Age of retinal hemorrhages by iron detection: an animal model.

Intraretinal hemorrhages have been found in some abusively injured infants and children. Intraretinal hemosiderin has been proposed as an indication of previous injury. The limits of the accuracy of the proposal have not been established. Experimental central retinal vein occlusion (CRVO) was produced in 20 eyes of adult rhesus monkeys as part of ongoing research by one of the authors (SSH). The animal experiments were conducted in accordance with a research protocol approved by the Animal Care Committee, University of Iowa. CRVO produced diffuse intraretinal hemorrhages. Clinical ocular examinations assessed the onset and time course of retinal hemorrhages. Enucleation specimens were used to assess hemosiderin in the retinas. Hemosiderin was detected within 2 days of induction of retinal hemorrhages. It was detected in only 4 of 11 eyes (36%) studied more than 1 week following induction of hemorrhages. In 2 eyes, hemosiderin was found 9 and 16.8 months after development of hemorrhages. Hemosiderin can represent organization of current hemorrhage rather than evidence of prior hemorrhage. This study does not allow specifying the duration of hemorrhages with greater precision than "more than 2 days prior to death," and that, only if there is no survival interval. Failure to detect hemosiderin does not exclude prior retinal hemorrhages.