Long-term Retinal Toxicity of Intravitreal Commercially Available Preserved Triamcinolone Acetonide (Kenalog) in Rabbit Eyes

Abstract

To investigate whether intravitreal Kenalog (IVTK; Bristol Meyers Squibb Company, Princeton, NJ) produces histologic or electroretinographic changes in the rabbit retina up to 3 months after injection. Ten Dutch-belted rabbits were injected with 4 mg/0.1 mL Kenalog in one eye and 0.1 mL physiologic salt solution (PSS) in the fellow eye. Simultaneous bilateral dark-adapted electroretinography was performed 2 weeks and 12 weeks after injection in 10 and 6 rabbits, respectively. Saturated a-wave amplitude, maximal scotopic b-wave amplitude, and individual a-wave and b-wave amplitudes of IVTK-injected and control eyes were compared at 2 and 12 weeks after injection. Light microscopy was performed on both eyes of three animals 3 months after injection. Immunohistochemistry was performed with antibodies recognizing vimentin and human alveolar macrophage (HAM)-56, markers of glial cells and macrophages, respectively. No significant difference was observed in the saturated a-wave or maximal scotopic b-wave amplitudes between the PSS-injected eyes and the IVTK-injected eyes at 2 weeks (P = 0.95 and P = 0.56, respectively) and 12 weeks (P = 0.82 and P = 0.17) after injection. Light microscopy and immunohistochemistry disclosed only rare macrophages in the vitreous of IVTK-injected eyes. Retinal layers, retinal pigment epithelium, and choriocapillaris in treatment and control eyes were unremarkable. No demonstrable electroretinographic or histologic changes occurred to suggest immediate or delayed widespread retinal toxicity of IVTK.