Table 2.
The De Boer rating scale
| Visual response | Rating |
|---|---|
| Unnoticeable | 9 |
| 8 | |
| Satisfactory | 7 |
| 6 | |
| Just admissible | 5 |
| 4 | |
| Disturbing | 3 |
| 2 | |
| Unbearable | 1 |
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