Five groups of visual impairment
| 0 | Blindness, no light perception |
| I (high degree of visual loss) | Perception of light, finger counting, recognition of hand motions |
| II (pronounced degree of visual loss) | 1/50–1/15 |
| III (distinct degree of visual loss) | 0.1–0.3 |
| IV (minor degree of visual loss) | 0.4–1.0 |