To evaluate the efficacy and safety of dexamethasone intravitreal implant (Ozurdex) in treating the refractory macular edema caused by retinal vein occlusion (RVO).

An observational case series study was conducted.Twenty-one eyes of 21 patients diagnosed as refractory macular edema secondary to RVO and treated with Ozurdex implant in Beijing Aier-Intech Eye Hospital from March 2016 to September 2019, who was with a course lasting longer than 3 months and received at least 2 times of anti-VEGF treatments, had recurrent macular edema and no visual improvement or even deteriorated, were included.Best corrected visual acuity (BCVA) was examined using standard visual chart and was converted to logarithm of the minimal angle of resolution (LogMAR) units and intraocular pressure (IOP) was examined.Optical coherence tomography (OCT) was used to measure central retinal thickness (CRT) in all eyes before and at 1, 2, 3 and 6 months after intravitreal injection of Ozurdex.The changes of BCVA, IOP and CRT before and after Ozurdex injection were observed and analyzed.During the 6-month follow-up, re-injection of Ozurdex or ranibizumab was adopted among those with macular edema recurrence or poor efficacy according to the subjects' conditions.Ocular adverse effects and potential systemic complications were observed.This study followed the Declaration of Helsinki and the study protocol was approved by an Ecthics Committee of Beijing Aier-Intech Eye Hospital (No.BJAIER2020IRB01).

The mean CRT at 1, 2, 3, 6 months after Ozurdex injection was (295.76±49.19), (280.33±39.44), (321.29±73.46), (300.29±75.10)μm, respectively, which were significantly decreased in comparison with (458.52±174.61)μm at baseline (all atP<0.05). There was no significant difference in mean BCVA at different time points before and after Ozurdex injection (F=1.975, P>0.05). During the follow-up, 10 eyes had macular edema recurrence at 2 to 6 months after first Ozurdex injection, with an average of (4.1±1.5) months.Among them, 8 eyes received second Ozurdex injection, and CRT was significantly reduced and BCVA was significantly improved at 6 months after the second Ozurdex injection in comparison with those at recurrence (t=5.254, P=0.001; t=4.277, P=0.004). The IOP was significantly elevated at 2 months after first Ozurdex injection in comparison with that at baseline (P=0.01). Ocular hypertension (IOP≥25 mmHg) was oberserved in 3 (14.3%) eyes during the follow-up period but were well controlled after local application of eye drops.No vitreous hemorrhage, retinal detachment, endophthalmitis or other serious adverse effects or systemic complications were observed.

One dose of intravitreal Ozurdex injection can significantly improve the structure and function of macula in refractory macular edema caused by RVO for 4 to 6 months and maintain the baseline visual acuity.Second administration of Ozurdex is still effective for recurrent RVO macular edema.Transitional IOP elevation is the main adverse event.

Retinal vein occlusion; Macular edema; Dexamethasone; Vascular endothelial growth factor; Refractory