ObjectiveTo investigate the effect of triamcinolone acetonide (TA) with different dosage and excipient on retina.MethodsThirty-two purebred New Zealand white rabbits randomly divided into 4 groups underwent intravitreous injection with TA. Group 1:4 mg TA without excipient; group 2:25 mg TA without excipient; group 3:4 mg TA with excipient; group 4:25 mg TA with excipient. Electroretinography (ERG) was performed on each rabbit before intravitreal injection, 1 week, 1 and 2 months after the injection. All the animals were killed and the eyeballs were extirpated 2 months after the injection, and pathological examinations including light and electron microscopy were performed.ResultsNo significant difference was found in the latent period of ERG at the points of time before and after the injection in all the groups, but the amplitudes of ERG waves was lower in groups containing excipient than that before the treatment (Plt; 0.01). The results of light and electron microscopy showed damages of tissue or structures of retina in various degrees in groups containing excipient.ConclusionIntravitreous injection of TA with the dosage of ≤25 mg without excipient does no harm to the retinal configuration and function, and excipient may lead to the change of retinal configuration and function.(Chin J Ocul Fundus Dis, 2005,21:229-232)