Diabetic Retinopathy

A Team Approach to Screening, Referral, and Treatment

Charles C. Wykoff, MD, PhD; David M. Brown, MD


March 20, 2012

In This Article

The Scope of Diabetic Retinopathy

An estimated 6.3% of the US population and 4% of the world's population has diabetes mellitus.[1] Diabetic retinopathy affects about one half of all people with diabetes mellitus and is the leading cause of vision loss and new-onset blindness in Americans 20-64 years of age.[2] Fortunately, several prospective clinical trials provide excellent data on the natural course of diabetic retinopathy and treatment strategies that are 90% effective in preventing severe vision loss.[3,4]

In its earliest clinical stage, diabetic retinopathy is called "nonproliferative diabetic retinopathy" and is characterized by retinal vascular abnormalities, such as microaneurysms, intraretinal hemorrhages, and cotton-wool spots (Figure 1). As diabetic retinopathy progresses, the closure of retinal vessels results in ischemia (impaired perfusion of retinal tissue). This ischemia is believed to stimulate the production of vascular endothelial growth factor (VEGF) and other cytokine mediators that can result in a transition to proliferative diabetic retinopathy (PDR). Proliferative diabetic retinopathy develops when new and abnormal blood vessels grow on the inner surface of the retina (Figure 2). With sufficient duration of diabetes, approximately 60% of patients will develop PDR; without intervention, nearly one half of eyes with PDR will progress to profound vision loss.[5]

Increased retinal vascular permeability may result in retinal thickening (edema) and lipid deposits (hard exudates). Known as "diabetic macular edema" (DME), this can occur at any stage of diabetic retinopathy. The term "clinically significant macular edema" is reserved for DME involving the center of the macula or threatening to spread into this area.


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