Retinal toxicity of intravitreal kenalog in albino rabbits

To evaluate possible toxicity of intravitreal Kenalog (commercial triamcinolone acetonide) to the retina of albino rabbits.

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.

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.

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.