Which description best represents Severe non-proliferative diabetic retinopathy?

• A. Mild hemorrhages only
• B. Moderate hemorrhages with CWS or exudate
• C. Four quadrants of hemorrhages, two beading, and one IRMA
• D. Neovascularization of the disc with vitreous hemorrhage

Answer: (C)

Severe non-proliferative diabetic retinopathy is defined by the 4-2-1 rule, which uses three specific signs to mark progression beyond mild or moderate NPDR: hemorrhages and/or microaneurysms in all four quadrants, venous beading in two or more quadrants, or intraretinal microvascular abnormalities in one or more quadrants. The description here lists four-quadrant hemorrhages, venous beading in two quadrants, and IRMA in at least one quadrant. This combination satisfies and exceeds the 4-2-1 threshold, making it the best representation of severe NPDR.

In comparison, mild NPDR shows only early changes like a few microaneurysms; moderate NPDR involves more widespread hemorrhages with cotton-wool spots or exudates but does not meet the 4-2-1 criteria; neovascularization with vitreous hemorrhage indicates proliferative diabetic retinopathy, which is beyond NPDR.