Drivers who fail to read a number plate from 20m (65ft) away when stopped by police will have their licences revoked immediately in a new crackdown.
Three forces in England are planning to test every motorist they stop in a bid to clamp down on drivers with defective eyesight.
Police say data from the tests will be used to improve understanding of the extent of poor driver vision.
The forces taking part are Thames Valley, Hampshire and West Midlands.
Officers can request an urgent revocation of a licence through the Driver & Vehicle Licensing Agency (DVLA) if they believe the safety of other road users will be put at risk if a driver remains on the road.
Under current rules, the only mandatory examination of a driver’s vision takes place during the practical test, when learners must read a number plate from 20 metres.
After a person has obtained a licence, it is up to them to inform the DVLA if they develop vision problems.