International Clinical Classification of Diabetic Retinopathy

Stage	Clinical Manifestations
Stage 1	No apparent retinopathy
Stage 2	Mild non-proliferative DRP: Only microaneurysms
Stage 3	Moderate non-proliferative DRP: Lesions between Stage 2 and Stage 4
Stage 4	Severe non-proliferative DRP, no signs of proliferative retinopathy, and any of the following: ① More than 20 intraretinal hemorrhages in each of 4 quadrants; ② Definite venous beading in 2 or more quadrants; ③ Intraretinal microvascular abnormalities (IRMA) in 1 or more quadrants.
Stage 5	Proliferative DRP, with one or more of the following: neovascularization, vitreous hemorrhage, preretinal hemorrhage, etc.

Explanation

DRP, Diabetic Retinopathy; IRMA, Intraretinal Microvascular Abnormalities.

Diabetic retinopathy is the most common microvascular complication and the leading cause of acquired blindness in adults. The 15-year prevalence rate is 98% for type 1 diabetes and 78% for type 2 diabetes.

References

Wilkinson CP, et al. Proposed international clinical diabetic retinopathy and diabetic macular edema disease severity scales. Ophthalmology. 2003;110(9):1677-82.