The results clearly show that the bevacizumab molecule can penetrate the retina and is also transported into the retinal pigment epithelium, the choroid and, in particular, into photoreceptor outer segments after intravitreal injection of Avastin. Active transport mechanisms seem to be involved.

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Aim: To evaluate the antiproliferative and cytotoxic properties of bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF), on human retinal pigment epithelium (ARPE19) cells, rat retinal ganglion cells (RGC5), and pig choroidal endothelial cells (CEC). Methods: Monolayer cultures of ARPE19, RGC5, and CEC were used. Bevacizumab (0.008-2.5 mg/ml), diluted in culture medium, was added to cells that were growing on cell culture dishes. Cellular proliferative activity was monitored by 59-bromo-29-deoxyuridine (BrdU) incorporation into cellular DNA and the morphology assessed microscopically. For cytotoxicity assays ARPE19, RGC5, and CEC cells were grown to confluence and then cultured in a serum depleted medium to ensure a static milieu. The MTT test was performed after 1 day. The ''Live/Dead'' viability/cytotoxicity assay was performed and analysed by fluorescence microscopy after 6,12,18,24, 30, 36, and 48 hours of incubation. Expression of VEGF, VEGF receptors (VEGFR1 and VEGFR2) and von Willebrand factor was analysed by immunohistochemistry. Results: No cytotoxicity of bevacizumab on RGC5, CEC, and ARPE19 cells could be observed after 1 day. However, after 2 days at a bevacizumab concentration of 2.5 mg/ml a moderate decrease in ARPE19 cell numbers and cell viability was observed. Bevacizumab caused a dose dependent suppression of DNA synthesis in CEC as a result of a moderate antiproliferative activity (maximum reduction 36.8%). No relevant antiproliferative effect of bevacizumab on RGC5 and ARPE19 cells could be observed when used at a concentration of 0.8 mg/ml or lower. CEC and ARPE 19 cells stained positively for VEGF, VEGFR1, and VEGFR2. More than 95% of the CEC were positive for von Willebrand factor. Conclusions: These experimental findings support the safety of intravitreal bevacizumab when used at the currently applied concentration of about 0.25 mg/ml. Bevacizumab exerts a moderate growth inhibition on CEC when used in concentrations of at least 0.025 mg/ml. However, at higher doses (2.5 mg/ml) bevacizumab may be harmful to the retinal pigment epithelium.

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ABSTRACT.Purpose: We aimed to evaluate the longterm effects of intraocular bevacizumab (Avastin Ò ) injections as adjuvant treatment in patients with neovascular glaucoma. Methods: Twenty eyes of 18 consecutive patients with secondary neovascular glaucoma caused by proliferative diabetic retinopathy (n = 7), ischaemic central retinal vein occlusion (n = 7), ischaemic ophthalmopathy (n = 2) and retinal ischaemia resulting from persistent detachment (n = 2) were treated with intraocular bevacizumab injections (1.25 mg ⁄ 0.05 ml) in addition to other treatments. The main outcome measure was the change in degree of iris rubeosis. Secondary outcomes included intraocular pressure (IOP), best corrected visual acuity (BCVA) and numbers of additional interventions or antiglaucoma medications administered after injection. Results: Mean (± standard deviation) follow-up was 67.7 ± 13.8 weeks (range 50-93 weeks). At the last follow-up, complete regression of rubeosis was detectable in five (20%) eyes, incomplete regression in seven (35%), stabilization in six (30%), and an increase in two (10%) eyes. Mean IOP was 26.0 ± 8.9 mmHg at baseline and significantly decreased to 14.75 ± 5.3 mmHg at the last follow-up visit (p = 0.000005). Mean baseline BCVA (logMAR [logarithm of the minimum angle of resolution] 1.43 ± 0.89) was stabilized during the follow-up period (logMAR 1.5 ± 0.98). Patients received an average of 2.75 injections. Additional treatments were laser photocoagulation in 13 (65%) eyes, cyclodestructive procedure in 14 (70%), cryopexy in six (30%), drainage procedures in two (10%), and vitrectomy in five (25%) eyes. Conclusions: Bevacizumab may be beneficial as adjuvant treatment in neovascular glaucoma because of its anti-angiogenic properties and its ability to prevent establishment or progression of angular obstruction. The causative disease inducing the angiogenic process requires treatment in all cases. Antiglaucoma treatment is needed in cases of persistent elevated IOP.

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