AIM: To compare the differences in the efficacy and safety of combination of intravitreal dexamethasone(Ozurdex)and ranibizumab or monotherapy of ranibizumab in eyes with macular edema secondary to retinal vein occlusion(RVO-ME).METHODS: Patients diagnosed with non-ischemic RVO-ME by fluorescein fundus angiography in our hospital from June 2020 to December 2022 were selected. All patients were initially treated with intravitreal injection of ranibizumab(0.5 mg), and 42 patients(42 eyes)who had central retinal thickness(CRT)≥300 μm after 2 wk were included. They were randomly divided into combined treatment group and monotherapy group. The combined treatment group(21 eyes)received Ozurdex intravitreal injection immediately, while the monotherapy group(21 eyes)was treated with ranibizumab intravitreal injection by 3+pro re nata(PRN). The changes of best corrected visual acuity(BCVA), CRT, and intraocular pressure before and at 2 wk, 1, 2, 3, 4, 5, and 6 mo after treatment were recorded, and the ocular or systemic complications were observed.RESULTS:The BCVA and CRT of all patients at 2 wk, 1, 2, 3, 4, 5, and 6 mo after treatment were significantly better than those before treatment(all P<0.01). There were statistical significance in the BCVA and CRT between two groups at 2 and 3 mo after treatment(all P<0.05). The most significant increase of BCVA in the combined treatment group occurred at 2 mo after treatment. The mean recurrence time of macular edema in the monotherapy group was 1.45±0.53 mo, with 4.21±0.78 injection times of ranibizumab. None of the patients showed serious complications after treatment. The most common complications in the combined treatment group were subconjunctival hemorrhage and elevated intraocular pressure, which were manageable with topical ocular hypotensive agents, and no patient required antiglaucoma or cataract surgery.CONCLUSION: Compared with monotherapy of ranibizumab, intravitreal injection of dexamethasone combined with ranibizumab can significantly improve the visual acuity and effectively reduce the macular edema in the treatment of RVO-ME, with a long duration of efficacy and less intravitreal injection of drugs.