Table 1 Correlation between disease severity levels according to the DRSS and ETDRS classification of DR
Disease severity [16] | Findings observable upon dilated ophthalmoscopy [16] | ETDRS level equivalent [16] | Risk assessment [16] | Prevalence of vision-related difficulty [17] |
|---|---|---|---|---|
No apparent retinopathy | No abnormalities | Level 10: DR absent | Â | Functional burden: 20.2% Reading: 11.7% Noticing objects to the side: 4.4% |
Mild NPDR | Microaneurysms only | Level 20: Very mild NPDR | Â | Functional burden: 20.4% Reading: 8.5% Noticing objects to the side: 2.8% |
Moderate NPDR | More than just microaneurysms but less than severe NPDR | Levels 35, 43: Mild, moderate NPDR less than 4:2:1 | One-year risk for early PDR: 5.4–11.9% One-year high-risk PDR: 1.2–3.6% | |
Level 47: Moderately severe NPDR less than 4:2:1 | One-year risk for early PDR: 26.3% One-year high-risk PDR: 8.1% | |||
Severe NPDR | No signs of PR but with any of the following:  Extensive (> 20) intraretinal hemorrhages in each of the 4 quadrants  Definite venous beading in ≥ 2 quadrants  Prominent IRMA in ≥ 1 quadrant | Levels 53A–53E: Severe to very severe NPDR, 4:2:1 rule | One-year risk for early PDR: 50.2% (severe NPDR) One-year high-risk PDR: 14.6% (severe NPDR)–45.0% (very severe NPDR) | Functional burden: 48.5% Reading: 33.3% Noticing objects to the side: 14.5% |
PDR |  ≥ 1 of the following:  Neovascularization  Vitreous/preretinal hemorrhage | Levels 61, 65, 71, 75, 81, 85: PDR, high-risk PDR, very severe, or advanced PDR |  | |
Ungradable | Â | Level 90: Cannot grade, even sufficiently for level 81 or 85 | Â |