Prospective evaluation of morphological and functional changes after repeated intravitreal dexamethasone implant (Ozurdex®) for retinal vein occlusion

Aims: To evaluate changes in macular morphology and function after repeated intravitreal dexamethasone implant (Ozurdex®) for macular edema (ME) due to retinal vein occlusion (RVO). Methods: Consecutive treatment-naïve patients with ME secondary to RVO were treated with Ozurdex and followed up to 12 months to evaluate functional and morphological outcomes by means of best-corrected visual acuity (BCVA) and microperimetry and by enhanced depth imaging optical coherence tomography, respectively. Results: Thirty-five eyes of 35 patients were included for the analysis (26 central RVO, 9 branch RVO). During the 12-month study period, 8 of the 35 eyes (23%) underwent 1 intravitreal dexamethasone implant, 13 of the 35 eyes (37%) underwent 2, and 14 of the 35 eyes (40%) underwent 3 intravitreal dexamethasone implants. At 1 month from the 1st intravitreal dexamethasone implant, the mean BCVA, retinal sensitivity and central macular thickness (CMT) significantly improved compared to the baseline values. At 3 months, the mean BCVA improvement was no more significant, while retinal sensitivity further improved and CMT slightly worsened, remaining, however, significantly better than at baseline. At 12 months, those eyes that had undergone 2 retreatments showed a significant improvement of the mean BCVA, mean retinal sensitivity and CMT compared to the baseline values [0.61 ± 0.29 logarithm of the minimum angle of resolution (LogMAR) vs. 0.82 ± 0.33 LogMAR, p = 0.011; 12.94 ± 4.73 dB vs. 10.75 ± 3.27 dB, p = 0.043, and 321 ± 91 μm vs. 735 ± 169 μm, p = 0.001, respectively]. In those eyes that had undergone only 1 retreatment, a significant improvement was recorded only for the CMT (500 ± 224 μm vs. 695 ± 302 μm, p = 0.044). The mean retreatment interval between the 1st and the 2nd injection was 4.5 ± 1.1 months (range 3-7 months), and between the 2nd and the 3rd injection it was 4.1 ± 1 months (range 3-6 months). Conclusions: In eyes with ME secondary to RVO, Ozurdex produces functional benefits as early as 1 month after treatment/retreatment. Current optical coherence tomography and microperimetry findings confirm the concept that, in most cases, the optimum retreatment interval should be