BBC News Online health staff
A third of UK drivers could be breaking the law and putting themselves and others at risk because of poor eye sight, research finds.
The RNIB is urging regular tests
A Royal National Institute for the Blind survey suggests as many as 13m drivers do not have regular eye tests and are unaware of changes in vision.
Basic eyesight tests on people who did not wear glasses revealed 65% of those who failed were drivers.
One in three of those who failed said they were not surprised.
They admitted that they had suspicions that their sight was not perfect.
The findings, based on research by Warwick University, contained in a report called The Road Ahead.
They suggest that many people are putting themselves at risk not only of accidents, but also of prosecution, as driving with uncorrected vision is an offence and can carry a fine of up to £1,000, three penalty points and possible disqualification.
Drivers are also legally obliged to wear glasses or contact lenses while driving if they need them.
A driver should be able to read a new number plate from the length of about five cars away.
As part of Eye Test Action Day (October 27) the RNIB is now calling on everyone to have regular tests.
Yvonne Fenner, 46, from Rickmansworth, Hertfordshire, admitted she was reluctant to wear glasses and so put off having her eyes tested even though she thought she might have a problem.
It was when she started a new job at British Airways and had to work shift patterns at Heathrow Airport that she started noticing her deteriorating sight.
"I was waking up early in the morning and noticed that my vision was very poor driving in the dark.
"I also couldn't see road markings clearly. Road signs were very blurred and it was only when I was very close to them I could see them properly."
Yvonne Fenner was shocked by how her sight had deteriorated
After two near misses in her car she decided to get her eyes tested and said she had been shocked when her optician said her eye sight had deteriorated quite badly.
She was told she would need glasses for driving and now always keeps one set in her car to ensure she never forgets them.
"I put off going for an eye test because I didn't want to wear glasses despite the fact that road signs were very blurred, but I realised I could not see road signs properly.
"I could not see things until I was up close to them."
Yvonne who has three children ranging in age from 10 to 17 realised she had been taking a big risk.
"I was driving home from a night out and nearly hit a car which had pulled out from a side road. It was frightening to realise I didn't see the car, until I almost hit it."
Another time she nearly hit an animal which was standing in the middle of the road.
"I could have braked sooner if I had been able to see it, but from a distance it was just a blur.
"These really made me think and that is why I got my eyes tested.
"I should have had my eyes checked when I first noticed that my eye sight had changed. Since getting my glasses I feel a much safer driver."
Optometrist Anita Lightstone, the RNIB's head of low vision, said the report showed a "worrying complacency".
"'The Road Ahead' reveals that people are not having regular eye tests and their sight is going unchecked and uncorrected. They may be driving while not able to see road signs clearly anymore or may be wearing glasses for driving which are no longer suitable.
"We are alarmed that one in three drivers are not getting their eyes tested regularly and that many people are not surprised to fail an eye test because they realise their sight isn't perfect."
She said regular eye tests were important, not only for correcting vision problems, but also because they can spot early indicators of other health problems, such as diabetes, glaucoma and cataracts.
She said that because some conditions only develop slowly that people would not be aware of them until their condition had significantly deteriorated.
"An eye test is a vital health check and can provide a quick diagnosis of a correctable or more serious eye condition.
"If they are picked up they can be treated quickly."
Many people are eligible for free eye tests, such as those under 16, or over 60, people who are over 40 whose mother, father, brother or sister has had glaucoma.