Smartphone-enabled retinal arteriovenous imaging and correlation with coronary SYNTAX score

OBJECTIVE: To assess the feasibility of measurement of retinal arteriovenous (AV) ratio using a smartphone, we performed a comparative evaluation with fundus camera imaging and coronary SYNTAX score. METHOD: Successive coronary artery disease (CAD) patients who underwent coronary angiography were recruited for smartphone retinal imaging. Following pupillary dilatation, fundus camera images and smartphone photography were performed. Video images were captured with a smartphone, edited and analysed. Retinal artery and vein size at 0.5 and 1 disc diameter (DD) were measured using DICOM software by two independent observers. Another observer calculated SYNTAX score. RESULTS: Analysable smartphone images were available in 91 (89.2%) of 102 patients. Tobacco use was found in 26%, hypertension in 54%, diabetes in 55%, and high LDL cholesterol in 50%. Median and 25–75 interquartile range (IQR) AV ratio at 0.5 and 1.0 DD, respectively, with smartphone were 0.48 (0.45–0.52) and 0.47 (0.45–0.52) and fundus camera were 0.48 (0.44–0.53) and 0.48 (0.45–0.53) (Spearman's correlation 0.80 and 0.79, p < 0.001). Coronary single vessel disease was in 21%, double vessel in 16%, triple vessel in 55%, normal angiogram in 8%, and median SYNTAX score was 18.0 (8.0–25.0). There was an inverse correlation of SYNTAX score with smartphone-derived AV ratio at 0.5 and 1.0 DD (rho −0.27,p = 0.007 and −0.26,p = 0.009) as well as with fundus camera (rho −0.37 and −0.38, p < 0.001). Trend-analysis showed an inverse association of smartphone AV ratio with increasing CAD (p(trend) <0.001). CONCLUSIONS: Smartphone-based retinal AV imaging is feasible and comparable to fundus-camera imaging. There is a significant inverse correlation with coronary angiographic severity.