ObjectiveTo observe the efficacy of dexamethasone intravitreal implant (DEX) combined with pars plana vitrectomy (PPV) in eyes with severe idiopathic epimacular membrane (IMEM). MethodsA prospective clinical case study. From December 2018 to May 2021, 24 patients with 25 eyes of severe IMEM diagnosed in Tianjin Medical University Eye Hospital were included in the study. Among them, 7 males had 7 eyes, 17 females had 18 eyes. Age was 57 to 84 years old. The IMEM stage was 3 to 4 examined by spectral domain optical coherence tomography (SD-OCT). All eyes were performed best corrected visual acuity (BCVA) and central macular thickness (CMT) by SD-OCT. The patients were randomly divided into PPV group (11 eyes) and PPV+DEX group (14 eyes). Standard PPV by three-channel 25G was performed. Phacoemulsification, membrane stripping and intraocular lens implantation were combined during the operation. Patients received vitreous injection of 0.7 mg DEX in PPV+DEX group at the end of the operation. At 1 week, 1 month, 3 months and 6 months after operation, the same equipments and methods were used to perform relevant examinations. The changes of BCVA and CMT were compared between the two groups by t test. ResultsCompared with before operation, at 1, 3 and 6 months after operation, the BCVA of the eyes in the PPV+DEX group was significantly improved (t=3.974, 4.639, 4.453), CMT was significantly decreased (t=2.955, 3.722, 4.364), the differences were statistically significant (P＜0.05); at 3 and 6 months after surgery, the BCVA of the eyes in the PPV group was significantly improved (t=2.983, 4.436), CMT was significantly decreased (t=2.983, 3.461), the differences were statistically significant (P＜0.05). ConclusionIn the treatment of severe IMEM, DEX can accelerate the early postoperative visual recovery and reduce CMT.