ObjectiveTo observe the short-term efficacy of posterior sub-tenon injection of triamcinolone acetonide (PSTA) in the treatment of macular edema due to ischemic retinal vein occlusions (RVO). MethodsA retrospective clinical study. A total of 53 eyes of 53 patients with RVO macular edema diagnosed by fundus color photography, fundus fluorescein angiography and optical coherence tomography (OCT) were included in the study. The best corrected visual acuity (BCVA) was detected by the international standard visual acuity chart, and the results were converted to the logarithm of the minimum angle of resolution (logMAR) visual acuity. The central macular thickness (CMT) was measured by OCT. Among 53 eyes, there were 27 eyes with ischemic RVO macular edema (ischemic group) and 26 eyes with non-ischemic RVO macular edema (non-ischemic group). The mean logMAR BCVA was 0.82±0.37, mean CMT was (662.1±216.7) μm in ischemic group. The mean logMAR BCVA was 0.41±0.23, mean CMT was (548.0±161.9) μm. The differences of logMAR BCVA and CMT between the two groups were both statistically significant (t=4.745, 2.258; P<0.05). All eyes were treated with a single sub-Tenon injection of 0.4 ml triamcinolone acetonide suspension (100 mg/ml).The mean logMAR BCVA, CMT before and 1, 3 months after the treatment between the two groups were observed and compared. ResultsOn 1 and 3 months after treatment, the mean logMAR BCVA in the non-ischemic group (0.32±0.25 and 0.27±0.29) were improved compared with ischemic group (0.76±0.37 and 0.41±0.79), the difference was statistically significant (t=5.052, 5.240; P<0.05). The mean logMAR BCVA before and after treatment had no statistically significant difference in ischemic group (F=0.516, P>0.05), but had a statistically significant difference in non-ischemic group (F=7.685, P<0.05). On 1 and 3 months after treatment, the mean CMT in the ischemic group were (534.7±223.4), (470.8±234.7) μm, which were lower (127.4±28.28), (191.4±34.55) μm before treatment. In the non-ischemic group, the average CMT was (426.2±188.8), (371.3±200.6) μm, which were lower (103.1±33.1), (164.9±49.6) μm. There were statistically significant differences in the mean CMT between the ischemic group and the non-ischemic group (F=17.040, 10.360; P<0.05). In non-ischemic group, CMT had a bigger reduction compared to the the ischemic group (t=2.056, 2.103; P<0.05). The difference of CMT decrease value between two groups was not statistically significant (t=0.560, 0.441; P>0.05). On 1 month after the treatment, there were 3 and 5 eyes had a higher intraocular pressure than 21 mmHg (1 mmHg=0.133 kPa) in ischemic and non-ischemic group, respectively; but all of them returned to normal after drug treatment. There were no drugs and ocular injection related complications. ConclusionPSTA of ischemic RVO macular edema can lower the CMT in the short term, but can't significant improve the visual acuity.