Novel Retinal Imaging in Assessment of Cardiovascular Risk Factors and Systemic Vascular Diseases

The eye is the only organ that allows direct visualization of the systemic neuro-vasculature using non-invasive imaging modalities, providing invaluable microstructural changes that often precede the macrovascular diseases such as stroke and ischaemic heart diseases. Using computer-aided analysis, wider retinal venules and narrower arterioles were found to be associated with an increased risk of cardiovascular diseases (CVD). For chronic kidney disease, narrower retinal arteriolar calibre, smaller retinal vascular fractal dimensions, arteriovenous nicking and opacification were significantly associated with lower estimated glomerular filtration rate, microalbuminuria and higher albumin/creatinine ratio. More recently, the use of artificial intelligence (AI) using deep learning was shown to have promising results in detecting age, gender, systolic blood pressure and smoking status from the fundus photographs. The same AI system also had comparable area under curve to the conventional risk calculators in predicting 5-year cardiovascular risks. Lastly, optical coherence tomography (OCT), with and without angiography, is also an effective imaging modality to evaluate the CVDs. Diabetic patients had thinner retinal nerve fibre layer. OCT angiographic changes may serve as markers of diabetes even in the absence of typical retinal changes. Future research is important to explore incorporating some of these parameters into the calculation and prognostication of the long-term cardiovascular risk outcome.