Abstract: Objective To investigate the effect and safety of 25-gauge vitrectomy combination with different dosage of intravitreal injection of triamcinolone acetonide (IVTA) for the treatment of the patients with idiopathic macular epiretinal membrane (iERM). Design Randomized controlled trial. Participants From April to October 2022, sixty eyes of 60 patients with iERM diagnosed by department of Ophthalmology at Tengzhou Central People’s Hospital were included. Methods The patients were classified randomly into vitrectomy combined with IVTA 1 mg group (20 eyes of 20 patients) and vitrctomy combined with IVTA 2 mg group (20 eyes of 20 patients) , and vitrectomy group (control group, 20 eyes of 20 patients). Before and 1, 3, 6 months after the surgery, best corrected visual acuity (BCVA, LogMAR) was measured using the international standard decimal visual acuity chart, intraocular pressure (IOP) was measured with non-contact tonometer, and central macular thickness (CMT), disorganization of retinal inner layers (DRIL) was assessed using the optical coherence tomography (OCT). Chi-square test was used for counted data and ranked data. One-way ANOVA was used for measurement data conforming to normal distribution, otherwise Kruskal-Wallis H test was applied. Comparison of BCVA and CMT before and after treatment within the group was performed using Friendman test. Main Outcome Measures BCVA, IOP, CMT, DRIL. Results One and three months after the surgery, the mean BCVA in vitrectomy combined with IVTA 1 mg and 2 mg group was higher than in vitrectomy group, and CMT was less than that in vitrectomy group (all P<0.05). But the difference was not statistically significant between vitrectomy combined with IVTA 1 mg group and IVTA 2 mg group (P>0.05). However, at 6 months postoperatively, there was no statistical differences among all the three groups regarding CMT, DRIL, and BCVA (all P>0.05). Three patients (15%) in the IVTA 2 mg group had varying degrees of IOP increase 1 month after surgery, all of which decreased to normal after medication. Conclusion Vitrectomy combined with IVTA 1 mg or 2 mg can accelerate postoperative visual improvement and CMT reduction in patients with iERM, but can not improve long-term prognosis. The effect of IVTA 1 mg is similar to that of IVTA 2 mg, but safer. (Ophthalmol CHN, 2024, 33: 39-45)

Key words:  idiopathic macular epiretinal membrane, vitrectomy, triamcinolone acetonide