Onset of cataract and its surgery have both practical and legal consequence for driving. In the UK the need to satisfy the number plate test is absolute in law (a standard number plate of 79.4 mm in height at 20.5 metres in good daylight). Empirically found to be equivalent to 6/10 Snellen,1 the test is consistent with the European Union (EU) Directive (now law),2 which requires a minimum acuity of 0.6 metric (= 6/10 Snellen), as well as a minimum field of vision of 120°. The paper in this issue of the BJO by Monestam and Wachtmeister (p 16), states a legal requirement for Sweden as 0.5 (6/12 Snellen) at the time of the study, though Sweden is now subject to the EU directive (and 0.6 acuity). This variation does not detract from the value of their paper which investigates driver patients’ largely subjective estimation of their visual function while driving, as well as their actual visual acuities both before and after modern cataract surgery. It is to some extent a measure of their driver …