Screening for hypertension using retinal vascular calibre in ultra-widefield fundus imaging

Introduction: Changes to the retinal vasculature are associated with hypertension independently of traditional risk factors. We investigated whether measurements of retinal vascular calibre from ultra-widefield fundus imaging are associated with hypertensive status. Methods: We automatically measured a sub-set of ultra-widefield retinal fundus images from subjects enrolled in the Northern Ireland Cohort of Longitudinal Ageing (School of Medicine, Dentistry and Biomedical Sciences Ethics Committee, Queen’s University Belfast, SREC 12/23). Subjects were categorised as normotensive or hypertensive, according to thresholds on systolic/diastolic blood pressure measurement (140/90 mm Hg) averaged over two sitting blood pressure measurements in a clinical setting. Vascular calibre in the peripheral retina was measured to calculate the nasal-annular arteriole-venule ratio (NA-AVR), a novel summative parameter. Results: Left eyes were analysed from 431 subjects (age range 50–59 years; mean age of 54.5 ± 2.8 years; 239 (55.5%) females), with 148 (34.3%) subjects categorised as hypertensive. Using a two-sample t-test, arterioles were thinner (p<0.005, 95% confidence interval [CI], -0.009mm, -0.004mm) and NA-AVR was smaller (p<0.005, 95% CI, -0.08, -0.04) in subjects with hypertension. The area under a receiver operator characteristic curve of NA-AVR for hypertensive status was 0.67 (95% CI, 0.61 to 0.72). Conclusions: In this study, automated measurement of NA-AVR in ultra-widefield fundus imaging was associated with hypertension. With further development, this could become a test for undiagnosed hypertension in people attending routine eye health check-ups.