Early Switch to Dexamethasone Intravitreal Implant in Patients with Diabetic Macular Edema Poorly Responding to Anti-VEGF Therapy: A Narrative Review

Diabetic macular edema (DME) is a potential complication of diabetic retinopathy (DR) and a leading cause of DR-related impairment of central vision. The pathogenesis of DME is complex and multifactorial. Vascular endothelial growth factor (VEGF) has been identified as a key mediator of DME, but inflammatory and neurodegenerative processes have also been implicated. Intravitreal therapy with anti-VEGF agents is currently the recommended first-line treatment for DME. However, substantial proportions of patients either fail to respond or achieve a suboptimal response to anti-VEGF therapy. In these patients, intravitreal corticosteroids represent a valid second-line therapeutic option. Dexamethasone (0.7 mg) intravitreal implant was approved in 2014 for the treatment of adults with DME-related visual impairment who are pseudophakic, insufficiently responsive to, or unsuitable for anti-VEGF therapy. At present, there is no consensus on the optimal timing for switching from anti-VEGF therapy to dexamethasone intravitreal implant. Evidence from several studies indicates that an early switch can be associated with better visual and anatomic outcomes compared with delayed intervention. This narrative review synthesizes current data on the use of dexamethasone intravitreal implant for DME, with particular emphasis on patients with a suboptimal response to anti-VEGF therapy switching early to corticosteroid treatment.