Table 2 Distributional characteristics, internal consistency reliability, and construct validity of VFQ-25 scales at baseline
Scale | N | Mean | SD | Range | Number of items | Cronbach's alpha†| Spearman correlations with ETDRS |
|---|---|---|---|---|---|---|---|
General vision | 670 | 69.5 | 17.4 | 20.0 – 100.0 |  |  | 0.39*** |
Ocular pain | 671 | 89.1 | 15.2 | 12.5 – 100.0 | 2 | 0.68 | 0.02 |
Near vision | 671 | 75.8 | 21.7 | 8.3 – 100.0 | 3 | 0.81 | 0.38*** |
Distance vision | 671 | 82.9 | 17.9 | 16.7 – 100.0 | 3 | 0.72 | 0.35*** |
Social function | 671 | 93.9 | 12.9 | 12.5 – 100.0 | 2 | 0.64 | 0.25*** |
Mental health | 671 | 77.2 | 21.3 | 0.0 – 100.0 | 4 | 0.79 | 0.28*** |
Role limitations | 670 | 81.4 | 23.1 | 0.0 – 100.0 | 2 | 0.75 | 0.32*** |
Dependency | 670 | 91.3 | 17.4 | 0.0 – 100.0 | 3 | 0.83 | 0.29*** |
Driving | 632 | 81.1 | 20.7 | 0.0 – 100.0 | 3 | 0.73 | 0.34*** |
Color vision | 665 | 94.6 | 14.7 | 0.0 – 100.0 |  |  | 0.12** |
Peripheral vision | 669 | 88.4 | 19.4 | 25.0 – 100.0 |  |  | 0.25*** |
Overall VFQ-25 score | 671 | 84.1 | 13.5 | 16.2 – 100.0 | 25 | 0.93 | 0.40*** |