Abstract
Purpose:
To evaluate the effect of intravitreal injection of bevacizumab or ranibizumab on aqueous vascular endothelial growth factor (VEGF) in patients with diabetic macular edema (DME).
Methods:
Patients with DME (age ≥ 20 years, type 1 or type 2 diabetes mellitus, central retinal thickness ≥ 250 μm and best corrected visual acuity ≤ 0.6 decimal visual acuity) were treated monthly or bi-monthly by intravitreal injection of 1.25 mg bevacizumab (IVB) or 0.5 mg ranibizumab (IVR). Aqueous samples were collected just before each injection. Aqueous VEGF concentrations were measured using enzyme-linked immunosorbent assay (ELISA).
Results:
Ten patients received IVB. Median aqueous VEGF concentration was 172.7 pg/mL before IVB and significantly reduced to 47.6 pg/mL one month after IVB (p < 0.05) and decreased below the lower limit of detection (p < 0.05). 12 patients received IVR monthly. Median aqueous VEGF was 265.2 pg/mL before IVR and significantly decreased below the lower limit of detection (p < 0.05) and remained below lower limit of quantitation two months after initial IVR. 7 patients received IVR bi-monthly. Median aqueous VEGF concentration was 178.5 pg/mL before IVR and significantly reduced to 75.4 pg/mL two months after IVR (p < 0.05). There was no significant difference in aqueous VEGF before initial injections among the three groups (p = 0.275). Aqueous VEGF one month after IVR was significantly less compared with IVB (p < 0.05). IVR did not maintain aqueous VEGF level below lower limit of quantitation for two months in the bimonthly group.
Conclusions:
The aqueous VEGF decreased one month after intravitreal injection of bevacizumab or ranibizumab in patients with DME. Intravitreal injections of ranibizumab suppressed aqueous VEGF more than that of bevacizumab. Intravitreal injections of ranibizumab did not maintain below lower limit of quantitation on aqueous VEGF for two months.