Surgical Management of Diabetic Macular Edema

Diabetic macular edema (DME) is the accumulation of fluid in the extracellular space within the macula and is a major cause of visual impairment among patients with diabetes. First-line treatment for DME includes pharmacotherapy with intravitreal anti-vascular endothelial growth factor medications and intravitreal corticosteroids. Alternative therapeutic strategies include laser photocoagulation for non-center involving DME, and surgical options such as pars plana vitrectomy (PPV) with or without internal limiting membrane (ILM) peel in cases with vitreoretinal interface anomalies or DME refractory to pharmacotherapy, and the Port Delivery System (PDS) for sustained release of anti-vascular endothelial growth factor (VEGF) medication. Our aim is to review the existing literature on surgical management of DME including imaging changes in chronic DME and the clinical relevance of surgical intervention.

Imaging changes associated with DME and a worse prognosis include disorganization of the retinal layer, disruption of both the external limiting membrane (ELM) and ellipsoid zone, and vitreomacular interface abnormalities. Studies involving pars plana vitrectomy with and without ILM peel show anatomic improvement but may not always be associated with significant change in visual outcomes. Early studies lacked detailed imaging of the retinal layers and PPV was likely performed as a last resort. In addition, the novel PDS is surgically implanted into the pars plana and works as a drug reservoir with controlled release of drug. However, it has been recalled in patients with wet age-related macular degeneration due to issues with dislodgement. Surgical interventions for DME include pars plana vitrectomy with and without ILM peel and new surgical therapies for DME such as the PDS and subretinal gene therapy have the potential to reduce the risk of DME progression.