Neovascularization in experimental retinal venous obstruction in rabbits.

Abstract Purpose: To investigate the later pathohistological changes in experimental retinal venous obstruction in rabbits. Methods: Experimental retinal venous obstruction was produced in retinal blood vessels of rabbits by trans-adventitial dropping of thrombin. Fundus observation was performed 3 months and 1 year thereafter. Retinal histological examinations were performed by fluorescein microscopy, light microscopy, and transmission electron microscopy. Results: Vessels with a rete mirabile and arteriovenous anastomosis were observed after 3 months. On a flat gelatin-fluorescein preparation, regions with no perfusion, thought to be areas of vascular occlusion in the periphery, were observed extensively. Clear leakage of gelatin-added fluorescein was noted from vessels in the periphery, and minute neovascularization with a rete mirabile from these vessels was confirmed. Newly formed retinal vessels were also observed by transmission electron microscopy. The endothelial cells of these newly formed vessels had a large nucleus, a number of ribosomes, and thin basement membrane. Proliferative changes included glial cells that had penetrated into the basement membrane of ghost vessels. Conclusion: Our long-term observations confirmed that proliferative changes and neovascularization occurred in this model of retinal venous obstruction.