Efficacy of dexamethasone intravitreal implant for refractory macular edema caused by retinal vein occlusion

Purpose: To investigate efficacy of dexamethasone intravitreal (DEX) implant in treating refractory macular edema caused by retinal vein occlusion. Methods: Retrospective chart review. Results: Twenty-two eyes with refractory macular edema caused by retinal vein occlusion were treated with a mean of 2.2 DEX over 12 months. Patient had previously received a mean of 7 treatments (laser, bevacizumab, and/or triamcinolone) for macular edema present for at least 4 months duration (mean 20.8 ± 17.6 months, range 4-72 months) before starting DEX. Mean baseline visual acuity was 20/91, and mean central subfield thickness was 506 μm. DEX improved mean best-corrected visual acuity to 20/75 and 20/66 at 7 weeks and 6 months follow-up, although it worsened to 20/132 at 12 months. Mean central subfield thickness improved to 292, 352, and 356 μm at 7 weeks, 6 months, and 12 months follow-up, respectively. There was a statistically significant association between number of DEX treatments and central subfield thickness (P = 3.28 × 10^-9). There was a statistically significant association between number of days followed and best-corrected visual acuity (P = 0.006). Six of 12 (50%) phakic patients developed visually significant cataract requiring surgery. Five of 22 (23%) patients developed ocular hypertension (intraocular pressure > 30) and consequently did not undergo further treatment with DEX. Conclusion: DEX resulted in sustained anatomical reduction of retinal vein occlusion- associated refractory macular edema, although this did not translate into long-term bestcorrected visual acuity improvement in either phakic or pseudophakic patients, possibly related to chronic structural alterations in the retina despite reduction of edema.