Evaluation of retinal vessels: Retinography will be performed using a Topcon TRC NW 200 nonmydriatic retinal camera (Topcon Europe B.C., Capelle a/d Ijssel, The Netherlands), obtaining nasal and temporal images centered on the disk. The nasal image with the centered disk will be loaded into the developed software, AV Index calculator (Ciclorisk SL, Salamanca, Spain, registry no. 00/2011/589). The software automatically recognizes the disk and draws two external concentric circles which delimit area A, between 0 and 0.5 disk diameters from the optic disk margin, and area B, between 0.5 and 1 disk diameters from the margin. The software first identifies the limits of the different vessels, after which it automatically recognizes arteries and veins, and makes multiple measurements of the diameter of the section of the vessels circulating through area B. It finally estimates the mean caliber of veins and arteries in mm, and these measurements are summarized as an arteriole-venule ratio, AVIx. An AVIx of 1.0 suggests that arteriolar diameters will be on average the same as venular diameters in that eye, whereas a smaller AVR suggests narrower arterioles. We used the pairs of main vessels in the upper and lower temporal quadrants, rejecting all other vessels, to improve reliability and increase efficiency of the process, analyzing measures for each quadrant separately and together to estimate the mean measure in each eye. [64].