20/20 vision

What is 20/20 vision ?

20/20 is a mathematical standard of 1’ of arc separation between the limbs of a letter E when viewed at 20 feet.

In the UK, we changed the imperial measurement of feet into metres and then rounded to 6 metres. The first number is the testing distance and in the UK we use 6 metres.

Lets see what its like.

A test chart that optometrists use is the best place to start and we have placed it on the left side with a scene on the right.

The line with red either side is the 6/6 line. Most people should be able to see below this line!

Please note that this is very simple and there are many other aspects to seeing well.


	From 6 metres this is what a chart looks like to a person with 6/4 vision


		This is what a person with good vision would be likely to see.



			With good vision it is easy to see the Waterworks Corner with time and distance to spare, enabling you to make a planned and safe manouvre to exit.


	From 6 metres this is what 6/9 could look like.


	And this is still legal to drive.




		However, with vision on the legal limit it is difficult to identify the signs until you are much closer, taking up valuable time at a busy interchange where traffic is switching lanes rapidly to join and leave the main road.


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