Early Treatment Diabetic Retinopathy Study (Etdrs) Classification

Non-proliferative diabetic retinopathy (NPDR):

• Mild NPDR
  • At least one microaneurysm must be present
• Moderate NPDR
  • Microaneurysms/intraretinal hemorrhage in 2 or 3 quadrants
  • Early mild intraretinal microvascular abnormalities (IRMA)
  • Hard exudates and cotton-wool spots may or may not be present
• Severe NPDR - any one of the following (4-2-1 rule)
  • 4 quadrants of microaneurysms and extensive intraretinal hemorrhages
  • 2 quadrants of venous beading
  • 1 quadrant of IRMA changes
• Very severe NPDR - any two of the following (4-2-1)
  • 4 quadrants of microaneurysms and extensive intraretinal hemorrhages
  • 2 quadrants of venous beading
  • 1 quadrant of IRMA changes

Proliferative diabetic retinopathy (PDR):

• PDR without high-risk characteristics (Early PDR)
  • Early neovascularization at the optic disc (NVD) or neovascularization elsewhere (NVE)
• PDR with high-risk characteristics as follows
  • NVD < 1/4 disc area with vitreous hemorrhage (VH) or preretinal hemorrhage (PRH)
  • NVD 1/4 to 1/3 of disc area with or without VH or PRH
  • NVE > 1/2 disc area with VH or PRH

Clinically significant macular edema: 1 of the following 3 criteria are present on slit-lamp examination with 90D lens

• Thickening of the retina at or within 500 micron of the center of the fovea.
• Hard exudates at or within 500 micron of the centre of fovea associated with adjacent retinal thickening.
• Development of a zone of retinal thickening one disc diameter or larger in size. At least a part of this should be within one disc diameter of the foveal center.

Advanced diabetic eye disease:

• Persistent vitreous hemorrhage
• Tractional retinal detachment
• Neovascular glaucoma