Efficacy of Intravitreal Injections of Antivascular Endothelial Growth Factor Agents in a Rat Model of Anterior Ischemic Optic Neuropathy

PURPOSE. We investigated the efficacy of intravitreal injections of anti-VEGF agents in a rat model of anterior ischemic optic neuropathy. METHODS. We applied laser-induced photoactivation on the optic nerve head after intravenously administered rose bengal (RB). The rats immediately received an intravitreal injection of either ranibizumab or PBS. The density of retinal ganglion cells (RGCs) was calculated using retrograde FluoroGold labeling. Visual function was assessed by flash visual-evoked potentials (FVEP). We investigated TUNEL assays of the retinal sections and ED1 staining of the optic nerve. RESULTS. After treatment, the RGC densities in the anti-VEGF-treated rats were not statistically significant different from those of the PBS-treated rats (57.0% vs. 40.0% in the central retinas; 39.8% vs. 33.6% in midperipheral retinas, both P > 0.05). Measurements of FVEP showed no statistically significant differences in preserved latency or amplitude of the P1 wave between anti-VEGF and PBS groups (latency 131 +/- 15 ms versus 142 +/- 14 ms, P = 0.157; amplitude 34 +/- 12 mu v versus 41 +/- 13 mu v, P = 0.423). Assays of TUNEL showed that there was no statistical difference in the number of apoptotic cells in the RGC layers between anti-VEGF and PBS groups (7.0 +/- 0.8 cells/high-power field [HPF] versus 7.8 +/- 1.3 cells/HPF; P = 0.275). In the optic nerves, we did not observe statistically significant differences in ED1-positive cells/HPF between anti-VEGF and PBS groups (P = 0.675). CONCLUSIONS. Intravitreal injections of anti-VEGF did not have a protective effect in the rat model of anterior ischemic optic neuropathy.