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In eyes with retinal vein occlusion, FA can be used to confirm the site of occlusion, detect macular edema, and determine if there is macular or peripheral ischemia (Fig. 7, 17, 18). New vessels can be differentiated from collaterals as the latter do not leak. Widefield FA may identify areas of peripheral nonperfusion not readily visible on standard FA, and help guide laser treatment to ischemic areas (Fig. 19).

Fig. 16. Diabetic macular edema (DME). Microaneurysms and hard exudates can be seen within the macula on color photograph (a). The early-phase fluorescein angiogram (b) showed multiple microaneurysms and masking from blot hemorrhages. The foveal avascular zone appears relatively intact despite DME. Diffuse leakage is confirmed in the late-phase angiogram (c).

Fig. 17. Nonischemic central retinal vein occlusion. Widespread flame and blot hemorrhages as well as venous congestion can be seen on the color photograph (a). On the early-phase fluorescein angiogram (b), arteriole filling can be seen at 9 s. However arteriolar-venous filling was prolonged. Lamellar flow can still be seen within the retinal veins at 21 s (c). Foveal avascular zone was preserved. In the 6-min frame (d), staining of the optic disc and the superotemporal vein can be seen, but there was no significant macular edema.

Fig. 18. Central retinal vein occlusion with macular ischemia. Scattered flame and blot hemorrhages can be seen on the color photograph (a). On the early-phase fluorescein angiogram (b), the foveal avascular zone appears enlarged and irregular. On the late-phase angiogram (c), a large area of nonperfusion is evident extending from the fovea towards the temporal retina. Staining of the optic disc and retinal veins can also be seen.

Fig. 19. Peripheral retinal nonperfusion secondary to superotemporal branch retinal vein occlusion. The superotemporal branch retinal vein is occluded beyond the arteriovenous crossing (arrow). No significant abnormality can be seen in the posterior pole. However, blot hemorrhages can be seen in the far periphery (a). Peripheral retinal nonperfusion can be seen in the corresponding location on the ultrawide-field fluorescein angiogram (b). Photocoagulation was performed targeting the areas of nonperfusion (c).

Fig. 20. Occlusive retinal vasculitis secondary to systemic lupus erythematosus. Early-phase fluorescein angiogram (a) showing pruning of peripheral vessels and extensive area of nonperfusion in the peripheral retina. Late-phase image (b) shows diffuse leakage indicating active vasculitis.

Other retinal vascular diseases in which FA is useful include retinal vasculitis (Fig. 20), Coat's disease (Fig. 21), Eales' disease (Fig. 22), radiation retinopathy (Fig. 23), and retinal angioma. In order to acquire the most relevant information, very early transit-phase images are particularly important for investigating choroidal circulation, retinal arteriolar occlusion, and cilioretinal artery perfusion. For evaluation of peripheral areas, peripheral images should be taken in order to produce a montage. Alternatively, UWF angiography can provide information on up to 200° of view in a single image.