Objective:To observe the short-term efficacy of sub-Tenon’s triamcinolone acetonide (TA) in the treatment of cystoid macular edema (CME) after cataract surgery.Methods:A retrospective study. From October 1, 2013 to October 1, 2018, 21 patients (21 eyes) with CME after cataract surgery diagnosed at The Affiliated Eye Hospital of Wenzhou Medical University were included in this study. All eyes underwent BCVA, intraocular pressure, frequency domain OCT examination. The standard logarithmic visual acuity chart was used for BCVA examination, which was converted into logMAR visual acuity when recorded. A frequency domain OCT instrument was used to measure the foveal retinal thickness (CRT). Among 21 eyes of 21 patients, 9 eyes were male and 12 eyes were female; the average age was 66.38±10.88 years. The average logMAR BCVA was 0.46±0.23; the average CRT was 519.90±131.59 μm; the average intraocular pressure was 11.01±3.97 mmHg (1 mmHg=0.133 kPa). All eyes underwent a single treatment of 100 mg/ml TA suspension 0.4 ml (containing TA 40 mg) under Tenon's capsule. The average follow-up time after treatment was 32.86±20.2 days. The changes of BCVA, CRT and intraocular pressure were observed 1 month after treatment. The BCVA, CRT and intraocular pressure before and after treatment were compared by paired t test. Results:One month after treatment, the average logMAR BCVA, CRT, and intraocular pressure of the CME eyes were 0.29±0.22, 307.71±35.82 μm and 14.19±6.30 mmHg, respectively. Compared with those before treatment, the differences were statistically significant ( t=5.252, 8.166, 4.128; P=0.000, 0.000, 0.001). Among 21 eyes, 13 eyes (61.90%) of the retinal cysts in the macular area completely disappeared; 8 eyes (38.1%) were still visible between the retinal layers. Three eyes with intraocular pressure over than 21 mmHg were treated with lowering intraocular pressure and returned to normal. Conclusion:Sub-Tenon’s capsular injection of TA to treat CME after cataract surgery can reduce CRT and improve vision in a short time.