socioeconomic status (SES) groups and may influence cardiovascular function differently. The retinal microvasculature allows for monitoring early changes in cardiovascular health, and therefore, we investigated whether retinal vessel calibers associate differently with modifiable risk factors in different SES groups.

METHODS

We included 1064 young adults (aged 20-30 years) grouped by low and high SES. The central retinal artery and vein equivalents (CRAE, CRVE) were determined from fundus images captured using the Dynamic Retinal Vessel Analyzer (Imedos Systems GmbH, Jena, Germany). We collected anthropometry, self-reported alcohol consumption, and biochemical data.

RESULTS

Retinal vessel calibers did not differ between SES groups (p ≥ .80) after adjusting for sex and ethnicity. Unique independent associations were observed in the low SES group, where CRAE (β = 0.08, p = .042) and CRVE (β = .14, p = .001) associated positively with cotinine and body mass index, respectively. In the high SES group, CRAE (β = -0.09, p = .027) associated negatively with alcohol consumption.

CONCLUSION

At young ages, retinal vessel calibers associated differently with modifiable lifestyle risk factors within each SES group. Our data highlight the importance of detecting adverse lifestyle risk factors among young adults from diverse socioeconomic settings to improve prevention of cardiovascular disease.

Diet Quality Indices Used in Australian and New Zealand Adults: A Systematic Review and Critical Appraisal

Distilling the complexity of overall diet into a simple measure or summative score by data reduction methods has become a common practice in nutritional epidemiology. Recent reviews on diet quality indices (DQI) have highlighted the importance of sound construction criteria and validation. The aim of this current review was to identify and critically appraise all DQI used within Australian and New Zealand adult populations. Twenty-five existing DQI were identified by electronic searching in Medline and hand searching of reference lists. DQI were constructed based on the respective national dietary guidelines and condition-specific recommendations. For preferable features of DQI, six captured the dimensions of adequacy, moderation and balance; five had a nested structure; 12 consisted of foods, food groups and nutrients; 11 used metric scoring systems and most of those with metric scales used normative cutoff points. Food frequency questionnaires, either alone or with other methods, were the most common dietary assessment method used in 20 DQI. For evaluation of DQI, construct validity and relative validity are reported. Based on our critical appraisal, Dietary Guideline Index (DGI), Dietary Guideline Index-2013 (DGI-2013), Total Diet Score (TDS), Healthy Eating Index for Australian Adults-2013 (HEIFA-2013), and Aussie-Diet Quality Index (Aussie-DQI) were the preferred DQI used in Australian adults according to dimension, indicator selection, scoring criteria and evaluation. Further work is needed to enhance the construction of all Australian and New Zealand DQI, especially in terms of dimension and structure, for alignment with recommended construction criteria.

Associations between dietary flavonoids and retinal microvasculature in older adults

PURPOSE

In this study, we assessed whether there are independent associations between dietary total flavonoid intake and major flavonoid classes with retinal arteriolar and venular calibre.

METHODS

Blue Mountains Eye Study participants aged 49+ years who had complete data on diet and retinal vessel measures were analysed (n = 2821). Dietary intake was assessed using a semi-quantitative Food-Frequency Questionnaire (FFQ). Flavonoid content of foods in the FFQ was estimated using the US Department of Agriculture Flavonoid, Isoflavone and Proanthocyanidin databases. Fundus photographs were taken and retinal vascular calibre was measured using validated computer-assisted techniques. The associations of intake of dietary flavonoids with retinal vessel calibre were examined in linear regression models and general linear model.

RESULTS

The highest quartile of intake was compared with the lowest quartile using multivariable-adjustment models. Participants with the highest proanthocyanidin intake had narrower retinal venules (223.9 ± 0.62 versus 226.5 ± 0.63, respectively; P_trend = 0.01); and the highest isoflavone intake was associated with wider retinal arterioles (188.1 ± 0.55 versus 186.3 ± 0.56, respectively; P_trend = 0.01). The highest apple/pear consumption (a dietary source of catechin) was associated with narrower retinal venules (223.8 ± 0.57 versus 226.1 ± 0.52; P_trend = 0.01) and wider retinal arterioles (187.9 ± 0.51 versus 186.2 ± 0.51; P_trend = 0.02). Further, participants who were in the highest versus lowest quartile of chocolate consumption had ~ 2.1 μm narrower retinal venules (multivariable-adjusted P = 0.03).

CONCLUSIONS

This study shows that higher intakes of specific flavonoid subclasses are associated with a favourable retinal microvascular profile. Greater consumption of flavonoid-rich apples/pears and chocolate was also associated with beneficial variations in retinal vascular calibre.

Role of age-related alterations of the cerebral venous circulation in the pathogenesis of vascular cognitive impairment

There has been an increasing appreciation of the role of vascular contributions to cognitive impairment and dementia (VCID) associated with old age. Strong preclinical and translational evidence links age-related dysfunction and structural alterations of the cerebral arteries, arterioles, and capillaries to the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. The low-pressure, low-velocity, and large-volume venous circulation of the brain also plays critical roles in the maintenance of homeostasis in the central nervous system. Despite its physiological importance, the role of age-related alterations of the brain venous circulation in the pathogenesis of vascular cognitive impairment and dementia is much less understood. This overview discusses the role of cerebral veins in the pathogenesis of VCID. Pathophysiological consequences of age-related dysregulation of the cerebral venous circulation are explored, including blood-brain barrier disruption, neuroinflammation, exacerbation of neurodegeneration, development of cerebral microhemorrhages of venous origin, altered production of cerebrospinal fluid, impaired function of the glymphatics system, dysregulation of cerebral blood flow, and ischemic neuronal dysfunction and damage. Understanding the age-related functional and phenotypic alterations of the cerebral venous circulation is critical for developing new preventive, diagnostic, and therapeutic approaches to preserve brain health in older individuals.

Association between head injury and concussion with retinal vessel caliber

The adverse long-term consequences following traumatic brain injury are poorly understood, particularly on the cerebral microvasculature. Retinal vessels are a surrogate marker of cerebral vascular changes. We therefore aimed to examine the cross-sectional association between serious head injury or being knocked unconscious, and/or concussion and retinal microvascular signs, specifically, mean retinal arteriolar and venular calibre, in older adults after accounting for potential confounders. This cohort study involved 2,624 adults with mean age of 66.9 (±9.1) years who self-reported head injury and concussion parameters, and had gradable retinal photographs. Face-to-face interviews with trained interviewers allowed participants to report prior serious head injury or being knocked unconscious, and/or a previous diagnosis of concussion by a medical professional. Fundus photographs were taken and retinal vascular calibre measured using computer-assisted techniques and summarized. There were 25.9%, 15.3% and 10.1% who reported a prior serious head injury or being “knocked unconscious”, concussion, and both, respectively. Participants in the first group compared to non-injured participants had significantly wider (~2 μm) mean retinal venular calibre (p = 0.02), after adjusting for age, sex, smoking, body mass index, mean arterial blood pressure, type 2 diabetes and fellow vessel calibre. No significant associations were observed in people reporting medically diagnosed concussion or with mean retinal arteriolar calibre. Our exploratory study suggests that head injury is independently associated with wider retinal venular caliber. These findings warrant further investigation in longitudinal cohort studies.

Dietary Patterns and Retinal Vessel Caliber in the Irish Nun Eye Study

BACKGROUND

Retinal vessel abnormalities are associated with cardiovascular disease risk. Widening of retinal venules is associated with increased risk of stroke while narrowing of retinal arterioles independently predicts incident hypertension, coronary heart disease and diabetes. Dietary factors are known to play an important role in cardiovascular health. However, few studies have examined the association between dietary patterns (DPs) and retinal microvascular health.

OBJECTIVE

To examine the association between 'a posteriori'-derived DPs and retinal vascular caliber (RVC) in older women with a restricted lifestyle.

METHODS

This was a cross-sectional study of 1233 participants (mean age: 76.3 years) from the Irish Nun Eye Study (INES). Computer-assisted software was used to measure RVC from digital eye images using standardized protocols. Dietary intake was assessed using a food frequency questionnaire (FFQ). DP analysis was performed using principal component analysis from completed FFQs. Regression models were used to assess associations between DPs and retinal vessel diameters, adjusting for age, body mass index, refraction, hypertension, diabetes mellitus, ischemic heart disease, cerebrovascular accident and fellow eye RVC.

RESULTS

Two DPs were identified: a 'healthy' pattern with high factor loadings for fruit, vegetables, wholegrains and oily fish and an 'unhealthy' pattern with high factor loadings for sugar and sweets, chips, high fat dairy products and French fries. Adjusted linear regression analysis revealed that those who adhered most closely to the unhealthy DP had wider central retinal venular equivalent (CRVE) (p=0.03) and narrower central retinal arteriolar equivalent (CRAE) (p=0.01) compared to the least unhealthy DP. No independent relationship was observed between the healthy DP and RVC.

CONCLUSION

In this cohort of older women with a restricted lifestyle, an unhealthy DP was independently associated with an unfavorable retinal profile, namely a widening of retinal venules and narrowing of retinal arterioles.

Dietary patterns and retinal vascular calibre in children and adolescents with type 1 diabetes

PURPOSE

To examine the association between dietary patterns and retinal vascular calibre in children and adolescents with type 1 diabetes.

METHODS

A hospital-based cross-sectional study of 83 children and adolescents with type 1 diabetes was conducted over an 8-month period. Dietary patterns were extracted using principal components analysis from completed food frequency questionnaires. Retinal vascular calibre was measured by a trained grader using a standardized protocol and later summarized as central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) using a semi-automated computer program.

RESULTS

Three major dietary patterns were identified as follows: (1) processed foods, (2) plant-based foods and (3) vegetable/fish avoidance pattern. The processed pattern had high component loadings for processed meats and high fat takeaway foods. The plant-based pattern had high component loadings for a number of fruits including, but not limited to, pineapple, grapes oranges and mangos as well as a smaller number of vegetables, including beans and leeks. The vegetable and fish avoidance pattern had high inverse component loadings for canned and fresh fish as well as a number of vegetables including, but not limited to, pumpkin, green beans, broccoli, sweet potato and cabbage. Adjusted regression analysis revealed the 'vegetable/fish avoidance' dietary pattern was associated with a wider CRVE (ExpB = 3.67, 95% CI = 0.11/7.24, p = 0.039). After multivariable adjustments, a vascular risk profile that included: older age, higher BMI, higher systolic blood pressure, greater gestational age, longer screen viewing time, lower maternal education level, lower physical activity levels and lower high-density lipoproteins concentrations were more likely to display narrower CRAE (ExpB = -2.43, 95% CI = -4.92/0.06, p = 0.041).

CONCLUSIONS

This study provides the first evidence for a diet-calibre relationship in children and adolescents with type 1 diabetes. This outcome has potential public health implications, as promotion of healthy eating patterns in children and adolescents might attenuate changes in microvasculature that have been related to an increased risk of microvascular disease, such as retinopathy, in adulthood. Additional studies are warranted to explore and validate this novel finding.

Fundus photography as a convenient tool to study microvascular responses to cardiovascular disease risk factors in epidemiological studies

The microcirculation consists of blood vessels with diameters less than 150 µm. It makes up a large part of the circulatory system and plays an important role in maintaining cardiovascular health. The retina is a tissue that lines the interior of the eye and it is the only tissue that allows for a non-invasive analysis of the microvasculature. Nowadays, high-quality fundus images can be acquired using digital cameras. Retinal images can be collected in 5 min or less, even without dilatation of the pupils. This unobtrusive and fast procedure for visualizing the microcirculation is attractive to apply in epidemiological studies and to monitor cardiovascular health from early age up to old age. Systemic diseases that affect the circulation can result in progressive morphological changes in the retinal vasculature. For example, changes in the vessel calibers of retinal arteries and veins have been associated with hypertension, atherosclerosis, and increased risk of stroke and myocardial infarction. The vessel widths are derived using image analysis software and the width of the six largest arteries and veins are summarized in the Central Retinal Arteriolar Equivalent (CRAE) and the Central Retinal Venular Equivalent (CRVE). The latter features have been shown useful to study the impact of modifiable lifestyle and environmental cardiovascular disease risk factors. The procedures to acquire fundus images and the analysis steps to obtain CRAE and CRVE are described. Coefficients of variation of repeated measures of CRAE and CRVE are less than 2% and within-rater reliability is very high. Using a panel study, the rapid response of the retinal vessel calibers to short-term changes in particulate air pollution, a known risk factor for cardiovascular mortality and morbidity, is reported. In conclusion, retinal imaging is proposed as a convenient and instrumental tool for epidemiological studies to study microvascular responses to cardiovascular disease risk factors.

Association between diet quality with concurrent vision and hearing impairment in older adults

OBJECTIVES

Published literature shows that individual nutrients could influence the risk of developing vision and hearing loss. There is, however, a lack of population-based data on the relationship between overall patterns of food intake and the presence of concurrent vision and hearing impairment. We aimed to assess the associations between diet quality with the prevalence and 5-year incidence of dual sensory impairment (DSI).

DESIGN

Cross-sectional and 5-year longitudinal analyses.

SETTING

Blue Mountains, Sydney, Australia.

PARTICIPANTS

2443 participants aged ≥50 from baseline were examined and followed over 5 years.

MEASUREMENTS

Dietary data were collected using a semi-quantitative food frequency questionnaire. A modified version of the Healthy Eating Index for Australians was developed to determine total diet score (TDS). Visual impairment was defined as visual acuity less than 20/40 (better eye), and hearing impairment as average pure-tone air conduction threshold greater than 25 dB HL (500-4000 Hz, better ear).

RESULTS

After adjusting for age, sex, education, noise exposure, current smoking, and type 2 diabetes, participants in the lowest compared to the highest quintile of TDS had a 2-fold increased likelihood of having prevalent DSI, odds ratio, OR, 2.62 (95% confidence intervals, CI, 1.08-6.36), P-trend=0.04. Significant associations were not observed between TDS and the prevalence of having a single sensory impairment (vision or hearing loss). Baseline TDS was not significantly associated with the 5-year incidence of DSI. Adherence to dietary guidelines was associated with a reduced likelihood of having DSI in cross-sectional, but not in longitudinal analyses.

CONCLUSIONS

Further studies with adequate power are warranted to assess the prospective relationship between diet quality and DSI.