Table 4.
Measures of Vision performance under different conditions and effect of aging. Numbers indicate the factor by which visual components decline from normal.
| Component | Description | Age Profile | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Normal | 60–65 | 65–70 | 70–75 | 75–80 | 80–85 | 85–90 | 90–95 | ||
| Low Contrast Acuity (LCA) | The clarity of vision when viewing low contrast surfaces, for example grey scale images are considered low contrast. | 20/27 | 1.1 | 1.2 | 1.5 | 1.8 | 2 | 3 | 4 |
| High Contrast Acuity (HCA) | The standard measure of visual performance is taken by measuring high contrast acuity. | 20/20 | 1 | 1 | 1.1 | 1.2 | 1.3 | 1.5 | 2 |
| Low Contrast Acuity in Low Luminance (LCALL) | Similar to LCA except in poorly lit environment. Home lighting can be as much as 4 times dimmer than a work or office environment. | 20/40 | 1.5 | 1.7 | 2 | 2.5 | 3 | 4 | 6 |
| Acuity in Glare (AG) | The ability to focus vision when competing light sources are present in the environment, this is sometimes referred to as disability glare. | 20/40 | 1.9 | 2 | 2.5 | 3 | 3.5 | 6 | 18 |
| Colour Discrimination (CD) | A person’s ability to distinguish between objects or lights having different colours. | 10 (D-15 Score) | 1 | 1 | 1 | 1 | 1 | 2.5 | 5 |
| Contrast Sensitivity (CS) | A person’s ability to visually distinguish an object that is poorly contrasted with its visual surroundings. | 1.85 | 1.1 | 1.2 | 1.3 | 1.5 | 3 | 3.5 | 6 |