Proposed International Classification of Diabetic Retinopathy

Although the Early Treatment of Diabetic Retinopathy Study (ETDRS) established a system for the staging of diabetic retinopathy and diabetic macular edema (DME) that is frequently used in clinical research, it is complex and difficult to use in the everyday clinical practice. Accordingly, there is a great need for a clinically useful scale to facilitate communication between the numerous caregivers that are involved in treating any given patient with diabetes. Such a scale would standardize diagnostic criteria and staging, provide more systematic evaluation of outcomes post therapy, and perhaps most importantly, promote more open communication and exchange of ideas. The proposed staging system has a small number of levels that are sufficiently distinct, are practical for a wide range of screeners with varying levels of expertise and access to technologies, and is a useful way to communicate findings and facilitate referrals. The proposed system has 5 levels of diabetic retinopathy:

Level 1: No apparent retinopathy
Level 2: Microaneurysms only
Level 3: Mild to moderate nonproliferative diabetic retinopathy (NPDR) with more than just microaneurysyms but less than severe NPDR
Level 4: Severe NPDR following the 4:2:1 rule, which includes any of the following: severe hemorrhages in 4 quadrants, venous beading in 2 or more quadrants, or prominent intraretinal microvascular abnormalities in 1 or more quadrants
Level 5: Proliferative diabetic retinopathy with neovascularization or vitreous or preretinal hemmorhage

For the staging of DME, 2 levels have been proposed: presence of DME and absence of DME. If DME is present, it is subdivided into moderate (retinal thickening or hard exudates approaching he center of the macula) or severe (retinal thickening affecting the fovea). Studies such as the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial and the Family Intervention of Nephropathy of Diabetes (FIND) consortium both will be examining retinopathy as secondary outcomes and will assist in the validation of this scale.