The cases of 310 patients with central retinal vein obstruction (CRVO) were reviewed. Included among these were 16 who presented with a nonischemic CRVO on fluorescein angiography that progressed to an ischemic CRVO. This subgroup was compared to a control group of 34 patients with a nonischemic CRVO that did not progress to the ischemic state with at least a one year follow-up. Among the eyes in the group that progressed, there was noted to be a higher incidence of initial visual acuity less than or equal to 6/30 (P = 0.005), severe macular edema (P = 0.021), and progressive intraretinal bleeding (P less than 0.0001) than in the control group. There was no significant difference between the groups in regard to age, sex, increased intraocular pressure, or systemic disease.