Safety and efficacy of dexamethasone intravitreal implant injection for macular edema associated with retinal vein occlusion

Purpose: To evaluate the safety and efficacy of dexamethasone intravitreal implant injection for retinal vein occlusion. Methods: Twenty-two patients with central or branch retinal vein occlusion who were treated with dexamethasone intravitreal implant (Ozurdex) injection for macular edema at the Hong Kong Eye Hospital between December 2011 and December 2013 were retrospectively reviewed. Best-corrected visual acuity, proportion of patients with 3-line gain in visual acuity, central macular thickness and intraocular pressure before and after implant were recorded, as were any complications. Results: Of the 22 patients, 11 each had central or branch retinal vein occlusion. The mean duration of follow-up was 9.6 months. The mean overall logMAR visual acuity improved from 1 to 0.67 (p < 0.0001) at 3 months and to 0.88 (p = 0.048) at final follow-up. The mean gain in visual acuity was 3.6 lines at 3 months, and 1.5 lines at final follow-up; 63.6% and 45.5% of patients at the respective follow-ups had gained ≥ 3 lines of vision. Nonetheless, 2 eyes lost ≥ 3 lines of vision at final follow-up. The mean central retinal thickness decreased from 589 µm to 327 µm at 3 months (p < 0.0001), and to 409 µm at final follow-up (p = 0.0001). Fifteen eyes had recurrence of macular edema after a mean of 4.5 months; recurrence was earlier in central than branch retinal vein occlusion by 1.1 months (p = 0.031). Three eyes had intraocular pressure >21 mm Hg. Five eyes out of 8 phakic patients developed cataract progression, of whom 2 subsequently underwent cataract extraction. Two eyes developed ischemic central retinal vein occlusion and had lost vision at final follow-up. There were no retinal tear, retinal detachment or endophthalmitis. Conclusion: Ozurdex is efficacious in treating macular edema associated with retinal vein occlusion in terms of the gain in visual acuity and reduction in central retinal thickness, even for patients with a long duration of macular edema and poor baseline visual acuity. It has a good safety profile. The main complications are cataract progression and increased intraocular pressure (IOP). The duration of effect may be shorter than 6 months, especially in patients with central retinal vein occlusion. Earlier retreatment may be considered in order to maximize visual benefits.