Absence of Histologic Retinal Toxicity of Intravitreal Bevacizumab in a Rabbit Model

Purpose: To evaluate the retinal toxicity of intravitreal bevacizumab in an animal model. Design: Animal study. Methods: Bevacizumab was injected into the vitreous of one eye of each of eight Dutch-belted rabbits; the other eye served as a control. Four rabbits received a dose of 1.25 mg/0.05 ml of bevacizumab intravitreally into one eye, and the other four rabbits were injected with 2.5 mg/0.1 ml of bevacizumab intravitreally into one eye. At one month, the rabbits were killed and both eyes enucleated. The eyes were fixed with paraformaldehyde 2% and examined by light microscopy. Results: In all injected and control eyes, there was mild vacuolization in the ganglion cell layer, and disruption of photoreceptor outer segments in both treated and control eyes, to the same degree, consistent with autolysis. The optic nerve, retina, and retinal pigment epithelium were otherwise normal by light microscopy with no evidence of toxicity. Conclusions: Intravitreal bevacizumab at doses of 1.25 mg and 2.5 mg showed no signs of retinal or optic nerve toxicity by light microscopy in this rabbit model.