Efficacy and safety of dexamethasone intravitreal implant in patients with retinal vein occlusion resistant to anti-VEGF therapy: a 12-month prospective study

Purpose: To evaluate the safety and efficacy of repeated intravitreal dexamethasone implant (Ozurdex) injections administrated on an ?as-needed? protocol for retinal vein occlusion patients with macular oedema, previously subjected to at least five anti-vascular endothelial growth factor (VEGF) injections with poor or no response. Methods: Prospective interventional case series of 13 branch retinal vein occlusion (BRVO) and 10 central retinal vein occlusion (CRVO) patients with persistent macular oedema (>250??m) after at least five anti-VEGF injections. Exclusion criteria included: baseline visual acuity worse than 1.5 logMAR, previous intravitreal implant, history of vitreoretinal surgery, manifest glaucoma or ocular hypertension, epiretinal membrane, retinal neovascularization, massive retinal or macular ischaemia, vitreous haemorrhage or severe lens opacity, previous laser photocoagulation treatment. Each patient received an initial intraocular dexamethasone implant and the procedure was repeated at 6?months ?as needed.? Patients were followed up at months 2, 4, 6, 8, 10 and 12 with spectral domain optical coherence tomography and best corrected visual acuity measurements. Exclusion criteria included: baseline visual acuity worse than 1.5?logMAR, previous intravitreal implant, history of vitreoretinal surgery, manifest glaucoma or ocular hypertension, epiretinal membrane, retinal neovascularization, retinal or macular ischaemia, vitreous haemorrhage or severe lens opacity, previous laser photocoagulation treatment. Patients on topical or systemic corticosteroid therapy (during the last 3?months), and known steroid responders as well as diabetic patients were also excluded. Results: In the BRVO group, the mean central retinal thickness (CRT) and best corrected visual acuity (BCVA) significantly improved from 482.92???139.99??m (0.55???0.12?logMAR) at baseline, to 369.31???119.72??m (0.43???0.18?logMAR) at 6?months (p?=?0.011/p?=?0.019). At 12?months CRT was 295.82???135.48??m (p?=?0.026) and BCVA 0.29???0.17?logMAR (p?=?0.002). Minimum CRT values were achieved at 3.45?months after the first injection, and 2.46?months after the second injection (197.00???84.27 and 180.00???76.89??m, respectively). Best BCVA values were achieved at a mean of 4???0.853?months after the first injection, and 4?months after the second injection (0.219???0.129 and 0.222???0.078?logMAR, respectively). In the CRVO group, neither the mean CRT nor BCVA improved significantly at 6?months: from 669.70???203.20??m (0.80???0.231?logMAR) at baseline, to 586.20???237.63??m (0.740???0.268?logMAR) at 6?months (p?=?0.131/p?=?0.333). At 12?months CRT was significantly improved: 549.90???191.26??m (p?=?0.047), but BCVA lacked significant improvement: 0.690???0.285?logMAR (p?=?0.072). Minimum CRT values were achieved at a mean of 2?months after the first injection, and also 2?months after the second injection (261.60???121.31 and 280.00???177.43??m, respectively). Best BCVA values were achieved at a mean of 2?months after the first injection, and 2?months after the second injection and were 0.390???0.173 and 0.385???0.233?logMAR, respectively. Cataract progression was a rare event (2/23 eyes), while transient steroid-induced ocular hypertension (5/23 eyes) was managed successfully with IOP-lowering medication Conclusion: Dexamethasone implant should be considered as an effective and safe alternative in patients with BRVO and CRVO who have failed anti-VEGF therapy. Shortening the re-injection interval especially for CRVO cases should be considered.