Preretinal Neovascularization by Laser-induced Thrombosis in Albino Rats and Inhibition of Neovascularization by Genistein

PURPOSE: To determine the effect of genistein, an inhibitor of protein tyrosine kinase, on preretinal neovascularization through the quantification of retinal neovascularization using image analyzer in an experimental rat model. METHODS: In 36 eyes of 36 rats, retinal vein occlusion was induced by photodynamic therapy with an argon green laser and systemic injection of rose bengal (40 mg/kg). The development and progression of retinal neovascularization was followed weekly by fluorescein angiography. Seven rats were sacrificed each week, after which two eyes were prepared with H and E staining for histologic examination, and five were prepared as a control group using ADPase staining for neovascularization analysis. In the remaining fifteen eyes, retinal vein occlusion was also induced using the same method. Immediately after vein occlusion, 4.0 mg of genistein dissolved in dimethyl sulfoxide (DMSO) was injected intraperitoneally twice a day for the first 7 days. Five rats were sacrificed each week and stained with ADPase. After ADPase staining, those samples with evidence of neovascularization were quantified using an image analyzer. RESULTS: No retinal neovasularizaion was found at the end of the first week. The size of retinal neovascularization for the five eyes sacrificed at the end of week 2 and 3 were 6.53+/-2.11 mm2 and 3.77+/-3.51 mm2 in the control group, and 2.22+/-1.01 mm2 and 1.64+/-0.88 mm2 in the genistein treatment group, respectively. Retinal neovascularization was successfully suppressed until two weeks after laser treatment by genistein in this rat neovascularization model. CONCLUSIONS: Genistein may be a useful treatment modality to suppress retinal neovascularization complicated with retinal ischemic injury.

The Relationship between the Capillary Nonperfusion Area and the Retinal Nerve Fiber Layer Defects in Branch Retinal Vein Occlusion Patients

PURPOSE: To determine the relationship between the capillary nonperfusion area and the retinal nerve fiber layer (RNFL) defects in branch retinal vein occlusion (BRVO) patients. METHODS: We compared the difference between the RNFL thickness of both eyes in unilateral BRVO patients using the scanning laser polarimeter (GDx R ). The mean RNFL thickness was calculated for each quadrant. Fluorescein angiography was done to determine the retinal capillary nonperfusion area and we evaluated the relationship between the retinal capillary nonperfusion area and the right-left difference of RNFL thickness. RESULTS: In left superior temporal BRVO group, the Average of RNFL was thinner (p=0.015) and the Integral was smaller (p=0.045) in the left BRVO eye than in the right normal eye in the superior temporal sector. In patients with the other sector BRVO, there was no significant difference of RNFL thickness between both eyes. As the retinal capillary nonperfusion area increased, the right-left difference of Average increased in the superior temporal sector in patients with left superior temporal BRVO (p=0.042). CONCLUSIONS: The scanning laser polarimeter allowed the quantification of RNFL defect in patients with BRVO, and it may help to evaluate the quantification of retinal ischemia.

Mechanism of Tissue Injury in Experimental Retinal Artery Occlusion: Morphological Study I

We used an animal model of laser-induced retinal artery occlusion to study the temporal and spatial patterns of tissue injury and to identify apoptosis-like morphologic changes.We performed fundus exam and fluorescein angiography for 2 weeks.Rats were sacrificed at 6 hours, 12 hours, 1 day, 2 days, 3 days, 7 days, and 14 days after arterial occlusion.The arterial reperfusion was seen from 6 hours to 4 days.We could observe vascular tortuosity and retinal hemorrhage in the fundus.Six hours after retinal arterial occlusion, there were a lot of cells which had chromatin condensation.One to three days membrane budding and apoptotic body were identifed after occlusion.Most of inner retinal layers were destroyed following 7days.These data demonstrated that retinal artery occlusion induces apoptotic cell death in the retinal ganglion cell and inner nuclear layer.

Apoptotic Cell Death in Experimental Retinal Vein Occlusion

We used an animal model of laser-induced retinal vein occlusion to study the temporal and spatial patterns of neuronal necrosis and apoptosis. After photodynamic retinal vein thrombosis with argon-green laser, rats were sacrificed at 6 hours, 12 hours, 1 day, 2 days, 3 days, 5 days, 7 days, and 14 days after vein occlusion. The temporal and spatial patterns of neuronal cell death were determined using light and electron microscopy, TdT-dUTP nick-end labeling[TUNEL]and DNA gel electrophoresis. The cells in retinal ganglion cell layer and inner nuclear layer showed both necrotic and apoptotic changes 12 hours after vein occlusion. The TUNEL positivity were detected at day 1 after vein occlusion and the number of positive cell increased until day 2, and decreased thereafter. DNA ladder pattern was observed 48 hours after vein occlusion by DNA gel electrophoreisis. These data demonstrated that retinal vein occlusion induces necrosis and apoptosis in the retinal ganglion cell and inner nuclear layer.

Apoptotic Cell Death in Experimental Retinal Vein Occlusion

We used an animal model of laser-induced retinal vein occlusion to study the temporal and spatial patterns of neuronal necrosis and apoptosis. After photodynamic retinal vein thrombosis with argon-green laser, rats were sacrificed at 6 hours, 12 hours, 1 day, 2 days, 3 days, 5 days, 7 days, and 14 days after vein occlusion. The temporal and spatial patterns of neuronal cell death were determined using light and electron microscopy, TdT-dUTP nick-end labeling[TUNEL]and DNA gel electrophoresis. The cells in retinal ganglion cell layer and inner nuclear layer showed both necrotic and apoptotic changes 12 hours after vein occlusion. The TUNEL positivity were detected at day 1 after vein occlusion and the number of positive cell increased until day 2, and decreased thereafter. DNA ladder pattern was observed 48 hours after vein occlusion by DNA gel electrophoreisis. These data demonstrated that retinal vein occlusion induces necrosis and apoptosis in the retinal ganglion cell and inner nuclear layer.