Explanation

"Potential driving instructors (PDIs) will have their eyesight tested at the start of their Part 2 examination. A number plate, where the letters and figures are 79 mm tall and 50 mm wide, must be read at a minimum distance of 26.5 metres (87 feet). If a PDI can't pass this test, their Part 2 examination will go no further. This won't, however, affect their licence to drive, as the ADI eyesight test standard exceeds the legal eyesight requirement."