OBJECTIVE: To investigate the safety and efficacy of intravitreal triamcinolone acetonide as treatment for macular edema associated with central retinal vein occlusion (CRVO). METHODS: We reviewed the medical records of 13 consecutive patients (13 eyes) with macular edema associated with CRVO who were treated with an injection of intravitreal triamcinolone acetonide (4 mg) at the University of Wisconsin and the Bascom Palmer Eye Institute. Each intravitreal injection was delivered through the pars plana using a 27- or 30-gauge needle. MAIN OUTCOME MEASURES: Change in Snellen visual acuity, clinical appearance of macular edema, measurement of foveal thickening with optical coherence tomography (OCT), and frequency of complications. RESULTS: The median age of the 13 patients was 67 years (interquartile range, 57-77 years), and the median duration of symptoms before injection was 8 months (interquartile range, 4-9 months). Mean baseline visual acuity was 20/500 in the affected eye. Mean visual acuity at the 6-month follow-up examination was 20/180 in the affected eye. All 13 patients completed the 6-month examination. Eyes with nonischemic CRVO (n = 5) demonstrated a significant improvement in visual acuity, whereas eyes with ischemic CRVO (n = 8) demonstrated a nonsignificant visual acuity improvement. No patient had a decrease in visual acuity. Mean baseline foveal thickness as measured by OCT was 590 micro m (retinal thickening = 416 micro m). Mean foveal thickness as measured by OCT at the 1-month follow-up examination in 12 patients was 212 micro m (retinal thickening = 38 micro m). At the 3-month follow-up examination, mean foveal thickness as measured by OCT for 13 patients was 193 micro m (retinal thickening = 19 micro m). Between the 3- and 6-month follow-up examinations, 4 patients developed a recurrence of macular edema. Three of the 4 patients were retreated with a second injection of triamcinolone. Two of these 3 patients experienced an improvement in visual acuity following retreatment. At the 6-month follow-up examination, mean foveal thickness as measured by OCT for 13 patients was 281 micro m (retinal thickening = 107 micro m). No adverse effects such as retinal detachment or endophthalmitis occurred. One patient experienced an increase in intraocular pressure that was controlled with 2 aqueous suppressants. CONCLUSIONS: Intravitreal injection of triamcinolone appears to be a possibly effective treatment in some patients with macular edema associated with CRVO. Patients with nonischemic CRVO may respond more favorably than patients with ischemic CRVO, and retreatment may be necessary in some patients. In this case series, severe complications were not noted.