Diabetic Retinopathy: Classification and Management for Residents
Last updated: October 2026
Diabetic retinopathy is the condition you will grade, treat and counsel for more than almost any other. This page gives you the classification, the exact definitions examiners expect, and a modern treatment framework based on the landmark trials.
Screening: when to start
- Type 1 diabetes: first examination about 5 years after diagnosis, then at least yearly.
- Type 2 diabetes: at diagnosis, because retinopathy may already be present, then at least yearly.
- Pregnancy: examine before conception or early in pregnancy, and follow more closely; retinopathy can progress quickly.
- Shorten the interval as retinopathy becomes more severe.
International (ICDR) classification
| Grade | Findings |
|---|---|
| No apparent retinopathy | No abnormalities |
| Mild NPDR | Microaneurysms only |
| Moderate NPDR | More than microaneurysms, but less than severe NPDR |
| Severe NPDR | Any one of the 4-2-1 rule, with no signs of PDR |
| PDR | Neovascularisation (disc or elsewhere) and/or vitreous or preretinal haemorrhage |
The 4-2-1 rule for severe NPDR
- 4 quadrants with severe intraretinal haemorrhages (20 or more in each quadrant), or
- 2 quadrants with definite venous beading, or
- 1 quadrant with prominent intraretinal microvascular abnormalities (IRMA)
Two or more of these features makes it "very severe" NPDR. These eyes carry a high risk of progressing to PDR within a year, so follow them closely.
High-risk PDR (Diabetic Retinopathy Study)
- NVD of at least about one-quarter to one-third of a disc area, or
- Any NVD with vitreous or preretinal haemorrhage, or
- NVE of at least half a disc area with vitreous or preretinal haemorrhage
Eyes with high-risk characteristics need prompt treatment. See landmark trials for DRS and ETDRS.
Diabetic macular oedema
- Modern practice: classify DME on OCT as centre-involving or non-centre-involving. This decides treatment.
- Classic ETDRS definition of CSME (still asked in exams), any one of:
- Retinal thickening within 500 µm of the centre of the macula
- Hard exudates within 500 µm of the centre with adjacent retinal thickening
- A zone of thickening one disc area or larger, any part of which is within one disc diameter of the centre
- On OCT, look for intraretinal cysts, subretinal fluid, hyperreflective foci and DRIL. See OCT reading tips.
Treatment framework
| Situation | Usual approach |
|---|---|
| Centre-involving DME with reduced vision | Anti-VEGF injections first line (Protocol T). Consider a steroid implant in pseudophakic eyes, poor responders, or when frequent visits are impossible. |
| Centre-involving DME with good vision (20/25 or better) | Close observation is reasonable, treating if vision drops (Protocol V). |
| Non-centre-involving DME | Observe, or focal laser to leaking microaneurysms threatening the centre. |
| Severe NPDR | Close follow-up. Consider early PRP in type 2 diabetes, poor compliance, or before cataract surgery. |
| PDR | PRP or anti-VEGF (Protocol S). PRP is safer when follow-up is uncertain, because anti-VEGF alone needs regular injections. |
| Non-clearing vitreous haemorrhage, tractional detachment threatening the macula | Vitrectomy, often with pre-operative anti-VEGF to reduce bleeding. |
Systemic control: the ophthalmologist's job too
- Tight control of blood sugar, blood pressure and lipids slows retinopathy. Tell the patient's physician what you have found.
- Fenofibrate has been shown to slow retinopathy progression in type 2 diabetes in large trials. Discuss it with the physician.
- Watch for early worsening: rapid improvement in HbA1c, pregnancy, and cataract surgery can all temporarily worsen retinopathy or DME. Examine before and soon after.
- Check kidney function in patients with severe retinopathy; retinopathy and nephropathy often travel together.
2026 update: newer drugs and recent DRCR Retina Network trials
| Topic | What to know |
|---|---|
| Faricimab | VEGF-A plus angiopoietin-2 inhibitor; YOSEMITE and RHINE showed vision gains equal to aflibercept with up to 16-weekly dosing in DME |
| Aflibercept 8 mg | PHOTON: non-inferior to 2 mg with dosing every 12–16 weeks in DME |
| Protocol W | Anti-VEGF for severe NPDR without DME reduced progression to PDR or centre-involving DME, but gave no visual benefit at 4 years: observation with close follow-up remains reasonable |
| Protocol S and CLARITY | Anti-VEGF is an alternative to PRP for PDR if follow-up is reliable; PRP is safer for patients likely to be lost to follow-up |
| Protocol V | Centre-involving DME with good vision (6/7.5 or better): observation, laser or aflibercept gave similar outcomes at 2 years |
| Fenofibrate | LENS (2024) and FIELD/ACCORD-Eye: fenofibrate slows progression of retinopathy; consider with the physician |
| Rapid glucose lowering | Big HbA1c falls (including with semaglutide or after bariatric surgery) can cause early worsening; examine before and after |
Sources for this update: Wykoff CC, et al. Faricimab for DME (YOSEMITE and RHINE). Lancet. 2022;399:741-755 | Maturi RK, et al. Four-year outcomes of aflibercept vs sham for severe NPDR (Protocol W). JAMA Ophthalmol. 2023;141:348-357 | Preiss D, et al. Fenofibrate and progression of diabetic retinopathy (LENS). NEJM Evid. 2024.
Viva pearls
- The earliest clinical sign of DR is a microaneurysm; the earliest pathological changes are pericyte loss and basement membrane thickening.
- IRMA are shunt vessels within the retina; NVE grow on the retinal surface and leak on angiography.
- Cotton-wool spots are infarcts of the nerve fibre layer, not exudates.
- Rubeosis needs urgent treatment (PRP plus anti-VEGF) before the angle closes.
Quick reference: Screening schedules card. More one-screen cards in the Clinic Desk Reference.
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Looking for an eye specialist in Ahmedabad? Read about diabetic retinopathy treatment at Sadbhaav or book a consultation with Dr. Dhaval Patel.