Figure 1

Retinal fundus photograph indicating vessels and zones of measurement. Figure 1 shows a retinal image centred on the optic disc. Line R indicates the optic disc radius, line B indicates the annulus 1 to 1.5 optic disc diameters from the centre of the optic disc (Zone B); line C indicates the annulus 1 to 2.5 disc diameters from the centre of the optic disc (Zone C). Zone B is the area of measurement for central retinal arteriolar equivalent and central retinal venular equivalent. Zone C is the area of measurement for fractal dimension. The dark and light lines in this greyscale reproduction indicate arterioles (light) and venules (dark) recognised by VAMPIRE vessel assessment software and corrected by a trained operator.