What each strength is for, the age it usually suits, and how far away it brings text into focus.
Typical age and the distance text is sharpest (for eyes with no focusing range left).
| Strength | Typical age | Sharp at |
|---|---|---|
| +1.00 | early to mid 40s | ~100cm |
| +1.25 | mid 40s | ~80cm |
| +1.50 | mid to late 40s | ~67cm |
| +1.75 | late 40s to around 50 | ~57cm |
| +2.00 | around 50 to mid 50s | ~50cm |
| +2.25 | mid 50s | ~44cm |
| +2.50 | mid to late 50s | ~40cm |
| +2.75 | late 50s to 60s | ~36cm |
| +3.00 | 60s and over | ~33cm |
| +3.50 | 60s and over, close work | ~29cm |