Safety of intravitreal triamcinolone acetonide:an electrophysiologic and histopathological study in rabbits

AIM: To evaluate the retinal safety of various doses of intravitreal triamcinolone acetonide (TA) in rabbits.Methods: Thirty New Zealand albino rabbits were divided into five groups (six animals each). In group 1 (control group), each animal received a single intravitreal injection of 0.1mL phosphate buffered saline. In groups 2, 3, 4 and 5, each rabbit received a single intravitreal injection of 4, 8, 16 and 32mg of TA, respectively. Each dose was contained in 0.1mL phosphate buffered saline. Clinical ocular examinations were performed before the injection and on the 1st, 3rd, 10th and 17th post-injection days. A standard dark adapted electroretinogram (ERG) was obtained before injection and on the 3rd, 10th and 17th post-injection days. After 17d, animals were sacrificed and their eyes prepared for pathological examination.RESULTS:By monitoring ERG as a functional index for the retina, intravitreal injection of 4mg TA showed no significant ERG changes. At doses of 8, 16 and 32, hyper-abnormal responses in a- and b- waves of ERG were detected on the 3rd post-injection day. These changes gradually returned back to normal limits after 17d. Histopathological examination of the retina of all animals showed no pathological changes.CONCLUSION: High doses of intravitreal TA seemed to have enhancing effects on the retinal function with gradual return to normal limits with no pathological changes detected in examined eyes