To investigate the clinical, histologic, and electroretinographic effects of intravitreal injection of triamcinolone acetonide suspension in the rabbit retina.
Three groups of 6 rabbits each received intravitreal injections. Group 1 received 4 mg of triamcinolone acetonide, group 2 received an equal volume (0.1 mL) of the corticosteroid supernatant, and group 3 received 4 mg of triamcinolone acetonide with the supernatant replaced with balanced salt solution. Uninjected left eyes served as controls. Electroretinograms were obtained at baseline and at 3 to 4 and 6 to 7 days after injection of triamcinolone. Enucleated eyes were examined histologically.
Ocular examination revealed no differences among the 3 groups. When subjected to stimulation with moderate to high flash intensities, eyes that had received intravitreal injections of triamcinolone (groups 1 and 3) had a 10% to 25% increase in dark-adapted a- and b-wave electroretinographic amplitudes. No histologic differences were observed between injected and control eyes.
Intravitreal injection of 4 mg of triamcinolone acetonide does not cause a toxic reaction in the rabbit retina after 7 days. Triamcinolone therapy may augment the rod-driven electroretinographic responses, suggesting a mechanism by which visual function may improve.
Evaluation of the toxic effects of triamcinolone is useful because of increased applications of intravitreal injection.