Reliable monitoring system for arteriovenous ratio computation

The degree of narrowing or widening in retinal vessels related to several cardiovascular diseases such as hypertension or diabetes may be measured by the arteriovenous ratio (AVR), that is, the relation between the artery and vein retinal vessel widths. Nevertheless, its lack of reproducibility, due mainly to a laborious manual calculation and the dependence of the vessels selected for its estimation, hinders its use in daily medical practice. This variation makes difficult to monitor the patient's condition over time. This paper describes a reliable AVR monitoring system which computes automatically the AVR from several images of the same patient acquired at different times using the same vessels measured at the same points. The system has been evaluated in a large data set of 158 pairs of images and good correlation results between medical experts and the system have been achieved.