Retinal Microvascular Abnormalities Correlate with Raised Risk of Mortality
Given that there are several aging clocks built on machine learning based analyses of retinal images, it shouldn't be too surprising to find that specific aspects of aging in the retinal microvasculature can be correlated the old-fashioned way with an increased risk of mortality. As researchers note here, the small vessels of the body and brain are prone to clearly identifiable forms of structural damage that result from processes associated with aging. This damage is only easily viewed in the retina, however.
The retinal arteriole has similar anatomical and physiological features to cerebral and coronary circulations. Given that retinal vessels can be easily and noninvasively observed, they can be used to monitor microvascular health status in vivo. Retinal microvascular abnormalities (RMA), including retinopathy, generalized or focal arteriolar narrowing (FAN), arteriovenous nicking (AVN), and Hollenhorst plaque (HP), are common in older persons, even in those without diabetes. These findings reflect cumulative vascular damage from hypertension, aging, and other biological processes and are hypothesized to serve as potential markers for cardiovascular diseases (CVD).
This study aimed to examine the relationships between RMA and the risk of all-cause and specific-cause mortality among U.S. adults. 5,775 individuals aged ≥ 40 years were included from the U.S. National Health and Nutrition Examination Survey, 2005-2008. RMA and its subtypes were manually graded from retinal photographs. Associations between RMA and the risk of all-cause and cause-specific mortality were examined with Cox regression analysis.
RMA were present in 1,251 participants (weighted, 17.9%), of whom 710 (weighted, 9.8%) had retinopathy, 635 (weighted, 9.3%) had AVN, 64 (weighted, 1.0%) had FAN, and 21 (weighted, 0.3%) had HP. During a median of 12.2 years of follow-up, 1,488 deaths occurred, including 452 associated with cardiovascular disease (CVD), 341 associated with cancer, and 695 associated with other causes. After adjusting confounding factors, the presence of any RMA and retinopathy at baseline was associated with higher risk of all-cause mortality (hazard ratios 1.26 and 1.36 respectively), CVD mortality (hazard ratios 1.36 and 1.53 respectively) and other-cause mortality (hazard ratios 1.33 and 1.55 respectively). Additionally, FAN was significantly associated with an increased risk of other-cause mortality (hazard ratio 2.06). Although AVN was not associated with mortality in the whole population, it was significantly related to higher risks of all-cause and CVD death in those with obesity (hazard ratios 1.68 and 1.96 respectively).