Levels of retinopathy grading used in this study
| NPDR = non-proliferative diabetic retinopathy, H/Ma = haemorrhage/microaneurysm, VB = venous beading, IRMA = intraretinal microvascular abnormalities, PDR = proliferative diabetic retinopathy. | ||
| From ETDRS.7 | ||
| A | Mild NPDR | At least one microaneurysm |
| (Definition not met for B, C, D, E, F) | ||
| B | Moderate NPDR | H/Ma > standard photograph No 2A |
| Soft exudates, VB, and IRMAs definitely present | ||
| (Definition not met for C, D, E, F) | ||
| C | Severe NPDR | H/Ma > standard photograph No 2A in all four quadrants |
| or | ||
| VB in two or more quadrants > standard photograph No 6B | ||
| or | ||
| IRMA > standard photograph No 8A in at least one quadrant | ||
| (Definition not met for D, E, F) | ||
| D | Very severe NPDR | Any two or more of C |
| (Definition not met for E or F) | ||
| E | Quiescent PDR | Proliferative DR previously treated with panretinal laser photocoagulation |
| (Definition not met for F) | ||
| F | Proliferative DR | Any of: NVD, NVE, preretinal, or vitreous haemorrhage or fibrous tissue proliferation |