Abstract
Purpose: :
To evaluate the concentration of vascular endothelial growth factor (VEGF) in the aqueous humor before and after intravitreal injection of bevacizumab (IVB) in eyes with neovascular glaucoma (NVG).
Methods: :
Twenty-eight eyes of 24 consecutive patients with NVG secondary to ischemic retinal diseases were enrolled in this prospective, interventional case series. Aqueous humor samples (200 µl) were obtained by paracentesis immediately before IVB (1.0 mg or 0.1 mg) and just before surgery or repeated IVB 1 week after the first injection. Control aqueous humor samples were also obtained at the beginning of cataract surgery in 12 eyes of 12 patients without diabetes mellitus. The VEGF concentration was measured using an enzyme-linked immunosorbent assay.
Results: :
The mean VEGF concentrations in the aqueous humor differed significantly between the control group and each NVG subgroup (P<0.001): control group, 150±57 pg/ml (mean±SD); stage 1 (iris/angle neovascularization only), 1,058±372 pg/ml; stage 2 (open-angle NVG), 5,856±5,204 pg/ml; and stage 3 (angle-closure NVG), 19,153±18,152 pg/ml. The intraocular pressure (IOP) was significantly correlated with the aqueous humor level of VEGF (R = 0.515, P = 0.005). The decreased levels of VEGF in the aqueous humor 1 week after IVB did not differ significantly between the high-dose (1.0 mg) and low-dose (0.1 mg) groups (P = 0.14). Both bevacizumab doses halted iris and angle neovascularization and reduced the VEGF level to the range of the control group 1 week after injection. The effect on IOP reduction was also similar between the high-dose (12±16 mmHg) and low-dose groups (10±9 mmHg). Neither dose caused adverse events throughout the study period (4.6±2.4 months).
Conclusions: :
Aqueous humor levels of VEGF increase with progression of NVG. The IOP may be an indicator that enhances the aqueous humor level of VEGF. Low-dose IVB (0.1 mg) seems to be as effective and safe as the current widely-used dose (1.0 mg or larger) for NVG during short-term follow-up.
Keywords: vascular endothelial growth factor • neovascularization • intraocular pressure