Drivers will be stopped by officers and asked to read the number plate of a vehicle 20.5 metres away in four operations across South Wales.
That task is part of practical driving tests in line with the DVLA's legal standard.
Now police can use new handheld devices at the roadside to report offending drivers to the DVLA and a licence removal notice can potentially be emailed straight back within minutes, making it an offence for them to get back behind the wheel.
South Wales Police says this will eliminate a "window of risk" that has existed, as drivers were previously free to drive away and wait until their licence was revoked by post.
The force says that highlighting the issue in public is even more important.
The primary focus is about raising general public awareness about the dangers of driving with poor vision. It is about tackling the public complacency which exists around the issue.
From today, drivers in Wales could have their licences revoked immediately if they fail a roadside eye test.
South Wales Police officers are stopping motorists to carry out on-the-spot eye tests for the first time since tough new rules were introduced, which can speed up the process of revoking driving licences.
Workers from the Driving and Vehicle Licensing Agency in Wales will be staging a 24-hour strike today in dispute over closures and job losses.
Members of the Public and Commercial Services union at 39 local and 10 enforcement offices in England, Scotland and Wales will take part in the industrial action. In Wales, the offices facing closure are Bangor, Cardiff and Swansea.
The union has delivered a 72,000 name petition opposing the closures, to the Department for Transport, saying it was the largest paper petition it had ever organised.
A union spokesman said: "We're very concerned about the lack of awareness among people that the offices are set to close or even that a consultation has been carried out."
DVLA said it could not guarantee a business-as-usual service because of the strike and asked people to avoid travelling to any DVLA office today.
Contact centres will be operating a reduced service and callers were warned to expect longer waiting times.
The organisation suggested conducting transactions by other means such as electronically or via the Post Office.
The PCS union have been protesting outside the DVLA in Swansea, during a visit by the Cabinet minister Francis Maude. They claim staff at the office could lose over 11 million pounds after the decision to restructure their pension scheme.
The Government insist that the scheme is still generous and beyond the dreams of most private sector employees.