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S. Yang, S. Joe, J.-U. Whang, J. Kim, Y. Yoon; Effect of Intravitreal Bevacizumab to Normal Retina and Cnv After Photodynamic Therapy in a Rat Model of Choroidal Neovascularization. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4950.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate how Pre-injection of intravitreal bevacizumab affect normal retinal layer adjacent to choroidal neovascular membrane and CNV after photodynamic therapy (PDT) in a laser-induced rat model of choroidal neovascularization(CNV).
Two weeks after induction of CNV in Brown-Norway rats, we divided eyes of rat in 3 groups as following 1)bevacizumab pre-injection+PDT (Pre-Be group), 2) normal saline pre-injection+PDT(Pre-NS group), 3)bevacizumab injection immediately after PDT.(Si-Be group).PDT was performed 2 weeks after induction of CNV. In Pre-Be group, intravitreal injections of 100µg/4µl were performed 24 hours before PDT. In Pre-NS group, the same amount (4µl) of intravitreal normal saline was injected intravitreally 24 hours before PDT. In Si-Be group, 100µg/4µl of bevacizumab injection was performed intravitreally immediately after PDT.After enucleation, Hematoxylin-eosin and TUNEL staining were performed 3, 6, 12 and 24 hours after PDT. Five different eyes including CNV were examined in each group. We investigated the difference of verteporfin distribution with confocal microscope in Pre-Be and Pre-NS group 15 minutes after injection of verteporfin. And we also evaluated cleaved caspase 3 induction. The number of TUNEL-positive cells in retinal layer adjacent to CNV and CNV were counted and compared among 3 groups after 3, 6, 12 and 24 hours after PDT.
There was more verteporfin distribution in Pre-NS group than Pre-Be group in outer retinal layer.TUNEL-positive cells were seen in outer nuclear layer predominantly adjacent to CNVs. There were also TUNEL-positive cells in CNVs. TUNEL-positive cells increased until 24 hours after PDT in outer nuclear layer, whereas TUNEL-positive cells in CNV increased until 12 hours after PDT and decreased thereafter.The rate of TUNEL-positive cells in outer nuclear layer 12 and 24 hours after PDT was significantly lower in Pre-Be group (63%±9% and 68%±13%, respectively) than Pre-NS group (81%±7% and 83%±9%, respectively) and Si-Be group (81%±10% and 85%±14% respectively).The rate of TUNEL-positive cells in CNV was not significantly different among 3 groups. The signals of cleaved caspase-3 in outer nuclear layer increased at 3 hour after PDT and then decreased. There was more signal in Pre-NS group.
In treating CNV with anti-vascular endothelial growth factor (VEGF) combined with PDT, pre-injection of anti-VEGF before PDT can help reducing the damage to normal retinal layer adjacent to CNV.
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