Table 2.

The differential diagnosis of ocular ischemic syndrome, diabetic retinopathy and central retinal vein occlusion [3,4].

	Ocular ischemic syndrome	Diabetic retinopathy	Central retinal vein occlusion
Age	50s to 80s	Variable	50s to 80s
Laterality	80% unilateral	Bilateral	Usually unilateral
Posterior segment signs
Retinal veins	Dilated but not tortuous	Dilated and beaded	Dilated and tortuous
Hemorrhages	Dot and blot, mid-periphery, in deeper retina layers	Dot, blot in deeper retina layers and flamme-shaped in in nerve fiber layer	Flamme-shaped in in nerve fiber layer
Microaneurysms	In midperiphery	In posterior pole	Variable
Hard exudates	Absent	Common	Rare
Optic disk	Normal	Diabetic papillopathy (rarely)	Swollen
Retinal arteria perfussion pressure	Decreased	Normal	Normal
Fluorescein angiography
Arterio-venous transie time	Prolonged	Usually normal	Prolonged
Choroidal filling	Delayed, patchy	Normal	Normal
Retinal vessel staining	Arteries > veins	Usually absent	Veins > arteries