I used to dread the thought that the time would come when my licence would be revoked and I would lose the freedom to drive where I wanted and when. However following a stroke about a month ago now I suddenly found myself off the road.
Will I ever drive again? Several people have said not but there is a bit of doubt so I thought I’d see what the rules are in the UK about eyesight and driving.
Most people know the rule that you must be able to read a numberplate from 20 m, wearing your glasses or contact lenses if you need them. This is a fairly basic test, but it’s useful because you can carry out a check for yourself quite readily.
Not everybody knows that you must also have vision at least as good as 0.5 on the Snellen scale. That’s the one that relates to the familiar where you have to read the letters in the rows going down from large to small. 0.5 is the same as 20/40: in other words it means you can read something from 20 feet a person with normal vision could read from 40.
You also need an adequate visual field. This is concerned with peripheral vision and it’s where I fall down. The detailed rules specify a horizontal field of 120 ° and no significant defect (I’m not quite sure what the definition is) within 20° of ‘fixation’. Fixation is the point you’re gazing towards.
This seems to exclude people like me who have homonymous hemianopia (loss of right peripheral vision in both eyes). For example I did this sketch of my visual field. The white areas where I can see normally. The black ones where I can see more or less nothing. The grey areas are where I can see something but it’s indistinct.
I should explain that where there’s a black areas I don’t see darkness Anything in the black regions simply doesn’t exist for me. It could just as well be round the back of my head.
The hemianopia (‘half blindness’) is not completely homonymous (the same in both eyes) but I’ve lost pretty well half the visual field, so I can’t have 120° left and things look fairly gloomy. Besides there clearly is a significant defect within 20° of fixation.
However there appears to be a lack of evidence that drivers with homonymous hemianopia are automatically unsafe and in some European the 120° rule is not absolute and an exception can be made in cases ‘duly justified by a favourable medical opinion and positive practical test’. In the Netherlands there are some 300 drivers who have hemianopia.
So some hope remains. I would need to learn to scan the road in a different and more deliberate way, and to take a test, but the idea of driving again is not completely out of the question.
Driving eyesight rules