Should intravitreal dexamethasone implant in refractory diabetic macular edema be used as an adjuvant therapy or switch therapy?

Purpose: To compare the outcomes of intravitreal dexamethasone implant used as either an adjuvant or a switching therapy for diabetic macular edema in patients with poor anatomic response after three consecutive monthly injections of ranibizumab.

Methods: This retrospective study included patients with diabetic macular edema who received three consecutive doses of ranibizumab as initial therapy and demonstrated poor response. A single dose of intravitreal de xamethasone implant was administered to these patients. The patients were divided into two groups according to the treatment modalities: the adjuvant therapy group, consisting of patients who continued treatment with ranibizumab injection after receiving intravitreal dexamethasone implant, and the switch therapy group, consisting of patients who were switched from ranibizumab treatment to intravitreal dexamethasone implant as needed. The main outcome measurements were best corrected visual acuity and central retinal thickness at baseline and at 3, 6, 9, and 12 months of follow-up.

Results: In this study that included 64 eyes of 64 patients, the best corrected visual acuity and central retinal thickness values did not significantly differ between the groups at baseline and at 6 months of follow-up (p>0.05). However, at 12 months, the best corrected visual acuity values in the adjuvant and switch therapy groups were 0.46 and 0.35 LogMAR, respectively (p=0.012), and the central retinal thickness values were 344.8 and 270.9, respectively (p=0.007).

Conclusions: In a real-world setting, it seems more reasonable to use intravitreal dexamethasone implant as a switch therapy rather than an adjuvant therapy for diabetic macula edema refractory to ranibizumab despite three consecutive monthly injections of ranibizumab. Patients switched to intravitreal dexamethasone implant were found to have better anatomic and visual outcomes at 12 months than those who continued ranibizumab therapy despite their less-than-optimal responses.