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G. Levi, T. Holmes, A. Invernizzi, C. Veronese, C. Rosina, E. Hermesmeyer, G. Staurenghi; Blood Flow Modification in Feeder Vessels After Intravitreal Injection of Bevacizumab (Avastin). Invest. Ophthalmol. Vis. Sci. 2008;49(13):321.
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To evaluate feeder vessels blood flow modification after intravitreal injection of Bevacizumab (Avastin) in patients with neovascular AMD.
11 eyes of 11 patients suffering with subfoveal neovascularization with evident feeder vessel were treated with intravitreal injection of bevacizumab (1.25mg). At baseline and 30 days after injection patients underwent ETDRS visual acuity examination and dynamic indocyanine green and fluorescein angiography using a confocal scanning laser ophtalmoscope (Heidelberg HRA, Heidelberg Engineering, Heidelberg, Germany). Thirty days after treatment we evaluated visual acuity changes using ETDRS visual acuity examination and vascular changes using aa prototype software package (developed by Lickenbrock Technologies, LLC). The software contains both interactive and automatic measurements of fill time and dye intensity to analyze blood-flow characteristics within the vessels.
Thirty days after bevacizumab treatment: 5 patients had stable visual acuity and 6 had improvement of visual acuity. In all 11 patients fluorescein angiography showed no difference before and after the treatment, but dynamic ICG angiography pre and post treatment showed important differences. These differences were confirmed by two trained observers, trained in observing blood flow and velocity of filling reduction in feeder vessel. The new software allow us to see changes in intensity at precise relative times before and after treatment, in the feeder vessels. We chose one point on the feeder vessel in a precise frame of the movie (dynamic indocyanine green angiography). We compared the before and after the treatment. The difference of intensity was statistically significant (P< 0.001).
In our cases we observed a new way of action of Bevacizumab. Our observation was objective by the use of a new software package. The hemodynamic changes (fill time and peak fluorescence intensity) we observed should be another parameter for evaluation of responce to anti-VEGF therapy. The visual acuity improvement or stability may be related to the observed hemodinamic changes. From a phatogenetic point of view these changes may be related to the a relationship between VEGF and Nitric Oxide (NO).VEGF induce activation of endothelial NO synthase with consequent increase of NO and vasodilatation. Anti-VEGF drugs stop this process and induce vasocostriction and stenosis. Further studies are needful to evaluate these previous observations.
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