Which of the following criteria defines 'high-risk' proliferative diabetic retinopathy (PDR) that mandates immediate PRP according to the Diabetic Retinopathy Study (DRS)?
- A Neovascularisation of the disc (NVD) of any size
- B NVD ≥ 1/4 to 1/3 disc area, or any NVD/NVE with preretinal/vitreous haemorrhage ✓
- C Neovascularisation elsewhere (NVE) alone, any size, without haemorrhage
- D IRMA (intraretinal microvascular abnormalities) ≥ 2 quadrants
Correct answer: B. NVD ≥ 1/4 to 1/3 disc area, or any NVD/NVE with preretinal/vitreous haemorrhage
Explanation
The DRS defined high-risk characteristics (HRC) of PDR mandating immediate PRP as: NVD ≥ 1/4 disc area (or 1/3 disc area in some references), OR any NVD or NVE accompanied by preretinal or vitreous haemorrhage. The DRS showed that immediate PRP in HRC-PDR reduced the risk of severe visual loss (less than 5/200) by 50%. Small NVD without haemorrhage and NVE without haemorrhage are non-high-risk PDR, where PRP is still generally recommended but is not classified as HRC. IRMA is a feature of severe NPDR (4-2-1 rule), not PDR.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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