Independent and Synergistic Effects of High Blood Pressure and Obesity on Retinal Vasculature in Young Children: The Hong Kong Children Eye Study

BACKGROUND: High blood pressure (BP) and obesity are becoming increasingly prevalent among children globally. Although prior studies have shown their adverse impacts on macrovascular health, less is known about their effects on microvascular heath. This study aims to evaluate the independent and synergistic effects of hypertensive BP and obesity on retinal vasculature in young children. METHOD AND RESULTS: 1006 children aged 6 to 8 years were recruited from the Hong Kong Children Eye Study. Quantitative retinal vascular parameters, including central retinal arteriolar and venular equivalents and retinal arteriolar and venular fractal dimensions, were measured from retinal photographs following a standardized protocol. BP and body mass index were categorized according to reference values from American Academy of Pediatrics and International Obesity Task Force guidelines respectively. Children with hypertensive systolic BP had the narrowest central retinal arteriolar equivalents compared with children with either elevated or normotensive systolic BP (162.4, 164.6, and 167.1 µm; P‐trend <0.001). Increased standardized systolic BP was associated with narrower central retinal arteriolar equivalents (β=−2.276 µm, P<0.001), wider central retinal venular equivalents (1.177, P=0.007), and decreased arteriolar fractal dimensions (β=−0.004, P=0.034). Children with obesity had the smallest arteriolar fractal dimensions compared with children with overweightness and normal weight (1.211, 1.234, and 1.240; P‐trend=0.004). Children with both hypertensive BP and either overweightness or obesity had the narrowest central retinal arteriolar equivalents and smallest arteriolar D(f) (P‐trend<0.001 and P‐trend=0.007). CONCLUSIONS: Our findings demonstrate the potential synergistic or additive effects for both hypertensive BP and obesity on retinal vasculature in children.