Background: To evaluate the changes in aqueous humor cytokine levels following consecutive intravitreal bevacizumab (Avastin, Genentech Inc., San Francisco, CA, USA) injections in eyes with choroidal neovascularization (CNV) due to age-related macular degeneration (AMD).
Method: Aqueous humor samples were collected at the time of intravitreal injection of 1.25 mg of bevacizumab every 7.0 (+/-2.0) weeks from ten eyes with AMD for the AMD group and during cataract surgery in nine eyes for the control group. Visual acuity with Early Treatment of Diabetic Retinopathy Study (ETDRS) letters and central macular thickness (CMT) using optical coherence tomography were measured before each injection in the AMD group. Aqueous cytokine levels were determined by immunoassay using multi-analyte biochip array technology (Evidence investigator cytokine and growth factor biochip array, RANDOX laboratories Ltd., Crumlin, UK).
Result: In the AMD group, mean +/- standard deviation(SD) aqueous VEGF levels decreased from 68.0 +/- 32.1 pg/ml at baseline to 26.3 +/- 19.0 pg/ml after the first injection (p = 0.028) and to 25.2 +/- 12.8 pg/ml after the second injection (p = 0.005). While CMT decreased from 307.7 +/- 102.0 mum to 206.8 +/- 141.5 microm (p = 0.037), ETDRS visual acuity increased from 17.6 +/- 11.7 letters to 22.0 +/- 15.6 letters after three consecutive injections (p = 0.017).
Conclusion: Significantly decreased VEGF levels were noted after the first injection of bevacizumab. These levels were maintained after the second injection, which paralleled the change in visual acuity and CMT.