Retinal toxicity of intravitreal triamcinolone acetonide at high doses in the rabbit

In order to study acute retinal toxicity of intravitreal triamcinolone acetonide (TA) at high doses in an animal model, thirty New Zealand albino rabbits were injected with intravitreal TA. The animals were divided in five groups: Group 1 received an intravitreal injection of 0.1 mL balanced salt solution; Group 2, 0.1 mL of the solvent (0.99 mg of benzyl alcohol); Group 3, received 4 mg/0.1 mL TA; Group 4, 20 mg/0.1 mL TA; and Group 5, 30 mg/0.1 mL TA. A standard light and dark adapted electroretinogram (ERG) was obtained prior and 28 days after the injection. The animals were sacrificed 28 days after the injection and the eyes were enucleated and examined by electron (EM) and light microscopy (LM) using hematoxylin-eosin, Nissl fluorescent, and immunohistochemistry (glial fibrillary acidic protein). No statistically significant differences in ERG before and 28 days after the injection were found. LM and EM did not show retinal damage in any animal. One eye developed bacterial endophthalmitis 14 days after the injection. Intravitreal TA up to 30 mg does not seem to have acute toxic effects on the function (ERG) or the structure (LM, EM) of the retina of albino rabbits.