The eye, the kidney & cardiovascular disease: old concepts, better tools & 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 endpoint 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 kidney suggest that non-invasive 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 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 remodelling and chorioretinal thinning. Clinical and pre-clinical OCT have linked retinal microvascular pathology to circulating and histological markers of injury within the kidney. The advent of OCT angiography allows contrast-free visualisation of intra-retinal 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.