Retinal toxicity of intravitreal Kenalog in albino rabbits

PURPOSE: To evaluate possible toxicity of intravitreal Kenalog (commercial triamcinolone acetonide) to the retina of albino rabbits. METHODS: Forty-three albino rabbits were injected intravitreally with 0.1 mL of experimental solution to the right eye and 0.1 mL of saline to the left eye (control). Rabbits in Group A (n = 28) were injected with 4 mg/0.1 mL of Kenalog suspension; rabbits in Group B (n = 8) were injected with 0.1 mL of Kenalog vehicle; and rabbits in Group C (n = 7) were injected with 4 mg/0.1 mL of triamcinolone acetonide. Rabbits were examined ophthalmoscopically and by electroretinogram (ERG) recordings before and at different time intervals after injection. At the end of follow-up, animals were killed and the retinas were prepared for light microscopy. RESULTS: Thirty-eight rabbits completed 4 weeks of follow-up. Follow-up for 8 and 17 weeks was completed by 29 and 3 rabbits, respectively. Intravitreal commercial Kenalog or its vehicle alone caused approximately 50% reduction in the ERG b-wave amplitude at the end of follow-up. Pure triamcinolone acetonide caused only mild (up to 14%) reduction of the ERG b-wave amplitude. Histologic examination of retinas exposed to Kenalog or its vehicle showed severe damage to all retinal layers in areas close to the site of Kenalog injection. CONCLUSIONS: Intravitreal injection of 4 mg Kenalog suspension is retinotoxic to albino rabbit eyes. The vehicle of Kenalog is probably the main cause of this toxicity.