Objective:To investigate the toxicity effect of intravitreous injection with conventional dosage of domestic triamcinolone acetonide (TA) on rabbits retina. Methods:Forty-eight healthy purebred New Zealand white rabbits nnderwent intravitreous injection. The right eye of the 24 animals was injected wilh sterile saline solution 0.1ml as the control A group; and the left eye was injected with TA suspension 4mg (0.1ml) as the B experimental group;The right eye of the other 24 animals was injected with TA 0.1ml wilhout excipient as the C experimenlal group

the exeipient removed was supplemented with terile saline solution;and the left eye was injected with exeipient 0.1ml separated from TA suspension as the D experimental group. Flash electroretinography (FERG) was performed on each animal before intravitreous injection

3 days

2 weeks

and 1 months after the injected. After the examination the animal was killed and the eyeballs were extirpated at the three points of time after the injected. The ultrastructural changes of the retina were observed by light and electron microscopy. Results:No significant difference was found in the latent period of b-wave of FERG before and after the injected

but the amplitudes of b-wave of FERG was lower in all the groups than that before the treatment in a short time after the injected (P<0.001).The amphtudes of b-wave of FERG was still lower in the excipient group 1 month after the injected (P<0.001). The results of light and electron microscopy showed the uhrastructural changes of the retina in the excipient group at all the three points of time after the injected

only short-time ultrastruetural changes in the other groups. Conclusion:Intravitreous injection of domestic TA with the dosage of 4mg may make the ultrastrueture changes and function of retina in short term

but the changes are temporal and reversible

and may mainly come flom the excipient.