Efficacy of Intravitreal dexamethasone implant in different patterns of diabetic macular edema

Purpose: Different patterns of diabetic macular edema (DME) suggest different pathogenesis and drug response. We evaluated the outcomes after intravitreal dexamethasone (DEX) implant for DME with or without serous retinal detachment (SRD). Methods: In this retrospective study, 22 naïve patients (23 eyes) with DME who underwent a single DEX implant were evaluated. Based on the optical coherence tomographic pattern of DME, 12 eyes had a cystoid macular edema pattern (Group 1) and 11 eyes had an SRD pattern (Group 2). The best-corrected visual acuity (BCVA), central retinal thickness (R), central retinal volume (CRV), SRD height (SRDh), and intraocular pressure (IOP) were recorded before and at two and four months after the treatment. Results: There were no significant differences between the groups regarding demographic, clinical data and outcomes at baseline. In Group 1, the CRT and CRV significantly decreased at two months (P = 0.002 and P = 0.01, respectively), while the BCVA significantly improved at four months (P = 0.03). In Group 2, the CRT and CRV significantly improved (P < 0.01 and P ≤ 0.01, respectively) during the follow-up period. At four months, both groups showed a recurrence of DME, Group 1 in particular (two-month CRT reduction, -149 ± 127 μm vs four-month CRT reduction, -72 ± 174 μm; P = 0.04). The mean reduction in CRV was significantly different at four months (Group 1, -0.49 ± 1.7 mm3vs Group 2, -1.3 ± 1.3 mm3; P = 0.04). In Group 2, the SRDh significantly decreased at two (P = 0.01) and four months (P = 0.01). Four cases with elevated IOP were managed. Conclusion: DEX implants were found to be effective in different patterns of DME. The SRD pattern may predict a longer-lasting morphologic efficacy.