Diabetic Macular Edema—2006

Diabetic macular edema (DME) is the most common cause of moderate visual loss among people with diabetes. Vascular endothelial growth factor (VEGF) is thought to play a role in the development of DME. In animal studies, exogeneous administration of VEGF induces diabetic retinopathy, and blocking VEGF has been shown to inhibit disruptions in the blood-retinal barrier.

In terms of diagnosis of DME, ocular coherence tomography (OCT) is the most frequently used diagnostic tool in clinical practice, although fundus photography can also be used. Biomicroscopy is not useful, as it can only detect DME after it has become very advanced. Once DME is detected, it should be staged according to the International Clinical Diabetic Retinopathy Disease Scale, which employs only 2 categories: DME present or DME absent. If DME is present, it should be further categorized as mild, moderate, or severe based on its proximity to the center of the fovea.

Laser photocoagulation is the main treatment option for DME. The Early Treatment of Diabetic Retinopathy Study (ETDRS) showed that laser photocoagulation can reduce moderate visual loss by 50%; however, 12% of patients failed to improve. Laser photocoagulation also is associated with a variety of complications, including choroidal neovascularization, and laser scar expansion. A number of pharmacologic options for DME are currently being tested, including the PKC-β inhibitor ruboxistaurin, steroid therapy in a variety of different delivery mechanisms (eg, intravitreal injections, implants), an anti-VEGF therapies such as pegaptanib and avastin (off label). Vitrectomy is also a therapeutic option for patients with vitreomacular traction.