Purpose
To evaluate the concentration of vascular endothelial growth factor (VEGF) in the aqueous humor, before and after intravitreal injection of Bevacizumab in eyes with neovascular age-related macular degeneration (AMD).
Methods
In this prospective study, 24 eyes of 24 patients with choroidal neovascularization secondary to neovascular AMD were treated with a single intravitreal injection of Bevacizumab (0,05mL, 1,25mg of Avastin). Aqueous humor samples were obtained before the intravitreal injection (baseline), at one week, one month and three months after the treatment. The VEGF concentration in the aqueous humor was measured using an enzyme-linked immunometric assay (Assay Designs® and Stressgen®, Enzo Biochem Inc, Farmingdale, NY). Best corrected visual acuity (BCVA), central retinal thickness (CRT) measured by spectral domain optical coherence tomography (SD-OCT), and fundoscopy were analyzed at the baseline, one week, one and three months after the treatment. Additionally, a correlation between improvement in the BCVA, CRT and VEGF concentration was investigated.
Results
A significant increase expression of VEGF was observed in the aqueous humor of eyes with neovascular AMD (mean: 179,71 pg/mL) at the baseline. Furthermore, a significant decrease in the VEGF levels (P<0.001) was observed in all time points after intravitreal injection, comparing with the baseline (1 week - 44.18 pg/mL; 1 month: 56,55 pg/mL; 84,44 pg/mL, P<0.001). One week post treatment, it was observed the highest reduction on the VEGF expression (75.41%). As expected, significant improvement on CRT (P<0,05) was observed after the single bevacizumab treatment (baseline - 420 μm; 1 week - 280,95μm; 1 month - 280,65μm and 3 months: 320μm; P<0.01). The improvement on the CRT was directed correlated with the reduction on the aqueous humor VEGF levels.
Conclusions
The lowest VEGF concentration in the aqueous humor in eyes with neovascular AMD was observed 1 week after Bevacizumab intravitreal injection. There was a significant increase in the VEGF concentration 3 months after the injection. A significant direct correlation was observed between the decrease on the CRT and VEGF levels. Therefore, the VEGF levels might be a potential marker for the neovascular activity.