Fig. 4. Extensive capillary nonperfusion appearing as widespread vascular filling defects and enlargement of the foveal avascular zone. Microaneurysms and surrounding retinal edema appear as hyperfluorescence.

Fig. 5. Retinal neovascularization is characterized by dye leakage into the vitreous. Note multiple microaneurysms, blocking defect from preretinal hemorrhage, and diffuse pruning of the capillary tree.

Fluorescein Angiography in the Evaluation of Diabetic Macular Edema

FA findings in the macula can be organized into three patterns (7). Focal leakage results from microaneurysms and dilated capillary segments, and causes focal macular edema (Fig. 6). Late ill-defined leakage of fluorescein results from a generalized breakdown of inner blood–retinal barrier and causes diffuse macular edema (Fig. 7). Late staining of

Fig. 6. Focal leakage from microaneurysms and dilated capillary segments causes focal macular edema.

Fig. 7. Diffuse macular edema in late frames appears as ill-defined leakage of fluorescein from a generalized breakdown of inner blood retinal barrier.

fovea with pooling of the dye into parafoveal cyst-like spaces in a petalloid pattern is named cystoid macular edema (Fig. 8). These patterns may be found alone or concurrently. Due to the ability to visualize the source and/or area of leakage, FA is often used to guide focal or grid macular photocoagulation in the treatment of diabetic macular edema (28).