Abstract:AIM: To induce a rat model of retinal vein occlusion (RVO) by photosensitizer erythrosin B and to observe temporal changes in retinal physiology and histology in the laser-induced model. METHODS: Ophthalmoscopy, fundus photography, and fluorescein angiography (FA) were performed following laser-induced central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) immediately after laser treatment and at 1 hour and 3 hours and 1 day,2, 4, 7, 14 and 21 days. Retinal histology was examined at 7, 14 and 21 days. RESULTS: For CRVO and BRVO, reperfusion of occluded branch veins was observed 7 days after treatment. Retinal edema and hemorrhages peaked on day 4, and by day 14, treated retinas appeared pale and yellow precipitate was observed by day 21 for CRVO upon ophthalmoscopy. In BRVO rats, retinal hemorrhages were limited to the vein-occluded region, although edema was more widespread and, to a limited extent, involved the untreated hemi-retina. Significant ganglion cell layer (GCL) cell loss was observed in both CRVO and BRVO groups after day 14. CONCLUSION: Laser-induced RVO in rats resulted in targeted vascular occlusion that persisted for 7 days. Significant GCL cell loss was seen within whole retina of both CRVO and BRVO model. This reproducible model provides a valuable tool for the study of the molecular events associated with retinal ischemia and cell death.