Laser for Diabetic Macular Edema

Diabetic macular edema (DME) is the most common cause of decreased vision in patients with diabetes, with an overall prevalence rate of 5% to 10% across all types of diabetes. A majority of people with diabetes have type 2 diabetes, and DME occurs earlier in the course of type 2 diabetes. Accordingly, timely identification and treatment of DME is of critical importance. DME can be categorized as focal (with hard exudates frequently occurring in a circular pattern) or diffuse (large number of zones of microaneurysms). DME is considered clinically significant (CSME) if there is thickening at or within 500 microns of the foveal center; if there are hard exudates within 500 microns of the foveal center with adjacent retinal thickening; or if there is a zone of retinal thickening at least 1 disk in diameter and any part of that zone is within 1 disk diameter of the foveal center. Currently, laser therapy is the primary treatment for DME, as it has shown to be an effective strategy for reducing the risk of vision loss. The Early Treatment of Diabetic Retinopathy Study (ETDRS) demonstrated efficacy of focal laser coagulation over a period of 3 years. For focal DME, focal laser coagulation can be used to treat the areas of leakage. For diffuse DME, grid or focal-grid combination therapy may be used. Fluorescein angiography may be a valuable strategy to identify zones of nonperfusion and to rule out central macular ischemia. Potential complications of laser photocoagulation include scarring, choroidal neovascularization, and decreased visual acuity.