| Number of items | Cronbach's alpha | Intraclass correlation, for test-retest reliability | Range of item-scale correlations | Convergent validity* | Discriminant validity** |
---|---|---|---|---|---|---|
General health | 1 | NA*** | 0.51 | NA | NA | NA |
General vision | 1 | NA | 0.48 | NA | NA | NA |
Near vision**** | 3 | 0.87 (0.85) | 0.76 (0.69) | 0.65 – 0.75 (0.69 – 0.73) | 100 (100) | 93.9 (100) |
Distance vision**** | 3 | 0.84 (0.79) | 0.85 (0.69) | 0.67 – 0.75 (0.57 – 0.69) | 100 (100) | 90.9 (100) |
Driving | 2 | 0.58 | 0.99 | 0.49 – 0.49 | 100 | 50.0 |
Peripheral vision | 1 | NA | 0.62 | NA | NA | NA |
Color vision | 1 | NA | 0.74 | NA | NA | NA |
Ocular pain | 2 | 0.44 | 0.75 | 0.28 – 0.28 | 0 | 81.8 |
Vision-specific | Â | Â | Â | Â | Â | Â |
   Role limitation | 2 | 0.82 | 0.88 | 0.70 – 0.70 | 100 | 90.9 |
   Dependency | 3 | 0.87 | 0.90 | 0.71 – 0.82 | 100 | 97.0 |
   Social function | 2 | 0.74 | 0.88 | 0.58 – 0.58 | 100 | 59.1 |
   Mental health | 4 | 0.84 | 0.94 | 0.62 – 0.75 | 100 | 90.9 |
25-item composite | 25 | 0.96 | 0.94 | NA | NA | NA |