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K. Matsuyama, N. Ogata, N. Jo, M. Wada, C. Shima, M. Matsuoka, M. Matsumura; Levels of Vascular Endothelial Growth Factor and Pigment Epithelium-Derived Factor in Human Eyes Before and After Intravitreal Injection of Bevacizumab. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5587.
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Vascular endothelial growth factor (VEGF), a strong angiogenic factor, has been implicated in the development of retinal neovascularization in diabetic retinopathy. Bevacizumab (Avastin) is a recombinant human monoclonal IgG1 antibody that inhibits human VEGF. Pigment epithelium-derived factor (PEDF) is an anti-angiogenenic factor that has been suggested to act as an inhibitor of VEGF function. The purpose of this study was to determine the level of VEGF and PEDF in the eye before and after an intravitreal injection of bevacizumab, and also to evaluate the effects of the intravitreal bevacizumab on PDR.
9 eyes of 8 patients were studied. Patients were included if they had neovascular glaucoma, rubeosis of the iris and/or angle structures with PDR, or aggressive PDR. Samples of aqueous humor were collected immediately before the intravitreal injection of bevacizumab and just before the vitrectomy. The concentrations of VEGF and PEDF in the aqueous humor were measured by ELISA, and the effects of intravitreal bevacizumab on PDR were evaluated.
The VEGF concentrations in the aqueous humor before the intravitreal injection of bevacizumab was 674.9 ± 228.5 pg/ml (mean ± SEM, n=9). Seven days later, it was significantly reduced at 8.0 ± 7.5 pg/ml (P = 0.005, n=8). All patients had a marked regression of the neovascular vessels after the injection at 7 days. Even 8 weeks after the injection of bevacizumab, the VEGF level was still lower than that of initial level when PRP was performed (320 to 0 pg/ml, n=1). On the other hand, the PEDF concentrations in the aqueous humor before the intravitreal injection of bevacizumab was 2.5 ± 0.6 µg/ml (mean ± SEM, n=9). Seven days later, it was 3.5 ± 0.8µg/ml. The difference of PEDF levels before and after the injection of bevacizumab was not significant (P = 0.20). During the vitrectomy, all patients had less intraoperative bleeding when the neovascular tissues were cut.
The significant decrease of VEGF in the aqueous humor at 7 days indicates that bevacizumab acts quickly, and intravitreal bevacizumab may have an adjtunctive role in the surgical treatment of PDR. However, intravitreal bevacizumab did not affect the level of intraocular PEDF.
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