Objective:To evaluate the effect of intravitreous injection with triamcinolone acetonide(TA) on macular edema caused by retinal vein occlusion. Methods:Examined by opthalmoscopy,optic coherent tomography(OCT),and fundus fluorescein angiography(FFA),42 patients(42 eyes) with macular edema caused by retinal vein occlusion were intravitreously injected with 0.1 ml TA(40 g/L). During the 3~6 months follow-up period,the visual acuity,intraocular pressure(IOP),inflammatory extent,manifestation of lens and fundus were observed,the retinal thickness was examined by OCT,and vascular leakage was detected by FFA. The visual acuity and retinal thickness were analyzed by ANOVA for Randomized Block Design. Results:After 3 months treatment,the average visual acuity was 0.40±0.27,which improved 3 lines in 33 eyes and not changed in 4 eyes,while the visual acuity was 0.17±0.17 before treatment,the difference was statistically significant(P < 0.05). The average macular thickness was(332.3±196.5)μm 3 months after treatment,while the macular thickness was(537.4±201.6)μm before treatment,the difference was statistically significant(P < 0.05). Three patients who recurred macular edema after 3 months were injected again,one occurred cataract . Three patients had the temporary high IOP(>21 mm Hg),and returned to normal IOP in 1 week without any drugs. The result of FFA showed less leakage of fluorescein after treatment. There were no severe complications such as vitrous hemorrhage,retinal detachment and endophthalmitis. Conclusion:Intravitreous injection with 4mg TA can be used to treat macular edema from retinal vein occlusion effectively,and improve the visual acuity. In those ischemic retinal vein occlusion patients who have recurrent macular edema,TA can be reinjected,but the long-term curative effects and complications should be further observed.