Classification of diabetic retinopathy

The first standardised classification of DR (Airlie House Classification) was developed in 1968. This classification was modified for use in the Early Treatment of Diabetic Retinopathy Study (ETDRS) which became the gold standard for classification of DR.

• The modified Airlie House Classification of DR is used in research and intervention studies all over the world.
• However this is a complex system and is not suitable for routine clinical use.
• A simplified version of DR classification was introduced based upon the findings of the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) and the ETDRS. This new version, international clinical disease severity scale has been developed for diabetic retinopathy and macular oedema:
  • retinopathy - five stages are recognised
    • no apparent retinopathy
    • mild non-proliferative retinopathy (NPDR)
    • moderate NPDR
    • severe NPDR
    • proliferative diabetic retinopathy
  • maculopathy
    • diabetic macular oedema apparently absent
    • diabetic macular oedema apparently present
      • can be further classified as mild, moderate and severe depending on the distance of the exudates and thickening from the center of the fovea (1).

A similar grading classification based on the ETDRS system has been developed in the UK; the English National Screening Programme for Diabetic Retinopathy (ENSPDR) which was later renamed the NHS Diabetic Eye Screening Programme (NDESP):

• retinopathy
  • R0 - none
  • R1 - background
  • R2 - preproliferative
  • R3 - proliferative (active)
  • R4 - proliferative (stable)
• maculopathy
  • M0 - none
  • M1 - maculopathy - can be further classified as:
    • focal oedema
    • diffuse oedema
    • ischaemic
    • mixed (2).

Note: NHS Diabetic Eye Screening Programme grading is based on retinal photographs and is a reporting, rather than a clinical, classification (3).

Reference:

1. Wu L et al. Classification of diabetic retinopathy and diabetic macular edema. World J Diabetes. 2013; 4(6): 290–294.
2. Ghanchi F; Diabetic Retinopathy Guidelines Working Group. The Royal College of Ophthalmologists' clinical guidelines for diabetic retinopathy: a summary. Eye (Lond). 2013 Feb;27(2):285-7. doi: 10.1038/eye.2012.287.
3. Broadbent D. Diabetic retinopathy: Fundamentals for primary care. Diabetes & Primary Care 2013;Vol 15 No 4