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FA is a valuable imaging tool in the assessment of DR and diabetic macular edema (DME). In particular, FA can highlight MAs, areas of nonperfusion, and neovascularization, as well as assess the integrity of the foveal avascular zone and macular edema. New vessels can be differentiated from intraretinal microvascular abnormalities as the latter do not leak (Fig. 14). Widefield angiography is now available on several commercially available devices (Fig. 15). The detection of DME using CFP has limited specificity as this modality relies on an indirect assessment based on the detection of loss of retinal transparency, hard exudates, and MAs near the fovea, albeit without appreciation of macular thickening. Incorporation of optical coherence tomography (OCT) has greatly improved the sensitivity and specificity of DME detection. On FA, however, DME can be readily identified in the presence of late leakage. In addition, identifying the origin of leakage (focal from MAs or diffuse), is essential to guide targeted focal laser treatment [14] (Fig. 16).

Fig. 14. Proliferative diabetic retinopathy. Ultrawide-field photography (a) and fluorescein angiography (b) showing preretinal hemorrhage, multiple areas of nonperfusion and neovascularization. On color photograph, an area of fibrosis and localized traction (arrows) can be seen in the superior retina. The view of the temporal retina is obscured by vitreous hemorrhage.

Fig. 15. Proliferative diabetic retinopathy with significant retinal nonperfusion. Montage of multiple 30° fluorescein angiography images can also provide information on the posterior pole as well as peripheral retina. Extensive areas of capillary nonperfusion, and areas of neovascularization can be seen in this eye.