Limitation of retinal injury by vitreoperfusion initiated after onset of ischemia. We tested whether vitreoperfusion, a new method of perfusing the vitreous cavity with solutions containing nutrients, can limit retinal injury if initiated after the onset of ischemia. Severe bilateral ocular ischemia was induced in cats with healed lensectomy-vitrectomy wounds; 30, 60, 90, or 120 minutes later, one eye from each of 18 cats underwent vitreoperfusion while the ischemia continued for 120 minutes. The other eye simultaneously underwent either continued untreated ischemia or reinstated circulation. The histopathologic abnormalities evident after 8 days depended on the duration of ischemia. Reinstated circulation yielded less retinal damage than continued ischemia. Nine additional cats underwent bilateral ischemia for at least 210 minutes. Vitreoperfusion was initiated in one eye after 30 minutes. In each cat, the vitreoperfused eye fared significantly better as observed histopathologically and electroretinographically. We believe that no other treatment has similarly limited retinal injury in vivo when initiated so long after total ocular ischemia has developed. 