Classification of central retinal vein occlusion.

Our prospective clinical study of 360 eyes with central retinal vein occlusion (CRVO) and our experimental studies on CRVO in 54 eyes of rhesus monkeys have shown that CRVO consists of the following two distinct entities: (1) Nonischemic CRVO in which there is essentially a stasis of retinal venous circulation; we call it venous stasis retinopathy (VSR). (2) Ischemic CRVO: We call this hemorrhagic retinopathy (HR). Our prospective clinical studies have revealed that it is absolutely essential to differentiate CRVO into VSR and HR because of their very different prognoses and management. VSR is a benign and self-limited condition, while HR is a severe, potentially blinding disorder. Lumping the two types of CRVO together as one disease has caused much confusion concerning the prognosis and management of CRVO. The basis of such a classification and differential diagnosis of VSR and HR is discussed at length.