Diabetic Retinopathy: Classification

Stages or severities of nonproliferative diabetic retinopathy (NPDR).

Stage Designation Description
I mild NPDR Only isolated microaneurysms (tiny bulges on fine blood vessels)
II moderate NPDR Fewer microaneurysms and intraretinal (“affecting within the retina”) hemorrhages than in severe NPDR, pearly veins in 1 quadrant at most
III heavy NPDR At least one of the following constellations is present (“4 – 2 – 1” rule):

    • More than 20 microaneurysms and intraretinal hemorrhages in each of the 4 quadrants.
    • Bead-like veins in at least 2 quadrants
    • Intraretinal microvascular (“affecting small vessels”) anomalies (IRMA) in at least 1 quadrant

Severity of diabetic retinopathy according to the ETDRS scale (from the Early Treatment Diabetic Retinopathy Study).

ETDRS score Severity score
10 No diabetic retinopathy (RD)
20 Microaneurysms only
35 Mild, non-proliferative DR
43 Moderately severe non-proliferative DR
47 Moderately severe nonproliferative DR
53 Severe non-proliferative DR
61, 65, 71, 75, 81 proliferative DR

Assessment:

  • 10/10 (smallest value on this scale): e.g., no retinopathy in either eye.
  • 53/53 (high value): e.g., advanced non-proliferative diabetic retinopathy (NPDR) in both eyes.
  • > 53/53: proliferative diabetic retinopathy (PDR).

Diabetic macular edema is said to be significant when any of the following criteria are met:

Diabetic macular edema Retinal edema extends into the fovea (visual fossa; center of the macula)
Retinal edema extends up to 500 μm from the center, possibly with hard exudates
Retinal edema extends to 1 500 μm from the center and has an area greater than one optic disc area (location visible in the fundus where the optic nerve exits the eye)