Background:Chronic systemic inflammation in patients with ankylosing spondylitis (AS) contributes to the development of cardiovascular disease (CVD). Microvascular changes are thought to precede clinically overt CVD and its early recognition could improve timely treatment. The microvasculature of the retina and fingertips are easily accessible for non-invasive visualization. Furthermore, previous studies have shown an association between CVD and respectively retinal morphology and digital microvascular function (fingertips), in patients without rheumatic diseases. The retinal and digital vasculature could provide an unique opportunity to recognize early signs of CVD in aS patients.Objectives:To investigate whether retinal vascular parameters and digital microvascular function in aS patients are associated with the 10 year CVD risk.Methods:Cross-sectional study in aS patients (diagnosis according to modified New York criteria) between 50-75 years without a history of diabetes mellitus or cerebrovascular disease. Consecutive patients were recruited consecutively from the Rheumatology outpatient clinic of the amsterdam UMC, location VUmc and Reade. Patient characteristics, CVD (risk factors), disease duration/activity (ASDAS), C-reactive protein and lipid profile were assessed. The digital microvascular function (the reactive hyperemia index, RHI) was tested through endo Peripheral arterial Tone measurement at the finger tips (EndoPAT). Retinal vascular parameters were assessed through fundus photography, and identified with Singapore I Vessel assessment (SIVA) software: central retinal artery and vein equivalent (CRAE, CRVE), arteriovenous ratio (AVR), curvature tortuosity arterioles and venules (cTORTa, cTORTv), fractal dimension of arteries and venules (FrDiA, FrDiV). SIVA parameters were reported as continuous values. The Framingham risk score (FRS) was calculated and classified based on the 10 years CVD risk (low risk <10%, intermediate risk 10-20%, high risk >20%). Linear regression analyses were used to determine the association between the FRS categories and retinal parameters or digital microvascular function (RHI), correcting for age and disease duration.Results:Fifty-three aS patients were included (age 60±6 years, 55% female, 74% HLA-B27 positive, disease duration 35 years ±13, aSDAS 2.3±1.0). Fifty-five% was currently treated with NSAIDs and 47% with a TNF inhibitor. Based on the FRS, 36% had a high risk of CVD in the next 10 years, 42% an intermediate and 12% a low risk. In multivariable analyses, patients with an intermediate and high risk of CVD (FRS) had a significantly lower diameter of the central retinal artery (CRAE; p<0.01 for both risk groups) and arteriovenous ratio (AVR; only for high risk; p=0.03) as compared with patients with a low risk. There was no association between the RHI and the cardiovascular risk.Conclusion:This study suggests an association between the 10 years CVD risk and the morphology of the retinal arterial vessels in older aS patients (≥50 years). This is in accordance with...