Absence of histologic retinal toxicity of intravitreal nanogold in a rabbit model

Purpose: To evaluate the retinal toxicity of intravitreal nanogold, a novel antiangiogenic and long-term delivery agent. Methods: One eye of each of 16 Dutch-belted rabbits was injected with intravitreal nanogold; the other eye served as a control. Eight rabbits received a dose of 67 mu mol/0.1 mL of nanogold intravitreally into 1 eye; the other 8 rabbits received a dose of 670 mu mol/0.1 mL of nanogold intravitreally into 1 eye. Eight rabbits were killed at 1 week, and eight were killed at 1 month; both eyes of each rabbit were enucleated. The eyes were fixed with 2% paraformaldehyde and sectioned for histologic examination. Results: In all injected and control eyes, there was mild vacuolization in the inner plexiform and ganglion cell layers. The retina and retinal pigment epithelium were otherwise histologically normal. Conclusion: Intravitreal nanogold at concentrations of 67 mu mol/0.1 mL and 670 [mu mol/0.1 mL showed no signs of retinal or optic nerve toxicity by light microscopy during histologic examination at 1 month.