| Improvement | Degradation | |||
| Dioptric power | n | % | n | % |
| <0.75 | 146 | 63.8 | 32 | 53.3 |
| 0.75 - 1.5 | 79 | 34.5 | 18 | 30.0 |
| >1.5 | 4 | 1.7 | 10 | 16.7 |
| Total | 229 | 100.0 | 60 | 100.0 |