Figure 2.3.

Retinal microvascular diameters. Figure 2.3 shows where retinal arteriolar and venular diameters can be assessed around the optic nerve. Red and blue color indicate the area on the fundus photo covered by an arteriole and venule, respectively, at 1 disk diameter from the optic nerve head. Retinal arteriolar and venular diameters are calculated as the average diameter of six arterioles or six venules, respectively.