• Written By: Purnima S. Patel, MD

    This large prospective study found that ischemic and nonischemic central retinal vein occlusion (CRVO) differ markedly in their characteristics and natural history.

    The authors investigated retinal and optic disk changes in 562 consecutive patients with CRVO (492 nonischemic and 89 ischemic) seen within three months of onset at their clinic between 1973 and 2000.

    They found that retinal and sub-internal limiting membrane hemorrhages and optic disk edema in ischemic CRVO were initially more marked and took longer to resolve than in nonischemic CRVO. Macular edema also was more marked initially in ischemic CRVO but it did not significantly differ in resolution time.

    Furthermore, macular retinal epithelial pigment degeneration, serous macular detachment and retinal perivenous sheathing developed at a higher rate in ischemic CRVO, and ischemic CRVO patients also had more retinal venous engorgement.

    Fundus imaging showed significantly more fluorescein leakage, retinal capillary dilatation, capillary obliteration and broken capillary foveal arcade in ischemic CRVO than nonischemic CRVO, and CRVO resolution time was longer in ischemic cases.

    They write that the natural history of a disease always acts as the gold standard against which the effect of various therapies can be judged. To that end, they hope that these findings will serve as a reference for future therapeutic trials.