Intravitreal micronized triamcinolone versus triamcinolone acetonide: a clinical and morphological comparative study

Nowadays many authors suggest the use of intravitreal triamcinolone acetonide (TA) for the treatment of vitreoretinal diseases, although it can be associated with a high risk of local toxicity. In order to develop a safer injection for clinical use, the purpose of our study is to evaluate the in situ safety of two different triamcinolone preparations, a commercially available TA and a micronized triamcinolone. The experiments were performed on 18 adult male age-matched New Zealand rabbits. The clinical examination included funduscopy with an indirect ophthalmoscope and intraocular pressure (IOP) measurement. At the end of the clinical observations, the animals were sacrificed and the eyes enucleated and processed for the morphological evaluation. In our study the main side effect observed was the IOP elevation in the group injected with triamcinolone acetonide. In addition, in the TA-injected group, one eye was enucleated following an endophthalmitis. Our study highlights that doses as low as 4 mg of triamcinolone acetonide injected into the rabbit vitreous may have a local toxic effect in terms of IOP elevation, endophthalmitis occurrence and changes in the retinal morphology. In contrast, the micronized triamcinolone injection shows a less toxic effect in situ, thus suggesting the alternative use of this more reliable preparation which seems to be safer for a clinical use.