Abstract
Purpose: :
To investigate the changes in concentration of vascular endothelial growth factor (VEGF) in the aqueous humor of patients with choroidal neovascularization (CNV) secondary to age related macular degeneration (AMD) during bevacizumab therapy and to correlate these changes with the modifications of visual acuity and foveal thickness.
Methods: :
7 patients affected by wet AMD (6 with a minimally classic CNV and 1 with an occult CNV) underwent repeated intravitreal injections of bevacizumab (2.00 mg, 0.08 ml) at 30 days intervals. Immediately before each injection visual acuity (by ETDRS charts) and foveal thickness (by OCT) were recorded. Aqueous humor samples (0.05 ml) were obtained straight after each injection through a hypotonizing paracentesis. The VEGF concentration in these samples was measured using an enzyme-linked immunosorbent assay (Quantikine®, R&D Systems).
Results: :
6 patients had 2 bevacizumab injections, while 1 received 3 injections. The mean aqueous humor VEGF concentration at the time of the first and of the second injection was 142.79 (± 79.81) and 37.93 (± 26.06) pg/ml, respectively. This change was statistically significant (p=0.005, paired t test). At the same time checks the mean visual acuity increased from 0.85 (±0.54) to 0.81 (±0.44) logMAR and the mean foveal thickness decreased from 260.57 (± 82.91) to 258.14 (±69.45) µm. In both cases the difference was not statistically significant. 30 days after the anti-angiogenic treatment the VEGF inhibition still ranged between 68 and 83% in all subjects but one. In this patient, who was the only one undergone three injections, the percentage of VEGF inhibition was 37% and 36% 1 month after the first and the second injection, respectively.
Conclusions: :
VEGF has been found to be expressed in the vitreous and aqueous of patients with neovascular ocular diseases and to be temporally, spatially, and quantitatively associated with new vessel formation. Several authors have also demonstrated that aqueous and vitreous levels of VEGF show a strong correlation with each other. Even 30 days after the intravitreal injection of bevacizumab a substantial decrease of VEGF in the aqueous humor of most patients with AMD was observed. This datum suggests that longer intervals between the injections might be considered. In the short follow-up time no correlation was founded between aqueous humor VEGF levels and visual acuity or foveal thickness modifications.
Keywords: age-related macular degeneration • injection • vitreous