Stupid Question

[Paul Osborne]

It has just occurred to me that when someone here says: 20/20 or 6/12 or 9/12 , that I don't really know what you mean.

I am asuming that you are all referring to the lines on the board (that I cant see with my left eye - the board that is). But I guess I could be wrong.

Yours Enquiringly

Mr Dumbarse

[John Smith]

Paul,

Don't worry, it confuses us all sometimes!

6/6 and 20/20 mean the same thing: normality. They are a fraction expressed in metres (6/6) or feet (20/20). In Europe, we tend to use 6/6.

Basically, a reading of 6/12 - which is roughly the driving standard - means that you can read someting 6 metres away that a "normal" person can see from 12 metres. It follows therefore that 6/6 means that you can see the same as a "normal" person, and the larger the second number, the worse the vision.

The number 6m isn't just arbitrary, it's theoretically the distance between your eye and the sight chart (via the mirror if used). Really bad vision can be stated as "counting fingers", and my bad eye is like that: it's also expressed as 6/60 - so I can only see one-tenth as well as some "normal" person - whatever that means!

[Andrew MacLean]

Paul for years I used to smile 'knowlingly' while people used expressions like "less than 6/60" and "waving hand". Unlike you I always lacked the common sense to ask, "what do you mean".

Fortunately I have a sister who works as a Public Health Specialist, and she explained it all to me! Now there is understanding behind the knowing smile

[Paul Osborne]

Ahhh right, thanks folks, that makes some sort of sense.

I now feel that I can use that knowing look when anyone mentions it, whilst really knowing that it is really all vague and down to mirrors and hand waving.



Yours

Mr Enlightened.

[Louise Pembroke]

I must find out my vital eye statistics so I can have that knowing look too! One of my eyes is down to hand waving, when I'm asked 'can you see my fingers' I pull the hand closer and say 'now I can'.

[Sweet]

Hehe it's all kinda confusing until you ask!

Americans use 20/20 and Europeans use 6/6

We put 6 first to mean that we are standing six metres away from the chart, or as with most places we are only three metres away but it is reflected in a mirror.

The lines on the chart then go down in value depending on what chart is used as they are all slightly different. The main lines are numbered as follows

60
36
24
18
12
9
6

6/12 as most know is the legal requirement needed to drive although i read somewhere about it going to be 6/9 but not so sure on that.

So basically if your eyesight is pretty good you will score less on the chart which is kinda confusing as higher numbers are usually better! But it is all down to how high the numbers are printed, as higher numbers mean that the letters are printed taller so can be seen better.

I now have 6/9 vision in my right eye which has been through hell most of last year and now just about manage 6/60 with the left grafted eye and just about 6/36 with pinholes so it is getting there! Just hope for smaller numbers as that means the letters are getting smaller so your vision is improving!!!!

Hoping that makes sense!

Sweet X x X

[Sallyuk]

I am so glad someone asked this question as I have been flummoxed by these numbers for some time now and didn't have the guts to ask !

Isn't it stupid how we let pride/embarassment get in the way of knowledge, especially as it can often come before a fall - literally !? I can now spout figures at others in the knowledge that I know what it means !

So a real big THANK YOU for voicing the question .

Sally

[GarethB]

For driving an HGV (Lorries) or a PSV (Buses) I think the limit is alreay 6/9, mainly because of the stopping distance can be larger than that of a car and if you drive a bus there is passenger safety to consider.

It is quite possible the change is to make car drivers meet the same standard which is sensible eve if it doe mean that my right eye easily fails the requirment.

John, the eye chart on the board, can you put which line equates to 6/6 (20/20) and 6/9 etc. I am sure it will be of interest/use to others in addition to myself.

Regards

Gareth

[Paul Osborne]

Sally: A pleasure to ask the obvious - looking darn stupid is my speciality!

Everyone else who replied: thank you for explaining and clarifying.

[John Smith]

John, the eye chart on the board, can you put which line equates to 6/6 (20/20) and 6/9 etc. I am sure it will be of interest/use to others in addition to myself.

Yes, that would be a good idea. I thought of it before, and then decided that I'd better not, as people will sit different distances from their monitors, and the monitors will be different sizes and resolutions, and adjusted differently, and be viewed under different lighting conditions...

Basically, I don't want people to self-diagnose unless of course one of the Optoms on here approve. My original idea was that the online snellen chartcould be useful to track changes in your own vision - if you could read 3rd line one day, and only the top the next, then you have a problem

I'd certainly be happy to include a printable chart though - does anyone know of a PDF of one?