Retinal microvascular signs and disability in the Cardiovascular Health Study

Transformative applications of oculomics-based AI approaches in the management of systemic diseases: A systematic review

BACKGROUND

Systemic diseases, such as cardiovascular and cerebrovascular conditions, pose significant global health challenges due to their high mortality rates. Early identification and intervention in systemic diseases can substantially enhance their prognosis. However, diagnosing systemic diseases often necessitates complex, expensive, and invasive tests, posing challenges in their timely detection. Therefore, simple, cost-effective, and non-invasive methods for the management (such as screening, diagnosis, and monitoring) of systemic diseases are needed to reduce associated comorbidities and mortality rates.

AIM OF THE REVIEW

This systematic review examines the application of artificial intelligence (AI) algorithms in managing systemic diseases by analyzing ophthalmic features (oculomics) obtained from convenient, affordable, and non-invasive ophthalmic imaging.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Our analysis demonstrates the promising accuracy of AI in predicting systemic diseases. Subgroup analysis reveals promising capabilities of oculomics-based AI for disease staging, while caution is warranted due to the possible overestimation of AI capabilities in low-quality studies. These systems are cost-effective and safe, with high rates of acceptance among patients and clinicians. This review underscores the potential of oculomics-based AI approaches in revolutionizing the management of systemic diseases.

Artificial intelligence in retinal imaging for cardiovascular disease prediction: current trends and future directions

PURPOSE OF REVIEW

Retinal microvasculature assessment has shown promise to enhance cardiovascular disease (CVD) risk stratification. Integrating artificial intelligence into retinal microvasculature analysis may increase the screening capacity of CVD risks compared with risk score calculation through blood-taking. This review summarizes recent advancements in artificial intelligence based retinal photograph analysis for CVD prediction, and suggests challenges and future prospects for translation into a clinical setting.

RECENT FINDINGS

Artificial intelligence based retinal microvasculature analyses potentially predict CVD risk factors (e.g. blood pressure, diabetes), direct CVD events (e.g. CVD mortality), retinal features (e.g. retinal vessel calibre) and CVD biomarkers (e.g. coronary artery calcium score). However, challenges such as handling photographs with concurrent retinal diseases, limited diverse data from other populations or clinical settings, insufficient interpretability and generalizability, concerns on cost-effectiveness and social acceptance may impede the dissemination of these artificial intelligence algorithms into clinical practice.

SUMMARY

Artificial intelligence based retinal microvasculature analysis may supplement existing CVD risk stratification approach. Although technical and socioeconomic challenges remain, we envision artificial intelligence based microvasculature analysis to have major clinical and research impacts in the future, through screening for high-risk individuals especially in less-developed areas and identifying new retinal biomarkers for CVD research.

The Influence of Coronary Heart Disease on Retinal Electrophysiological Examination (Full-field, Pattern and Multifocal Electroretinograms)

PURPOSE

To evaluate the influence of coronary heart disease (CHD) on retinal function using a battery of electrophysiological measures.

MATERIALS AND METHODS

We conducted a prospective pilot study comparing 34 patients with a confirmed diagnosis of CHD with 21 healthy participants. Further inclusion criteria were a decimal visual acuity (VA) of 0.8 or better and patient age between 40 and 80 years. All participants were divided into three groups according to the severity of CHD (1, 2 or 3 vessels involved) and one healthy control group. Testing was performed on one eye per patient, either selecting the eye with higher VA or, when equal, selecting randomly. The test procedure consisted of a pattern electroretinogram (ERG), a full-field ERG, a multifocal ERG and an ophthalmic screening examination.

RESULTS

Implicit times of the b-wave measured using scotopic full-field ERG were significantly prolonged in all CHD patient groups (p < .000). Thus, full-field ERG allowed clinicians to differentiate between healthy patients and those suffering from CHD. The multifocal ERG showed significantly different results concerning the amplitude density (p < .008) in each patient group compared with the control group. CHD had a significant impact on cone-pathway function, although the severity of CHD did not correlate with functional deficiencies of cone cells.

CONCLUSIONS

Confirmed coronary vascular diseases are correlated with macular cone and bipolar cell function, which can be detected by measuring electrophysiological retinal signals.

Optical Coherence Tomography Angiography in Type 1 Diabetes Mellitus. Report 4: Glycated Haemoglobin

The purpose of this study was to evaluate specifically the relationship between glycated haemoglobin (HbA1c) levels and retinal optical coherence tomography (OCT) and OCT angiography (OCTA) parameters in type 1 Diabetes Mellitus (DM). A total of 478 type 1 DM patients and 115 controls were included in a prospective OCTA trial (ClinicalTrials.gov NCT03422965). Subgroup analysis was performed for controls, no diabetic retinopathy (DM-no DR) and DR patients (DM-DR), and HbA1c levels. OCT and OCTA measurements were compared with HbA1c levels (current and previous 5 years). DM-no DR patients with HbA1c levels >7.5% showed lower VD than DM-DR and controls (20.16 vs. 20.22 vs. 20.71, p < 0.05), and showed a significant correlation between HbA1c levels and FAZc (p = 0.04), after adjusting for age, gender, signal strength index, axial length, and DM disease duration. DM-DR patients with HbA1c > 7.5% presented greater CRT than DM-no DR and controls (270.8 vs. 260 vs. 251.1, p < 0.05) and showed a significant correlation between HbA1c and CRT (p = 0.03). In conclusion, greater levels of HbA1c are associated with OCTA changes in DM-no DR patients, and with structural OCT changes in DM-DR patients. The combination of OCTA and OCT measurements and HbA1c levels may be helpful to identify patients at risk of progression to greater stages of the diabetic microvascular disease.

Insights into Systemic Disease through Retinal Imaging-Based Oculomics

Among the most noteworthy developments in ophthalmology over the last decade has been the emergence of quantifiable high-resolution imaging modalities, which are typically non-invasive, rapid and widely available. Such imaging is of unquestionable utility in the assessment of ocular disease however evidence is also mounting for its role in identifying ocular biomarkers of systemic disease, which we term oculomics. In this review, we highlight our current understanding of how retinal morphology evolves in two leading causes of global morbidity and mortality, cardiovascular disease and dementia. Population-based analyses have demonstrated the predictive value of retinal microvascular indices, as measured through fundus photography, in screening for heart attack and stroke. Similarly, the association between the structure of the neurosensory retina and prevalent neurodegenerative disease, in particular Alzheimer's disease, is now well-established. Given the growing size and complexity of emerging multimodal datasets, modern artificial intelligence techniques, such as deep learning, may provide the optimal opportunity to further characterize these associations, enhance our understanding of eye-body relationships and secure novel scalable approaches to the risk stratification of chronic complex disorders of ageing.

Association between Retinal Vascular Geometric Changes and Cognitive Impairment: A Systematic Review and Meta-Analysis

Background and Purpose

Previous studies have explored the association between retinal vascular changes and cognitive impairment. The retinal vasculature shares some characteristics with the cerebral vasculature, and quantitative changes in it could indicate cognitive impairment. Hence, a comprehensive meta-analysis was performed to clarify the potential relationship between retinal vascular geometric changes and cognitive impairment.

Methods

Relevant databases were scrupulously and systematically searched for retinal vascular geometric changes including caliber, tortuosity, and fractal dimension (FD), and for cognitive impairment. The Newcastle-Ottawa Scale was used to evaluate the methodological quality of included studies. RevMan was used to perform the meta-analysis and detect publication bias. Sensitivity analyses were also performed.

Results

Five studies that involved 2,343 subjects were finally included in the meta-analysis. The results showed that there was no significant association between central retinal artery equivalents (Z=1.17) or central retinal venular equivalents (Z=1.74) and cognitive impairment (both p>0.05). Similarly, no significant difference was detected in retinal arteriolar tortuosity (Z=0.91) and venular tortuosity (Z=1.31) (both p>0.05). However, the retinal arteriolar FD (mean difference: −0.03, 95% CI: −0.05, −0.01) and venular FD (mean difference: −0.03, 95% CI: −0.05, −0.02) were associated with cognitive impairment.

Conclusions

A smaller retinal microvascular FD might be associated with cognitive impairment. Further large-sample and well-controlled original studies are required to confirm the present findings.

Retinal Vascular Changes and Prospective Risk of Disabling Dementia: the Circulatory Risk in Communities Study (CIRCS)

AIM

To investigate the association of retinal vascular changes with a risk of dementia in longitudinal population-based study.

METHODS

We performed a nested case-control study of 3,718 persons, aged 40-89 years, enrolled between 1983 and 2004. Retinal vascular changes were observed in 351 cases with disabling dementia (average period before the onset, 11.2 years) and in 702 controls matched for sex, age, and baseline year. Incidence of disabling dementia was defined as individuals who received cares for disabilities including dementia-related symptoms and/or behavioral disturbance. Conditional logistic regression analysis was used to calculate odds ratio (OR) and multivariable adjusted OR (Models 1 and 2) for incidence of disabling dementia according to each retinal vascular change. Regarding confounding variables, Model 1 included overweight status, hypertension, hyperglycemia, dyslipidemia, and smoking status, whereas Model 2 also included incidence of stroke prior to disabling dementia for further analysis.

RESULTS

The proportion of cases (controls) with retinal vascular changes was 23.1 (15.7)% for generalized arteriolar narrowing, 7.7 (7.5)% for focal arteriolar narrowing, 15.7 (11.8)% for arteriovenous nicking, 10.5 (9.3)% for increased arteriolar wall reflex, and 11.4 (9.8)% for any other retinopathy. Generalized arteriolar narrowing was associated with an increased risk of disabling dementia: crude OR, 1.66 (95% confidence interval, 1.19-2.31); Model 1: OR, 1.58 (1.12-2.23); Model 2: OR, 1.48 (1.04-2.10). The number of retinal abnormalities was associated in a dose-response manner with the risk.

CONCLUSION

Generalized arteriolar narrowing and total number of retinal abnormalities may be useful markers for identifying persons at higher risks of disabling dementia.

Associations between retinal microvascular changes and dementia, cognitive functioning, and brain imaging abnormalities: a systematic review

Retinal microvascular changes can be visualized noninvasively and have been associated with cognitive decline and brain changes in relation to aging and vascular disease. We systematically reviewed studies, published between 1990 and November 2012, on the association between retinal microvascular changes and dementia, cognitive functioning, and brain imaging abnormalities, in the context of aging and vascular risk factors. In cross-sectional studies (k=26), retinal microvascular changes were associated with the presence of dementia (range of odds ratios (ORs) 1.17;5.57), with modest decrements in cognitive functioning in nondemented people (effect sizes -0.25;0.03), and with brain imaging abnormalities, including atrophy and vascular lesions (ORs 0.94;2.95). Longitudinal studies were more sparse (k=9) and showed no consistent associations between retinal microvascular changes and dementia or cognitive dysfunctioning 3 to 15 years later (ORs and hazard ratios 0.77;1.55). However, there were indications of prospective associations with brain imaging abnormalities ((ORs) 0.81;3.19). In conclusion, particularly in cross-sectional studies there is a correlation between retinal microvascular changes and dementia, cognitive impairment, and brain imaging abnormalities. Associations are strongest for more severe retinal microvascular abnormalities. Retinal microvascular abnormalities may offer an important window on the brain for etiological studies.

Relation of pulse pressure to long-distance gait speed in community-dwelling older adults: findings from the LIFE-P study

Background

Reduced gait speed is associated with falls, late-life disability, hospitalization/institutionalization and cardiovascular morbidity and mortality. Aging is also accompanied by a widening of pulse pressure (PP) that contributes to ventricular-vascular uncoupling. The purpose of this study was to test the hypothesis that PP is associated with long-distance gait speed in community-dwelling older adults in the Lifestyle Interventions and Independence for Elders Pilot (LIFE-P) study.

Methods

Brachial blood pressure and 400-meter gait speed (average speed maintained over a 400-meter walk at “usual” pace) were assessed in 424 older adults between the ages of 70–89 yrs at risk for mobility disability (mean age = 77 yrs; 31% male). PP was calculated as systolic blood pressure (BP) – diastolic BP.

Results

Patients with a history of heart failure and stroke (n = 42) were excluded leaving 382 participants for final analysis. When categorized into tertiles of PP, participants within the highest PP tertile had significantly slower gait speed than those within the lowest PP tertile (p<0.05). Following stepwise multiple regression, PP was significantly and inversely associated with 400-meter gait speed (p<0.05). Other significant predictors of gait speed included: handgrip strength, body weight, age and history of diabetes mellitus (p<0.05). Mean arterial pressure, systolic BP and diastolic BP were not predictors of gait speed.

Conclusions

Pulse pressure is associated long-distance gait speed in community-dwelling older adults. Vascular senescence and altered ventricular-vascular coupling may be associated with the deterioration of mobility and physical function in older adults.