Diabetic Retinopathy Severity
Ophthalmology
The international clinical scale, with the 4-2-1 rule for severe non-proliferative disease.
How it is calculated
- No apparent retinopathy: no abnormalities.
- Mild non-proliferative disease: microaneurysms only.
- Moderate non-proliferative disease: more than microaneurysms alone, but short of the severe criteria.
- Severe non-proliferative disease is the 4-2-1 rule — any one of: more than 20 intraretinal haemorrhages in each of all four quadrants, definite venous beading in two or more quadrants, or prominent intraretinal microvascular abnormalities in one or more quadrant — with no proliferative signs.
- Proliferative disease: neovascularisation, or vitreous or preretinal haemorrhage. Any proliferative sign overrides every non-proliferative criterion.
- Macular oedema is graded separately, by how close the thickening or hard exudate comes to the centre of the macula. Centre-involving oedema is what drives treatment in most guidelines.
References
- Wilkinson CP, Ferris FL III, Klein RE, et al. Proposed international clinical diabetic retinopathy and diabetic macular edema disease severity scales. Ophthalmology 2003;110:1677-1682.
About these tools
OcuLearning Clinical Tools is part of an educational platform. These calculators are provided for learning and reference, and are not medical advice, a diagnosis, or a treatment recommendation.