Figure 3.

Retinal vascular network geometric indices. Retinal photographs (left panels) of the left eye taken using the Canon CR-1 fundus camera (Canon Inc., Tokyo, Japan) with a field of view of 45° in (a) a healthy volunteer and (b) a patient with chronic kidney disease (CKD). Arterial and venous branches are binarized and segmented (middle panels) before being transformed into vessel (arterial) skeleton maps (right panels) for fractal dimension (Df) analyses. The vessel segmentation and skeleton maps demonstrate retinal vessel rarefaction in CKD compared with health, which is not evident from the standard retinal photographs; health Df_arteries = 1.47 and CKD Df_arteries = 1.18. Retinal photographs and segmentation images used under Creative Commons license from https://www5.cs.fau.de/research/data/fundus-images/. Vessel skeleton map images kindly provided by Stephen Hogg (VAMPIRE group, University of Dundee, Dundee, UK). To optimize viewing of this image, please see the online version of this article at www.kidney-international.org.