Summary of chart design
| Chart | No of letters per line | Line interval in logMAR | Single letter value in logMAR | Total No of letters | Acuity range at 6 metres |
| ETDRS | 5 | 0.1 | 0.02 | 120 | +0.82 to −0.48 |
| RLM A | 3 | 0.1 | 0.033 | 39 | +0.72 to −0.48 |
| RLM B | 2 | 0.1 | 0.05 | 26 | +0.72 to −0.48 |
| RLM C | 3 | 0.15 | 0.05 | 27 | +0.72 to −0.48 |
| Snellen | 1 to 8 | 0.08 to 0.22 | 0.01 to 0.11 | 45 | +1.0 to −0.18 |
The number of letters per line, line interval and single letter value are constant throughout for each chart design except the Snellen chart where the range of values has been given.