Purpose: To compare efficacy of simultaneously administered intravitreal dexamethasone implant (DEX implant) and ranibizumab (simultaneous double protocol) injections with ranibizumab monotherapy for diabetic macular edema (DME) at month 24.
Methods: This is a prospective, consecutive, clinical interventional study. Naïve eyes with DME were randomized into two groups: 34 eyes received simultaneous double-protocol therapy and 34 eyes received ranibizumab monotherapy. The primary efficacy endpoint was change in visual acuity in month 24. The secondary efficacy endpoints were to evaluate gain of ≥15 letters, morphological changes and central foveal thickness. Decreased vision from DME (study eye BCVA, 20/40 or worse Snellen equivalent using ETDRS testing), the presence of DME with ≥300 μm foveal intraretinal cystoid spaces (within 1000 μm of the centre of the fovea), subfoveal neuroretinal detachment (SND), intraretinal hyperreflective foci (HRF, within 500 μm of the centre of the fovea) or foveal lipid exudates and external limiting membrane (ELM) and ellipsoid zone (EZ) disruption (within 500 μm of the centre of the fovea) on SD-OCT were eligible to enrol.
Results: The mean baseline BCVA was 48 ± 23 letters in double protocol group and 52 ± 14 letters ranibizumab monotherapy group (p = 0.416). The mean number of ETDRS letters changed from baseline at 12 months versus change from baseline at month 24 in double protocol group and ranibizumab monotherapy group were +21.6 versus +20.2 and +9.6 versus +9.1, respectively. At the month 24 time point, 65.4% of patients in double protocol group and 26.2% of patients in ranibizumab monotherapy group had gained ≥15 ETDRS letters in BCVA from baseline (p < 0.001). The external limiting membrane (ELM) and ellipsoid zone (EZ) integrity were better in the double protocol group in comparison to ranibizumab monotherapy group at month 24. In addition, there was no statistically significant increase in the proportion of patients with epiretinal membrane in double protocol group at month 24, by the contrast with ranibizumab monotherapy group (p = 0.06 and p = 0.04 in the double protocol and ranibizumab monotherapy groups, respectively). From baseline to month 24, the mean central foveal thickness (CFT) was 672 ± 293 μm reduced to 278 ± 84 μm in double protocol group and was 631 ± 279 μm reduced to 356 ± 108 μm in ranibizumab monotherapy group (p < 0.001 and p < 0.001). From baseline to month 24, 38% (13/34) of eyes in double protocol group and 18% (6/34) of eyes in ranibizumab monotherapy group had at least 5 mmHg of IOP elevation (p = 0.012). Two grades or more increased cataract density were detected 27% (6/22) of eyes in the double protocol group and in 12.5% (3/24) of eyes in the ranibizumab monotherapy group from baseline to month 24 (p = 0.032).
Conclusion: According to the improvements in visual acuity and morphological changes achieved at month 24, the simultaneous double protocol therapy can be an effective treatment option for DME with inflammatory biomarkers on OCT or/and decreased visual acuity.
Keywords: Dexamethasone implant; diabetic macular edema; double protocol; optical coherence tomography; ranibizumab.