Annual Literacy Scores by group
| Year | Group | Letter-ID (raw score) | Comparison groups | Effect size (Cohen’s d)* |
| 1 | Comparison | 25 | Comparison versus adherent | 0.06 |
| Adherent | 24.3 | Comparison versus non-adherent | 0.06 | |
| Non-adherent | 24.3 | Adherent versus non-Adherent | 0.00† | |
| 2 | Comparison | 34.7 | Comparison versus adherent | 0.05 |
| Adherent | 34.4 | Comparison versus non-adherent | 0.13 | |
| Non-adherent | 34.0 | Adherent versus non-Adherent | 0.07 | |
| 3 | Comparison | 39.1 | Comparison versus adherent | 0.08 |
| Adherent | 38.8 | Comparison versus non-adherent | 0.18 | |
| Non-adherent | 38.4 | Adherent versus non-Adherent | 0.11 |
SD 10.9 at year 1, 5.6 at year 2 and 3.8 at year 3.
*Based on group difference divided by the pooled SD of letter-ID score.
†In year 1, there is no difference as spectacle wear has not commenced.
ID, identification.