Police have been out and about today asking motorists to stop and read the registration plate of a vehicle parked 20.5 metres away - the legal standard set by the DVLA.
They are warning that drivers who fail this roadside eyesight test could have their licence revoked instantly.
Many sailed through the spot-check - but for others it was a wake-up call, as our correspondent Carl Edwards reports.
More top news
Wrexham man Christopher Matthew Griffiths has been jailed for cutting his dog's ears off. Traces of cocaine were found in the dog's urine.
Stephen 'Beano' Pike stabbed his neighbour Clint Simms on his doorstep in Ely, Cardiff. He was jailed for life at Cardiff Crown Court today.
Police appeal after a man sexually assaulted a teenage girl sat beside him on an Arriva train to between Cardiff and Pontypridd.