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Y. Zhang, L.–O. Atchaneeyasakul, T.J. McFarland, P. Wallace, K. Mose, D.J. Wilson, B. Appukuttan, J. Stout; Natural History and Retinal Pathology in a Rat Model of Retinal Vein Occlusion . Invest. Ophthalmol. Vis. Sci. 2006;47(13):506.
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© ARVO (1962-2015); The Authors (2016-present)
While induction of central retinal vein occlusion (CRVO) or branch retinal vein occlusion (BRVO) in the rat is a potentially informative model of human ischemic disease, current data is insufficient to construct an accurate and clear picture of this model’s natural course. The purpose of this study is to observe chronological changes in retinal venous occlusion and retinal pathology in a laser induced vein occlusion model.
To produce CRVO or BRVO in rat eye, thrombi were induced in all or half (temporal or nasal) of retinal branch veins with green laser irradiation of veins infused with rose bengal. Contralateral eyes acted as a non–lasered control. Fundus photography and fluorescein angiography (FA) were performed immediately after laser treatment and at 3, 6 hours and 2, 4, 7, 14 and 21 days after treatment. Retinal pathology/histology was examined at the 4, 7, 14 and 21 days and the number of retinal ganglion cell (RGC) was counted and compared.
For CRVO and BRVO extensive retinal edema was apparent 1 hour after treatment. Retinal hemorrhages and reperfusion of occluded branch veins were observed 1 to 2 days after treatment. Despite complete resolution of venous occlusion, retinal edema and hemorrhages peaked on day 4. After 14 days, affected retinas appeared pale and thin. Many atrophic plaques and yellow precipitates were observed at day 21. In BRVO model, retinal hemorrhage was limited to the vein–occluded region, however edema was not limited to the occluded area. For the CRVO group, significant decrease of retinal ganglion cells (RGCs) was observed at 14 and 21 days when counting whole retina (31%, 30% cell loss), and peripheral (36%, 27%) or para–optic retina (29%, 33%) (P<0.05). In the BRVO group, significant decrease of RGCs (P<0.05) was found at 21 days in whole retina (9.5% loss of cells), at 14 and 21 days in peripheral retina (14.5%, 18.4%) and no change in para–optic retina. However when comparing the lasered side to the unlasered side of same eye, there was no significant change in whole retina and para–optic retina, with the exception of a decrease (12.9%) at 21 days in peripheral retina.
In CRVO or BRVO rat model, vein occlusion persisted for 2–4 days, and retinal reaction (edema, hemorrhage) peaked at the 4th day after laser. Ischemia caused significant RGC loss in both models after 14 days, especially in peripheral retina of CRVO. Evaluation of electroretinogram and relation to the pathological findings is of interest.
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